Importing Miriad files into AIPS

A question from Danny:

Hello AIPS ninjas.

Is there any way to import miriad *.uv files -the kind that are whole directories full of binary files- into AIPS?

~Danny

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AIPS system temperatures.. in miriad?

So we're trying to reduce our data in AIPS and then image in it miriad. Sounds familiar. Anyway, we want to use options=systemp when inverting the uv data. However, I've noticed that miriad doesn't appear to correctly import the system temperatuers from AIPS when using "fits" to read in the fits file that I wrote with AIPS using FITTP. In fact, it sets all the system temperatures to 60K, exactly.

There is an option in fits (varwt) to use the reciprocal of the noise variance on a visibility as its weight, but the system temperatures are still set to 60K.

Ideas?

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Mosaicing: AIPS/Miriad/whatever works!

Is anyone familiar with mosacing techniques in AIPS, Miriad, or both? I have 21cm VLA spectral line data, taken mosaic-style, and am having a heck of a time trying to stitch the pointings together. Here's what I have done so far:

Reduced in the standard manner with AIPS up until the 'SPLIT' step
Wrote out each pointing with FITTP
Loaded into Miriad
In Miriad, 'invert', 'mossdi', and 'restor', mostly with the defaults for parameters

The best way I can describe the results is like a bad patchwork quilt...does anyone know of a good cookbook or guide for putting together pointings into a mosaic? I know AIPS has some tasks for this (VTESS/UTESS/LTESS) but I haven't had success with them. Thanks!

Katie

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Reference Frequencies (AIPS v. Miriad)

I went back and reviewed my early post; this is an update, with a few more details.

I've been working with GMRT data reduced in AIPS, and ATCA data reduced in MIRIAD.
It turns out that (at least for GMRT observations) AIPS gives the reference frequency (in imhead or prtan) as the frequency in the middle of the first channel, whereas Miriad gives the reference frequency (in prthd or uvlist, options=spectral) as that measured at the end of the first channel. But don't freak out yet--the channels still contain the same data, they are just identified differently in AIPS vs Miriad. See "read more" for details.


It's relatively easy to see from reading the headers, so I'm not sure why this caused me trouble when I first posted it (notice the "at Pixel" in the AIPS header):

From AIPS:

AIPS 1: Image=NGC2997 (UV) Filename=15JAN .UVLIN . 1
AIPS 1: Telescope=GMRT Receiver=GMRT
AIPS 1: Observer=PISANO User #= 43
AIPS 1: Observ. date=14-JAN-2007 Map date=18-APR-2007
AIPS 1: # visibilities 325734 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN BASELINE TIME1
AIPS 1: WEIGHT SCALE
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 1 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 128 1.4129999E+09 0.50 3.1250000E+04 0.00
AIPS 1: IF 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 09 45 38.811 1.00 3600.000 0.00
AIPS 1: DEC 1 -31 09 27.768 1.00 3600.000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Rest freq 0.000 Vel type: RADIO wrt YOU
AIPS 1: Alt ref. value 0.00000E+00 wrt pixel 1.00
AIPS 1: Max version number of extension files type HI is 1
AIPS 1: Max version number of extension files type FQ is 1
AIPS 1: Max version number of extension files type AN is 1

From MIRIAD:

****************************************************************
Filename: 15jan.uvlin/
Telescope: GMRT
Object: ngc2997 Observer: PISANO
First time: 07JAN15:18:31:06.8
Number of antennae: 30
Polarisations Present: RR,LL
Type of correlations present: crosscorrelation
----------------------------------------------------------------
Spectral Correlations:
Spectrum Channels Freq(chan=1) Increment Restfreq
1 128 1.41302 0.000031 1.42041 GHz
Total number of correlations: 83387904
Correlations are stored in 16-bit form
----------------------------------------------------------------
J2000 Source RA: 9:45:38.811 Dec: -31:09:27.76
Apparent Source RA: 9:45:58.554 Dec: -31:11:18.61

As a side note, when checking the reference freq in AIPS check the outputs of both imhead and prtan--an AIPS bug is that occassionally they don't match!
From Chapter 8 of the AIPS cookbook:
"Another, more serious, problem is that two locations in the FITS file give the "reference frequency" -- the header and the antenna table. In principle these should agree. However there are instances when they will differ. Task FITS will issue a warning when this happens, and will use the antenna table reference frequency as the true reference frequency. In some cases this will be the correct frequency. In others it will not."...pg 8-7

**Note, this is now consistent with one of Laura's later posts (Edited by KMH 9/6/07).

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