EXOPHA
	
USAGE
    exopha -o outfile -r rate -e error -i instrume -f filter -x exposure
	    
DESCRIPTION

 This script generates one channel OGIP FITS PHA file for the Low Energy 
 telescope used in conjunction with the Channel Multiplier array detectors 
 (CMA1 and CMA2) on board EXOSAT. Response matrices suitable for the spectral 
 files generated by this script are available in the HEASARC calibration
 database. The PHA file and response matrices are in XSPEC compatible format.
 To create the PHA file, the script invokes the task 'ascii2pha' available 
 within the heasarc package currently distributed with ftools. The required
 input paramaters are : count rate and error, detector name, filter, exposure
 and output filename. The filter values for both CMA1 and CMA2 are : 
 PPL, 4Lex, 3Lex,Bor,AL/P. Since the CMA1 and CMA2 (all filters) response 
 matrices are on-axis, the count rate for off-axis sources should be 
 corrected as observed on-axis using 'exovign'. Deadtime due to 
 telemetry loss can considerably effect the count rate and ultimatly 
 the flux estimate. The input count rate should therefore derived from 
 images or lightcurves corrected for deadtime using 'cmadead'.
 All input parameters can be entered either in response to prompts or 
 on the command line by using the appropriate flags.
 
FLAGS

     -h - Prints this help file
     -y - overwrite an existing FITS file 

    the following flags require arguments
     -o - the output FITS file name 
     -r - the count rate
     -e - the count rate error
     -i - the instrument [CMA1 or CMA2 only]
     -f - the filter [3Lx, 4Lx, Al/P, Bor, PPL]
     -x - the exposure time in seconds

 Parameters set within the script and relevant for the EXOSAT mission:

 telescope=EXOSAT
 areascal=86.4

EXAMPLES 

   Create a CMA1 pha file with a count rate of 2e-3 +/- 1e-3
   in the 3Lx filter with an exposure of 2000 seconds   
  > exopha -o output.pha -r 2e-3 -e 1e-3 -i cma1 -f 3Lx -x 2000