Local FITS Keywords
at Other Institutions


File keywords_local.html
Last updated by Tom Kuiper on 2000 July 11.

Introduction

As intended by its creators, use of FITS grew faster than the evolution of its standards. As a result, there are now many separate, locally-defined keywords, not all of which are adequately documented. Here's an example:

Integration Time
Keywords Where Used Reference Meaning
EXPOSURE HEASARC http://heasarc.gsfc.nasa.gov/\
  docs/heasarc/ofwg/docs/\
    ofwg_recomm/r11.html		 integration or exposure time in seconds
SDF http://www.cv.nrao.edu/fits/\
  documents/drafts/dishfits/
Lick http://www.ucolick.org/~sla/fits/
EXPTIME HST http://archive.stsci.edu/keyword/
SOHO http://orpheus.nascom.nasa.gov/
ELAPTIME Keck http://www.ucolick.org/~sla/fits/
OBSTIME Bell Labs   This could be distinguished from EXPOSURE if the observing mode is factored in to calculating EXPOSURE from OBSTIME
SEST La Silla  
CLASS  
TTIME Keck http://www.ucolick.org/~sla/fits/ Target length of time for the exposure (sec); has same value as EXPOSURE. It could be distinguished from EXPOSURE if TTIME were the intended integration time and EXPOSURE were the actual integration time.

Local Keywords Elsewhere

The following is an evolving compilation of keywords used by other institutions. If a definition appears to be unique, it is probably safe to use it as a DSN FITS keyword.

SEST La Silla

KeywordExampleExplanationComment
OBSTYPE'SIG ' type of observation (SIG/REF/CAL/DAR/COM/AVE) Similar function as NOAO IRAF package's DATA-TYP
POWER-S 5.78776460E+04 power received in the signal phase
POWER-R 5.79042331E+04 power received in the reference phase
TLOAD 282.10 cold load temperature (K) = SDF keyword TCOLD
DBLOAD 3.1998 load attenuation (dB)
CHOPPERW 1.0078 chopper wheel factor
TAU-ATM 0.1010 optical depth of the atmosphere (neper)
NPHASE 0 number of frequency phases
DELTAF1 0.000000 frequency offset, phase 1 (Hz)
PTIME1 0.000000 duration of phase 1 (sec)
WEIGHT1 0.000000 weight of phase 1
DELTAF2 0.000000 frequency offset, phase 2 (Hz)
PTIME2 0.000000 duration of phase 2 (sec)
WEIGHT2 0.000000 weight of phase 2
UTC '23:07:17.00' universal time at start of observation
JDATE 2450981.46339120 julian date at start of observation
TMODE 'ENABLED ' telescope mode
RA 238.26378291 object apparent right ascension (deg)
DEC -54.61217813 object apparent declination (deg)
RAOFF 0.00000000 offset in right ascension (sky deg)
DECOFF 0.00000000 offset in declination (sky deg)
AZOFF 0.00000000 offset in azimuth (sky deg)
ELOFF 0.00000000 offset in elevation (sky deg)
AZPOINT 0.20305309 total pointing offset in azimuth (instr.deg)
ELPOINT -0.05057055 total pointing offset in elevation (instr.deg)
AZCORR -0.00011111 pointing correction in azimuth (sky deg)
ELCORR 0.00352778 pointing correction in elevation (sky deg)
REFRAC 0.01450700 refraction angle at current elevation (deg)
VLSR -44500.000 velocity of reference channel (m/s) similar to SDF (RVSYS-VFRAME) for VELDEF = "RADI-LSR"
DELTAV -1.93202950E+03 velocity spacing of channels (m/s)
RELEASE'dev ' software version