[daip] UVCON with IN2NAME .NE. BLANK
Leonia Kogan
lkogan at nrao.edu
Sat Feb 12 12:38:58 EST 2011
Subhashis,
I showed you, in my previous messages, that UVCON works including
multiplication the source model given by IN2NAME with given clean
components and ...
You ask me to run UVCON with your model. I am afraid it will involve me
in investigation of your model :( Additionally I am not so good in
zip/unzip. Instead I want to show the apparent way how I created the
model with clean components:
1. Run UVCON with bparm=-1,0 aparm =0.33 0 40, -1, 1 17.5 15 30 0 (this
your aparm with only one difference; 2 hours observation instead of 5)
in2name =' ', smodel =1 0 DO3DIMAG = 0
2. Run IMAGR using the UVCON output UV data as input;
CELLSIZE 6 6 imsize 1024 1024 NFIELD =1 gain 0.1
NITER=200(or less) UVWTFN 'NA'
I used these parameters. You are better off to use the same ones for
simplicity of the comparison
3. The output of IMAGR is the image with CLEAN components which can be
used as IN2NAME in UVCON
Use the AIPS task CCMOD to modify the CC table as you want:
specifically to create 3 components (1 flux unit each
at 0, -1800, -2700)
Use the AIPS task PRTCC to check the effect of CCMOD
4. Now you can run UVCON using the IN2NAME (output of IMAGR:
item3) with modified CC table, the relevant BCOMP, NCOMP
I ran UVCON => IMAGR using the same model IN2NAME the same BCOMP, NCOMP
with the same APARMs, but different BCOMP:
1) BCOMP=-1 0 0 0 0 1 =>no random pointing error; model is multiplied by
the dish beam with flat illumination
I GOT THE RIGHT IMAGE AFTER IMAGR: three components at the right
positions; the most low component is redused by the primary beam
up to 30%
2) BCOMP=-1 0 0 0 5 1 10 => small random pointing error; model is
multiplied by the dish beam with flat illumination
I GOT THE RIGHT IMAGE AFTER IMAGR: three components at the right
positions; the most low component is reduced by the primary beam
up to 30%. Negligible distortion of the image.
3) BCOMP=-1 0 1 0 30 1 10 => visible random pointing error; model is
multiplied by the dish beam with flat illumination
I GOT THE distorted IMAGE AFTER IMAGR (some noise,
three components at the right positions; the amplitude of the
3 components are wrong
So this test confirms that UVCON provides a reasonable result!!!!!
I'd like you to reproduce the described tests, hoping toget absolutely
the same outputs.
LK
Subhashis Roy wrote:
> 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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>
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