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%\Large 
%\centerline {\bf Project Description}
%\normalsize

\section{Results from Prior NSF Support}
\subsection{High Elevation Antarctic Terahertz (HEAT) telescopes for Ridge A}

In 2010, the PI initiated an NSF-funded (ANT-0944335, 10/2010-9/2014, \$1.486M) program to build two 60 cm terahertz telescopes for robotic operation
at the summit of the Antarctic high plateau with the dual purpose of
site testing and performing leading edge terahertz astronomy.  These
High Elevation Antarctic Terahertz (HEAT) telescopes operate from 150
to 600 microns wavelength and observe the brightest and most
diagnostic far-infrared lines in the Galaxy.  An international
collaboration with Australia's University of New South Wales provided
the PLATeau Observatory for Ridge A (PLATO-R), a platform for power
and satellite communication.  In January 2012, PLATO-R and the first
HEAT prototype were successfully deployed to Ridge A and have
performed admirably. 

\subsubsection{Broader Impacts: Activities}

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.28,angle=0]{figures/HEATPLATO.jpg}
\includegraphics[scale=0.172,angle=0]{figures/EM.jpg}
\caption{\label{heatplato} {\small (left) A new far-infrared
    astronomical observatory was established on Ridge A, the inland summit
    of the polar plateau, as a joint collaboration between the University
    of Arizona and the University of New South Wales in Australia in
    January 2012. Consisting of a (blue) High
    Elevation Antarctic Terahertz (HEAT) telescope and the (yellow and
    green) PLATeau
    Observatory (PLATO-R) instrument and engine modules, the observatory
    is designed to operate unattended for 12 months at a time.  }}
\end{figure}

The High Elevation Antarctic Terahertz (HEAT) telescope
is forging 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 HEAT telescopes' key science project is a THz
survey of the Galactic Plane observable from Antarctica in the CO
J=7-6 and [CI] J=2-1 lines at 809~GHz, [NII] at 1461~GHz, and
ultimately the [CII] line at 1900~GHz.  Via spatially and
spectrally-resolved 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}.
These science goals are discussed further in Section~\ref{goals}. The initial
proposal supports the HEAT telescopes through the
first 2 full years of science operations at Ridge~A, which lies about
110 miles inland from the Chinese Kunlun station at Dome~A but at
essentially the same elevation.


\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.20,angle=0]{figures/HEAT-open.jpg}
\includegraphics[scale=0.30,angle=0]{figures/HEAT-closed.jpg}
\caption{\label{heat} {\small (left) The 3-mirror
    off-axis Gregorian telescope, cryogenic receiver system and frozen
    PI are visible in this image. (right) Enclosed in a fiberglass
    shell and teflon film  ``window'' that is transparent to THz
    radiation, the HEAT telescope is ready for observations (January
    2014).}}
\end{figure}

\noindent For orientation, the facility is shown in
Figures~\ref{heatplato} and \ref{heat}.  It is comprised of several
components: PLATO-R's yellow {\bf instrument module} houses 20 kW hr of
  LiFePO4 batteries, power distribution electronics, supervisor computers, and
  Iridium modems and antennas.  A 4-panel {\bf Solar Cube} provides up
  to 800 W of solar power to the instrument module during the summer
  months.  PLATO-R's green {\bf engine module} houses 800 liters of AN8
  fuel in an internal bladder and another 800 liters in external fuel
  barrels.  Two diesel engines are housed inside the
  temperature-controlled module, providing up
  to 1500W of power to the instrument module during winter. Finally,
  the {\bf HEAT telescope} is connected to the yellow instrument module by
  a 10-meter umbilical which supplies ethernet and power.  HEAT is a
  62~cm aperture off-axis Gregorian telescope, like SPT.  
  Optically, it is
  comprised of 1) a 45-degree flat mirror which steers in
  elevation and represents the only
  moving part of the telescope, 2) an off-axis parabolic
  primary mirror, and 3) an elliptical camera mirror, which re-images
  the Gregorian focus to a small cryostat cooled to 50K by a Sunpower
  Cryotel CT Stirling cycle cryocooler.  The initial deployment
  featured 810 and 492 GHz receivers for atomic carbon and was swapped for
  810~GHz and 1460-1500~GHz receivers starting in January 2014. 

\smallskip

\noindent \noindent The design and philosophy behind HEAT and PLATO-R
more closely resembles a space observatory than a typical ground based
telescope.  The program has been a remarkable success; since the
beginning of the effort in October 2010, the team has:

\begin{enumerate}
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\item Designed, constructed, and deployed an autonomous,
robotic observatory for the most remote site on Earth, and an extreme
environment, using a blend of solar and diesel power, to operate
without physical human intervention for a year at a time. 

\item Deployed cryocooled heterodyne receiver systems and telescopes at
  THz frequencies that 
  operate for a year at a time between servicings, with a total
  power budget of less than 200W. 

\item Developed and deployed an advanced telescope scheduling system that can
  autonomously execute an observing plan with little human
  involvement, with a 2 watt computing power budget using mobile phone
  ARM processors. 

\item Developed and deployed a data processing system that can return
  fully-reduced spectroscopic maps of the 4th Galactic quadrant over
  the 'soda straw' bandwidth of an Iridium modem (2400 baud)... using the same
  mobile phone CPU.

\item Generated the deepest large-scale maps of the ISM in neutral
  carbon at 370 $\mu$m, with CO J=13-12 and [NII] at 200 $\mu$m
  installed in 2014, and
  ultimately ionized carbon at 158 $\mu$m (this proposal).
  By exploring molecular clouds and their
  environments in tracer species {\it other} than CO, HEAT will probe
  the entire carbon trail \& the full life cycle of interstellar clouds.  

\item Provided the data products freely to the astronomical community
  after collection and calibration, with no proprietary period.

\end{enumerate}

\subsubsection{Intellectual Merit: Site testing results}

HEAT's sensitivity is owed to
the superlative atmospheric conditions above the summit of the
Antarctic plateau.  The
extreme cold and exceptional dryness allow ground-based observations
into the otherwise forbidden THz windows.  Figure~\ref{atmo}
demonstrates the exceptionally {\bf transparent} and {\bf stable} 
conditions that are routinely available
at Ridge~A.  To illustrate, HEAT measured 131 days in 2015 in which the
daily mean opacity at 200~$\mu$m (1.5~THz) was below 1.5.  In comparison,
the APEX radiometer for 2015 indicated only 3 such days for the
Chajnantor plain, and the best estimates for Cerro Chajnantor
(CCAT) indicate 10 days.  Ridge~A is especially remarkable in that
51 days of the 2015 yielded usable atmospheric transmission in the 150
micron window, containing the pivotal 158~$\mu$m ionized carbon line! 

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.29,angle=0]{figures/tipper2015.png}
\includegraphics[scale=0.34,angle=0]{figures/atmo.png}
\caption{\label{atmo} {\small (left) Daily mean PWV in 2015 shows an
    incredibly stable, transparent atmosphere, with a median winter
    PWV of 105 microns and a best quartile of 65 microns! Such dry
    air conservatively leads to the upper-two (blue and red) transmission plots shown
    at right. The
    bottom two (green and yellow) curves represent the ALMA site and Mauna Kea, respectively.
    Ridge~A opens entirely new atmospheric windows to routine
    observations from the ground.}}
\end{figure}

A tabular comparison of Ridge~A to other well-known
submillimeter sites is shown in Table~\ref{compare}. To the
proposers' knowledge, the Ridge~A results are the best measured anywhere from
the ground.  That such conditions are frequently realizable makes them
even more remarkable.  

\begin{table*}[!hbt]
\centering
\small
\begin{tabular}{|c|c|c|c|c|}
\hline
{\bf Site} & {\bf 25\%ile \hfill  50\%ile } & {\bf Median winter} & {\bf
  Best 25\% winter} & {\bf Best 10\% winter} \\

   & {\bf winter PWV} & {\bf transmission} & {\bf
   transmission} & {\bf  transmission} \\
   & {\bf (mm) } & {\bf @660 GHz} & {\bf @1500 GHz} & {\bf @2000 GHz} \\
\hline \hline
Ridge A, 4040m & 0.07  \hfill   0.11 & 79\% & 50\% & 30\% \\
South Pole, 2850m & 0.23  \hfill   0.32 & 52\% & 9\% & 1\% \\
Plano Chajnantor, 5050m & 0.35  \hfill   0.60 & 47\% & 10\% & 2\% \\
Mauna Kea, 4100m & 1.0   \hfill  1.5 & 15\% & 0\% & 0\% \\
\hline
\end{tabular}
\caption{\label{compare} { \it Comparison of Ridge~A with other
    established submillimeter observing sites, based on 2012-15 HEAT data
    for Ridge A, 2012-15 radiosonde data for
    South Pole, and Chajnantor from 2012-15 APEX radiometer data, Mauna Kea
    from literature 
    values \citep{delgado,hogg}. }}
\end{table*}

The high elevation, cold stable atmosphere and benign wind conditions
at Ridge~A  {\bf open the Terahertz windows to ground-based observatories and 
are unlikely to be matched anywhere else on Earth}.  Thus, even with
an initial deployment of cooled Schottky diode mixer receivers, HEAT's
sensitivity to each spectral line is already extremely competitive.  


\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.55,angle=0]{figures/HEATimg.eps}
\includegraphics[scale=0.38,angle=0]{figures/filament.png}
\includegraphics[scale=0.38,angle=0]{figures/filament2.png}
\caption{\label{filament} { \small
(left) Integrated intensity map of [CI] line emission toward $l$=328$^o$
    shows that diffuse atomic carbon emission fills the Galaxy and is
    nearly as abundant as CO. 
    (center) The molecular gas shown by HEAT's
    detected line emission at -78 km/s V$_{lsr}$ (contours) appears to
    be associated with self-absorption in the 21 cm HI line (color
    scale) at the same velocity.  The high abundance of 
    [CI] suggests that this molecular gas is chemically-young; it has
    not yet converted much of its elemental carbon to CO.  Such a
    signature is indicative of a natal cloud.   Establishing where
    these clouds are forming in a Galactic context is one of the
    primary goals of the HEAT telescope and one of the main motivations
    to extend its initial mission.  }}
\end{figure}

\subsubsection{Intellectual Merit: Astronomical Results}

In the light of 370~$\mu$m (809 GHz) atomic carbon J=2-1 emission, 
HEAT has obtained high-fidelity strip maps of the Galactic Plane
as well as a high priority $1^o\times1^o$ maps
that are now publically
available.  With a 3-sigma rms noise level of 100 mK and almost 10
square degrees released, these are the
largest, most sensitive maps in the atomic carbon line to date.  

Early results of these data indicate that atomic carbon, while
of lower surface brightness than CO, is more widespread and is only
slightly less abundant on large scales.  
Since all [CI] emission stems from regions
where hydrogen is molecular, this implies that a substantial fraction
(at least 30\%) of the molecular mass is not probed by CO emission,
the so-called ``CO-dark gas'' \citep{Grenier05, Wolfire10}.  HEAT has
already produced in its 2014 season maps of CO J=13-12 data at
1497~GHz and to-be-downlinked results at [NII] 1461~GHz
(Figure~\ref{THzresults}).  

Specific regions in the first square degree to be mapped by
HEAT (at $l$=328$^o$) are already providing evidence of molecular
cloud formation. 
[CI] appears to be well correlated with cold HI gas observed in
absorption.  A quiescent filament spanning 0.5 degrees on the
sky is observed at -78 km/s V$_{lsr}$ with high [CI] abundance
relative to CO, suggestive of recent cloud formation (Burton et
al. 2014). 

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.9in}{\includegraphics[scale=0.3,angle=0]{figures/THzresults.png}}}
{\parbox{2.5in}{\caption{\label{THzresults} { \small Commissioning
        observations of CO J=13-12 toward two high mass star forming
        regions performed by HEAT in 2014. In total, HEAT's 2014
        observations at 200 microns nearly quadruple the amount of
        THz measurements made from the ground! }}}} 
\end{minipage}
\end{figure}


\subsubsection{Publications and Research Products}

The first major data releases (DR1 and DR2) from the HEAT
telescope are online and
comprise data acquired during the 2012 and 2013 seasons at Ridge~A. Preliminary 2014 data are now available in DR2.  The following papers have been published or are currently in press at
the time of review.  {\bf Please visit \underline{
    soral.as.arizona.edu/heat/}  for data and updates on publications
  and results!} 

\begin{enumerate}
\setlength{\topsep}{-1ex}
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\item Kulesa, C., ``Terahertz Spectroscopy for Astronomy: From Comets
  to Cosmology'', IEEE Transactions on Terahertz Science and
  Technology, 2011, 1, 232. 

\item C. Kulesa, C. Walker, A. Young, J. Storey, and M. Ashley, ``HEAT:
  The High Elevation Antarctic Terahertz Telescope'', 22nd
  International Symposium on Space Terahertz Technology, (2011), 9. 

\item Craig A. Kulesa, Michael C.B. Ashley, Yael Augarten, Colin
  S. Bonner, Michael G. Burton, Luke Bycroft, Jon Lawrence, David
  H. Lesser, John Loomis, Daniel M. Luong-Van, Christopher L. Martin,
  Campbell McLaren, Shawntel Stapleton, John W.V. Storey, Brandon
  J. Swift, Nicholas F.H. Tothill, Christopher K. Walker and Abram
  G. Young, ``Opportunities for Terahertz Facilities on the High
  Plateau'', IAU Symposium 288, 2012, 256.

\item Burton, M.~G., Braiding, C., Glueck, C., Kulesa, C. et
  al.\ 2013, ``The Mopra Southern Galactic Plane CO Survey'', PASA, 30, 44.

\item Burton, M.~G., Ashley, M.~C.~B., Braiding, C., Storey, J.W.V.,
  Kulesa, C., Hollenbach, D., Wolfire, M., Glueck, C., Rowell, G.,
  ``The Carbon Inventory in a Quiescent, Filamentary Molecular Cloud
  in G328'', 2014, ApJ, 782, 72.

\item Kulesa, C. A., Honniball, C., Lesser, D., Swift, B. J., Walker,
  C.K., Young, A.G., ``The High Elevation Antarctic Terahertz (HEAT)
  telescopes on Ridge~A, Antarctica'', IEEE Transactions on Terahertz
  Science and Technology, 2015, in review.

\item Kulesa, C. A, Ashley, M.,~C.~B., Braiding, C., Storey, J.W.V.,
  Lesser, D., Hollenbach, D., Wolfire, M., ``An Antarctic [CI] and CO Survey of the Milky Way'', 2015, ApJ, in review.

\item Kulesa, C.A., Ashley, M.~C.~B., Storey, J.W.V., Honniball, C., 
  Lesser, D., Walker, C.K., Young, A.G., ``New Far-Infrared and
  Terahertz Astronomical Capabilities over the High Antarctic
  Plateau'', 2015, ApJ, in review. 

\end{enumerate}


\subsubsection{Relation to Current Proposal}

Much of the effort to date has
focused on the technological development of this pathfinding
observatory and achieving its first results.  The current 2-year AAG
program maintains the current facility and provides for
the publishing of these first results.  While the choice of
Schottky diode mixer
receivers at an operating temperature of 50K was done for robustness, 
the state of the art in detector sensitivity is achieved using
superconducting devices at temperatures of $\sim$4K.  Now that basic operation
of HEAT and PLATO-R has been proven, augmentation of a
superconducting receiver system would improve the mapping speed and
scientific capability of the system by an order of magnitude. 
{\bf The goal of this proposal is to develop a superconducting
  receiver system using existing 
  best-of-breed Hot Electron Bolometer (HEB) 
  mixers from 1.4-1.9~THz to augment the
  existing cryogenic Schottky diode mixers from 0.8 to 1.5~THz. This
  augmentation will bring world-class instrument sensitivity to the
  very best site on Earth for
  astronomy at terahertz frequencies.}  This represents the next development
phase for the observatory. 

\section{Science Goals}
\label{goals}

\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}. 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.   The
most recent decadal 
survey, ``Astro2010: New Worlds, New Horizons'', specifically
identifies the questions ``{\it What controls the mass-energy-chemical
cycles within galaxies}'', ``{\it how do stars form}'', ``{\it what
  determines the 
star formation rates and efficiencies in molecular clouds}'', and
``{\it what determines the properties of pre-stellar cloud cores and what
is the origin of the stellar mass function}'' as among the key
questions for radio and (sub)millimeter facilities in this decade.
Further, the specific recommendation is made: {\bf ``A large-field
  mapper operating at 
millimeter and submillimeter wavelengths is required to pave the way
for follow-up observations with ALMA''}.   HEAT is a direct answer to
this recommendation and is available now!
\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.0in}{\includegraphics[scale=0.3,angle=0]{./figures/LifeCycle-ISM.eps}}}
{\parbox{3.1in}{
\caption{\label{cycles} {\small The HEAT telescopes 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}

\subsection{Goal 1:  Observing the Life Cycle of Interstellar Clouds}

\noindent \fbox{\parbox{6.4in}{
The formation of interstellar clouds is a prerequisite for star
formation, yet the process has not yet been identified
observationally!  HEAT is designed
with the unique combination of mapping speed, 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.  HEAT can distinguish
between the mechanisms proposed to form clouds 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 region, HEAT will generate a better characterized catalog of
interstellar clouds than CO or HI surveys alone.  

Since the [C~II] and [C~I] line emissivity selects
{\it 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. 

\subsection{ Goal 2: Constructing a Milky Way Template for Star Formation}

\noindent \fbox{\parbox{6.4in}{
HEAT probes 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.
}}

\smallskip

[C~II] and [N~II] are 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.  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}. 

\subsection{Implementation of Science Objectives}
\label{survey}

HEAT's science drivers highlight a 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 APEX, and the
ALMA and SMA interferometers (in addition to current studies using
Herschel data).   How will the HEAT telescope address
the scientific goals that have been illustrated? 

\subsubsection{A Robotic Superconducting HEB Mixer Receiver at 4 Kelvin}

The main technical advance of this proposal is to integrate a
highly-sensitive receiver capability to the autonomous HEAT telescope.  The
current deployment of Schottky diode mixers are robust, operate at ambient
temperatures,
and improve substantially when cooled. Nevertheless, they are a factor
of $\sim$3 less sensitive than superconducting Hot Electron
Bolometer (HEB) mixers.  This sensitivity is most
critical for the very highest frequencies (e.g. 1.9~THz) where the
good weather opportunities are limited.  In order to maximize the
science return at the highest frequencies, state-of-the-art mixers
must be deployed. 

\smallskip

\noindent {\bf Technical Readiness:  Mixers and LOs}
The team is well prepared to deliver an exemplary 1.5 and 1.9 THz HEB
mixer receiver system at 4K to augment the 50K Schottky system.
J.R.~Gao in the Division of Sensor
Research and Technology at SRON in the
Netherlands has delivered among the most sensitive HEB mixers
in the world (e.g. Kloosterman et al. 2013).  Indeed, recent
lab results delivering a noise temperature of 650K DSB at 1.9~THz have
been achieved (Gao, private communication), and the HEAT team has
pumped these SRON mixers in 2015 for the STO-2 project (Section~\ref{synergies})
in the Arizona laboratory with an available
Virginia Diodes 1.9~THz LO module that provides a suitable 10~uW of LO power.
The noise temperature measured in Arizona with a slightly thicker LO diplexer
(mylar beamsplitter) than used at SRON was 750K, an excellent result at this
frequency.  By comparison, Herschel/HIFI delivered a noise temperature
of $\sim$1300K DSB at the
[CII] line.  Gao's team at SRON will provide two new HEB
mixers at 1.5 and 1.9~THz for 
use with HEAT.  The existing, proven 1.9~THz VDI LO will be used; a new 1.5~THz LO
will be purchased from Virginia Diodes to observe the [NII] line and
CO 13-12 at 1497~GHz.  The University of Arizona will fabricate the
coupling optics, electronics and packaging to integrate 
with the existing HEAT telescope optics as was done for the Schottky
mixers.  The existing IF amplifier and Berkeley ROACH(2)-based FFT
spectrometer system will be used, providing two independent
2~GHz-wide digitized spectral bandpasses, providing 320 km/s
instantaneous bandwidth at
the [CII] line and 700 km/s at the [CI] J=2-1 and CO J=7-6 lines.

\smallskip

\noindent {\bf Technical Readiness: Cryogenic System}

To house the SRON mixers, we will develop a hybrid cryostat that
leverages the very successful design currently used on HEAT
(Figure~\ref{heat}).  The proposed cryostat has a radiation shield cooled
to 50K by the current Sunpower Cryotel CT stirling engine, which also 
cools the existing Schottky diode mixers and maintains an excellent vacuum
year-round through cryopumping.  When the weather is especially good,
a second cold work surface is cooled even further to 4-6K using a
Sumitomo RDK-101 
cold head attached to a matching CNA-11 helium 
compressor in a specially-insulated vessel,
modified to operate from PLATO-R's 120 VDC bus with 800W of input power.  
Helium compressor lines are short, insulated, with seals
replaced with fluorosilicone rings rated to -60C and
temperature-regulated.  The compressor will be integrated to the HEAT
telescope and PLATO-R system using an industrial, cold-rated, simplified VFD
(variable frequency drive).  The system will be environmentally tested to
-60C using a large dry ice chamber.  This hybrid system provides year-round
observations with Schottky diode mixers at 810 GHz or 1460 GHz 
at a low total power consumption of 150-200W, and
superconducting operation at 4-6 Kelvin with a total power consumption
of 1000W during the days of best weather, when precipitable water
vapor drops to 100 microns (0.1 mm) or lower.  PLATO-R can already provide
this power capability. Table~\ref{sense} shows the
measured noise temperatures of the HEAT receivers at different operating
temperatures, demonstrating the marked improvement possible with the
4K system.  

\begin{table*}[!hbt]
\centering
\small
\begin{tabular}{|c|c|c|c|}
\hline
{\bf HEAT Receiver} & {\bf T$_{rec}$ at 290K  } & {\bf T$_{rec}$ at 50K} & {\bf
 T$_{rec}$ at 4.5K} \\
\hline \hline
0.8 THz Schottky & 5000K & 1500K & -- \\
1.5 THz Schottky & 10000K & 3500K & -- \\
1.5, 1.9 THz HEB & -- & -- & 750K \\
\hline
\end{tabular}
\caption{\label{sense} { \small  Double-sideband receiver noise
    temperatures for HEAT receivers at different temperatures.
    Mapping speed is inversely-proportional to receiver noise
    temperature squared; so a 2x reduction 
in noise temperature generally results in a 4-fold increase in mapping
speed. }}
\end{table*}


\medskip

\subsubsection{Uniqueness of a [CI], [CII], [NII] and CO Survey}
\label{THz}

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!  Figure~\ref{PDRplot} depicts a plane-parallel
cross-sectional representation of an interstellar cloud which
highlights several ways that HEAT's THz surveys can shed new light on
our understanding of the life cycles of clouds.  In particular, a significant column of ``hidden'' gas exists between where the atomic to
molecular transition of H to H$_2$ takes place, and where CO finally
  becomes the dominant form
  of gas-phase carbon.  This translucent material is best probed by
  [CII] and [CI].  Both lines are therefore more revealing than CO of
  the formative and destructive states in the evolution of a molecular
  cloud.  They will reveal natal molecular (H$_2$) regions that are
  weak or absent in CO emission. 

\begin{figure}[!hbt]
\centering
\begin{minipage}{6.5in}
{\parbox{3.3in}{\includegraphics[scale=0.75,angle=0]{./figures/PDRplot.eps}}}
{\parbox{3.1in}{\caption{\label{PDRplot} {\small {\bf The uniqueness of
          HEAT's [CI], [CII] and
      [NII] surveys.}  A model depiction of the intensity of
    diagnostic lines of carbon and nitrogen species as viewed through a UV-illuminated
    cloud from depths of $A_V$=0 to 20 mag.   Vertical purple lines overlay the
    HII-to-HI-to-H$_2$ boundaries found at the edges of dense interstellar
    clouds.  This figure demonstrates that [CII] and [CI] probe H$_2$ clouds
with little CO, and that adding [NII] disentangles the 
[CII] emission stemming from ionized gas.}}}}
\end{minipage}
\end{figure}

This proposal brings the crucial [CII]
mapping capability to HEAT, with the high sensitivity needed to perform a
statistically meaningful survey of Galactic emission.  This is a
unique capability that cannot be done from the ground.  There are no
space observatories that can provide these data, and the only
suborbital platforms (SOFIA \& balloons) can only fly for limitied
missions. 
HEAT will uniquely measure all three principal forms
of carbon in the gas phase:  ionized, neutral, and molecular.  
In combination with existing infrared, HI and CO
surveys, the potential to identify the formation and destruction of
molecular clouds and GMCs observationally may finally be realized! 
This survey 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.  

\subsubsection{Broad Mapping Coverage of the Galactic Plane}

Interstellar pressure, abundances, and physical
conditions vary strongly as a function of Galactocentric radius, so it is
necessary to probe both the inner and 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 Ridge~A ($0
> l > -100^o$) in [CI] and [NII],  with smaller regions mapped in [CII].  
The survey 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, and high luminosity portions of the LMC.  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'' Spitzer Legacy program
\citep{evans} and the Herschel ``GOTC+'' open time key program
\citep{langer}.  The target line sensitivity is set to identify all
ionized, atomic, and molecular (CO) carbon to a column density
corresponding to a visual extinction of 1 magnitude ($1.8 \times
10^{21}$ cm$^{-2}$) or less.

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 using the On-The-Fly (OTF), or ``drift
scanning'' technique.  HEAT can reach the requisite sensitivity of
1$\sigma$=0.15~K~\kms\ per beam at 810~GHz 
over a fully sampled square degree in 10 days,
assuming median winter conditions of $\tau_{810}\sim$0.5. 
20 square degrees distributed from  $0 > l > -20^o$ and $-45 > l >
-100^o$ will be mapped in $\approx$300 days.  The superconducting
[NII] channel will map a square degree in 3-7 days during typical winter
weather, and the superconducting [CII] channel will map a square degree in 15
days during the best weather, when the opacity at 1900~GHz drops to 2.  
It is expected that 2-3 square degrees
can be mapped per season in [CII] to the nominal sensitivity (3$\sigma$ rms
noise of 1K or less) and an additional 2 square degrees to shallow
sensitivity (3$\sigma$ rms noise of 2K or less) toward regions with
anticipated bright [CII] emission.  In two seasons, 10 square degrees
in [CII] will be observed towards carefully selected Galactic regions including
spiral arm and inter-arm regions, bright PDRs and diffuse clouds.  

\subsubsection{Broader Impact: Synergies with Other Observatories}
\label{synergies}

{\bf HEAT is timely}.  The Spitzer  Legacy program
GLIMPSE, and Herschel program Hi-Gal,
provide a thermal infrared survey of the
Galactic plane that provides a complete census of OB stars, the
stellar structure of the molecular ring, maps
interstellar dust, and constrains extinction laws as a function of
galactocentric radius.   HEAT provides the best corresponding
spectroscopic survey that will provide key 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.  

\smallskip

HEAT naturally complements the results provided by 
SOFIA and Herschel.  The higher angular resolution
afforded by larger telescopes necessarily reduces their field of
view and mapping speed.  For example, the most
intensive [CII]-related key project for Herschel is
``GOTC$^+$'' (PI: W. Langer), which observed the [CII] line
toward over 900 selected points in the Galactic Plane with the HIFI
instrument.  HEAT, by virtue of being a dedicated mapping instrument
with a focused mission and a long mission lifetime, will 
map almost 500 times the areal coverage of ``GOTC$^+$'' during this
proposal period, and will exceed the Herschel coverage in [CII] by a
factor of 200 in a single season.  Given the expiration
of Herschel and SOFIA's limited flying hours, the terahertz astronomy
provided by the HEAT telescope has become even more critical!

\smallskip

Similarly, the small field of view of the {\bf ALMA interferometer}
(7-30$''$) means that many tens of thousands of pointings will be needed to
map a single square degree.   Multi-square-degree large-scale imaging
with ALMA will be prohibitively time consuming but is 
a task very effectively performed by single-dish telescopes like HEAT.
Indeed, HEAT's Southern survey
in atomic carbon, [NII], [CII] and high-J 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. 

\smallskip

Finally, the reflight of the Stratospheric Terahertz Observatory
(STO-2: PI-Walker,
DPI-Kulesa) is a 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], and [O~I]. The STO-2 science flight will occur in
2016 and will last for $\sim$2 weeks. Such flights can be repeated on 2-3
year timescales.  HEAT plays an important role with respect to STO-2,
which has a restricted view of the Galactic Plane (from l=-20 to l=-50) owing to
Solar angle restrictions and the occulting of the sky by the helium
balloon itself.  HEAT will map the
important southern Lupus, Carina, and Chamaeleon 
molecular cloud complexes, in addition to deeper, smaller scale maps
of the Large Magellanic Cloud.  HEAT and STO-2
observations will be carefully coordinated to provide maximum science return.


\subsubsection{Broader Impact: Site testing of the coldest
  place on Earth}

Analysis of 1~km land surface temperatures from the MODIS instruments
on NASA's Aqua and Terra satellites
shows surface skin temperatures that exceed the record low temperature
of -89.2C measured at Vostok in 1983.  One such site
to have experienced temperatures as low as -92C twice in the last 3
seasons, is a mere 26 km from HEAT and PLATO-R, which lie at a
comparatively ``warm'' location.  One hypothesis suggests that the local
topography drives the cold air drainage rate;  when winds are calm, 
local minima act
as ``sinks'' for cold air and represent places where record cold
temperatures are achieved. In contrast, HEAT \& PLATO-R lie along the
ridge where the coldest air easily drains downhill and
the turbulent boundary layer becomes vanishingly small. 
Indeed, during such periods of calm, HEAT typically witnesses 
a sharp rise in air temperatures (from -75C to -55C), not a
drop as is common at downstream sites such as Vostok or South
Pole Station.  In collaboration with lead NSIDC 
researcher Ted Scambos, remote weather monitoring systems
will be installed both at Ridge~A and at a neighboring
``cold'' site as a part of the fieldwork that services HEAT and
PLATO-R.  These weather monitoring systems, already funded separately
and ready to deploy, will
address critical questions for aeronomy and glaciology:
\begin{enumerate}
\setlength{\topsep}{-2ex}
\setlength{\partopsep}{-2ex}
\setlength{\itemsep}{-0.7ex}
\setlength{\parsep}{-0.7ex}
\item What is controlling the record minimum skin temperature level,
  which is consistently -91.5 to -93C in several widely-spaced
  locations? 
\item Does air drainage rate, related to local topography, control the
  inversion layer temperature gradient?  What weather patterns favor record low temperature events? 
\item Can increasing CO$_2$, CH$_4$, etc. levels in the atmosphere, or
  changing H$_2$O or SO$_2$ in the stratosphere, affect the minimum
  temperature levels over time?  
\end{enumerate}

\subsubsection{Science Products and Dissemination}

Access to HEAT data products to the greater scientific community
will be provided through a web browser interface that will
interface with a SQL database that accesses and the FITS data cubes
that HEAT generates.   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.  Early access of data downlinked 
from the experiment in the current season will be released each
Fall. A more formal annual data release will be made
each Spring after the annual collection of raw data products from HEAT.  
This annual data 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 freely available from the HEAT web
    page: {\tt \small http://soral.as.arizona.edu/heat/}}}

\smallskip

\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 of each member in
the organization. 

\begin{table*}[!hbt]
\centering
\small
\begin{tabular}{|l|c|c|l|}
\hline
{\bf Participant} & {\bf Affiliation} & {\bf Participation
  Activity} \\
\hline \hline
Michael Ashley & UNSW &  PLATO-R lead; site testing\\
\hline
Michael Burton & UNSW & Lead: Companion CO Survey from the Mopra 22m\\
\hline
J.R. Gao & SRON & Provides HEB mixers for 1.5-1.9 THz channels \\
\hline
David Hollenbach & SETI & Advisor: ISM physics \\
\hline
Craig Kulesa &  Univ. Arizona & PI, HEAT development and testing, ISM physics \\
\hline 
Mark McCaughrean & ESA & Advisor: synergy with Planck and JWST \\
\hline
Ted Scambos & NSIDC &  ``Coldest Place on Earth'' site testing
campaign\\
\hline
Christopher Walker & Univ. Arizona &  Co-PI, leads student advising \\
\hline
Mark Wolfire & U. Maryland & Advisor: PDR modeling \\
\hline
Abram Young & Univ. Arizona & Systems lead: leads cryostat design \\
\hline
\end{tabular}
\caption{\label{roles}  Activities of the HEAT Instrument and Science Team}
\end{table*}

\begin{figure}[!htb]
\centering
\includegraphics[angle=0,scale=0.4]{./figures/Gantt.png}
\caption{ \label{gantt} High level project timeline}
\end{figure}

Collectively the HEAT
team members represent many years of instrument building, observing
experience, and theoretical expertise.  As related by Table~\ref{roles}, 
the main components of the organization are the PI, who has overall 
responsibility for the project and coordinates the activities of the 
participants; Co-PI Walker who shares in these
responsibilities and leads the student advising efforts; and the
distributed members of the science team who act as an advisory council
to the PI and Co-PIs to ensure that the project stays on course. 
A schedule of key project milestones and tasks is provided in
Figure~\ref{gantt}. 
Routine communications between project participants is essential.
There will be monthly science team telecons
to monitor progress and provide insight into solutions to
emerging problems, and redefine priorities as needed. A HEAT wiki
at Arizona will provide a resource for team communications and
documentation.  

A schedule of key project milestones and tasks is provided in
Figure~\ref{gantt}.  A maintenance servicing of the Ridge~A robotic
facility will be undertaken in 2016-17 to resupply the site with the
810 GHz and 1.5 THz Schottky mixers.  In 2016-17, an aggressive receiver
development effort will be coordinated between Arizona and SRON to
develop a cold-rated HEB receiver system for deployment in the
the 2017-18 field season.  Each year, a readiness review
will be performed prior to shipping to assess the following system
requirements:  1) fully remote operation, 2) low power
dissipation 3) receiver sensitivity, and 4) receiver stability. 
A second HEB receiver system will be constructed in 2018 to exchange with
the first, minimizing time and risk in the deep field.  
The HEAT team will continue to work closely with the NSF,
USAP, ASC, and the International Community to implement an optimal
plan for deployments to Ridge~A (see Supplementary Documents).

\medskip
\noindent \fbox{\parbox{6.4in}{\bf Note that without an active NSF
    program, e.g. this proposed project, we cannot continue to operate HEAT
    and must disassemble and retrograde the experiment.  We
    cannot service it without NSF and USAP logistical backing, nor are
    we allowed to leave it idle on the plateau.}}

\section{Broader Impact: Education}

\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 THz 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 THz 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 9 Ph.D. dissertations. 
Numerous undergraduate research projects have also resulted. {\bf The most
recent and notable is an 3-14~um infrared sky brightness
monitor for HEAT designed and built by undergraduate Casey Honniball as part of her
independent study research.}  In the proposed budget for HEAT, partial
funding for 
one undergraduate and one graduate student 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 and the US will be ongoing. 

\subsection{HEAT: A Portable, Accessible THz Telescope for Education}

Two HEAT telescopes and receivers were constructed, so that one would
be swapped 
with the other in the field, allowing one to be in operation at
Ridge~A while the other is refurbished at Arizona.  The 'off duty'
HEAT telescope remains a complete facility: with heterodyne receiver, IF
processor, FFT spectrometer, and data system.  However its portability
and accessibility makes it particularly ideal for education: it is
effectively ``an ALMA dish in a box''. We 
propose to use the 'off duty' telescope in support of
education and public outreach activities.  Roof-top astronomical 
observations in CO J=1-0 from campus, and 492 GHz [CI] observations
during the best 
spring and fall weather on Mt. Lemmon (9157' elevation) would be
undertaken by undergraduate and graduate students to gain expertise in
terahertz astronomy and astronomical spectroscopy.  Unlike optical
telescopes, HEAT can be used day and night, on-site or remote, 
making it ideal for classroom instruction.  
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. We will exploit the 'off duty' telescope as a 
hands-on demonstrative laboratory with the goal of providing students
with an intuitive understanding of underlying physical concepts.  

\subsection{Development of a NOVA ScienceNow video}
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.   The overall
HEAT experiment and particularly the human
story of deployment to Ridge~A captures the kind of 'high
adventure' spirit that drives many young individuals to science in the
first place -- but which many scientific programs fail to advance.  Many
of us gained our scientific awareness and creative excitement through programs
like PBS's NOVA, and it would seem only appropriate for us to ``pay it
back'' by collecting
the videographic and photographic materials needed to produce a short
science video highlight for the program.  Initial interest in this 
development at NOVA was highly favorable and would be explored for the
2016-17 or 2017-18 deployment to Ridge~A. 

\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[Burton et al.(2014)]{burt14} Burton, M.~G., Ashley, M.~C.~B., Braiding, C., Storey, J.W.V.,
  Kulesa, C., Hollenbach, D., Wolfire, M., Glueck, C., Rowell, G.,
  ``The Carbon Inventory in a Quiescent, Filamentary Molecular Cloud
  in G328'', 2014, ApJ, 782, 72

\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[Chamberlin et al.(2000)]{chambFTS}  Chamberlin, R.A., Martin,
  R.N., Martin, C.L., \& Stark, A.A. ``Submillimeter atmospheric FTS at
  the geographic South Pole.''  Proc. SPIE. 4855, 609 (2000) 

\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[Delgado et al.(1999)]{delgado} Delgado, G., Otarola, A.,
  Belitscky, V., Urbain, D., Hills, R., \& Martin-Cocher, P.
  ``Determination of Precipitable Water Vapour at Llano de Chajnantor
  from Observations of the 183 GHz water line.''  ALMA Memo \#271.1.
  (1999)


\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 \& 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[Grenier et al.(2005)]{Grenier05} Grenier, I.~A., 
Casandjian, J.-M., \& Terrier, R.\ 2005, ``Unveiling Extensive Clouds
of Dark Gas in the Solar Neighborhood'', Science, 307, 1292 

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

\bibitem[Hogg(1992)]{hogg} Hogg, D.E.  ``A summary of the data
  obtained during the MMA site survey.''  ALMA Memo \#79  (1992) 

\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[Kloosterman et al.(2013)]{kloos} J. L. Kloosterman, D. J. Hayton,
Y. Ren, T. Y. Kao, J. N. Hovenier, J. R. Gao, T. M. Klapwijk, Q. Hu, C.
K. Walker, and J. L. Reno, ``Hot electron bolometer heterodyne receiver with a 4.7-THz quantum cascade
laser as a local oscillator'', 2013, Appl. Phys. Lett., 102, 011123.

\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[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[Langer et 
al.(2010)]{langer} Langer, W.~D., Velusamy, T., Pineda, J.~L., et
  al.\ 2010, ``C+ detection of warm dark gas in diffuse clouds'', \aap, 521, L17 
\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[Miao et al.(2001)]{miao} Miao, J., Kunzi, K., Heygster, G.,
  Lachlan-Cope, T.A., \& Turner, J.  ``Atmospheric water vapor over
  Antarctica derived from Special Sensor Microwave/Temperature 2 data.''
  Journal of Geophysical Research. 106, 10187 (2001). 

\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[Paine et al.(2000)]{paine00} Paine, S., Blundell, R., Papa,
  D.C., Barrett, J.W., \& Radford, S.J.E.  ``A Fourier Transform
  Spectrometer for Measurement of Atmospheric Transmission at
  Submillimeter Wavelengths.''  Publications of the Astronomical Society
  of the Pacific. 112, 108 (2000) 

\bibitem[Paine, S.(2004)]{paineAM} Paine, S. ``The am Atmospheric
  Model.''  SMA Technical Memo \#152. (2004) 

\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[Saunders et al.(2009)]{saunders} Saunders, W., Lawrence,
  J.S., Storey, J.W.V., Ashley, M.C.B., Minnis, P., Winker, D., Liu,
  G., \& Kulesa, C.  ``Where is the best site on Earth?  Domes A, B, C
  and F, and Ridges A and B.'',   Publications of the
  Astronomical Society of the Pacific.  (2009) 
 

\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[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, 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[Wolfire et al.(2010)]{Wolfire10} Wolfire, M.~G., 
Hollenbach, D., \& McKee, C.~F.\ 2010, \apj, 716, 1191 


\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}

