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ASTRO

The software ASTRO can be used to simulate these OBS commands. Astronomers are urged to download the most recent version of GILDAS at http://www.iram.fr/IRAMFR/GILDAS../IRAMFR/GILDAS to prepare their proposals.

 ASTRO\LINE name frequency band

where

$\circ$
name is a line name to label the plot.
$\circ$
frequency is the rest frequency in GHz.
$\circ$
band is the sideband: LSB or USB.

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

 ASTRO\NARROW Qi Qj /RECEIVER Band_Number
 ASTRO\SPECTRAL iunit bandwidth fcent /NARROW Narrow_input -
                                          [/BAND Mode] -
                                          /RECEIVER Band_Number

where

$\circ$
Qi Qj are the two 1 GHz wide ``quarters'' to be analyzed by the narrow-band correlator (see Sect.[*] for more details).
$\circ$
Band_Number is the receiver band to which the unit should be connected (1=3 mm, 2=2 mm, 3=1 mm, 4=0.8 mm).
$\circ$
iunit is the correlator unit number (1 to 8).
$\circ$
bandwidth is the bandwidth of the corresponding correlator unit in MHz (20, 40, 80, 160 or 320).
$\circ$
fcent is the center frequency (in MHz) of the correlator unit in the third IF (100-1100 MHz).
$\circ$
Narrow_input is the IF output (1 or 2).
$\circ$
Mode is used to indicate the sideband code: LSB, USB (SSB modes), or DSB. The DSB mode provides twice as many channels as the LSB or USB modes for the same bandwidth.

A session to design the above correlator setup could be:

LINE HCOP-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

Fig.[*] displays this example of frequency coverage.

Figure: Example of spectral coverage by the narrow-band correlator, as produced by the ASTRO LINE command. Possible contamination by instrumental interferences are indicated.
\includegraphics[width=\textwidth]{noema-intro3}


next up previous contents index
Next: Sensitivity Up: Correlators Previous: Spectral units of the   Contents   Index
Gildas manager 2015-03-19