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\Large 
\centerline {\bf Project Description}
\normalsize
\vspace{0.25cm}

\section{Results from Prior NSF Support}
The investigators of this proposal 
have committed to developing instrumentation and science for
submillimeter astronomy at Dome~A, the summit of the Antarctic
plateau.  This effort stems in part from the experience of developing 
heterodyne receivers for the  1.7~m AST/RO telescope at the South
Pole, particularly {\it PoleSTAR}, a 4 pixel 810 GHz
receiver which was funded by the NSF Office of Polar
Programs (A. Stark--PI: OPP-0126090). 

In 2006 funding was obtained through NSF/OPP (ANT-0538665: Walker-PI,
Kulesa-CoPI) to perform 
a design study for HEAT.  This proposal is based upon that design
study.  In 2007 an NSF-SGER proposal was funded (ANT-0735854:
Walker-PI, Kulesa-CoPI) to construct 
{\tt Pre-HEAT}, a 450~$\mu$m tipper and spectrometer. {\tt Pre-HEAT}
was constructed 
and successfully deployed to Dome~A with the University of New South
Wales' PLATeau Observatory ({\tt PLATO}) in January 2008. The effort
was an international collaboration between the US, China, UK and
Australia.  The
overland traverse and installation of {\tt PLATO} at Dome~A was led by
the Polar Research Institute of China and the Chinese Academy of
Sciences. As of the writing of 
this proposal, {\tt Pre-HEAT} is still taking data after 140 days of
continuous operation (Kulesa et al. 2008). 
Its principal science products are submillimeter
atmospheric transmission data and Galactic spectra of the $^{13}$CO
J=6-5 line.   The proposed HEAT telescope
will use the same optics, receiver, and spectrometer technologies as
Pre-HEAT.  Furthermore, the same international
collaboration that successfully fielded Pre-HEAT will take the
proposed HEAT observatory to Dome~A. 

Finally, a multi-institutional team led by Co-PI Walker and
assisted by the PI was
awarded an NSF MRI grant (AST-0421499) to construct {\it SuperCam}, a
64 pixel, 
heterodyne array for the Heinrich Hertz Telescope (Groppi et al
2006). {\it Supercam} represents the cutting edge of heterodyne array
technology in terms of integrated mixers (Puetz et al 2006) and IF
processor/spectrometer technology.  The prototype IF processor and
spectrometer for {\it SuperCam} were used as receiver subsystems for
Pre-HEAT, and will be baselined for HEAT.  {\it Supercam} will be
commissioned at the HHT by the end of 2008.  

The experience and heritage gained through each of these unique
efforts will be instrumental in making HEAT a reality.  


\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.3in}{\includegraphics[scale=0.73,angle=0]{../figures/preheat.eps}}}
{\parbox{3in}{
\caption{\label{preheat} { 
The {\tt Pre-HEAT} telescope, installed at Dome~A with the PLATeau
Observatory (PLATO).
  A technological prototype for the proposed HEAT telescope, {\tt
  Pre-HEAT} has a 20 cm clear aperture combined with a 660~GHz Schotty diode
receiver and a digital FFT spectrometer.  It was deployed to Dome~A 
on an overland
traverse led by the Polar Research Institute of China.  Its measurements of the
submillimeter opacity at Dome~A are the basis for the expected
performance of HEAT described in this proposal.  Preliminary
astronomical observations have been performed and the first
astronomical spectra are being processed. 
}}}}
\end{minipage}
\end{figure}

\vspace{-0.25cm}

\section{Research Activities}

The proposed High Elevation Antarctic Terahertz Telescope (HEAT) will
forge new capabilities for ground-based infrared and submillimeter
astronomy, by providing a window on the Universe which otherwise would be
unavailable except via suborbital or space-based platforms.  The
pioneering surveys to be performed by HEAT will be made
available to the entire astronomical community.  HEAT represents a
true international pioneering effort (US, UK, Australia, and China)
in keeping with the spirit of the International Polar Year ({\tt
www.ipy.org}: 2007-2009). 
Here, we outline HEAT's ``key project'', a THz survey of the Galactic
Plane observable  
from Dome~A, Antarctica. HEAT is the Dome A component of the multinational 
``AstroPoles'' program which has been offically endorsed by the Joint
Committee for  
the IPY (see attached letter).  This proposal supports the
development of the HEAT telescope through its first two years of science
operations.  

\subsection{Introduction}

From the Milky Way to high redshift protogalaxies, the internal
evolution of galaxies is determined to a large extent by the life
cycles of interstellar clouds, as shown in Figure~\ref{cycles}.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.7in}{\includegraphics[scale=0.4,angle=0]{../figures/LifeCycle-ISM.eps}}}
{\parbox{2.6in}{
\caption{\label{cycles} { HEAT will
    observe the fine structure lines of [N~II], [C~II], [C~I], and CO that
    probe the entire life cycle of interstellar clouds.   In
    particular, HEAT will witness the transformation of neutral atomic
clouds into star-forming clouds, the interaction of the interstellar
medium (ISM) with the young stars that are born from it, and the
return of enriched stellar material to the ISM by stellar death. }} }}
\end{minipage}
\end{figure}

These clouds are largely comprised of
atomic \& molecular hydrogen and atomic helium, which are 
notoriously difficult to detect under normal interstellar
conditions.  Atomic hydrogen is detectable via the
21~cm spin-flip transition and provides the observational basis for
current models of a multiphase Galactic ISM.  Its emission
is insensitive to gas density and does not always discriminate between 
cold (T$\sim$70K) atomic clouds and the warm (T$\sim$8000K) neutral medium
that is thought to pervade the Galaxy. 
Furthermore, neither atomic helium nor molecular hydrogen
(H$_2$) have accessible emission line spectra in the prevailing
physical conditions in cold interstellar clouds.   Thus, it is important
to probe the nature of the ISM via rarer trace elements. 
Carbon, for example, is found in ionized form (C$^+$) in neutral clouds,
eventually becoming atomic (C), then molecular as carbon monoxide (CO)
in dark molecular clouds. 

Although we are now beginning to understand star formation, the
formation, evolution and destruction of molecular clouds remains
shrouded in uncertainty. 
The need to understand the evolution of interstellar clouds in the context 
of star formation has become a central theme of contemporary
astrophysics.  Indeed, the National Research Council's
most recent {\it Decadal Survey} has identified the study of star
formation as one of the key recommendations for new initiatives in
this decade.  HEAT is designed with the goal of providing insights
into the gaps in our knowledge of the Life Cycle of the ISM. 

\subsection{HEAT Science Goals}
\label{goals}

Via resolved [C~II], [C~I], CO, and [N~II] line emission, HEAT uniquely probes
the pivotal formative and disruptive stages in the {\bf life cycles of
interstellar
clouds} and sheds crucial light on the {\bf formation of stars} by
providing new insight into the relationship between
interstellar clouds and the stars that form in them; a central
component of {\bf galactic evolution}.  A detailed study
of the ISM of the Milky Way is needed to construct a template
to {\bf interpret global star formation in other spiral galaxies}.

The {\bf science mission} of HEAT is to make significant
contributions to achieving the two major science goals described 
below. Using the proposed instrument and observing methodology,
the minimum mission is expected to be achievable in two seasons of survey
operation from Dome~A. 

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.9in}{\includegraphics[scale=0.65,angle=0]{../figures/m33.eps}}}
{\parbox{2.4in}{
\caption{\label{m33} { The location of GMCs in the nearby
    spiral galaxy M33 are overlaid upon an integrated intensity map of
    the HI 21~cm line \citep{enga03}.  These observations show that
    GMCs are formed from large structure of atomic gas, foreshadowing
    the detailed study of GMC formation that HEAT will provide in the
    Milky Way.}}}}
\end{minipage} 
\end{figure}

\bigskip
\noindent {\bf Goal 1:  Observing the Life Cycle of Interstellar Clouds}
\medskip

\noindent \fbox{\parbox{6.4in}{
The formation of interstellar clouds is a prerequisite for star
formation, yet the process has not yet been observed! HEAT is designed
with the unique combination of sensitivity and resolution needed to
observe atomic clouds in the process of becoming giant molecular
clouds (GMCs) and their subsequent dissolution into diffuse gas via
stellar feedback.
}}

\smallskip

Theories of cloud formation are guided and constrained by observations
of the atomic and molecular gas components. Based primarily on HI and
CO observations, several mechanisms have been proposed to consolidate gas
into GMC complexes (Figure~\ref{m33}).  HEAT can distinguish these
processes by 1) accounting for the entire H$_2$ mass (including H$_2$
clouds with little CO) when computing global measures of the
interstellar medium, and 2) constructing spatial and kinematic comparisons of
sufficient resolution, spatial coverage and dynamic range to probe a
wide range of interstellar phases and environments.   Within its
survey, HEAT will generate a more complete \& characterized catalog of
interstellar clouds than CO or HI surveys alone.  


Since the [C~II] (and [C~I]) line emissivity 
barometrically selects
clouds of atomic gas and H$_2$ clouds with little CO, regions of GMC
formation may therefore be tracked by a large density of clouds per beam, 
or regions with individual
clouds with higher than average columns or pressures. With HEAT's
high spectral resolution, these regions can be identified with
superrings or spiral arms or convergent parts of a turbulent
medium.  With guidance from 2MASS extinction mapping and existing CO
and 21~cm HI surveys, 
HEAT will follow cold HI clouds and H$_2$ clouds as they transit
the spiral potential, and will witness the process of cloud formation
directly from the atomic substrate or small H$_2$ clouds.  Similarly, 
the [N~II] luminosity determines the ionizing
luminosity of OB stars, a standard metric for the star formation rate.  
Therefore, [N~II] observations of ionized gas provide an extinction-free, 
low-density measurement of the location and rate of star
formation in the Galaxy. 

{\it HEAT's high spectral resolution enables crucial
kinematic studies of the Galaxy to be made}. HEAT will determine
the kinematics and thermal pressures of supershells, fossil
superrings, and new molecular clouds condensing out of old superrings
and supershells via gravitational instability. HEAT can
determine the role of OB association-driven supershells and superrings
in the production of molecular clouds and the cycling of gas between
the various phases of the ISM. Since [N~II] measures the flux of
ionizing photons, and [C~II] measures 
their impact upon neighboring cloud surfaces, HEAT will measure the
resolved photoevaporating atomic or ionized gas driven from clouds
with UV-illuminated surfaces, thereby determining the rate of
mass loss from all cataloged clouds, and their destruction
timescales. HEAT's survey will correlate the star formation rate in a
given OB association with the rate of destruction of any nearby
(within 30 pc) natal GMC.  Such
measurements are crucial for models of star formation feedback and
galactic evolution. 

\bigskip
\noindent {\bf Goal 2: Constructing a Milky Way Template for Star Formation}
\medskip

\noindent \fbox{\parbox{6.4in}{
HEAT will probe the relation between the gas surface density on
kpc scales and the N$^+$-derived star formation rate, so that we might
be able to better understand the empirical Schmidt Law used to estimate the
star forming properties of external galaxies.
}}

[C~II] and [N~II] will be the premier
diagnostic tools for far-infrared studies of external galaxies 
with large redshifts (e.g. with Herschel \& ALMA). In
such spatially unresolved galaxies, however, only global properties
can be measured.  
Detailed interstellar studies of the widely varying
conditions in our own Milky Way Galaxy
serve as a diagnostic template or ``Rosetta
Stone'' that can be used to translate the global properties of more distant
galaxies into reliable estimators of star formation rate and state of
the ISM. The HEAT mission covers a
broad range of density and UV intensity, establishing the relationship
between physical properties, [C~II], [C~I], CO, [N~II], HI, FIR
emission, and star formation.   This relationship can be tested by
application to nearby galaxies in the SINGS Spitzer Legacy Survey
\citep{sings}, for which a large amount of ancillary optical, infrared
and submm data exist.  

For example: star formation within galaxies is commonly described by
two empirical 
relationships: the variation of the star formation rate per unit area
with the gas surface density \citep{schm59,kenn98} and a
surface density threshold below which star formation is
suppressed \citep{mart01}.  The Schmidt Law has been evaluated from the radial
profiles of HI \& CO emission for tens of galaxies. The mean
value of the Schmidt index, $n$, is $1.4 \pm 0.15$ \citep{kenn98}, 
valid for kpc
scales. This empirical relationship is used in most models of galaxy
evolution with surprising success given its simplicity. 
Furthermore the SFR-dense gas relation established in nearby galaxies
is a linear one (Gao \& Solomon 2004) and this has been extended  to
the Milky Way dense cores (Wu, Evans, Gao et al. 2005),
and possibly high-z galaxies and QSOs as well (Gao et al. 2007),
implying that the same physics drives the active
massive star formation in both GMC dense cores and galaxies near and far.

Oddly, there
has been little effort to evaluate the Schmidt Law in the Milky Way
owing to the difficulty in deriving the star formation rate as a
function of radius within the plane. 
The HEAT survey of CO, [C~I], [C~II] and [N~II]
emission provides an initial set of data to calculate the Schmidt Law
in the Galaxy. The [N~II] line is an excellent tracer of the star
formation rate as it measures ionizing luminosity with unmatched
sensitivity, angular and spectral resolution, and is unaffected by
extinction.  The [C~I] and [C~II] lines, in conjunction with HI~21cm
and CO line emission, provide the first coherent 
map of the neutral interstellar gas surface density and its variation
with radius. HEAT's high spectral resolution allows one to assign a
radial location of any emission feature assuming a rotation curve. A
preliminary Schmidt Law will be 
constructed from the radial profiles of the star
formation rate derived from [N~II] emission and the gas surface
density.  The column density threshold
is inferred from the absence of star formation activity in the outer
radii of galaxies where there is still a significant reservoir of
gas \citep{kenn98}.   Alternately, a threshold-less relation can be
constructed by 
eliminating the HI gas that is inert to star formation
\citep{blitz06}.  Accounting for the H$_2$ clouds seen only in [C~II]
emission provides a far more detailed test of such a Schmidt Law
formalism than do the CO clouds alone.   


\subsection{Properties of the Proposed Survey}
\label{survey}

HEAT's science drivers represent an initial
survey that would not only provide the first comprehensive view of interstellar
clouds and their evolution in the Galaxy, but would also serve as a reference
for contemporary focused studies with Herschel, SOFIA, APEX, and the
ALMA and SMA interferometers.  The following properties define the science
requirements for the HEAT survey.

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.5in}{\includegraphics[scale=0.33,angle=0]{../figures/footprint.eps}}}
{\parbox{2.8in}{
\caption{\label{beams} { The power of HEAT: Each of the 3
    heterodyne beams of HEAT are overlaid upon
    a 2MASS infrared image of NGC~6334, a massive Southern star
    forming region, and representative of the kinds of regions that
    HEAT will survey.  The beams will measure
    high-resolution spectra in the 0.8, 1.5, and 1.9~THz bands
    respectively.  The (inset) synthetic spectra of 
    NGC~6334 depict a small fraction of the spectral coverage achieved
    with each of HEAT's receiver channels. }}}}
\end{minipage}
\end{figure}

\subsubsection{High Resolution Spectroscopic Imaging}

Techniques commonly used to diagnose the molecular ISM 
include submillimeter continuum mapping of dust
emission \citep{hild83} and dust extinction mapping at optical and
near-infrared wavelengths \citep{lada94}.  Large format detector
arrays in the infrared are now 
commonplace, and with the advent of bolometer arrays like SCUBA at the
JCMT and SHARC at the CSO, both techniques have performed degree-scale
maps of molecular material.  However, these techniques have limited
applicability to the study of the structure of the
Galactic ISM due to the complete lack of kinematic information.   

The confluence of many clouds along most Galactic lines of sight can only 
be disentangled with spectral line techniques.  Fitting to a model of
Galactic rotation is often the
only way to determine each cloud's distance and location within the
Galaxy.  With
resolution finer than 1~\kms, a cloud's kinematic location can
be even distinguished from other phenomena that alter the lineshape, such as 
turbulence, rotation, and local effects such as protostellar
outflows.  These kinematic components play a vital role in the
sculpting of interstellar clouds, and a survey that has the goal of
understanding their evolution {\bf must} be able to measure them.  
{\bf HEAT will easily resolve the
intrinsic profiles of Galactic interstellar lines, 
with a
resolution of $<$0.4~\kms\ up to 370~\kms\ of spectrometer
bandwidth, comparable to the Galactic rotational velocity. }


\subsubsection{A Terahertz Galactic Plane Survey}

Molecular line surveys have been performed over the entire sky in the
light of the 2.6~mm 
J=1-0 line of \co, and have been used to synthesize our
best understanding of the molecular content of the Galaxy.  Still, our
understanding of the evolution of Galactic molecular clouds is
woefully incomplete.  As already described in Section~\ref{goals}, the
dominant spectral
lines of the Galaxy are the fine structure far-infrared and
submillimeter lines of [C~I], CO, [C~II] and [N~II].  They probe and regulate 
all aspects of the formation and destruction of star forming clouds.
In combination with HI and low-J CO surveys, 
they will provide the first barometric maps of the Galaxy, and illuminate
the properties of clouds and their life cycles in relation to their
location in the Galaxy.   They will highlight the delicate interplay
between (massive) stars and the clouds which form them, a critical
component of galactic evolution.  
A THz survey will dramatically enhance the value
of existing mm-wave CO observations by providing critical excitation
constraints.  


\subsubsection{Angular Resolution and Fully Sampled Maps}

Good angular resolution is a critical aspect of improvement for a new
Galactic survey.  Previous surveys of [N~II] and [C~II] were limited
to very small regions (KAO, ISO) or had low angular resolution (COBE,
BICE) \citep{benn94,naka98}.  HEAT will fully sample both species over
significant regions of sky 
to their diffraction limited resolution of 1.7$'$ and 1.3$'$,
respectively.  Arcminute resolution with proper sampling 
is crucial to disentangling
different clouds and cloud components over large distances in the
Galaxy.  For example, the Jeans length for star formation in a GMC is
approximately 0.5~pc.   This length scale is resolved by HEAT to a
distance of 500~pc at CO~J=7$\rightarrow$6 \& [C~I], and 1200~pc at
[C~II].  Warm and cold HI clouds and GMCs can be resolved well past
10~kpc. 

\subsubsection{High Sensitivity}
\label{sensitivity}

HEAT's sensitivity is owed mostly to
the superlative atmospheric conditions above Dome~A, Antarctica.  The
extreme cold and exceptional dryness allow ground-based observations
into the otherwise forbidden THz windows, as demonstrated 
by the {\tt Pre-HEAT} experiment, which has measured 
low atmospheric opacity at short submillimeter wavelengths for
significant periods of time.  A plot of the 661~GHz opacity, and a 
derived submillimeter
atmosphere for the best conditions, are shown in
Figure~\ref{atmo}.  By comparison, the best 492~GHz opacity measured
by \citet{chamb97} at South Pole was 0.34, and the median was
0.7 (the intrinsic 492 and 661~GHz opacities are essentially 
identical). Early in
the season, these conditions {\bf have already been exceeded at Dome~A}.  
The high elevation, cold
atmosphere and benign wind conditions at Dome~A 
{\bf definitively open the Terahertz windows to ground-based observatories and 
are unlikely to be matched anywhere else on Earth}.  For up-to-date
information about the state of Pre-HEAT and its data products please see: {\tt
  http://soral.as.arizona.edu/heat/} .  HEAT's
sensitivity to each spectral line is discussed below.

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.8,angle=0]{../figures/tipper.eps}
\includegraphics[scale=0.8,angle=0]{../figures/transplot.eps}
\caption{\label{atmo} { Preliminary 661~GHz tipper data from Pre-HEAT and the
    corresponding best atmospheric transmission measured
    at Dome~A, 
modeled through the {\tt am} atmospheric model code distributed by
    S. Payne.  The best observing conditions are expected from July
    through September; i.e. they are yet to come!  }}
\end{figure}

\medskip

\noindent {\it CO J=7-6 {\rm and} [C~I] J=2-1}
\smallskip

We aim to detect all CO and C$^0$ to A$_V$=1-2,
where most hydrogen has formed H$_2$ and CO is just
forming.  This extinction limit corresponds to
N(CO)$\sim 5 \times 10^{15}$~cm$^{-2}$ and $N(C)=1.6\times
10^{16}$~cm$^{-2}$, for integrated intensities of 3~K~\kms\ in CO
J=7-6 and 1.8 K~\kms\ in [C~I].   These sensitivity limits are
achievable (3$\sigma$) within 1.6 and 5 minutes, respectively, of
integration time at 810~GHz in {\it median} winter atmospheric
conditions (T$_{sys}\sim$8,000K) on Dome~A.  Limits on line emission 
in that time would constrain the gas density, based
upon the line brightness of millimeter wave transitions.  The atomic
carbon emission will correspond well to diffuse gas, whereas the CO
J=7-6 emission will probe warm, dense regions and should be
properly referenced to existing lower-J CO surveys from e.g. the
NANTEN(2), and AST/RO telescopes.  

\medskip
\noindent {\it [N~II] and [C~II]}
\smallskip

The fine structure lines of ionized carbon and nitrogen represent the
dominant coolants of the interstellar medium of the Galaxy and
starforming galaxies.  Indeed, the integrated intensity of the
158~\micron\ [C~II] line alone represents close to 1\% of the bolometric
luminosity of the Galaxy!  In an absolute sense, 
these lines are relatively easy to detect in the ISM.  
Our most demanding requirements for detection of [C~II] and [N~II]
lie in the search for the formation of giant molecular clouds
(via [C~II]) and the measurement of the diffuse warm ionized medium in the
Galaxy (via [N~II]).  A flux limit of 1~K~\kms\ will detect [N~II] in
warm diffuse 
ionized gas as far away as the Molecular Ring, achievable in good winter
weather in 9 minutes with appropriate velocity smoothing to 5~\kms.


Similarly, the accumulation of GMCs from
many cold neutral clouds of atomic hydrogen occurs at low relative
column densities of $\sim 5\times 10^{20}$~cm$^{-2}$.  Since essentially all
carbon in such clouds is ionized, $N(C^+) \sim
10^{17}$~cm$^{-2}$.  At the $T=70$K common in cold atomic clouds and PDRs, and
$n_{\rm H} = 10^3$~cm$^{-3}$, the expected C$^+$ line emission would
be 2.5~K~\kms, detectable in 10 minutes in excellent winter weather on
Dome~A.  The 3$\sigma$ limit achievable with deep
integrations (2 hours) with HEAT would reach $n_{\rm
 H} = 10^2$~cm$^{-3}$.  This {\it pressure} limit would readily
determine whether 
interstellar material causing significant
infrared extinction, but without CO,
is gravitationally bound and likely to be a forming
molecular cloud, or is simply a line of sight with numerous
overlapping diffuse HI clouds.  

\subsubsection{Mapping Coverage of the Galactic Plane}

\begin{figure}[!hbt]
\centering
\includegraphics[scale=1.6,angle=0]{../figures/mapping.eps}
\caption{\label{GLIMPSE} { GLIMPSE map of the Galactic Plane from the
    Spitzer Space Telescope from outside the Molecular Ring
    through the Scutum-Crux Spiral Arm to Carina ($-30^\circ > l >
    -70^\circ$).  Most of this entire region will be mapped at 0.8~THz
    by HEAT.  
    The yellow
    rectangles highlight the regions to be explored by HEAT in its
    first two seasons in [C~II] and [N~II]; these $l$ and $b$ cuts in
    Galactic coordinates will sample the widest dynamic range of
    physical conditions in the unconfused Plane of the Galaxy. 
    A definitive chemical and kinematic
    survey of star forming clouds covering over 50
    square degrees in CO and [C~I], 20 square degrees in [N~II]
    emission, and 10 square degrees in [C~II] emission 
    can be performed in that time.
    No other site on Earth allows regular access to both
    far-infrared lines. }}
\end{figure}

From previous CO surveys it
is known that the scale height of CO emission toward the inner Galaxy 
is less than one degree \citep{dame87,dame01}.  The BICE experiment
demonstrated that the C$^+$ distribution is more extended, but still
is confined to $|b| < 1$. 
Interstellar pressure, abundances, and physical
conditions vary strongly as a function of Galactocentric radius, so it is
necessary to probe the inner Galaxy, the outer Galaxy, and both spiral
arms and interarm regions, to obtain a statistically meaningful survey
that encompasses the broad dynamic range of physical conditions in the
Galaxy.  Ultimately, we propose to
probe the entire Galactic plane as seen from Dome~A ($0
> l > -120^o$).  However, 
for the two year survey period of this proposal, using a
Schottky mixer receiver system, an initial total of
50 square degrees will be targeted.  
Figure~\ref{GLIMPSE} demonstrates the sky coverage of HEAT's
initial survey of the Galactic Plane, 
with the two seasons' focused coverage of [C~II] and [N~II]
schematically highlighted
in yellow.  It will probe three crucial components of the Galaxy; 
the Scutum-Crux spiral arm, an inter-arm region, and
portions of the Carina, Lupus, and Chamaeleon~II cloud
complexes (not all of which are shown in Figure~\ref{GLIMPSE}). 
The Galaxy survey will coincide
with GLIMPSE, a Spitzer Space Telescope (SST) Legacy Program
\citep{benj03} and will be designed to maximize
coverage with the ``Cores to Disks'' SST Legacy program
\citep{evans}.

The remaining sky coverage in the Galactic Plane survey will be
provided by a future, upgraded instrument package from SRON, featuring
a cryocooled 4K HEB receiver system -- not included within the scope of
this proposal.  

\subsection{Survey Activities}

\subsubsection{Mapping Strategy}

The most efficient mode of data collection 
which produces the highest fidelity images is 
On-the-Fly (OTF) mapping.  In this mode, the telescope continuously 
scans across a field while the backends are 
read-out at a sufficient rate to eliminate aliasing and beam smearing.  

The broad coverage of the HEAT survey and the circumpolar
nature of the sky rotation over Antarctica lends itself naturally
to efficient, 24-hr/day mapping. HEAT can reach the requisite sensitivity of
1$\sigma$=0.2~K~\kms\ per beam at 810~GHz (1$\sigma$=0.9~K~\kms\ at
1.4~THz) over a fully sampled square degree in 10 days,
assuming median winter conditions of $\tau_{810}\sim$0.5. 
30 square degrees distributed from $-20 > l > -70^o$ will be mapped 
in $\approx$300 days.  Some overlap in mapping coverage between the
two survey years is expected. 
When the atmospheric opacity at 1.9~THz drops below $\sim$2, 
focused surveys including C$^+$ will begin.  Of the best
40 days of winter weather, 3 weeks will be devoted to
a medium-sensitivity C$^+$ survey (1$\sigma \sim$1.5~K~\kms), with each square
degree of mapping requiring about 5 days each, for a total of up to 5
square degrees of coverage per season.  10 days will be devoted to
deep C$^+$ surveys of selected regions guided by 2MASS and GLIMPSE
extinction maps for the formation of 
molecular clouds -- a total of 0.5~square degrees will be mapped to
1$\sigma \sim 0.4$~K~\kms\ per season.

HEAT's wide IF bandwidth
allows detection of the 158, 205, and 370~$\mu$m dust continuum
emission.  Thus, we will also simultaneously record total power scans
and construct shallow dust continuum maps.  

\begin{table*}[!hbt]
\centering
\small
\begin{tabular}{|l|c|c|l|}
\hline
{\bf Participant} & {\bf Team} & {\bf Affiliation} & {\bf Participation
  Activity} \\
\hline \hline
Michael Ashley & I & UNSW &PLATO systems, Antarctic astronomical instrumentation\\
\hline
Yu Gao & S & PMO & Extragalactic submm astronomy; Milky Way template lead\\
\hline
Jeffrey Hesler & I & Virginia Diodes, Inc. & Schottky mixer
development and LO technology\\
\hline
Craig Kulesa & I, S &  Univ. Arizona & PI, HEAT development and testing, ISM physics \\
\hline 
Chris Martin & I, S & Oberlin College & Antarctic Astronomy and
Instrumentation \\
\hline
Mark McCaughrean & S & Exeter & Antarctic astronomy, star formation,
synergy with JWST \\
\hline
Michael Schein & I & Univ. Arizona & Telescope design and contruction \\
\hline
Sheng-Cai Shi & I & PMO & Submillimeter instrumentation lead at PMO \\
\hline
Gordon Stacey & I, S & Cornell & Far-infrared Instrumentation \& spectroscopy\\
\hline
Antony Stark & I, S & SAO/CfA & Telescope Optics \& Systems; Synergy with AST/RO \\
\hline
John Storey & I, S & UNSW & PLATO Systems, Site testing, Polar Operations \\
\hline
Nick Tothill & I, S & Exeter & Antarctic submillimeter astronomy \\
\hline
Christopher Walker & I, S & Univ. Arizona &  Co-PI, receiver
development and testing \\
\hline
Lifan Wang & S & Texas A\&M & CCAA lead -- Coordinate US and Chinese efforts \\
\hline
Ji Yang & S & PMO & Submillimeter science lead at PMO \\
\hline
\end{tabular}
\caption{\label{roles}  Activities of the Science ({\bf S}) and
  Instrumentation ({\bf I}) Teams}
\end{table*}

\subsubsection{Science Products and Dissemination}

A primary challenge of OTF mapping is data management.
We therefore plan to adopt a scheme akin to that 
developed at FCRAO, whereby coadded and regridded data is written as FITS \&
CLASS files, and headers for 
each scan are written into a MySQL relational database, which 
facilitates efficient logging and retrieval of the data.  This
software is being developed as part of the PIs' efforts on SuperCam,
and will be completed before the proposed effort on HEAT begins.
The most demanding storage
requirements for the final 50 square degree maps, regridded to 50$''$ spacing,
with 1024 spectral points per grid position, is 4~GB.  This volume can
be readily handled by embedded computers with disks of nonvolatile
flash memory.  

Access to these data products to the greater scientific community
will be provided through a web browser interface that will
interface with MySQL and the FITS data cubes.   Standard Virtual
Observatory (VO) services will be enabled in this interface.  
Preprocessed data cubes
will be transferred from HEAT over Iridium satellite, while
raw data will be collected from the telescope annually during
maintenance, and hopefully earlier with an occasional downlink from
NASA's TDRSS-1 satellite using a portable field antenna.
Thus, there will be biannual data products -- a
preliminary release midseason (August of 2010 and 2011), and a final
release of the previous season's data in February of 2011 and 2012.  The
final release will be fully calibrated and will include all science
products.  

\smallskip
\noindent \fbox{\parbox{6.4in}{All science tools, packaged reduction software,
    data products and 
    science products will be made available from the HEAT web
    page:    {\tt http://soral.as.arizona.edu/heat/}}}

\smallskip

\subsubsection{Synergies with Other Observatories}

{\bf HEAT is timely}.  The Spitzer Space Telescope Legacy program GLIMPSE, 
provides a thermal infrared survey of the
Galactic plane that provides a complete census of OB stars, the
stellar structure of the molecular ring, maps the warm
interstellar dust, and constrains extinction laws as a function of
galactocentric radius.   HEAT will provide the best corresponding
interstellar cloud survey that will provide the kinematic information
that can associate star formation with specific clouds of molecular
gas.  HEAT can measure the
dense cloud material that forms stars,  cloud interactions with
formed stars, and kinematic disruptions by mass ejection, outflow, and
supernova remnants.  

HEAT naturally complements the capabilities of heterodyne receivers on
SOFIA and Herschel.  The higher angular resolution
afforded by larger telescopes necessarily reduces their field of
view and mapping speed.  {\bf The HEAT survey would require 
many months of dedicated observing time on either Herschel or SOFIA,
inconsistent with their
use as general purpose observatories.}  In contrast, HEAT is a
dedicated mapping 
instrument with a focused mission and a lifetime that exceeds the
grasp of long duration balloons.  HEAT will provide
ideal reference maps of THz line emission for more detailed
followup with SOFIA and Herschel.  Indeed, the HEAT data distribution and
databasing system will be aligned as much as possible with that of 
Herschel/HIFI. 

Similarly, the small field of view of the ALMA interferometer
(7-30$''$) means that many tens of thousands of pointings will be needed to
map a single square degree.  Even with ALMA's planned mosaicing
capability, such large scale surveys are unlikely to be scheduled. 
Furthermore, ALMA will not have such near-THz receivers for some
time.  However, HEAT's Southern survey
in atomic carbon and CO emission will be an ideal survey for active
star forming clouds and cores and represents an exceptional reference
map for detailed follow-up with ALMA when it becomes available. 

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO)
and the Receiver Lab Telescope (RLT) of the Smithsonian
Astrophysical Observatory have made
pioneering, targeted observations of [N~II] (Oberst et al. 2006,
Marrone et al. 2005).  These observations have been 
helpful in optimizing the larger scale survey possible with HEAT from
Dome~A.  

The Stratospheric TeraHertz Observatory (STO: PI-Walker, DPI-Kulesa) is a
recently funded long duration balloon (LDB) project which complements
the galactic plane survey capabilities of HEAT. It has a 0.8m aperture
and is designed to observe high lying THz lines including [C~II],
[N~II], [O~I], and HD. The first STO science flight will occur in late
2010 and will last for $\sim$2 weeks. Such flights can be repeated on two
year timescales. HEAT and STO observations will be coordinated to
provide maximum science return. 


\subsubsection{Roles of the Collaboration Participants}

Personnel who will initially develop and use HEAT
comprise the Science~(S) and Instrument~(I) Teams tabulated in
Table~\ref{roles}.  {\it 
Both graduate and undergraduate students will participate in
the instrument development and science study.}

\section{Research Instrumentation and Needs}
\label{instrument}

\subsection{Overview}

HEAT will be a fully automated, state-of-the-art THz observatory
designed to operate autonomously from Dome A in Antarctica. The
combination of high pressure altitude (4,700~m), low precipitation, and extreme
cold make the far-IR atmospheric transmission exceptionally good
from this site. In Figure~\ref{atmo} we present a plot of the
measured atmospheric transmission above Dome A, modeled as a function of
wavelength, which indicates that winter weather at Dome~A
approaches (to order of magnitude) the quality of that achieved
by SOFIA.  The wavelengths of several important
astrophysical lines are indicated with arrows. HEAT is designed to
take advantage of these unique atmospheric conditions and observe
simultaneously in [C~II](158 $\mu$m), [N~II](205 $\mu$m), and CO 
J=7$\rightarrow$6 \& [C~I] (370 $\mu$m). 

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{4.1in}{\includegraphics[scale=0.91,angle=0]{../figures/concept.eps}}}
{\parbox{2.2in}{
\caption{\label{concept} { HEAT concept: The telescope has an effective
collecting area of 0.5m. Elevation tracking is accomplished by
rotating the off-axis parabola. The Schottky mixers used in
the instrument package are efficiently cooled to $\sim$80~K using
a reliable off-the-shelf closed-cycle cryocooler. }} }}
\end{minipage}
\end{figure}

\smallskip
A conceptual drawing of HEAT is shown in Figure~\ref{concept}. For
robustness and efficiency, the telescope and instrument are integrated
into a common optical support structure (OSS). 
HEAT will be mounted on top of a University of New South Wales Plateau
Observatory (PLATO), a successor to the AASTINO
(Automated Astrophysical Site-Testing InterNational Observatory)
deployed to Dome~C in 2003. PLATO provides power and communications
for the HEAT telescope and 
instrument. The total power budget for HEAT (including cryogenics, telescope 
drive system, and instrument control system is maximally 600~W, which is
readily provided by efficient, high reliability generators 
within PLATO.  Data
transfer and control of HEAT will be done via satellite and is
described in more detail in Section~\ref{control}. 
UNSW will participate in the HEAT's design,
integration, deployment, and operation (see Support Letter from J. Storey).
HEAT will replace {\tt Pre-HEAT} on PLATO's side-looking port, and
will therefore be mounted in exactly the same manner as shown in 
Figure~\ref{preheat}. 

\subsection{Telescope}

The telescope is designed to have maximum simplicity and the minimum
number of optical components.  The design draws heritage from the
successful {\tt Pre-HEAT} telescope currently at Dome~A.  Incoming
light is reflected horizontally off a 45$^\circ$, $0.5 
\times 0.7$~m f/2 off-axis parabolic mirror. The
converging beam passes through an HDPE lens to match the Gaussian beam
propagating from the Schottky receiver feedhorns.  The
primary mirror will be fabricated from aluminum on a numerical milling
machine and will achieve a surface roughness $\le 3\,\mu$m rms.  Elevation
slewing is achieved by rotating the primary.   
From Dome~A, the Galactic Plane can be mapped purely with sidereal-rate
scanning.  The absolute pointing accuracy will be
better than 
30$^{\prime\prime}$, about 1/3 of the smallest diffraction-limited beam. The
slew speed will be 2$^\circ$/sec.  The University of Arizona has a
long history of building state-of-the-art telescopes and, with
oversight from members 
of the Instrument Team, has the expertise required to optimize the telescope
for operation in a Polar environment.  The telescope cost estimate,
which includes fabrication, and testing of the
telescope and drive system, is provided in the budget. 

To prevent ice accumulation, the telescope window can be warmed to
5-10$^\circ$C above ambient by resistive heaters controlled by PLATO.
A small fan inside the HEAT enclosure prevents front from accumulating
on the inside of the window. 
Additional passive and active resistive heating inside the PLATO
instrument module keeps the HEAT receiver module and electronics at
-30$^\circ$C or warmer.  A small radome made of a low-loss
dielectric (HDPE) film encircles the primary mirror. 
This optical configuration provides an unobstructed view of
the sky. 

\subsection{Receiver}

\subsubsection{Design Approach}

Heterodyne receivers are needed to achieve the sensitive, high
spectral resolution ($R=\lambda/\Delta\lambda > 10^6$) observations of
[N~II], [C~II], and CO/[C~I]
required for the proposed Galactic plane survey. The key components of a
submillimeter-wave heterodyne receiver are the mixer and local
oscillator (LO).   There are 3 types of mixers in common
use; the Schottky diode mixer, the SIS mixer, and, more recently, the
Hot Electron Bolometer (HEB) mixer. The Schottky diode mixer is
somewhat less sensitive than either SIS or HEB mixers and requires more
LO power, but is exceptionally stable in operation and
{\bf can operate at ambient temperature}.  In contrast, SIS and HEB
receivers require 
cooling to LHe temperatures (4K).   HEAT's aggressive development
schedule combined with the critical need for robust technologies that
will work at low power and in a harsh environment leads us to select
Schottky mixer systems for the initial deployment of HEAT.   Virginia
Diodes, Inc. has a long history of delivering submm-wave Schottky
mixer systems and has demonstrated sub-harmonically pumped
Schottky mixers using lower frequency LO sources (see Support Letter
from J. Hesler). 
Virginia Diodes will deliver one such mixer at 1.9~THz and another at
810~GHz.   The 1.5~THz Schottky receiver system will come from JPL via
an internally-funded program.  Though the system will function well at ambient
temperatures, we plan to improve HEAT's sensitivity to within a factor
of $\sim$3 of demonstrated THz HEB systems by cooling the 
mixer blocks to $\sim$80K using economical, low power, commercial
Stirling-cycle
cryocoolers such as those sold by Qdrive and Sunpower, Inc. In this
manner we will achieve a solid blend of good sensitivity and 
experimental robustness.   We
anticipate delivered cooled DSB receiver noise temperatures in the vicinity
of 2000K at 0.8~THz, 4000K at 1.4~THz and 6000K at 1.9~THz. 
A future 4K cryocooled SIS and HEB receiver system 
for HEAT is now in development at the Space Research Organization of
the Netherlands. 

\subsubsection{Receiver Optics}

A close-up of the receiver optics is shown in Figure~\ref{optics}. The
incoming beam from the primary encounters a bandpass filter centered
on the [C~II] (1.9~THz) line; this ``through'' beam passes to the
1.9~THz mixer from VDI.  A wire grid directs the
horizontal and vertical polarization components of the reflected beam
from the bandpass filter into the 0.8~THz and 1.5~THz mixers.  

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.5in}{\includegraphics[scale=0.8, angle=0]{../figures/optics.eps}}}
{\parbox{2.8in}{
\caption{\label{optics} { The optical subsystem for
 HEAT's receiver optics consists of a 1.9~THz bandpass filter and a wire grid.
 When the incoming beam encounters the filter, all
 but a narrow range of frequencies around the [C~II] line 
 are reflected to the wire grid, which splits the 1.5
 and 0.8~THz beams by polarization orientation.
 }}}}
\end{minipage}
\end{figure}


\subsubsection{IF Processor}

The entire IF processing and
spectrometer system will be leveraged from the successful design
being implemented in SuperCam (the PI's 64-pixel, 345~GHz array receiver).
Funds will only be needed to rework the 8-channel prototype IF
processor from SuperCam for operation with 1~GHz of output bandwidth.
In order to
simultaneously detect the CO J=7$\rightarrow$6 and [C~I] lines in
separate sidebands, the 0.8~THz mixer will
have an IF center frequency of 1.5~GHz and then be upconverted to 5~GHz 
to match the other channels for subsequent IF processing. Low-noise
5 and 1.5~GHz IF amplifiers are readily available.

The IF processor board provides each channel with an
initial 48 dB of gain, a variable digital attenuator, a 1~GHz bandpass
filter, a mixer conversion to baseband, a low pass filter, and 
50~dB of baseband gain.  An additional circuit provides total-power
measurements of the IF power for telescope pointing and continuum
measurements.  

\subsubsection{FFT-in-FPGA Spectrometer}

The HEAT Galactic Plane surveys require both fine kinematic resolution
(1~MHz)  
to disentangle cloud components and wide instantaneous bandwidth
($\ge$~1~GHz) to span the 
velocity dispersion of the Galaxy.
{\bf  Recent gains in high-speed ADCs and FPGAs have
made such a wide bandwidth, direct-digitization spectrometer
economically feasible.  } 
The baseband output of the IF processors is fed into two direct
digitization spectrometer boards, each board with 2-IF inputs.
For each IF input the spectrometer board provides 1~GHz of
instantaneous bandwidth at 
1~MHz resolution.   The resulting velocity coverage (up to 
370~km/s at a resolution $\le 0.4$~km/s) enables all three
lines to be resolved and observed throughout the Milky Way.  
Omnisys Inc. has already
designed and delivered 8 of these boards for the PI's Supercam array project.
The delivered system is
depicted in Figure~\ref{FFTspec} and
performs admirably.  The measured Allan variance (stability) time is
650 seconds 
when using a 5~GHz noise source that has been downconverted through
the Caltech  
IF processor board.   Funds are requested to purchase two
additional boards for HEAT (see quote from Omnisys).  

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.8in}{\includegraphics[scale=0.9,angle=0]{../figures/spectrometer.eps}}}
{\parbox{2.5in}{
\caption{\label{FFTspec} { The assembled 8-board, 16~GHz FFT spectrometer from the
PIs' Supercam project is no larger than a rack-mounted PC and requires
only 200 watts of input power!  One-fourth of this
spectrometer system will be purchased for HEAT. }}}} 
\end{minipage}
\end{figure}

\subsubsection{Calibration}

HEAT will be able to calibrate observations through several means. 1)
A two-temperature absorbing load will be located below (and
accessible by) the
primary mirror, allowing standard chopper wheel calibration
to be performed. 2) HEAT will routinely perform sky-dips to
compute the atmospheric optical depth in each of its three wavelength
bands. 3) HEAT will regularly observe a standard list of calibration
sources. 

\subsubsection{Control System and Communication}
\label{control}

The HEAT control system consists of several subsystems; 
the telescope drive system, receiver frontend
({\it e.g.} mixers, LOs, and cryostat) computer, and backend
(spectrometer) computer.  The subsystems communicate via SPI, CAN and
I$^2$C digital buses, whereas communication to the PLATO supervisor is
done through TCP/IP over ethernet.  The subsystem control is based on
Technologic Systems TS-ARM embedded computers that draw
less than 2 watts of power, run the open-source NetBSD operating
system, and have been field-tested to survive the cold.   These systems
provide digital I/O, analog-to-digital conversion, serial I/O, and
CAN, SPI and I$^2$C bus interfaces for 
control of the various electronic subsystems in HEAT.  These
single-board computers are redundant and contain a
watchdog circuit that will reset the system in case of a major
software or hardware malfunction.  Like Pre-HEAT, 
HEAT will be designed to work 
autonomously for up to a week at a time, performing pre-programmed
observational programs and storing astronomical and housekeeping data
in non-volatile memory.  Preprocessed sample data will be uploaded to
control centers at the Universities of Arizona and New South Wales
via dedicated Iridium satellite channels located on each
``supervisor'' board.  Raw data will be recovered from HEAT each year
during maintenance and processed into the released data products.  We
aim to also integrate a portable field antenna for NASA's TDRSS-1
satellite for routine downlink of raw data well in advance of annual
maintenance.  

\subsection{Integration and Testing}

The use of already-developed subsystems in HEAT
allows system integration and testing to be performed in a timely manner. 
A testing schedule is provided in Figure~\ref{gantt}.

\vspace{-0.2cm}
\begin{enumerate}
\setlength{\topsep}{-5ex}
\setlength{\partopsep}{-5ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item {\bf Cold component testing} will be used to determine limiting
temperatures for reliable operation of constituent components in each
subsystem.  These component tests will define a process by which the
telescope can be nominally operated in a range of highest reliability, or
safely resurrected from an idle state in which all components have been
cold-soaked. 

\item  {\bf Subsystem testing} will demonstrate
the proper functionality of large components of the HEAT system, such
as the assembled telescope drive system or the Schottky instrument
package and control electronics, or the spectrometer and data system.

\item {\bf Integrated system testing} involves the interplay of subsystems in the
actual collection of data, such as performing on-the-fly mapping
observations with active receivers, spectrometers, data system, while
monitored over a Iridium satellite connection; i.e. normal
astronomical operation
at Dome~A. 

\item   {\bf Failure Mode testing} involves the intentional
disabling of a component to observe the fault handling and
interplay of the hardware and software systems.   A Failure Mode Effects Criticality
Analysis (FMECA) will be generated to determine system robustness to
component failure.  System reliability will then be
enhanced through application of redundancy, increased reliability rated
components, and improved operational design where indicated.

\end{enumerate}

The combination of Schottky diode receivers, 
interchangable computer control subsystems, redundant Iridium communication
links, watchdog reset systems, diesel power generation with solar
panel backup, and a largely fixed, stable, simple optical system, 
all contribute to a highly {\bf reliable and robust system}.


\section{Project Management}
\label{management}

\subsection{Organization}
HEAT is an exciting, challenging project that requires the coordinated 
participation of scientists and engineers from several academic institutions
and leading-edge companies.  Collectively the HEAT
team members represent many years of successful telescope and
instrument development in Antarctica. 
Table~\ref{roles} provides a listing of the
roles and responsibilities of each member in the
organization.   

A schedule of key project milestones and tasks is provided in
Figure~\ref{gantt}.   
Based upon the 2006 design study funded by NSF-OPP,
the project will begin with a 
design review by the instrument and science teams. Procurement of key
components will begin soon after, following the spending profile
outlined in the budget. Integration and test of the receiver system
will take place at the Univ. of Arizona in the PIs' (Walker/Kulesa) lab in spring
2009, starting with the 0.8 and 1.5 THz units, and finishing with the
1.9 THz receiver.  The receiver module
and telescope will then be shipped to the University of New South
Wales, where an extended period of integration and testing with
PLATO subsystems will occur; including system evaluation in a -80$^o$C
environmental chamber (see Support Letter from J. Storey).   HEAT will
then ship from Australia in October 2009, with deployment to Dome~A
in January 2010. 

Routine communications between project participants is essential.
There will be quarterly telecons between Science and Instrument team
members to monitor progress, provide insight into solutions to
emerging problems, and redefine priorities as needed. There will
be bimonthly telecons and quarterly meetings (primarily through
teleconferencing) between the PIs and Technical Leads
(particularly Storey - PLATO and Hesler - Mixers).  Annual meetings of
the international collaboration (CCAA lead - L. Wang) will be
scheduled to discuss requirements for
Antarctic logistics before coordinating with respective agencies
(i.e. USAP and PRIC).  Student exchange between Arizona and Purple
Mountain Observatory will be organized by the PIs and the science and
instrumentation leads at PMO (J.Yang and S.-C. Shi).  This effort will
give graduate students the opportunity to work at the partner
institution, broadening their skill sets. 

\begin{figure}[!htb]
\centering
\begin{minipage}{6.5in}
{\parbox{4.5in}{\includegraphics[angle=0,scale=0.85]{../figures/gantt.eps}}}
{\parbox{1.9in}{\caption{ \label{gantt} First year timeline: one year
of fabrication, 
integration and testing is followed by up to two years of survey
work at Dome~A. 
Leverage of technologies from commercially available 
mixers and IF technologies from the Co-PI Walker's
SuperCam instrument development makes this timeline achievable. 
}}}
\end{minipage}
\end{figure}

The ability to meet the proposed schedule is made possible by the heavy
leveraging of IF processor and spectrometer technology funded through
NSF/MRI for Supercam, the 64-beam heterodyne array receiver effort led
by Co-PI Walker and assisted by PI-Kulesa.  The aggressive schedule is
also aided by the use of commercially-available mixer and cryogenic
hardware.  It should be noted that the same basic telescope and receiver 
subsystems were deployed to Dome~A for the single-mixer {\tt Pre-HEAT}
telescope in 5 months from start-to-finish
(June through October).  Here, we are aiming for a 9 month deployment
schedule, using the same basic designs, electronics, and software as
Pre-HEAT.   Furthermore, HEAT will be constructed by the same people who
successfully constructed Pre-HEAT. 
The simplicity of the telescope design and operation in 
combination with the expertise at University of Arizona in developing
optical systems for ground and space is a solid match. 

\subsection{Logistics: Deployment to Dome A}
 
Antarctic science has reached a level of maturity where several options exist
for fielding instruments on remote sites.  The successful deployment
of PLATO and Pre-HEAT to Dome~A is a clear demonstration of a working
international collaboration.  For Dome~A, the best scenarios include:

\begin{enumerate}
\setlength{\topsep}{-1ex}
\setlength{\partopsep}{-1ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item {\bf (Chinese) Traverse from Zhongshan to Dome~A}:  UNSW has
  recently signed a Memorandum of Understanding (provided in the
  Supplementary Documentation) with the Polar
  Research Institute of China and the National Astronomical
  Observatories of China for Chinese deployment of a UNSW PLATO to
  Dome~A in 2007-8.   HEAT could be installed
  as part of the 2009-10 Chinese traverse or, ideally, combined with
  alternative transport options described below.  

\item {\bf Twin Otter Air Support}:  With the PLATO observatory modules
  successfully operating at Dome~A, the most massive components of a
  Dome~A traverse are already on-site.  If HEAT is
  brought in with the Chinese traverse along with new PLATO equipment
  and fuel, 
  USAP Twin Otter air support would allow personnel to be flown in (to
  Dome~A or to join the traverse part-way) from South
  Pole or the nearby AGAP field camps to facilitate the HEAT
  installation and maintain the facility annually.

\end{enumerate}

The HEAT team will work closely with the NSF, USAP, Raytheon
Polar Services, and the International Community to implement an optimal plan
for deployment to Dome~A. If, for some unforeseen reason, a traverse
were not available in 2009-10, deployment could be delayed until 
2010-11 and one season of data would be collected.  In that
event, support for a second season of operations would be sought
separately. 

\section{Educational Impact}

The visage of the dusty lanes of
the Milky Way has inspired artistic and scientific imaginations
for generations. This inherent fascination is a powerful tool to
attract ``students'' of all ages and callings 
to a better, more literate appreciation of the sciences.   Thus, spreading
enthusiasm for science and training the next generation of scientists
is a significant component of this research program.  Three examples
of these efforts to be performed during the proposal performance
period are outlined below.

\subsection{Instrument Development Experience}

The training of students in the development of state-of-the-art
instrumentation is essential to the future of science. This is
particularly true in mm/submm astronomy where technological advances
are happening so rapidly. 
Ironically, there are only a handful of laboratories in the world
where students gain hands-on experience in the design, fabrication,
and fielding of radio astronomy instrumentation. In Co-PI Walker's lab we
have had a number of students (both graduate and undergraduate)
participate in the development of submm-wave instrumentation
for Antarctica (i.e. AST/RO) and the Heinrich Hertz Telescope
(HHT) on Mt. Graham, Arizona. This work, and the astronomy that has
come from it, has been a major component of 7 Ph.D. dissertations and
numerous undergraduate research projects. HEAT is a natural extension
of these research efforts. In the proposed budget for HEAT, funding for
one graduate student in the summer is requested. However, as is customary in
the lab, many other students will also participate in making the
program a success. Indeed, one of the most important aspects of
training students in instrument development is experience in working
in teams. Astronomical instrumentation is becoming ever more complex,
and requires the talents of many individuals. Providing students with
both technical training and team-work experience increases their
probability of success. This is especially true for the HEAT project, where direct collaborations between students and faculty at universities in Australia, China, the UK, and the US will be ongoing.

\begin{figure}[!htb]
\centering
\begin{minipage}{6.5in}
{\parbox{4in}{\includegraphics[angle=0,scale=0.75]{../figures/stellarium.eps}}}
{\parbox{2.2in}{\caption{ \label{stellarium} 
{Open source planetarium software
    such as {\tt stellarium} represent useful tools with which maps of
    the sky at other wavelengths can be rendered.
}}}}
\end{minipage}
\end{figure}


\subsection{Web-based Outreach}

The broadest impact of the proposed research however may be drawn from
the use of these surveys as educational and outreach tools.   
More people rely on the Internet for news, information, and
entertainment than ever before; a trend which is unlikely to change
soon.  Thus, providing online outreach tools that are accessible and
interesting is an excellent way of reaching a
wide range of people.   Distributed software should be operable on
multiple platforms and be open source, so that others in the online 
community can embrace and extend what is provided within the
confines of this study.  A practical application would be to present 
a view onto the multi-wavelength Universe using existing planetarium
software.  For example, Stellarium ({\tt http://www.stellarium.org/})
is a visually stunning, 3D,  open source planetarium package for
Unix/Macintosh/Windows (Figure~\ref{stellarium}).  
Writing a plugin to allow the
user to put on different wavelength ``glasses'' to view the IRAS
100~\micron\ sky in place of the visible sky -- or CO J=1-0 or HI
21~cm emission, is an entirely tractable possibility and could be used to
visualize the Galaxy in new ways.  Familiar with the Stellarium source
code, PI-Kulesa would be responsible for implementing these
visualization tools.

\subsection{ K-12 Outreach: A Student Radio Telescope}

In support of education and public outreach activities, Co-PI Walker 
and his students have constructed a remotely operable, steerable, 3.5~m
Student Radio Telescope 
(SRT) for observing the HI line in the Milky Way. The SRT has been used as 
a instructional tool in undergraduate courses (both major and
non-major).  Students from on and off
campus will soon be able to monitor and control
observations with the SRT. Unlike optical telescopes, the SRT can be
used day and night, making it ideal for classroom instruction.  Like
HEAT, the SRT is a spectroscopic Galactic Plane survey
telescope. During the course of developing and operating HEAT we will
develop instructional modules for various age groups that focus on the
science and technology of HEAT and use the SRT as a ``hands-on''
laboratory with the goal of providing students with an intuitive
understanding of underlying physical concepts.  

\clearpage

\pagestyle{empty}

\begin{thebibliography}{}

\bibitem[Alves, Lada, \& Lada(1999)]{alves99} Alves, J., Lada, 
C.~J., \& Lada, E.~A.\ 1999, ``Correlation between Gas and Dust in Molecular Clouds: L977'', \apj, 515, 265 

\bibitem[Bennett et al.(1994)]{benn94} Bennett, C.~L., et al.\ 
1994, ``Morphology of the interstellar cooling lines detected by COBE'',
ApJ, 434, 587

\bibitem[Benjamin et al.(2003)]{benj03} Benjamin, R.~A.~et 
al.\ 2003, ``GLIMPSE. I. An SIRTF Legacy Project to Map the Inner Galaxy'', 
PASP, 115, 953 

\bibitem[Blitz \& Rosolowsky(2006)]{blitz06} Blitz, L., \& 
Rosolowsky, E.\ 2006, ``The Role of Pressure in GMC Formation II: The
H$_2$-Pressure Relation'', \apj, 650, 933 

\bibitem[Carpenter, Snell, \& Schloerb(1995)]{carp95} 
Carpenter, J.~M., Snell, R.~L., \& Schloerb, F.~P.\ 1995, ``Star Formation in the Gemini OB1 Molecular Cloud Complex'', \apj, 450, 201

\bibitem[Chamberlin, Lane, \& Stark(1997)]{chamb97}
Chamberlin, R.A., Lane, A.P., and Stark, A.A., 1997, ``The 492 GHz
Atmospheric Opacity at the Geographic South Pole'', ApJ, 476, 428.
 
\bibitem[Dame et al.(1987)]{dame87} Dame, T.~M.~et al.\ 1987, ``A composite CO survey of the entire Milky Way'', ApJ, 322, 706 

\bibitem[Dame, Hartmann, \& Thaddeus(2001)]{dame01} Dame, 
T.~M., Hartmann, D., \& Thaddeus, P.\ 2001, ``The Milky Way in Molecular Clouds: A New Complete CO Survey'', ApJ, 547, 792 

\bibitem[Engargiola, Plambeck, Rosolowsky, \& 
Blitz(2003)]{enga03} Engargiola, G., Plambeck, R.~L., 
Rosolowsky, E., \& Blitz, L.\ 2003, ApJS, 149, 343 

\bibitem[Evans et al.(2003)]{evans} Evans, N.~J.~et al.\ 
2003, ``From Molecular Cores to Planet-forming Disks: A SIRTF Legacy
Program'', PASP, 115, 965

\bibitem[Gao et al.(2004)]{Gau04}Gao, J. R., Hajenius, M., Baselmans, J., Klawijk, P., de Korte, Voronov, B.,
and Gol'tsman, G., 2004, ``NbN Hot Electron Bolometer Mixers with Superior
Performance for Space Applications'', International Workshop on Low Temperature
Electronics, 23-24 June 2004, (invited paper).

\bibitem[Gao \& Solomon(2004)]{gao04} Gao, Y., \& Solomon, P.~M.\
  2004, ``The Star Formation Rate and Dense Molecular Gas in
  Galaxies'', \apj, 606, 271 

\bibitem[Gao et al.(2007)]{2007ApJ...660L..93G} Gao, Y., Carilli, C.~L., 
Solomon, P.~M., \& Vanden Bout, P.~A.\ 2007, ``HCN Observations of Dense Star-forming Gas in High-Redshift Galaxies'', \apjl, 660, L93 

\bibitem[Giannini et al.(2000)]{Giannini00} Giannini, T.\ et al.\
2000, ``Looking at the photon-dominated region in NGC 2024 through FIR
line emission'',  \aap, 358, 310

\bibitem[Goldsmith(1998)]{gol98} Goldsmith, P., in ``Quasioptical
Systems'', pub. IEEE Pressm 184.

\bibitem[Groppi et al.(2006)]{grop06} Groppi, C., et al.\ ,
  ``SuperCam: a 64-pixel heterodyne imaging array for the 870-micron
  atmospheric window''.  2006, Proc. SPIE, 6275, 62750O.

\bibitem[Hesler et al.(1997)]{hesler} Hesler, J., Hall, W., Crowe, T.,
  Weikle, R. M. II, Deaver, B., Bradley, R., Pan, S.-K., ``Fixed-Tuned
  Submillimeter Wavelength Waveguide Mixers Using Planar
  Schottky-Barrier Diodes'', 1997, IEEE Transactions on Microwave
  Theory and Techniques, 45, 653.

\bibitem[Hildebrand(1983)]{hild83} Hildebrand, R.~H.\ 1983, 
``The Determination of Cloud Masses and Dust Characteristics from
  Submillimetre Thermal Emission'', QJRAS, 24, 267 

\bibitem[Kaufman, Wolfire, Hollenbach, \& 
Luhman(1999)]{kauf99} Kaufman, M.~J., Wolfire, M.~G., 
Hollenbach, D.~J., \& Luhman, M.~L.\ 1999, ``Far-Infrared and
Submillimeter Emission from Galactic and Extragalactic
Photodissociation Regions'',  \apj, 527, 795

\bibitem[Kennicutt(1998)]{kenn98} Kennicutt, R.~C.\ 1998, ``The Global Schmidt Law in Star-forming Galaxies``, \apj, 498, 541 

\bibitem[Kennicutt et al.(2003)]{sings} Kennicutt, R.~C., 
Jr., et al.\ 2003, ``SINGS: The SIRTF Nearby Galaxies Survey'', PASP, 115, 928 

\bibitem[Krauss(1966)]{krau66}  Krauss, J., ``Radio Astronomy'', 1966,
  Mcgraw-Hill, NY

\bibitem[Kulesa \& Black(2002)]{kule04} Kulesa, C.~A.~\& 
Black, J.~H.\ 2002, Chemistry as a Diagnostic of Star Formation, 60 

\bibitem[Kulesa et al.(2005)]{rhooph} Kulesa, C.~A., 
Hungerford, A.~L., Walker, C.~K., Zhang, X., \& Lane, A.~P.\,
``Large-Scale CO and [C~I] Emission in the $\rho$ Ophiuchi Molecular
Cloud'',  2005, \apj, 625, 194.

\bibitem[Kulesa et al.(2008)]{kulesa08} Kulesa, C.A, et al., 
  ``Pre-HEAT: Submillimeter Site Testing and Astronomical Spectra from
  Dome A, Antarctica'', Proc SPIE 7012, in press (2008).

\bibitem[Lada, Lada, Clemens, \& Bally(1994)]{lada94} Lada, 
C.~J., Lada, E.~A., Clemens, D.~P., \& Bally, J.\ 1994, ``Dust extinction and molecular gas in the dark cloud IC 5146'', \apj, 429, 694 

\bibitem[Lawrence(2004)]{Law04} Lawrence, J. S., 2004, ``Infrared and submillimetre atmospheric characteristics Of high Antarctic plateau sites'', PASP, 116, 482

\bibitem[Marrone et al.(2005)]{marrone05} Marrone, D.~P., 
Blundell, R., Tong, E., Paine, S.~N., Loudkov, D., Kawamura, J.~H., Luhr, 
D., 
\& Barrientos, C.\ 2005, ``Observations in the 1.3 and 1.5 THz
Atmospheric Windows with the Receiver Lab Telescope'', proceedings of
the 16th International Symposium on Space Terahertz Technology



\bibitem[Martin \& Kennicutt(2001)]{mart01} Martin, C.~L.~\& 
Kennicutt, R.~C.\ 2001, ``Star Formation Thresholds in Galactic
Disks'', \apj, 555, 301 

\bibitem[Nakagawa et al.(1998)]{naka98} Nakagawa, T., Yui, 
Y.~Y., Doi, Y., Okuda, H., Shibai, H., Mochizuki, K., Nishimura, T., \& 
Low, F.~J.\ 1998, ApJS, 115, 259 

\bibitem[Oberst et al.(2006)]{oberst06} Oberst, T.~E., et al.\ 
2006, ``Detection of the 205 um [N II] Line from the Carina
Nebula'', ApJ, 652, L125 

\bibitem[Puetz et al.(2006)]{puetz}  Puetz, P., Hedden, A., Gensheimer, P., Golish, D., Groppi, C.E.,
  Kulesa,  C., Narayanan, G., Lichtenberger, A., Kooi, J.W., Wadefalk,
  N., Weinreb, S., \& Walker, C.K.,  ``345 ~GHz Prototype SIS Mixer
  with Integrated MMIC LNA'',  {\it  International Journal of Infrared
  and Millimeter Waves}, 2006, 27, 1365.

\bibitem[Sakamoto et al.(1995)]{sako95} Sakamoto, S., 
Hasegawa, T., Hayashi, M., Handa, T., \& Oka, T.\ 1995, ``The Five College Radio Astronomy Observatory CO Survey of the Outer Galaxy'', ApJS, 100, 125 

\bibitem[Schmidt(1959)]{schm59} Schmidt, M.\ 1959, ``The Rate of Star
  Formation'', ApJ, 129, 
243 

\bibitem[Simon et al.(2001)]{simo01} Simon, R., Jackson, 
J.~M., Clemens, D.~P., Bania, T.~M., \& Heyer, M.~H.\ 2001, ``The Structure of Four Molecular Cloud Complexes in the BU-FCRAO Milky Way Galactic Ring Survey'', \apj, 551, 747 

\bibitem[Schlecht, et al.(2001)]{schle01}Schlecht, C., G. Chattopadhyay, A. Maestrini, A. Fung, S. Martin, D. Pukala, J. Bruston, and I. Mehdi,
``200, 400, and 800 GHz Schottky diode substrateless multipliers: Design and Results,'' 2001 IEEE, MTT-S International Microwave Symp. Digest, 
Phoenix, Az, pp. 1649-1652, May 2001.

\bibitem[Stark \& Brand(1989)]{star89} Stark, A.~A.~\& Brand, 
J.\ 1989, ``Kinematics of molecular clouds. II - New data on nearby giant molecular clouds'', \apj, 339, 763 

\bibitem[Walker et al.(1992)]{wal92} Walker, C.K., J. Kooi, M. Chan,
H. G. LeDuc, P. L. Schaffer, 
J. E. Carlstrom, and T. G. Phillips, 1992, ``A low noise 492~GHz SIS 
waveguide receiver'', Int. J. of IR and MM Waves, vol. 15, 
no. 3, pp. 477-492.

\bibitem[Walker, Carlstrom, \& Bieging(1993)]{walker93} Walker,
C.\ K., Carlstrom, J.\ E., \& Bieging, J.\ H.\ 1993, ``The IRAS
16293-2422 cloud core - A study of a young binary system'', \apj, 402, 655

\bibitem[Walker et al.(1998)]{wal98} Walker, C. K., Hungerford, A.,
Narayanan, G., Groppi, C., Bloomstein, T., Palmacci, S., Stern, M., \&
Curtin, G., ``Laser Micromachining of Silicon: A New Technique for
Fabricating TeraHertz Imaging Arrays'', Proc. SPIE, 3357, 45. 

\bibitem[Walker et al.(2001)]{wal01} Walker, C. K., Groppi, C.,
d'Aubigny, C., Kulesa, C., Hungerford, A., Jacobs, K., Graf, U.,
Schieder, R., \& Martin, C.,  2001, PoleSTAR: A 4-Pixel 810 GHz Array
Receiver for AST/RO, ``Proceedings of the 12th International Symposium
on Space TeraHertz Technology'', San Diego, CA, Eds. Mehdi \& McGrath,
JPL.

\bibitem[Wu et al.(2005)]{wu05} Wu, J., Evans, N.~J., II, 
Gao, Y., Solomon, P.~M., Shirley, Y.~L., 
\& Vanden Bout, P.~A.\ 2005, ``Connecting Dense Gas Tracers of Star
Formation in our Galaxy to High-z Star Formation'', \apjl, 635, L173 

\end{thebibliography}

\end{document}

