[daip] UVCON with IN2NAME .NE. BLANK
Subhashis Roy
roy at ncra.tifr.res.in
Fri Feb 11 15:11:27 EST 2011
Hi Leonid,
Please try with the attached file ('3SRC.CCMODEL.FIT.bz2') as IN2NAME to
UVCON and check what you get.
You shall need to use 'bunzip2' to uncompress it and then load it in Aips
with 'FITLD'. Then use it as IN2NAME.
IN2NAME contains a map with 3 Clean components each of 10 Jy (inserted
through CCMOD) detailed below.
-----------------------------------------
Ncomps 3 sort on: FLUX (DESCAB)
Comp Delta X Delta Y Flux Total
# asec asec Jy Jy
1 0.00 0.00 10.0000000 10.0000000
2 0.00 -1800.15 10.0000000 20.0000000
3 0.00 -2699.99 10.0000000 30.0000000
--------------------
However, in the IMAGR output (CELL=2.7; IMSI=2048; UVTAP=20,20; UVRA 0 28;
others are default) made from the data generated by UVCON (inputs below)
you will notice peak flux density of the source at the centre ~5 Jy.
If I use BPARM(3)=0; BPARM(5)=0 in UVCON; I get back the right flux
density for the source at the centre.
--------------------------------------------------------------------------
AIPS 1: UVCON Generates UV data for a given array and model
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INFILE '/tmp/VLA-A_UVCON Antenna location file name
AIPS 1: IN2FILE *all ' ' TSYS and Efficiency
AIPS 1: BLANK=>INFILE's data are used
AIPS 1: for TSYS and Efficiency
AIPS 1: OUTFILE *all ' ' Antenna location file name
AIPS 1: Positions are in equatorial
AIPS 1: coordinate system.
AIPS 1: IN2NAME '3SRC.CCMODEL' Model image name (name)
AIPS 1: The both dimensions of the
AIPS 1: model must be 2**N pixels
AIPS 1: IN2CLASS 'FLATN' Model image name (class)
AIPS 1: IN2SEQ 1 Model image name (seq. #)
AIPS 1: IN2DISK 5 Model image disk unit #
AIPS 1: INVERS 0 CC file version #.
AIPS 1: OUTNAME 'GAIN.ERR3SRC' Output UV file name (name)
AIPS 1: OUTCLASS 'UVCON' Output UV file name (class)
AIPS 1: OUTSEQ 0 Output UV file name (seq. #)
AIPS 1: OUTDISK 5 Output UV file disk unit #.
AIPS 1: NMAPS 1 No. maps to use for model.
AIPS 1: BCOMP *all 0 First CLEAN comp to sub.
AIPS 1: 1 per field. 0 => 1
AIPS 1: NCOMP 3 *rest 0 Last CLEAN comp to sub.
AIPS 1: to use (0 => all)
AIPS 1: FLUX 0 Lowest CC component used.
AIPS 1: CMETHOD 'DFT' Modeling method:
AIPS 1: 'DFT','GRID'; ' '=>DFT
AIPS 1: CMODEL ' ' Model type: 'COMP','IMAG'
AIPS 1: ' ' => 'COMP' => CC compon
ents
AIPS 1: 'IMAG' => image
AIPS 1: FACTOR 1 Factor times model fluxes.
AIPS 1: 0 => 1
AIPS 1: SMODEL *all 0 Source model, 1=flux,2=x,3=y
AIPS 1: See 'explain'.
AIPS 1: RASHIFT *all 0 Shift of the model center
AIPS 1: relatively of the initial
AIPS 1: RA=0, per field (asec)
AIPS 1: DECSHIFT *all 0 Shift of the model center
AIPS 1: relatively of the initial
AIPS 1: declinat., given at APARM(3)
AIPS 1: per field (asec)
AIPS 1: APARM 0.33 0 Control information:
AIPS 1: 40 -5 1: Frequency of chan. 1, GHz
AIPS 1: 5 17.5 2: Wavelength of ch 1, cm
AIPS 1: 10 30 IF both .LE. 0 then
AIPS 1: 0 0 wavelength = 0.1 cm
AIPS 1: 3: Source declination, deg
AIPS 1: 4: Min hour angle, hours
AIPS 1: 5: Max hour angle, hours
AIPS 1: The hour angles are for
AIPS 1: the given array center
AIPS 1: 6: Min antenna elevation, deg
AIPS 1: 7: Integration time, sec
AIPS 1: 0 => 1.D6
AIPS 1: to simmulate snapshot
AIPS 1: 8: Bandwidth(increment) of
AIPS 1: the freq. channel, MHz
AIPS 1: >=0 => it is increment to
AIPS 1: simulate multi chann. data
AIPS 1: =0 => Bandwidth = 1MHz
AIPS 1: <0 => one channel data to
AIPS 1: simulate multi frequency
AIPS 1: UV coverage
AIPS 1: 9: Number of freq. channels
AIPS 1: 0 => 1
AIPS 1: 10: Max blockage allowed
AIPS 1: 0 => 1 no blockage
AIPS 1: BPARM -1 0 Control information:
AIPS 1: 1 0 1: Multiplier of the calcul.
AIPS 1: 60 1 noise. 0 => 1
AIPS 1: 150 *rest 0 -1 => 0 (no noise)
AIPS 1: 2: Atmosphere noise at zenith
AIPS 1: in degrees.
AIPS 1: 3: RMS of pointing error,
AIPS 1: random among all antennas
AIPS 1: but constant in time,
AIPS 1: in arcsec
AIPS 1: If (BPARM(3).LT.0) then
AIPS 1:
AIPS 1: the phase and amplitude
AIPS 1: errors of each antenna
AIPS 1: are simulated instead
AIPS 1: of pointing error.
AIPS 1: ABS(BPARM(3)) is half
AIPS 1: range of homogeneously
AIPS 1: distributed phase, rad
AIPS 1:
AIPS 1: BPARM(4) is half
AIPS 1: range of homogeneously
AIPS 1: distributed natural LOG
AIPS 1: of factor to amplitude
AIPS 1:
AIPS 1: BPARM(5):
AIPS 1: 0 => only one (first)
AIPS 1: clean component is
AIPS 1: affected by the
AIPS 1: phase/amp noise
AIPS 1: 1 => all clean
AIPS 1: components are affected
AIPS 1:
AIPS 1: 4: global pointing error,
AIPS 1: constant in time for all
AIPS 1: antennas,
AIPS 1: in arcsec
AIPS 1: 5: RMS of pointing error,
AIPS 1: random among all antennas
AIPS 1: and in time,
AIPS 1: in arcsec
AIPS 1: 6: Type of the primary beam
AIPS 1: 1 => circular dish with
AIPS 1: the flat illumination
AIPS 1: 2 => illumination is 10dB
AIPS 1: down at the dish edge
AIPS 1: 3 => illumination is 15dB
AIPS 1: down at the dish edge
AIPS 1: The dish diameter is given
AIPS 1: at the INFILE (antenna 1)
AIPS 1: 4 => Gaussian beam with
AIPS 1: given BMAJ, BMIN, BPA
AIPS 1: in degrees
AIPS 1: 5 => Gaussian beam with
AIPS 1: variable BMAJ, BPA
AIPS 1: depending on the time
AIPS 1: .GT.0 =>Multiply the model
AIPS 1: by the primary beam.
AIPS 1: 0 => Not multiply the
AIPS 1: model by the primary beam.
AIPS 1: 7: Time tolerance, in minutes
AIPS 1: 0 => 1
AIPS 1: If the difference of the
AIPS 1: current and previous time
AIPS 1: is < the time tolerance,
AIPS 1: the pointing error or the
AIPS 1: phase of the antenna or
AIPS 1: primary beam parameters
AIPS 1: are not changed
AIPS 1: 8: Shift the UV data by
AIPS 1: RASHIFT, DECSHIFT?
AIPS 1: 0 => yes shift
AIPS 1: 1 => no shift
AIPS 1: 9: Range of the primary beam
AIPS 1: 0 => 2.5
AIPS 1: 10: If OUTFILE.NE.BLANK then
AIPS 1: 0 => calculate OUTFILE and
AIPS 1: exit
AIPS 1: 1 => calculate OUTFILE and
AIPS 1: carry out the rest of
AIPS 1: job
AIPS 1: CPARM *all 0 Frequencies of the group(IFs)
AIPS 1: begins
AIPS 1: 1: Number of the groups (IFs)
AIPS 1: 2-10 Frequency of group(IFs)
AIPS 1: begins in MHz
AIPS 1: BMAJ 1.5 FWHM major axis of the
AIPS 1: Gaussian primary beam, degree
AIPS 1: See help for the variable
AIPS 1: primary beam (BPARM(6)=5)
AIPS 1: BMIN 1.5 FWHM minor axis of the
AIPS 1: gaussian primary beam, degree
AIPS 1: BPA 0 Position angle of Gaussian
AIPS 1: primary beam, degree
AIPS 1: DO3DIMAG 0 1 => use W term calculating
AIPS 1: visibilities (only if
AIPS 1: CMETHOD='DFT', and
AIPS 1: CMODEL ='COMP')
AIPS 1: 0 => no W term calculating
AIPS 1: visibilities
--------------------------------------------------------
On Thu, 10 Feb 2011, Leonia Kogan wrote:
> Subhashis,
>
> As you requested I have carried out the test of UVCON with IN2NAME.NE.blank.
>
> 1. I created the image with CC table attached. You can see this CC table
> contents at the attachment. The lines 2,3,4 of the table correspond to the 3
> components you wanted to simulate. So the relevant piece of UVCON inputs is
> IN2NAME = , INVERS = 1, NMAPS=1, BCOMP=2, NCOMP=4.
> I do not understand what NMAPS=3, and NCOMP=2,2,2 means in your test?
>
> 2. I did not look at the individual baseline amplitude. Instead I created the
> image based on the UVCON UV data output.
>
> 3. I ran IMAGR and got the image you can see at the second picture of the
> attachment. You see the image is precisely the expected one !!!
>
> So UVCON works.
>
> Comments:
>
> I (and you also probably) used at the UVCON with DO3DIMAG=0
> That means that W term=0 when the visibilities are calculated in UVCON.
> Actually the Wterm = W(in lambdas)*(l**2) may be very big for some baseline:
> ~1E4 *(0.5/57)**2 ~1 !
> I built the image considering the flat sky. Eric made a test using IMAGR with
> curvature of the sky and did not get so excellent image.
> Anyway UVCON does what it expects to do.
>
> LK
>
>
>
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