Re: Flexible Image Transport System (FITS) file format support

[Thomas D. Dean]

I downloaded rosat_pspc_rdf2_3_bk1.fits from
http://heasarc.gsfc.nasa.gov/docs/heasarc/ofwg/ofwg_samples.html

octave:115> [fid,msg]=fopen("rosat_pspc_rdf2_3_bk1.fits","r");
octave:116> [hdr1,cnt]=fread(fid,[80,36],"uchar",0);cnt
cnt =  2880
octave:117> char(hdr1')
<snip>
ans =
SIMPLE  =                    T / file does conform to FITS standard     
BITPIX  =                   16 / number of bits per data pixel         
NAXIS   =                    2 / number of data axes                   
NAXIS1  =                  512 / length of data axis1 1          
NAXIS2  =                  512 / length of data axis   2         
EXTEND  =                    T / FITS dataset may contain extensions    
CONTENT = 'IMAGE   '           / PSPC TOTAL-BAND BACKGROUND            
ORIGIN  = 'USRSDC  '           / origin of processed data              
DATE    = '11/04/94'           / FITS creation date (DD/MM/YY)          
TELESCOP= 'ROSAT   '           / mission name                    
INSTRUME= 'PSPCC   '           / instrument name                       
OBS_MODE= 'POINTING'           / obs mode: POINTING,SLEW, OR SCAN    
IRAFNAME= 'rp110590n00_bk1.imh' / IRAF file name                        
MJDREFI =                48043 / MJD integer  SC clock start         
MJDREFF =  8.79745370370074E-01 / MJD fraction SC clock start           
ZERODATE= '01/06/90'           / UT date of SC start (DD/MM/YY)         
ZEROTIME= '21:06:50'           / UT time of SC start (HH:MM:SS)         
RDF_VERS= '2.3     '           / Rationalized Data Format release ver
RDF_DATE= '24-MAR-1994'        / Rationalized Data Format release date  
PROC_SYS= 'SASS7_1 '           / Processing system                      
PROCDATE= '8-APR-1994 10:37:07' / SASS SEQ processing start date        
REVISION=                    2 / Revision number of processed data      
FILTER  = 'NONE    '           / filter id: NONE OR BORON               
OBJECT  = 'XRT/PSPC PSF AR LAC' / name of object                       
RA_NOM  =         3.320239E+02 / nominal RA (deg)                     
DEC_NOM =         4.551389E+01 / nominal DEC (deg)                
ROLL_NOM=        -1.349511E+02 / nominal ROLL (deg CCW  North)         
EQUINOX =         2.000000E+03 / equinox                         
OBS_ID  = 'CA110590P.N2'       / observation ID                       
ROR_NUM =               110590 / ROR number                       
OBSERVER= 'MPE, ROSAT-TEAM'    / PI name                            
SETUPID = 'NOMINAL '           / Instrument setup                  
DATE-OBS= '20/06/90'           / UT date of obs start (DD/MM/YY)        
TIME-OBS= '11:24:43.000'       / UT time of obs start (HH:MM:SS)        
DATE_END= '20/06/90'           / UT date of obs end   (DD/MM/YY)        
TIME_END= '13:07:12.000'       / UT time of obs end   (HH:MM:SS)        
<snip>
## use the values from BITPIX, NAXIS, NAXIS1, NAXIS2
octave:118> [bin1,cnt]=fread(fid,[512,512],"uint16",0);cnt
cnt =  262144
octave:119> fclose(fid)
ans = 0

plotting this with plot(bin1') gives something like what one would
expect from an intensity(?) plot.

One should be able to read the fits files with native octave code.