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Fits Headers Again



Below is some stuff copied (now directly) out of TN-67.  My plan is to make 
two files.  One is the fixed stuff and one varies run by run.  My question 
is, what is a fits extension?   Is it everything after the:  EXTEND 
=                      T/ line below or is it something else?

Tom Droege


Recommendations:
       Switch RA and DEC axis.
       CTYPE1 and CTYPE2 must read 'RA---TAN' and 'DEC--TAN', respectively.
       EXPOSURE keyword must be present, with correct exposure time in 
secomds.
       It's better to use reference pixels in the middle of image: CRPIX1, 
CRPIX2=1024.
       CDELT1 and CDELT2 are missing now, they must contain pixel 
increment at the reference pixel. In simpler terms, pixel size with 
possible negative sign if coordinate is decreasing with increasing pixel 
coordinates. Size is expressed in decimal degrees.
       Keyword IMAGETYP with possible values 'object', 'dark', 'flat' and 
'zero' should be included if IRAF proceessing of images will be used.
       Change DATE-OBS to include time as well, not only date.
       Inclusion of the following keywords may be useful
       RDNOISE in electrons.
       GAIN in electrons/ADU.
       CCD-TEMP or CAMTEMP with temperature in degrees Celsius.
       AIRMASS
Example of enhanced header after star matching (image H3R1659-826.fts):
SIMPLE  =                    T / file does conform to FITS standard
BITPIX  =                   16 / number of bits per data pixel
NAXIS   =                    2 / number of data axes
NAXIS1  =                 2043 / length of data axis 1
NAXIS2  =                 2037 / length of data axis 2
EXTEND  =                    T / FITS dataset may contain extensions
COMMENT   FITS (Flexible Image Transport System) format defined in Astronomy an
COMMENT   Astrophysics Supplement Series v44/p363, v44/p371, v73/p359, v73/p365
COMMENT   Contact the NASA Science Office of Standards and Technology for the
COMMENT   FITS Definition document #100 and other FITS information.
CTYPE1  = 'RA---TAN'           / Inserted by fitsblink
CRVAL1  =   2.263508539420E+02 / Inserted by fitsblink
CRPIX1  =   1.021500000000E+03 / Inserted by fitsblink
CROTA1  =   8.974035779811E+01 / Inserted by fitsblink
CTYPE2  = 'DEC--TAN'           / Inserted by fitsblink
CRVAL2  =   1.723629532873E+00 / Inserted by fitsblink
CRPIX2  =   1.018500000000E+03 / Inserted by fitsblink
CROTA2  =   8.974035779811E+01 / Inserted by fitsblink
BSCALE  =                   1.
BZERO   =               32768.
LATITUDE=                  42.
LONGITUD=                 -88.
FILTER  = 'V       '
DATE    = '2000-04-25'
DATE-OBS= '2000-04-25'
UT      = '07:49:52.00'
TIMESYS = 'UT      '
COMMENT    This file produced by TASS RawToFITS program  Version 1.1
CDELT1  =   2.150392161597E-03 / Inserted by fitsblink
CDELT2  =   2.150050490463E-03 / Inserted by fitsblink
IMAGETYP= 'object  '           / insert_keywords
EXPOSURE=         1.500000E+01 / insert_keywords
EXPTIME =         1.500000E+01 / insert_keywords
MATCHED =                    T / Inserted by fitsblink
END