OSO-8 Software:
Example 2 - Extract a spectrum from a raw PHA file

artist concept of OSO-8

To extract a spectrum from the raw PHA data use the tasks osofindfast (step 1) and osopha (step 2).

Osofindfast, for a given sky position determines times when that position was viewed by the A, B or C detector. Osopha extracts a 63 channel PHA spectrum from the raw PHA data, and lightcurves in different energy bands with 40.96 sec time resolution.

* Obtaining the "good observing days" PHA data for input to osopha The PHA filenaming convention is Npha_XXXX_YYYY.fits where N is the detector (A, B, or C), XXXX and YYYY are the mission elapsed day number of the start and stop of this file (from 176 to 1369). The start and stop days are not all separated by the same amount. There is not a direct way to find the appropriate PHA file for a given position or time, however osofindfast can be used to determine the "good observing days". These day numbers are embedded in the raw rates filenames listed by osofindfast for the appropriate detector. After determining the "good days", the appropriate PHA files to input in the osopha are located in the OSO8 FTP area.

* Using osopha Run the routine OSOPHA. This task will produce both a collimator-corrected light-curve AND a 1-63 channel PHA spectrum (NON-background subtracted ; integration time of each data bin is 40.96 seconds). Before running this tool it is necessary to create an ASCII file containing a list of raw PHA files which correspond to the "good observing days".

% cat a0620_list

% osopha
Equinox (d/f 1950)[1950.0] 
RA in hh mm ss.s or degrees[95.046] 
DEC in dd mm ss.s or degrees[-0.32] 
Rootname for generated spectral (+rates) output[a0620] 
Desired detector [1=B,2=C]:[2] 
Input listfile containing raw PHA files[a0620_list] 
Contaminating srces in FOV check?(d/f no)[no] 
Start PHA channel for broad-band light-curve (d/f 1)[1] 
End PHA channel for broad-band light-curve (d/f 63)[63] 
No. raw data integ. records (d/f=1  BC=40.96s)[1] 
Low c/s threshold  for lightcurve (d/f -10000)[-10000.] 
High c/s threshold  for lightcurve (d/f 10000)[10000.] 
Start PHA  for soft-band lightcurve [1-63] (d/f 5)[5] 
End PHA  for soft-band lightcurve [1-63] (d/f 14)[14] 
Start PHA  for hard-band lightcurve[1-63] (d/f 15)[15] 
End PHA  for hard-band lightcurve[1-63] (d/f 63)[63] 
Input observation start date (dd/mm/yy)[29/09/75] 
Input observation start time (hh:mm:ss)[00:00:00] 
Input observation end date (dd/mm/yy)[03/10/75] 
Input observation end time (hh:mm:ss)[00:00:00] 
OSOPHA 1.0.0 start PHA + rates..
 OBJECT NAME                     a0620
 SOURCE RA and DEC (1950)   95.046  -0.320
 RAW DATA FILE LIST a0620_list
 START and END channels for LC creation    1  63
 Integration time (no. raw data records to integrate) 1   
 INTENSITY CUT (cnts/sec)   -10000.000   10000.000
 Mean BROAD band BKGD level (c/s)        0.000
 Mean SOFT band BKGD level (c/s)        0.000
 Mean HARD band BKGD level (c/s)        0.000
 START day (of 1975) and MILLISECS of that day : 
                        272           0
 END day (of 1975) and MILLISECS of that day : 
                        276           0
 Creating a0620.lc
 Creating a0620.spec
 MEAN RATE (+error) for PHA data (c/s/detarea) :  
                            8.083     0.002
 HARDNESS RATIO for PHA  data :   0.021
 PHA ACCUMULATION TIME (secs) : 26202.357
 NET AREA of detector (sq. cm) : 61.67
 INTEGRATED RATE for PHA data (c/s) :  498.4867
 **** OSOPHA 1.0.0   **** finished

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