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\title{An Introduction to the IRAM NOEMA interferometer}
\author{J.M. Winters\\
(update 2016)\\
\mbox{}\\
Past contributors: S. K\"onig, R. Neri, S. Guilloteau, R. Lucas}
\date{\today \\ Version 5.1--00}
\makeindex{}

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\begin{document}

\def\degr{\hbox{$^\circ$}}
\def\arcmin{\hbox{$^\prime$}}
\def\arcsec{\hbox{$^{\prime\prime}$}}

\maketitle{}

\begin{center}
  Institut de Radio Astronomie Millim\'etrique\\
  300 Rue de la Piscine\\
  F-38406 Saint Martin d'H\`eres
\end{center}

This document introduces IRAM's NOEMA to
potential users. It contains general information about the capabilities
and performance of the interferometer and on related documentation.

\begin{rawhtml}
  Note: this is the on-line version of the "Introduction to NOEMA" 
  A <A HREF="../../pdf/noema-intro.pdf"> PDF version</A> is also available.
\end{rawhtml}

Related information is available in:
\begin{latexonly}
\begin{itemize}\itemsep -1mm
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/gildas-intro-html/gildas-intro.html}{GILDAS: Grenoble Image and Line Data Analysis Software}}
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/astro-html/astro.html}{ASTRO: Astronomical Software To pRepare Observations}}
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/clic-html/clic.html}{CLIC: Continuum and Line Interferometric Calibration}}
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/pdbi-cookbook-html/pdbi-cookbook.html}{NOEMA: Calibration Cookbook}}
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/map-html/map.html}{NOEMA: Mapping Cookbook}}
\end{itemize}
\end{latexonly}

\begin{rawhtml}
  <UL>
  <LI> <A HREF="../gildas-intro-html/gildas-intro.html"> GILDAS:</A> Grenoble
  Image and Line Data Analysis Software
  <LI> <A HREF="../astro-html/astro.html"> ASTRO:</A> A Software to pRepare
  Observations 
  <LI> <A HREF="../clic-html/clic.html"> CLIC:
  <LI> NOEMA:
  <A HREF="../pdbi-cookbook-html/pdbi-cookbook.html"> Calibration CookBook</A>
  <LI> NOEMA:
  <A HREF="../map-html/map.html"> Mapping CookBook</A>
\end{rawhtml}

\noindent
Revision 5.1: NOEMA Antenna 8, NOEMA 2SB receivers (SSB mode)\\
Revision 5.0: NOEMA Antenna 7\\
Revision 4.2: Band 4\\
Revision 4.1: WideX\\
Revision 4.0: NGR system and extended array configurations\\

\newpage
\tableofcontents

\newpage
\section{Description} \index{NOEMA interferometer}

The NOrthern Extended Millimeter Array (NOEMA) is located in the South
of the French Alps, near St Etienne en D\'evoluy in the  D\'epartment
Hautes Alpes. The interferometer's altitude is 2560\,m at the
intersection of the Azimuth and Elevation axes of the  telescopes, and
its longitude and latitude are 05:54:28.5 E and 44:38:02.0 N at the
array phase center. The interferometer currently  comprises

\begin{itemize}
\item Eight antennas of 15\,m diameter,

\item one north-south track 368\,m long,

\item one east-west track 760\,m long,

\item a wide-band correlator \textit{WideX}\index{WideX} covering a
      bandwidth of 3.6\,GHz in dual polarization with a channel spacing of
      1.95\,MHz that is able to accommodate up to 8 antennas,

\item a flexible spectral narrow-band correlator, consisting of 8
      independent units with resolutions ranging from 0.039\,MHz to
      2.5\,MHz, and with 128 to 512 associated channels per unit that can
      process the signals from up to 6 antennas,

\item dual polarization receivers\index{receivers}: a 3\,mm receiver
      band tunable between 76.5 and 116\,GHz, a 2\,mm band (130 to 178\,GHz), 
      and a 1.3\,mm receiver band tunable between 202 and 274\,GHz.
%, and a 0.8\,mm receiver band covering the 277 to 371\,GHz frequency range.
\end{itemize}

\noindent The eight antennas of the interferometer can be positioned
on 32 stations layed out along a ``T'' shaped track\index{tracks} (see
Figure\,\ref{pdblayout}).

The north-south arm is 368\,m long, and the east-west oriented arm
extends 216\,m west and 544\,m east of the intersection. The angle
between the arms is 75\degr. The station names are taken from the arm
orientation and a two digit code indicating the distance from the
track intersection (station W00) in 8\,m units.

Each antenna \index{antenna} is a 15\,m diameter Cassegrain telescope
constructed largely of carbon fiber. The primary mirrors have a
surface accuracy below 50\,$\mu$m rms. The antenna mounts incorporate
self propelled transporters for moving the antennas along the tracks
between stations. The antennas are equipped with three receiver bands,
observing in dual polarization in the 3\,mm, 2\,mm, and 1.3\,mm
%, and  0.8\,mm
atmospheric windows, respectively. The 3\,mm SIS mixers have typical
SSB receiver noise temperatures between 25\,K and 35\,K, the 2\,mm
mixers have typical noise temperatures between 25\,K and 50\,K, and the
1.3\,mm SIS mixers have typical receiver noise temperatures between 25\,K
and 60\,K.
%, and the noise temperatures at 0.8\,mm are typically 30-50\,K. 
More  details about the receivers are given in
Sect.\,\ref{receiversec}, a summary can be found in
Table\,\ref{receivertab}.

The two IF-channels (one per polarization), each 7.8\,GHz wide, are
transmitted by optical fibers to the central building. Details on the
IF transport and processing are given in Sect.\,\ref{ifproc}.

The wide-band correlator WideX\index{WideX} with fixed spectral
resolution, capable of processing 28 baselines (8 antennas), is
available  in parallel with a narrow-band correlator, the latter
comprising eight correlator units. Each of the eight units is a fully
independent,  flexible entity, capable of processing 15 baselines (6
antennas).  Full 2-bit sampling scheme is used to give 88\%
efficiency. For  details of the unit capabilities, see
Sect.\,\ref{correlsec}.

A 64-bit Linux computer and several embedded processors control the
interferometer and acquire the data. The user interface, \obs\ ,  is a variant
of PaKo, familiar to most users of the IRAM 30\,m telescope.

Each interferometer ``configuration'',\index{configuration} i.e. the
placement of the 8 antennas on given stations within the array,
simultaneously provides 28 baselines. 
For each configuration, a list of projects is provided to the on-site 
operator and the astronomer on duty, 
allowing for a flexible
scheduling of the observations well adapted to the actual
meteorological conditions. Depending on the weather and on the season, 
configurations are
changed every two to six months, so a project that requires two
configurations will on average take about four months to be completed.

\begin{figure}[t]
  \includegraphics[width=\textwidth]{noema-intro-uv-cover}
  \caption{Example of uv-coverage (left) and interferometer station layout 
(right) for the 8D configuration, as produced by the 
   \astro\  \index{ASTRO} {\tt UV\_TRACK} command. 
The shaded circle at the center of the 
uv-plane shows the antenna shadowing region.}
\label{pdblayout}
\end{figure}

\section{Capabilities}

\subsection{Spatial Resolution}

Three primary 8 antenna configurations (see Table~\ref{configs}) are
available  that can be combined to produce maps with different angular
resolution. All three configurations are usually scheduled during the
course of a year. During the summer period (May until September) each
antenna undergoes a thorough maintenance and the interferometer is
operated in a 7 antenna D configuration. Since the narrow-band
correlator can process the signals from 6 antennas only, 
corresponding subsets of the full array
have been selected to provide optimum sampling of the
uv plane. These subsets  will be connected to the high spectral
resolution units of the narrow-band correlator (see Table~\ref{configs}).

\begin{table}
\caption{Configurations of the eight-antenna array and their six-antenna 
subsets \index{configuration}}
\label{configs}
\begin{center}
\begin{tabular}{|l|c|c|c|c|c|c|c|c|}
\hline
Name & \multicolumn{8}{c|}{Stations}  \\
\hline
8A  & W27 & W09 & E68 & E23 & E12 & N46 & N29 & N20 \\
8A6 & W27 & W09 & E68 & E23 & --- & N46 & N29 & --- \\
8C  & W23 & W20 & W05 & E23 & E16 & E04 & N20 & N13 \\
8C6 & --  & W20 & W05 & E23 & E16 & --- & N20 & N13 \\
8D  & W12 & W08 & W05 & E10 & E04 & N13 & N09 & N02 \\
8D6 & W12 & W08 & --- & --- & E04 & N13 & N09 & N02 \\
\hline
\end{tabular}
\end{center}
\end{table}

The general properties of these configurations (numbers
refer to  a source at  20$^\circ$ declination) are:

\begin{itemize}

\item {\bf D} -- the compact configuration with just the D array for
maximum sensitivity.\index{sensitivity} This configuration is best
suited for detection experiments and coarse mapping (resolution $\sim
3.7''$ at 100\,GHz and  $\sim 1.6''$ at 230\,GHz). This configuration
provides the lowest phase noise and highest sensitivity.
\item {\bf C} -- the next most compact configuration provides a fairly complete
coverage of the uv-plane (low sidelobe level) and is well adapted to
combine with D for low angular resolution studies ($\sim$2.6$''$ at
100\,GHz, $\sim$1.1$''$ at 230\,GHz) and with A for higher resolution
($\sim$1.4$''$ at 100\,GHz, $\sim$0.6$''$ at 230\,GHz).  C alone
($\sim$1.9$''$ at 100\,GHz, $\sim$0.85$''$ at 230\,GHz) is also well
suited for snapshot and size measurements, and for detection
experiments  at low source declination.
\item {\bf A} -- the most extended configuration alone is well suited
for mapping or size measurements of compact, strong sources. It
provides a resolution of $1.0''$ at 100\,GHz, $\sim$0.43$''$ at
230\,GHz.
\end{itemize}

The three configurations \index{configuration} can be used in
different combinations to achieve complementary sampling of the
uv-plane,  and to improve on angular resolution and
sensitivity.\index{sensitivity} The combinations AC, ACD, and CD are
reasonably suited for all  declinations above 0\degr\, (see
Tables\,\ref{beamCD} to \ref{beamACD}). For lower source declinations,
the beam becomes increasingly  elliptical. Sources lower than
-25\degr\, declination cannot reasonably be observed from Plateau de
Bure. Mosaicing is usually done with D  or CD, but the combination ACD
can also be requested for high resolution mosaics. 

The antenna half-power beam size is 50\arcsec\ at 100\,GHz and the
shortest possible antenna spacing is 24\,m to avoid collisions between
two antennas. Even taking into account projection effects that shorten
the effective baseline, sources larger than about 15\arcsec\ are
already heavily resolved at 100\,GHz. In these cases, additional
short-spacing observations should be acquired by observing a raster-
or  OTF- (On-The-Fly) map using the IRAM 30~m telescope\footnote{see
also the
\href{http://www.iram-institute.org/medias/uploads/IRAM_memo_2008-2-short-spacings.pdf}{IRAM
memo 2008-2}: {\it Single-dish observation and processing  to produce
the short-spacing \newline \hspace*{4mm} information for a millimeter
interferometer} by N.J. Rodr{\'i}guez-Fern{\'a}ndez, J.  Pety \&
F. Gueth}. The short-spacing information can then easily be added to
the uv-tables obtained from the interferometer by means of  the 
GILDAS\index{GILDAS}
\mapping\ \index{MAPPING} software.

Tables\,\ref{beamD}-\ref{beamA} give a summary of possible beam
sizes\index{beam sizes} at various observing frequencies in different
configurations using natural weighting. The numbers were obtained
assuming observations of the target source from 4~hours before to
4~hours after transit down to elevations above 20 degrees. Typical
uv-coverages and resulting beam shapes for the eight-element array are
shown in Figs.\,\ref{fig:8cd} (D and CD) and \ref{fig:8ac} (AC and A).

\begin{table} 
\caption{Beam sizes for configuration D} 
\label{beamD} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 3.89 & 3.27 & 2.59 & 2.18 & 1.69 & 1.42 & 11 \\ 
60 & 3.65 & 3.22 & 2.43 & 2.14 & 1.58 & 1.4 & 24 \\ 
40 & 3.8 & 3.19 & 2.53 & 2.13 & 1.65 & 1.38 & 23 \\ 
20 & 4.34 & 3.2 & 2.89 & 2.13 & 1.88 & 1.39 & -165 \\ 
0 & 5.56 & 3.2 & 3.7 & 2.13 & 2.41 & 1.39 & 10 \\ 
-20 & 8.81 & 2.93 & 5.87 & 1.95 & 3.83 & 1.27 & 3 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 

\begin{table} 
\caption{Beam sizes for configuration C} 
\label{beamC} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 2.01 & 1.48 & 1.34 & 0.99 & 0.87 & 0.64 & 14 \\ 
60 & 1.99 & 1.44 & 1.32 & 0.96 & 0.86 & 0.62 & 19 \\ 
40 & 2.16 & 1.42 & 1.44 & 0.94 & 0.94 & 0.61 & 199 \\ 
20 & 2.66 & 1.41 & 1.77 & 0.94 & 1.15 & 0.61 & 15 \\ 
0 & 3.6 & 1.4 & 2.4 & 0.93 & 1.56 & 0.61 & 12 \\ 
-20 & 5.28 & 1.34 & 3.52 & 0.89 & 2.29 & 0.58 & 5 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 


\begin{table} 
\caption{Beam sizes for configuration CD} 
\label{beamCD} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 2.86 & 2.19 & 1.91 & 1.46 & 1.24 & 0.95 & 12 \\ 
60 & 2.73 & 2.12 & 1.82 & 1.41 & 1.18 & 0.92 & 19 \\ 
40 & 2.87 & 2.06 & 1.91 & 1.37 & 1.24 & 0.89 & -161 \\ 
20 & 3.38 & 2.03 & 2.25 & 1.35 & 1.47 & 0.88 & -165 \\ 
0 & 4.54 & 2.04 & 3.02 & 1.36 & 1.97 & 0.88 & 11 \\ 
-20 & 6.71 & 1.82 & 4.47 & 1.21 & 2.91 & 0.79 & 4 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 

\begin{table} 
\caption{Beam sizes for configuration AC} 
\label{beamAC} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 1.52 & 1.25 & 1.01 & 0.83 & 0.66 & 0.54 & 6 \\ 
60 & 1.46 & 1.14 & 0.97 & 0.76 & 0.63 & 0.49 & 32 \\ 
40 & 1.53 & 1.11 & 1.02 & 0.74 & 0.66 & 0.48 & 31 \\ 
20 & 1.8 & 1.1 & 1.2 & 0.73 & 0.78 & 0.48 & -157 \\ 
0 & 2.41 & 1.12 & 1.6 & 0.74 & 1.04 & 0.48 & 197 \\ 
-20 & 3.5 & 1.05 & 2.33 & 0.7 & 1.52 & 0.45 & -173 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 

\begin{table} 
\caption{Beam sizes for configuration ACD} 
\label{beamACD} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 2.16 & 1.78 & 1.44 & 1.19 & 0.94 & 0.77 & -159 \\ 
60 & 1.97 & 1.86 & 1.31 & 1.24 & 0.85 & 0.8 & 67 \\ 
40 & 2.16 & 1.67 & 1.44 & 1.11 & 0.94 & 0.72 & 28 \\ 
20 & 2.58 & 1.65 & 1.72 & 1.1 & 1.12 & 0.72 & -160 \\ 
0 & 3.65 & 1.66 & 2.43 & 1.11 & 1.58 & 0.72 & -167 \\ 
-20 & 4.92 & 1.5 & 3.28 & 1 & 2.13 & 0.65 & -175 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 

\begin{table} 
\caption{Beam sizes for configuration A} 
\label{beamA} 
\begin{center} 
\begin{tabular}{|r|r|r|r|r|r|r|r|}  
\hline 
 Dec. & \multicolumn{2}{c|}{100\,GHz} & \multicolumn{2}{c|}{150\,GHz} & \multicolumn{2}{c|}{230\,GHz} & PA\\   
\hline  
    & Maj. & Min. & Maj. & Min. & Maj. & Min. & \degr \\   
\hline  
80 & 1.11 & 0.85 & 0.74 & 0.57 & 0.48 & 0.37 & 26 \\ 
60 & 1.06 & 0.79 & 0.71 & 0.52 & 0.46 & 0.34 & 37 \\ 
40 & 1.11 & 0.77 & 0.74 & 0.51 & 0.48 & 0.33 & 36 \\ 
20 & 1.29 & 0.78 & 0.86 & 0.52 & 0.56 & 0.34 & 30 \\ 
0 & 1.66 & 0.8 & 1.1 & 0.53 & 0.72 & 0.34 & 21 \\ 
-20 & 2.52 & 0.77 & 1.68 & 0.51 & 1.09 & 0.33 & 10 \\ 
\hline 
\end{tabular} 
\end{center} 
\end{table} 


\begin{figure}
  \includegraphics[height=.8\textheight]{noema-intro-config-D}
  \includegraphics[height=.8\textheight]{noema-intro-config-CD}
  \caption{uv-plane coverage and beamshapes for the D and CD (8 antenna) configurations. 
           Contour levels are at 5\%, 10\%, 20\%, and 50\%. Frequency is 100\,GHz.}
  \label{fig:8cd}
\end{figure}
\begin{figure}
  \includegraphics[height=.8\textheight]{noema-intro-config-AC}
  \includegraphics[height=.8\textheight]{noema-intro-config-A}
  \caption{uv-plane coverage and beamshapes for the AC and A (8 antenna) configurations. 
           Contour levels are at 5\%, 10\%, 20\%, and 50\%. Frequency is 100\,GHz. 
           Note the different scaling of the beam maps with respect to Fig.~\ref{fig:8cd}.}
  \label{fig:8ac}
\end{figure}

\newpage

\subsection{Receivers}\label{receiversec}\index{receivers}

All antennas are equipped with dual polarization, low noise,  2SB
receivers (currently operated in SSB mode) for the 3\,mm, 2\,mm, and
1.3\,mm atmospheric windows.  The frequency ranges are 76.5\,GHz to
116\,GHz for band 1, 130\,GHz to 178\,GHz for band 2, and 202\,GHz to
274\,GHz for band 3.  Receiver tuning will preferentially be done on a
fixed frequency grid\index{Frequency grid} of 500\,MHz step width,
on which the receiver performance is optimized (see Sect.~\ref{astrosec} 
for more details).  The basic receiver
characteristics are summarized in Tab.~\ref{receivertab}.

Each receiver band has dual-polarization capabilities with the two RF
channels, one per polarization, observing at the same sky frequency.
Only one band can be observed at any time.  Time-shared observations
between different RF bands (e.g., band 1 and band 3) are possible in
well justified cases, they are however not very efficient.

The mixers can be tuned LSB or USB throughout most of the accessible
frequency range (see Tab.~\ref{receivertab}).  The typical image band
rejection is 15-20\,dB. Each of the two polarizations delivers a
bandwidth of 7.8\,GHz, but only up to 3.6\,GHz can be processed by the
current correlators (4.2-7.8\,GHz IF frequency).

The two IF-channels (one per polarization) are transmitted by optical
fibers to the central building.    


\begin{table}[t]
\caption{Receiver specifications. The {\it sky frequency} 
range $\rm F_{sky}$ refers to a centering 
of the respective sky frequency at the center of the IF band at 6\,GHz}
\label{receivertab}
\begin{center}
\begin{tabular}{|lccc|}
\hline
                      & Band 1    & Band 2   & Band 3     \\
\hline
  $\rm F_{sky}$ range/[GHz]   & 76.5--116  & 130--178 & 202--274  \\
 $\rm T_{rec}$/[K] LSB &  25--35    & 25--50   & 25--60    \\
 $\rm T_{rec}$/[K] USB &  25--35    & 25--50   & 30--60    \\
 $\rm G_{im}$/[dB]     & $<$ -15    & $<$ -15  & $<$ -15   \\
 RF LSB/[GHz]         &  76.5--104 & 130--166 & 202--262  \\
 RF USB/[GHz]         &  88.5--116 & 142--178 & 214--274  \\
\hline
\end{tabular}
\end{center}
\end{table}

\subsection{Correlators}\label{specres}\index{correlators}
\subsubsection{Wideband correlator}

The wide-band correlator WideX\index{WideX} can accommodate up to 8
antennas. It gives access to the two 3.6\,GHz wide IF bands
simultaneously (one in each polarization).  WideX provides a fixed spectral resolution of
1.95\,MHz over the full bandwidth and is available in parallel to the
narrow-band correlator  (see Sect.~\ref{ifproc}).

\subsubsection{IF processor and narrow-band correlator}\label{ifproc} 

\begin{figure}[t]
  \includegraphics[width=\textwidth]{noema-intro-if1}
 \caption{Example of spectral coverage as produced by the \astro\ \index{ASTRO}
{\tt LINE} command (see Sect.~\ref{astrosec}). The image band is
plotted for information only, the receivers are operated in {\bf
single side band} mode. Possible contamination by instrumental
interferences in the signal band are indicated in green. IF frequencies
respecting the 500\,MHz spaced  tuning grid are indicated by dashed magenta 
lines. The IF frequency on which the tuned sky frequency is centered, 
is shown by a magenta solid line}
  \label{if1plot}
\end{figure}

The narrow-band correlator can process the two 3.6\,GHz wide
IF-channels only partially.
It accepts as input two signals of 1\,GHz
bandwidth, that must be selected within the 3.6\,GHz delivered by the
receiver. In practice, a dedicated IF
processor \index{IF processor} splits
the two input 4.2--7.8\,GHz bands in four 1\,GHz ``quarters'', labeled
{\em Q1...Q4} (see Fig.~\ref{if1plot}). Two of these quarters must be
selected as narrow-band correlator inputs. 
The IF
processor converts the four selected 1\,GHz wide slices of the 4.2-7.8\,GHz
first IFs down to 0.1-1.1\,GHz, the input range of the narrow-band
correlator. 
Spectral resolutions range from 40\,kHz to 2.5\,MHz in eight
independent spectral units.
Only six antennas can be
processed with the  narrow-band correlator. The system allows the
following choices: \index{correlator narrow input}

\begin{itemize}
\item first correlator entry can only be Q1 HOR, or Q2 HOR, or Q3 VER,
or Q4 VER
\item second correlator entry can only be Q1 VER, or Q2 VER, or Q3
HOR, or  Q4 HOR
\end{itemize}

\noindent where HOR and VER refers to the two polarizations:

\vskip 4mm 
\begin{flushleft}
\begin{center}
\begin{tabular}{l|cccc}
\hline\noalign{\smallskip}
Quarter  & Q1 & Q2 & Q3 & Q4 \\
IF1 [GHz]& 4.2 - 5.2   &  5.0 - 6.0  &  6.0 - 7.0  & 6.8 - 7.8\\
\noalign{\smallskip}\hline\noalign{\smallskip}
input 1 & HOR  & HOR  & VER  & VER  \\
input 2 & VER  & VER  & HOR  & HOR  \\
\noalign{\smallskip}\hline
\end{tabular}
\end{center}
\end{flushleft}
\bigskip

Note, that the combination VER VER is not allowed.\\

{\em How to observe two polarizations?} To observe simultaneously two
polarizations at the same sky frequency, one must select the same
quarter (Q1 or Q2 or Q3 or Q4) for the two narrow-band correlator
entries. This will necessarily result in each entry seeing a different
polarization. The system thus gives access to 1\,GHz $\times$ 2
polarizations.\\ \index{narrow-band correlator}

{\em How to use the full 2\,GHz bandwidth of the narrow-band
correlator?} If two different quarters are selected (any combination
except  VER VER is possible), a bandwidth of 2\,GHz can be analyzed by
the narrow-band correlator. Only one polarization per quarter is
available  in that case; this may or may not be the same polarization
for the two chunks of 1\,GHz.\\

{\em Is there any overlap between the four quarters?} In fact, the
four available quarters are 1\,GHz wide each, but with a small overlap
between some of them: Q1 is 4.2 to 5.2\,GHz, Q2 is 5.0 to 6.0\,GHz, Q3
is 6.0 to 7.0\,GHz, and Q4 is 6.8 to 7.8\,GHz. This results from the
combination of filters and LOs used in the IF processor.\\

{\em Is the 2\,GHz bandwidth necessarily contiguous?} No. Any
combination (except VER VER) of two quarters can be selected. Adjacent
quarters will result in a (quasi) continuous 1.8-2\,GHz
band. Non-adjacent quarters will result in two separate 1\,GHz
bands.

%{\em Where is the selected sky frequency in the IF band?} It would seem 
%natural to tune the receivers such that the selected sky frequency
%corresponds to the middle of the IF bandwidth, i.e. 6.0\,GHz. However,
%this corresponds to the limit between Q2 and Q3. If your project
%depends on the narrow-band correlator, it is therefore highly
%recommended to center a line close to the center of a quarter (see Section
%``ASTRO'' below). 

\subsubsection{Spectral units of the narrow-band correlator}\label{correlsec} 

\begin{table}[t]
\caption{Configurations of the narrow-band correlator units}
\label{correltab}
\begin{center}
\begin{tabular}{crrc}
\hline
\hline
 Spacing & Channels & Bandwidth$^1$  & Mode$^2$ \\
 \multicolumn{1}{c}{(MHz)} & & \multicolumn{1}{c}{(MHz)} & \\
\hline
 0.039 & 1 x 512 &  20 & SSB \\
 0.078 & 1 x 512 &  40 & SSB \\
 0.156 & 2 x 256 &  80 & DSB \\
 0.312 & 1 x 256 &  80 & SSB \\
 0.625 & 2 x 128 & 160 & DSB \\
 1.250 & 1 x 128 & 160 & SSB \\
 2.500 & 2 x  64 & 320 & DSB \\
\hline
\end{tabular}
\end{center}
\begin{list}{}{}
\item[$^1$:]  Note that 5\% of the passband are lost at both ends of 
              each subband.
\item[$^2$:] {\tt DSB Mode} provides twice as many channels as each 
              of the {\tt SSB} modes for the same bandwidth but the 
              central channels suffer from the Gibbs effect. 
\end{list}
\end{table}

The narrow-band correlator \index{narrow-band correlator} can process
the signals from up to 6 antennas. It has 8 independent units which
can be placed anywhere in the 100--1100\,MHz band (1\,GHz bandwidth),
by steps of 0.25\,MHz. Each unit can be operated in seven modes, as
shown in Table~\ref{correltab}. Each mode is characterized in the
following by couples of total bandwidth/number of channels. In the 3
double-sideband modes (DSB, 320\,MHz/128 channels, 160\,MHz/256
channels, 80\,MHz/512 channels -- see Table~\ref{correltab}) the two
central  channels may be perturbed by the Gibbs phenomenon if the
observed source has a strong continuum. When using these modes, it is
recommended  to avoid centering the most important part of the lines
in the middle of the band of the correlator unit. In the remaining SSB
modes  (160\,MHz/128 channels, 80\,MHz/256 channels, 40\,MHz/512
channels, 20\,MHz/512 channels) the two central channels are not
affected by the Gibbs  phenomenon and, therefore, these modes may be
preferable for some spectroscopic studies. Because of signal
apodization, the effective spectral  resolution is slightly broader
than the channel spacing (by about a factor 1.6 in the standard case
for NOEMA, that uses a Welch time-lag  window).

In addition to the spectra produced every integration time ({\tt
subscan} in the \obs\ terminology), the correlator units output every
second the visibility for a pseudo-continuum channel
\index{pseudo-continuum channel} created by averaging data from
several spectral  channels.

The 8 units can be independently connected to the first or the second
correlator entry, as selected by the IF processor (see above).  Please
note that the center frequency is expressed in the frequency range
seen by the narrow-band correlator, i.e. 100 to 1100\,MHz. The
correspondence to the sky frequency depends on the parts of the
3.6\,GHz IF1 bandwidth which have been selected as correlator inputs
and on the selected receiver side band (LSB or USB): Use the \astro\
\index{ASTRO} software (see Sect.~\ref{astrosec}) to display the
relation between sky- and IF1 frequencies.\\

\newpage

\subsubsection{ASTRO}\label{astrosec}\index{ASTRO}

The software \astro\ can be used to simulate and visualize the
receiver/correlator configuration. Astronomers are urged to download
the most recent version of GILDAS \index{GILDAS} at  {\tt
\href{http://www.iram.fr/IRAMFR/GILDAS}{http://www.iram.fr/IRAMFR/GILDAS}}
to prepare their proposals.

The previous {\tt LINE} command has been replaced by several new
commands (see internal help).  The behavior of the {\tt LINE} command
can be changed by the {\tt SELECT BURE 1995|2000|2006|2013|2015}
command. Default is 2015, equivalent to the new {\tt SELECT NOEMA}
command.

\begin{itemize}
\item {\tt LINE}: receiver tuning
\item {\tt NARROW}: selection of the narrow-band correlator inputs
\item {\tt SPECTRAL}: spectral correlator unit tuning
\item {\tt PLOT}: control of the plot parameters. 
\end{itemize}

The following \astro\ command will produce a plot of the frequency
range covered by WideX and showing the four IF windows of which two
must be connected to the narrow-band correlator (an example is shown
in Fig.~\ref{if1plot}):

\begin{verbatim}
 ASTRO\LINE name frequency band [/FIXED_FREQ|/ONGRID]
\end{verbatim}

where

\begin{itemize}\itemsep -1mm
\item[$\circ$]{\tt name} is a line name to label the plot.
\item[$\circ$]{\tt frequency} is the tuning frequency in GHz.
\item[$\circ$]{\tt band} is the sideband: LSB or USB.
\item[$\circ$]{\tt \verb|/FIXED_FREQ|}: This option can be used to ignore the 
500\,MHz spaced tuning grid
\item[$\circ$]{\tt \verb|/ONGRID|}: This option centers the line frequency
automatically on the IF tuning grid
\end{itemize}

The two IF processor inputs for the narrow-band correlator and the
setup of the spectral units are selected by the two commands

\begin{verbatim}
 ASTRO\NARROW Qi Qj /RECEIVER Band_Number
 ASTRO\SPECTRAL iunit bandwidth fcent /NARROW Narrow_input -
                                          [/BAND Mode] -
                                          /RECEIVER Band_Number
\end{verbatim}

where

\begin{itemize}\itemsep -1mm
\item[$\circ$]{\tt Qi Qj} are the two 1\,GHz wide ``quarters'' to be analyzed 
by the narrow-band correlator (see Sect.\,\ref{ifproc} for more details).
\item[$\circ$]{\tt Band\_Number} is the receiver band to which the unit 
should be connected (1\,=\,3\,mm, 2\,=\,2\,mm, 3\,=\,1\,mm).
\item[$\circ$]{\tt iunit} is the correlator unit number (1 to 8).
\item[$\circ$]{\tt bandwidth} is the bandwidth of the corresponding correlator 
unit in MHz (20, 40, 80, 160 or 320).
\item[$\circ$]{\tt fcent} is the center frequency (in MHz) of the correlator 
unit in the third IF (100-1100\,MHz).
\item[$\circ$]{\tt Narrow\_input} is the IF output (1 or 2).
%\item[$\circ$]{\tt Band\_C} is the bandpass to be used to produce the 
%temporal data (in MHz: contiguous section of {\tt Bandpass}).
%\item[$\circ$]{\tt IF3\_C} is the center frequency to be used for 
%{\tt Band\_C} (same units as for {\tt IF3\_Frequency}).
\item[$\circ$]{\tt Mode} is used to indicate the sideband code: SSB mode 
or {\tt DSB}. The DSB mode provides twice 
as many channels as the SSB modes for the same bandwidth.
\end{itemize}

\begin{figure}
  \includegraphics[width=\textwidth]{noema-intro3}
  \caption{Example of spectral coverage by the narrow-band correlator,
           as produced by the \astro\ {\tt LINE} command. Possible 
           contamination by instrumental interferences are indicated in green.}
  \label{astroplot}
\end{figure}


A session to design the above correlator setup (shown in
Fig.\,\ref{astroplot}) could be:

\begin{verbatim}
LINE HCO+-HCN 87.00 LSB 6500    ! Define the receiver tuning. ASTRO displays
                                ! the full 3.6 GHz frequency coverage by WideX.
NARROW Q1 Q3                    ! Selects the 4.2GHz - 5.2GHz and 6GHz - 7GHz windows 
                                ! of the 4-8GHz IF1 band. Polarization is HOR HOR. 
SPECTRAL 1 160 1020 /NARROW 1   ! Correlator unit #1 covers the [940,1100] IF3 band 
                                ! on the first IF input (4.2GHz - 5.2GHz).
SPECTRAL 2  20  210 /NARROW 1   ! Correlator unit #2 samples a narrow line centered at
                                ! 210MHz in the IF3 band of the first correlator input.
SPECTRAL 3  20  770 /NARROW 1
SPECTRAL 4 160  350 /NARROW 1
SPECTRAL 5 160  475 /NARROW 1
SPECTRAL 6  40  750 /NARROW 2   ! Correlator unit #6 covers the [730,770] IF3 band on 
                                ! the second IF input (6GHz - 7GHz).
SPECTRAL 7 320  400 /NARROW 2
SPECTRAL 8 320  925 /NARROW 2
\end{verbatim} 

\subsection{Sensitivity}

\subsubsection{Detection experiments}

The point source sensitivity \index{sensitivity} (one $\sigma$ level,
in Jy) for an $N_a$ antenna array, over a bandwidth $B$ in a time
$T_{\rm ON}$ is given by

\begin{equation}
\sigma = \frac{J_{\rm pK} T_{\rm sys}}{\eta \sqrt{N_a (N_a-1) T_{\rm ON} B}} \frac{1}{\sqrt{N_{\rm pol}}}
\end{equation}

where 
\begin{itemize}

\item $J_{pK}$ is the antenna efficiency \index{antenna efficiency}
(Jy\,K$^{-1}$) i.e. $2k/(\eta _a A)$ with $\eta _{a}$ the aperture
efficiency, $A$ the antenna collecting area, and $k$ the Boltzmann
constant (22\,Jy\,K$^{\rm -1}$ at 85\,GHz, 29\,Jy\,K$^{\rm -1}$ at
150\,GHz, and 35\,Jy\,K$^{\rm -1}$ at 230\,GHz). These factors were
determined for stable atmospheric  conditions.
\item $\eta$ is an additional efficiency factor due to atmospheric
decorrelation. The short and long term  atmospheric phase fluctuations
depend on the baseline length and water vapor content of the
atmosphere. Typical summer (winter) values for $\eta$ are 0.9 (0.9) in
band 1, 0.8 (0.85) in band 2, and 0.6 (0.8) in band 3.
\item $T_{\rm sys}$ is the system temperature \index{system
temperature} outside the atmosphere, i.e. corrected for atmospheric
transmission: $T_{\rm sys}$ = 100\,K (90\,K) below 110\,GHz,
increasing to 185\,K (175\,K) between 110 and 116\,GHz,  
 $T_{\rm sys}$ = 150\,K
(130\,K) in band 2 below 150\,GHz, and increasing to   200\,K (170\,K)
between 150\,GHz and 178\,GHz, and  $T_{\rm sys}$ =  250\,K (200\,K)
in band 3  in typical summer (typical winter)
conditions. These system temperatures apply to   sources at $\delta
\ge 20^\circ$.
\item $N_{\rm a}$ is the number of antennas: currently 8 when using WideX but 
$N_{\rm a} = 6$ for spectral resolutions better than 2\,MHz.
\item $T_{\rm ON}$ is the on-source integration time in seconds (2 to
8 hours, depending on source declination).  Because of various
calibration overheads, the total observing time is typically 1.6
$T_{\rm ON}$.
\item $B$ is the noise equivalent bandwidth of the correlator in Hz,
equal to 1.88 times the channel separation; the effective channel
width for standard apodization (using a Welch time-lag window) is 1.60
times the channel separation. Available resolutions range from 40\,kHz
to 2.5\,MHz for  spectral line observations using the  narrow-band
correlator, and from 2\,MHz for line projects up to  3.6\,GHz for
continuum projects using WideX.  
\item $N_{\rm pol}$ is the number of polarizations: 1 for single
polarization and 2 for dual polarization (see Sect.\,\ref{ifproc} for
details).
\end{itemize}

Assuming typical winter conditions at the NOEMA site, 8 antennas, an
integration time of one hour in a 3.6\,GHz bandwidth and using both
polarizations, we find point source sensitivities $\sigma$ of
0.06\,mJy at 90\,GHz, 0.12\,mJy at 150\,GHz, and 0.23\,mJy at
230\,GHz.  For a full synthesis (e.g., 2 configurations or 10 hours on
source), this goes down to about 0.02\,mJy, 0.04\,mJy, and 0.07\,mJy,
respectively.

\subsubsection{Mapping}

The rms brightness temperature is related to the point source
sensitivity by

\begin{equation}
\delta T_m = \frac{\rho \lambda^{2}}{ \theta _{1} \theta _{2} } \sigma
\end{equation}

where $\lambda$ is the wavelength in millimeters, $\theta _1$ and
$\theta_2$ are the beam major and minor axis in arcseconds, $\sigma$
is the point source sensitivity in Jy, and $\rho$\,$\simeq$\,15 for
untapered maps with natural weighting.

For a typical experiment with configuration AC or CD, tracking the
source for 8 hours (but spending 2 hours on calibration) on each
configuration, we obtain $\delta T_{AC}$\,=\,0.12\,K and $\delta
T_{CD}$\,=\,0.03\,K, for 0.625\,MHz channel spacing with the spectral
correlator, with the same assumptions as above at 90\,GHz, but using 6
antennas, only. The factor $\rho$ is increased by uniform weighting
and tapering: the amount depends on the uv-coverage and on the phase
noise as a function of baseline lengths, but tapering also increases
the synthesized  beam size.

An equivalent way to look at noise in a map is by comparison to the
single-dish sensitivity (given here for position switching)

\begin{equation}
\delta T_s = \frac{2 T_{sys}}{\sqrt{T_{ON} B}} 
\cdot \frac{1}{\sqrt{N_{\rm pol}}}
\end{equation}

which is typically $\delta T_s$\,=\,2.7\,mK in one hour (for a channel
spacing of 0.625\,MHz and a frequency below 110\,GHz).

The mapping sensitivity is roughly related to $\delta T_s$ by

\begin{equation}
\delta T_m = \frac{\Omega ^2}{(\theta _1 \theta _2)} \frac{\delta T_s}
{\eta \sqrt{N(N-1)} }
\end{equation}

where $\Omega$ is the size of the antenna primary beam in seconds of
arc. Then $\delta T_{CD}\,=\,70\, \delta T_s$  and $\delta
T_{AC}\,=\,250\,\delta T_s$. In practice, a source that is well
detected but unresolved at the 30\,m telescope can  easily be imaged
at NOEMA.

\section{Proposal Preparation}

To exploit the full capabilities of NOEMA, proposals must be written
with special care. It is of the utmost importance to  provide the
following parameters:

\begin{itemize}
\item A source list with accurate coordinates, velocities/redshifts
\item Observing frequencies
\item A source list with velocities and line width for spectral line
observations
\item Required spatial and spectral resolution, and estimate of
required sensitivity
\item For special cases: Required accuracy of the bandpass calibration
(e.g., a weak line on a strong continuum, high precision relative
astrometry)
\item Dates to be avoided during scheduling, e.g., because of sun avoidance
(a circle of 32 degree radius), phase stability requirements (daytime
is often difficult in summer), or other reasons (specify)
\item Any other stringent constraint (e.g. coordinated observations)
\end{itemize}

{\bf This information is absolutely required to decide about the
feasibility of the program, a prerequisite before the program
committee  can consider the proposal}.

\subsection{The Proposal Management System (PMS)}

Proposals must be submitted \index{proposal submission} through the
Proposal Management System (PMS) \index{PMS} at URL:
\href{http://pms.iram.fr}{http://pms.iram.fr}.\\

Proposal editors will have to create a PMS account to be
able to login and prepare/submit their proposals. To do so, it is
sufficient to click on the URL above and to follow the instructions
on-screen that guide the proposal editor through the submission
process.  The submission procedure consists in filling in an on-line
form with the details of the requested observations (source
coordinates, receiver  setups, array configuration, etc.), and to
upload a single file in pdf format containing the scientific and
technical justification. A LATEX template is provided from the PMS
submission page. This file may be customized, but proposers should
respect the following requirements:  (1) a normal proposal may contain
up to two pages of text describing the scientific aims and technical
description (4 pages for a Large  Program, see below) (2) you may add
up to two pages of figures, tables, and references (but don't mix text
with  figures, tables, and references!), and (3) the font size must be
11pt or larger.\\

For a proposal to be complete, PMS requires that all authors validate
their identity (e-mail and affiliation) and their participation to
the proposal before the deadline.  The editor of the proposal will
have to send invitations to all authors through PMS by clicking an
\emph{invitation} button. We urge proposal editors to invite the
authors through PMS well before the deadline to give them enough time
to validate their identity before the deadline. Authors that fail to
validate their participation will automatically be dropped from the
proposal.\\

PMS will be opened for submission of new proposals about three weeks
before the deadline\footnote{PMS remains open at all times for
submission of Director Discretionary Time proposals.}. Proposers may
modify their proposals in PMS until the deadline, in which case the
\emph{submit} button must be activated again after modification of the
proposal. Please avoid  last minute submissions when the network could
be congested. If you experience any difficulty with the submission
process in PMS, please contact us at \htmladdnormallink{{\tt
pms-feedback@iram.fr}}{mailto:pms-feedback@iram.fr} for help. You may
also use this e--mail address for bug reports, general questions and
comments.\\

\section{Observing Procedures}\label{proceduresec}

After a proposal has been accepted, observing procedures will have to
be prepared. All choices have to be finalized. This implies some
additional work with your {\tt local contact}. Non standard
observations may require an in-house collaborator.

The following procedure is a standard one, which can be used for
``normal'' projects (full scale mapping on one object).

\subsection{Setup Procedure}

The standard setup defines the target source(s), configures the
spectral correlator, selects the observing frequency, and leaves the
system ready for receiver tuning. {\bf WideX is always activated by
default, no further settings are required in the observing procedure}.

%\clearpage

\begin{verbatim}
!----------------------------------------------------------------------
!
! PR:SETUP-zzzzzzzz.OBS ! Setup procedure for project "zzzzzzzz"
!
!    - Date:          23-Jun-2016
!    - Author:        
!    - PI:            
!    - Local contact: 
!    - Project ID:    zzzzzzzz
!    - Verified by:   person (date)
!
!    - Rating:                       A / B 
!    - Number of telescopes assumed: 8 
!    - Observing mode:               mapping/detection/moving body,track-sharing/mosaic
!    - Observing goal:               'm' lines, 'n' continuum
!    - Time:                         [A,B,C,D,any] Any = CD (specify 'Any' if not ABCD)
!
!    - Requested on-source time (h): sum(time) 
!
! if 1 source & 1 field, or(!) equal for all fields/sources
!    - Requested sensitivity:        20mJy/80kHz
! if rms different for all fields/sources (i.e. 4 sources)
! order should be same as 'Let name_source' below!!!!
!    - Requested sensitivity:        [20mJy/80kHz,15mJy/80kHz,20mJy/160kHz,10mJy/40kHz]
! or(!) e.g. source 1,3,4 ask same rms
!    - Requested sensitivity:        [(1,3-4) 20mJy/80kHz,(2) 10mJy/40kHz]
!^^ Leave only line that is relevant for this setup. ^^
!
!    - Requested minimum S/N:        (will be filled by IRAM staff)
!
!    - Water limit:                  (will be filled by IRAM staff)
!    - Obs date constraint:          [dd-Mon-yyyy, dd-Mon-yyyy to dd-Mon-yyyy] 
! ^^ enter begin and end date for each observable(!!) time span, or single day 
!
!    - Sun avoidance:                dd-Mon-yyyy to dd-Mon-yyyy 
!    - Other comments:               
! 
!------------------------------------------------------------------------
! Do not edit directly, but copy first then 
!
!       1: replace "zzzzzzzz" by the project number
!       2: enter the respective information in the preamble
!       3: for summer projects, replace 'number of telescopes assumed: '8' by '7'
!
!        All lines marked !**! must be customized.
!            lines marked !* ! can be modified.
!
!------------------------------------------------------------------------
SET\END                           ! Finish previous observation
@ PR:defaults                     ! Restore defaults parameters
!
SET\PROJECT zzzzzzzz              !**! Specify project number for further 
!
SYMBOL GO "@ PR:observe-all zzzzzzzz" !* ! data processing
CATA SOU INTER_BASE:iram.sou      !* ! 
CATA PHA INTER_BASE:phase-pdb.sou !* ! 
LET RECEIVER 1                    !**! Choose observing receiver: receiver 1 @ 3mm
!                                                                 receiver 2 @ 2mm 
!                                                                 receiver 3 @ 1mm
! 
LET LOW_LIMIT 15.                 !* ! Low elevation limit 15 degrees
SAY "Project 'PROJECT' starting"  !
!
SYMBOL NAME "NNNN EQ 2000 00:00:00.00 00:00:00.00 LSR 0.0"   !**! Source 
!                                 
LET N_SUBSCANS 45                 !* ! Scan length (in seconds)
LET N_SCANS 30                    !* ! Number of scans on SOURCE (22.5 minutes = 30*45sec)
LET N_SOURCES 1                   !* ! use SYMBOL NAME if N_SOURCES.EQ.1
IF (N_SOURCES.GT.1) THEN                   !
  LET NAME_SOURCE[1:N_SOURCES]   ".." ".." !* Enter list of sources (maximum 30)
  LET N_SCANS_SOURCE[1:N_SOURCES] .. ..    !* Enter time per source (in scans)
ENDIF
!
LET CALIBRATOR_1 "......."        !**! 1st phase calibrator
LET CALIBRATOR_2 "......."        !**! 2nd phase calibrator
LET CALIBRATOR_3 "......."        !* ! 3rd phase calibrator (if necessary)
LET N_CALIBRATORS 2               !* ! Use 2 phase calibrators every N_SCANS
LET N_SUBS_CAL  45                !* ! Scan length on calibrator (in seconds)
LET N_SCANS_CAL  3                !* ! Nb scans on each calibrator (3 scans)
                                
LET FSWI_CAL  .FALSE.             !* ! No fast-switching by default

LET N_MOSAIC 0                    !* ! No mosaic mode
IF (N_MOSAIC.NE.0) THEN
   DEFINE REAL X_MOSAIC[N_MOSAIC] Y_MOSAIC[N_MOSAIC] T_MOSAIC[N_MOSAIC] /GLOBAL
   LET X_MOSAIC .. ..             !* ! offsets in arcsec
   LET Y_MOSAIC .. ..             !* ! offsets in arcsec
   LET T_MOSAIC .. ..             !* ! in units of N_SUBSCANS
ENDIF
!
LET SOLVE_POINT YES          
LET SOLVE_FOCUS YES         
!
LET FOCUS_RECEIVER 'RECEIVER'     !* ! Focusing on observing receiver 
LET POINT_RECEIVER 'RECEIVER'     !* ! Pointing on observing receiver 
!
LET SOLVE_POLAR "B"               !* ! Solve point on Polar: B=both, V, or H
!
LET POINT_SOURCE_1 "......."      !**! 1st pointing source
LET POINT_SOURCE_2 "......."      !* ! 2nd pointing source
LET FOCUS_SOURCE_1 "......."      !**! 1st focusing source
LET FOCUS_SOURCE_2 "......."      !* ! 2nd focusing source
!
SET\UNLOCK
!
@ PR:spec-defaults                ! define standard correlator setup 
!
NARROW Q3 Q3 /REC 'RECEIVER'      !**! Define quarters to be connected to 
!                                      the two correlator inputs of the NARROW BAND 
!                                      CORRELATOR  @ the chosen receiver band
!
SPECTRAL 1 320  260 /NARROW 1 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 2 320  480 /NARROW 1 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 3 320  710 /NARROW 1 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 4 320  940 /NARROW 1 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 5 320  260 /NARROW 2 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 6 320  480 /NARROW 2 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 7 320  710 /NARROW 2 /REC 'RECEIVER' !**! Define correlator configuration
SPECTRAL 8 320  940 /NARROW 2 /REC 'RECEIVER' !**! Define correlator configuration
!
LINE xxxx yyyy LSB 6500 /REC 'RECEIVER'    !**! Define observing frequency
!
IF (N_SOURCES.GT.1) THEN
  SOURCE 'NAME_SOURCE[1]' /TYPE OBJ         
 ELSE
  SOURCE 'NAME' /TYPE OBJ          
ENDIF
!
SET\RECE 'RECEIVER' /POLAR 'SOLVE_POLAR' ! Choose receiver band for the observation
!
SET\OBS
!
LOAD /TUNING                          ! Load frequency, but don't move antenna now
!
! Make sure any changes in the spectral configuration will be detected:
SET\LOCK
!
LET CHANGE_SPECTRAL .FALSE.       !* ! .TRUE. if need to switch to broad_band
!
IF (CHANGE_SPECTRAL) THEN
   SPECTRAL /BROAD
ENDIF
!
SET SHOW OFF
!
TYPE PR:clean.obs
SAY "Project zzzzzzzz   Type: Detection  /  Category: 3mm, dual polarization" !**!
SAY " "
SAY "        Tuning Receiver "'RECEIVER'":              LSB           " !**!
SAY " "
!
! Insert here any other instructions to the operator/astronomer
!
SAY "Frequency sent, receivers may be tuned"
SAY "Execute all observations by typing GO"
SAY " "
SAY "Type END when project is finished"
SAY " "
SYMBOL PROCEED /INQUIRE "Type RETURN to remove this page: "
SET SHOW ON
SET SHOW ON
\end{verbatim}

All information appearing on lines marked {\tt !**!} must have been
supplied in the observing proposal, lines marked {\tt !* !} will use
default values if not specified. The remaining part of the procedure
will be defined by IRAM personal (your {\tt local contact},
usually). The project number (zzzzzzzz in this example) is assigned by
IRAM when observing proposals are received.

After final checking by IRAM staff, this file will be given to the
{\tt  operators}, together with a copy of the proposal and any
accompanying information the {\tt PI} may find useful. This small
``dossier'' will be updated by the {\tt operator} and {\tt on-duty
astronomer} during observations, and a copy of it will be given to the
{\tt PI} when he/she visits Grenoble for data reduction after the
project is completed. In particular, the {\tt on-duty astronomer}
will fill in a {\tt NOTE file} that summarizes the  individual
conditions and particular problems encountered during each track
observed. The {\tt NOTE file} will provide some suggestions  in cases
where the data calibration is not straight-forward.

\subsection{Phase Calibrator List} \index{phase calibrator}

The current
\href{http://www.iram.fr/IRAMFR/PDB/bure/phase-pdb.sou}{list of phase
calibrators} used at NOEMA includes over 3000 objects.  Flux densities
at 85\,GHz are indicated in Jy. The flux density is followed by the
spectral index, by the flux  at 230\,GHz if measured, or 0 if no
measurement is available. The last column gives the date, at which the
flux has been measured. Be  careful: most if not all sources are
variable (both flux and spectral index vary). All coordinates are
equatorial J2000.0. Bandpass  calibrators should be selected among the
strongest phase calibrators, 4\,Jy or more if possible, but even
0.3\,Jy (at the designated  observing frequency) sources are
sufficiently strong as phase calibrators.

The planets are not sufficiently point-like to be used as bandpass
calibrators in any configuration.
%
%To find phase calibrators for your source, use the \astro\ procedure name {\tt FIND\_CALI.ASTRO}.


\section{Array Operation}

Since projects are spread over typically four months, the presence of
visiting astronomers when their observations are scheduled is
practically impossible to guarantee. In the course of observations and
data processing, four ``people'' will play a role: the {\tt  proposal
PI (PI)}, i.e. any member of the team that proposed the observations,
the {\tt local contact}, \index{local contact} the {\tt on-duty
astronomer}, i.e. an  IRAM staff member present on the site, and the
array {\tt operator}. The {\tt local contact} is an IRAM astronomer
assigned to each  project that does not have an in-house collaborator.
His/her role is to help the {\tt PI} in preparing the observations and
in properly ca\-li\-brat\-ing the data. In case of any problem,
question, or doubt, the {\tt PI} should contact his {\tt local
contact}. The  {\tt PI} can monitor the progress of his project on the
web: {\tt
\href{http://www.iram.fr/IRAMFR/PDB/ongoing-last.html}{http://www.iram.fr/IRAMFR/PDB/ongoing-last.html}};
this page is updated  three times per day. Note that checking results
obtained in a given configuration, making intermediate data
reductions, etc. is not the  responsibility of the {\tt local
contact}. In certain cases, and upon request, remote login to a
VISITORS account on the Grenoble  computers can be granted to the {\tt
PI} to help him in this task.

The array is regularly operated by one {\tt operator} and one {\tt
on-duty astronomer}. The {\tt operator} has responsibility for
conducting all observations, following pre-established observing
procedures or under the supervision of the {\tt on-duty astronomer} in
case of unanticipated events. {\tt Operators} have also full authority
for all safety measures.  Receiver tuning is done by the {\tt
operator}. The {\tt on-duty astronomer} must assess the data quality
during the observations by monitoring the array performance on
standard calibrators. The {\tt PI} usually will not be present on the
site, but is expected to come to Grenoble for data  calibration, once
the project is finished.

\subsection{Observations}

The PI must specify all aspects of his program in an observing
procedure. Standard observations can be made using general, parametric
procedures. An example is given in Sect.\,\ref{proceduresec}.

The operator will execute the observing procedure, and the on-duty
astronomer will monitor the data quality by examining the observations
of phase calibration sources. \index{phase calibrator} In the case of
peculiar observing conditions (high or exceptionally low phase
drifts, calibrators too weak, etc.), the on-duty astronomer has full
authority to modify the parameters of the observing procedures.
He/She will, of course, try to consult with the {\tt PI} or {\tt local
contact}.

Non-standard observations may require a specific arrangement with the
{\tt local  contact} or {\tt on-duty astronomer}, or may even require
an in-house collaborator.

\subsection{Data Handling}

Raw data, corresponding to individual dumps of the correlator buffers,
are not stored. Instead, a real-time job applies automatic
calibrations (clipping corrections, atmospheric model, etc.) before
writing on disk. This pre-calibrated data is archived daily, and
sorted on a project by project basis.

Except for specific experiments, {\tt PIs} will only have access to
the sorted data, which contain the source data and all the calibration
measurements acquired by the observing procedure. {\tt PIs} will have
exclusive access to their data for a three year proprietary period 
(counting from the end of the last semester of observations of the project), 
but no exclusive rights over the
calibration data, which are duplicated in special data files to
monitor a posteriori the performance of the  interferometer.

Off-line calibration (RF bandpass, phase, flux, and secondary
amplitude calibration) is the {\tt PI}'s responsibility. It is
possible to recalibrate the data for atmospheric transmission and
receiver temperature. Recalibrating the IF bandpass is not possible.

\section{Documentation and Help}

NOEMA is a complex instrument. Previous knowledge of interferometry is
necessary to use it correctly, and  reading a standard textbook for
this field is highly recommended (e.g., Thompson A.R., Moran J.M., and
Swenson G.W., 2001 {\em  Interferometry and Synthesis in Radio
Astronomy. Second Edition}, John Wiley \& Sons, Eds.). Information
specific to the IRAM Northern Extended  Millimeter Array (NOEMA) is
available on the
\href{http://iram-institute.org/EN/content-page-96-7-56-96-0-0.html}{NOEMA
documentation  web pages} and in the following documents:

\begin{itemize}
\item{NOEMA
\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/astro-html/astro.html}{\astro\
Users Guide:}}\\ \astro\ is a graphic program to help planning
observations. It is particularly useful for complex observing programs
such as series of  snapshots on many sources or complex line setups
\item{NOEMA
\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/pdbi-cookbook-html/pdbi-cookbook.html}{Calibration
Cookbook:}}\\ A hitch-hiker's guide to calibrating NOEMA data with \clic\ 
\item{NOEMA
\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/clic-html/clic.html}{CLIC
Users Manual:}}\\ Detailed documentation of the off-line calibration
program. It assumes the user has previous knowledge of interferometry
\item{NOEMA
\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/map-html/map.html}{Mapping
Cookbook:}}\\ A hitch-hiker's guide to produce and analyze images from
NOEMA with the \gildas\ software
\item{\href{http://www.iram.fr/IRAMFR/GILDAS/doc/html/gildas-intro-html/gildas-intro.html}{\gildas\
Users Manual:}}\\ Documentation of the mapping and display
software. \gildas\  \index{GILDAS} is an image processing system with many
capabilities, and the documentation  assumes the user has a basic
knowledge of image processing
\end{itemize}

Although these manuals are updated relatively frequently, only the
on-line help within the programs has the latest revisions.


\newpage

\addcontentsline{toc}{section}{Index}
\printindex

\end{document}

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