[daip] Re: Fwd: [HelpDesk #7037] UVGLU
Thomas Greve
tgreve at roe.ac.uk
Tue Feb 4 11:36:24 EST 2003
> "crazy" is not well defined - what do you mean?
horizontal and vertical stripes (see attached jpg).
Apologies for the lack of information.
The data are VLA data at 24GHz. Two 50MHz wide IFs in spectral
line mode (left and right polarization). 7 channels each 3.125MHz wide.
I have one data set (A) in which the IF2 is centered at 24.09510GHz.
The channels are as follows
CH frq
1 24.085725
2 24.088850
3 24.091975
4 24.095100
5 24.098225
6 24.101250
7 24.104375
The header:
AIPS 1: Image=05129+60 (UV) Filename=4C60N_12 .SPLIT . 1
AIPS 1: Telescope=VLA Receiver=VLA
AIPS 1: Observer=AI104 User #= 333
AIPS 1: Observ. date=12-NOV-2002 Map date=09-JAN-2003
AIPS 1: # visibilities 659183 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 3 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 2 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 7 2.3995100E+10 4.00 3.1250000E+06 0.00
AIPS 1: IF 2 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 05 12 54.800 1.00 3600.000 0.00
AIPS 1: DEC 1 60 30 52.001 1.00 3600.000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 1.22500E+05 wrt pixel 4.00
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type AN is 1
AIPS 1: Maximum version number of extension files of type WX is 1
and another data set (B) for which the IF2 is shifted by 2 channels to
lower frequencies, i.e.
CH frq
1 24.079475
2 24.082600
3 24.085725
4 24.088850
5 24.091975
6 24.095100
7 24.098225
The header:
AIPS 1: Image=05129+60 (UV) Filename=4C60N_20 .SPLIT . 1
AIPS 1: Telescope=VLA Receiver=VLA
AIPS 1: Observer=AI104 User #= 333
AIPS 1: Observ. date=20-DEC-2002 Map date=09-JAN-2003
AIPS 1: # visibilities 691214 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 3 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 2 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 7 2.3995100E+10 4.00 3.1250000E+06 0.00
AIPS 1: IF 2 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 05 12 54.800 1.00 3600.000 0.00
AIPS 1: DEC 1 60 30 52.001 1.00 3600.000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 1.22500E+05 wrt pixel 4.00
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type AN is 1
AIPS 1: Maximum version number of extension files of type WX is 1
In the following I'm only talking about the IF2-data.
I want to make a 9 channel data-set, i.e. DBCON the channels which
are overlapping and UVGLU the end channels.
What I do is that I UVCOP channels 1-5 from A and channels 3-7
from B and DBCON them. That works!
I then UVCOP channels 1-2 from B and channels 6-7 from A.
I then want to UVGLU them to the central (DBCON'ed) channels,
and this is where I run into problems.
While UVGLU ends succesfully, only a fraction of the visibilities
which were in the original files end up in the UVGLU'ed file.
This almost certainly why the resulting image looks bad (see the
attached jpg-file).
The headers (after UVCOP) of the files I want to UVGLU are
A:
AIPS 1: Image=05129+60 (UV) Filename=4C60N2_12_12.UV . 1
AIPS 1: Telescope=VLA Receiver=VLA
AIPS 1: Observer=AI104 User #= 333
AIPS 1: Observ. date=12-NOV-2002 Map date=04-FEB-2003
AIPS 1: # visibilities 659183 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 3 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 2 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 2 2.4095100E+10 4.00 3.1250000E+06 0.00
AIPS 1: IF 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 05 12 54.800 1.00 3600.000 0.00
AIPS 1: DEC 1 60 30 52.001 1.00 3600.000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 1.22500E+05 wrt pixel 4.00
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type WX is 1
AIPS 1: Maximum version number of extension files of type AN is 1
B:
AIPS 1: Image=05129+60 (UV) Filename=4C60N2_20_12.UV . 1
AIPS 1: Telescope=VLA Receiver=VLA
AIPS 1: Observer=AI104 User #= 333
AIPS 1: Observ. date=20-DEC-2002 Map date=04-FEB-2003
AIPS 1: # visibilities 691015 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 3 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 2 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 2 2.4088850E+10 4.00 3.1250000E+06 0.00
AIPS 1: IF 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 05 12 54.800 1.00 3600.000 0.00
AIPS 1: DEC 1 60 30 52.001 1.00 3600.000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 1.22500E+05 wrt pixel 4.00
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type WX is 1
AIPS 1: Maximum version number of extension files of type AN is 1
I realise that the FREQ in the two hearders do *not* obey
the freq+1 rule required by UVGLU. But the data do.
Maybe this is the problem. I have tried (using PUTHEAD) to change
the value of FREQ so that it matches the data - but so far that
hasn't made UVGLU work properly.
question: does the data have to be taken at the same time in order
to be UVGLU'ed?
The only way around the above problem is to DBCON the channels which
overlap, and then make separate images of the end channels.
So in the end, my only problem is that I can't make a plot
which show all 9channels in one go, but rather I have to
plot 2 channels, then the 5 overlapping channels, and then
the last two channels.
Cheers
Thomas
-------------- next part --------------
A non-text attachment was scrubbed...
Name: output.jpg
Type: image/jpeg
Size: 114491 bytes
Desc:
URL: <http://listmgr.nrao.edu/pipermail/daip/attachments/20030204/db83c9c1/attachment.jpg>
More information about the Daip
mailing list