Linux Utility function to convert a GBTIDL keep (FITS) file to an AIPS SDFITS file.
Jay Lockman provided a test GBTIDL keep file (calibAGBT2C_023_03.fits) for conversion to an AIPS file.
This GBTIDL file contains an observation of a region near the galatic plane.
idlToSdfits has only one required input argument, the input GBTIDL keep file. Optionally
an output file name can be specified
An example of the entire process of mapping the M81/M82 group of galaxies is available.
An example of execution Spectral Processor (SP) processing by idlToSdfits to produce
foo.fits is below:
% idlToSdfits -o foo.fits calibAGBT02C_023_03.fits
Output Name is foo.fits
Reading IDL Keep File: Number of Rows = 1040
VFRAME: -5592.15
RVSYS: 0.00
CRVAL2 GLON: 134.48
CRVAL3 GLAT: 7.55
Row= 101 Channels= 1024: YY 24.360 K
Row= 202 Channels= 1024: XX 22.755 K
Row= 303 Channels= 1024: YY 24.302 K
Row= 404 Channels= 1024: XX 22.684 K
Row= 505 Channels= 1024: YY 24.566 K
Row= 606 Channels= 1024: XX 22.959 K
Row= 707 Channels= 1024: YY 25.103 K
Row= 808 Channels= 1024: XX 22.909 K
Row= 909 Channels= 1024: YY 25.540 K
Row= 1010 Channels= 1024: XX 22.844 K
Polarization Ids: XX (n=2)
Polarization Ids: YY
Writing Galactic positions
1-4: 2.347 0.132 257.000 0.077
1.117 0.000 1.550 0.573 0.000 1.550
1.297 0.000 1.550 0.053 0.000 1.550
1.162 0.000 1.550 0.376 0.000 1.550
Writing data word 0: 2.3472
Writing data word 1440000: 1.5726
Writing data word 2880000: 1.5466
writeSdfits: 12798720 data bytes (4441 FITS blocks)
El Stats: med=17.965 ave=17.966 rms=0.195 min=17.505 max=18.354
The region was observed in elevation range 17.505 to 18.354 d.
Tsys XX Stats: med=22.698 ave=22.696 rms=0.232 min=21.978 max=23.421
Tsys YY Stats: med=24.857 ave=24.853 rms=0.273 min=24.019 max=25.668
Wrote AIPS UV-FITS file: foo.fits
idlToSdfits summarizes the data in the keep file and writes out a .tex file.
Below is foo.tex:
The GBT observations by Lockman of source G133.5+3.0
were processed on 2005SEP02 using 'idlToSdfits' version 5.0.
GBT Project AGBT02C_023_03 was processed for imaging by AIPS.
The region was observed in Linear Polarization.
Center frequency was 1422.005317 MHz and the bandwidth was 5.000000 MHz.
The spectrum had 1024 spectral channels, with 4883 Hz channel width.
The Doppler tracking First LO reference frame was 'RADI-LSR',
and the velocity resolution was 1.029 km/sec.
The Line Rest Frequency for these observations was 1420.405800 MHz.
The velocity range is 190.057 to -864.218 km/sec.
The map contained 1040 integrations from scans 8256 to 8268.
The region was observed on 2003-05-31T01:51:32.00 until 2003-05-31T02:36:58.89.
Integration time was 2 seconds per spectrum.
The coordinate system of the observation was GALACTIC.
The average coordinates of these observations were 133d30'05", 7d51'01".
The region was observed in elevation range 17.505 to 18.354 d.
The median system temperature of all XX scans was 22.698 K.
The minimum, maximum and RMS system temperatures of
all XX scans were 21.978, 23.421 and 0.232 K.
The median system temperature of all YY scans was 24.857 K.
The minimum, maximum and RMS system temperatures of
all YY scans were 24.019, 25.668 and 0.273 K.
The idlToSdfits command line arguments are:
idlToSdfits -o foo.fits calibAGBT02C_023_03.fits
AIPS Hints
There is extensive help on Single Dish imaging in the AIPS Cookbook. However
a few points should be noted for convenient use of the AIPS SDFITS file.
- Use AIPS task UVLOD to read the output of idlToSdfits
- Look at the AIPS messages to find the catalog entry containing the data
getn ?
- If the data were observed in Galactic coordinates, you must convert the UV-Data header to RA/Dec values for the imaging step. Also the frequency axis may require updating
for older versions of AIPS. Use the commands below:
keystr 'RA'; keyword 'ctype4'; puthead
keystr 'DEC'; keyword 'ctype5'; puthead
keystr 'RA'; keyword 'ptype1'; puthead
keystr 'DEC'; keyword 'ptype2'; puthead
keystr 'FREQ'; keyword 'ctype3'; puthead
- Use PRTSD to look at the values in your data set
- Use POSSM to make an intensity versus channel/frequency spectral plot
- Use SDIMG to make images
- Look at the AIPS message to find the new image Cube
getn ??
- If the data header was converted to RA/DEC, convert back to galatic using:
keyword 'ctype1'; keystr 'glon-sin'; puthead
keyword 'ctype2'; keystr 'glat-sin'; puthead
If no arguments are given, the idlToSdfits prints a short bit of help
% idlToSdfits
idlToSdfits: Take a GBTIDL Keep file and
convert it to an AIPS-compatible Single Dish Fits File
idlToSdfits: usage
idlToSdfits [-t] [-c <start>:<stop>] [-o <outName>] <idlFitsFileName>
where [-t] optionally replace channel 1 with Tsys
(in order to produce a continuum image)
where [-c <start>:<stop>] optionally select channels for output
channel number range from 1 to N
where [-o <outName>] optionally specify output file name
where <idlFitsFileName> input name of IDL keep file to convert
example: idlToSdfits -t -c 10:20 -o output.fits input.fits
------------ Glen Langston == glangsto@nrao.edu
------------ December 07, 2005
-- GlenLangston - 07 Dec 2005
Revision r1.3 - 07 Dec 2005 - 16:45 GMT - GlenLangston
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idlToSdfits 
calibAGBT02C_023_03.fits 
foo_Cal.ps 
foo_CalSmall.gif 
