National Aeronautics and Space Administration

HEAO-1 Software:
Example 1 - Extracting a Lightcurve

Using a2source (step 1)

Run the task A2SOURCE. This tool determines the days of the mission when the source is MOST likely to have been scanned by the A-2 instrument (the `good' observing days). For example, consider the source SMC X-1 (coordinates R.A.(1950)=01^h 15^m 45.7^s, Dec (1950)=-73° 42' 21.8'')

% a2source
Equinox (d/f 1950)[1950] 1950
RA in hh mm ss.s or degrees[] 01 15 45.7
DEC in dd mm ss.s or degrees[] -73 42 21.8
Name of the source:[] smcx1
A2SOURCE 1.1.0 start calculations
          RA      DEC    B1950       01 15 45.7  -73 42 21.8
          RA      DEC    B1978.0     01 16 30.2  -73 33 31.3
          RA      DEC    J2000       01 17 05.3  -73 26 34.4
          L(II)   B(II)                 300.415   -43.560
          EC.LNG  EL.LAT  1978.0        312.050   -66.468
Output file created : smcx1_hedfiles.lis
Output file created : smcx1_medfiles.lis

% cat smcx1_hedfiles.lis

# File listing for :
# RA      DEC    B1950       01 15 45.7  -73 42 21.8
a2_xrate0506hed_128.raw
a2_xrate0507hed_128.raw
....... etc etc
a2_xrate0536hed_128.raw
a2_xrate0874hed_128.raw
a2_xrate0875hed_128.raw
....... etc etc
a2_xrate0904hed_128.raw
a2_xrate0506hed_512.raw
a2_xrate0507hed_512.raw
....... etc etc
a2_xrate0536hed_512.raw
a2_xrate0874hed_512.raw
a2_xrate0875hed_512.raw
....... etc etc
a2_xrate0904hed_512.raw

Using a2lcurve (step 2) Run the task A2LCURVE. This tool generates a background-subtracted light curve from either the MED detector OR from one of the 3 HED detectors, for a single source position (the code analyses the 5.12 sec data ONLY).

% a2lcurve
Equinox (d/f 1950)[1950.0] 
RA in hh mm ss.s or degrees[] 01 15 45.7
DEC in dd mm ss.s or degrees[] -73 42 21.8
Input listing file[] smcx1_hedfiles.lis
rootname for generated lightcurve:[] smcx1
Input observation start date (dd/mm/yy)[01/08/78] 20/04/78
Input observation start time (hh:mm:ss)[00:00:00] 
Input observation end date (dd/mm/yy)[07/08/78] 20/05/78
Input observation end time (hh:mm:ss)[00:00:00] 
Detector for light curve generation [2=HED-1,3=HED-2,4=HED-3]:[2] 
First discovery scalar for detector  [+/- 1 - 8]:[1] 
Second discovery scalar for detector  [+/- 1 - 8]:[2] 
Third discovery scalar for detector  [+/- 1 - 8]:[3] 
Fourth discovery scalar for detector [+/- 1 - 8]:[4] 
Beginning scan angle limit for detector :[0.0] 
Ending scan angle limit for detector :[360.0] 
Filter data by McIlwain L parameter?[yes] 
Upper limit McIlwain L value [Earth radii]:[1.2] 
Background type [0 = scanned, 1 = Marshall, 2 = input]:[1] 
Using background values from Marshall table
A2LCURVE 1.1.0 start light curves
 
 OBJECT NAME            smcx1
 SOURCE RA AND DEC (1950)   18.940 -73.706
 DETECTOR    2 DISCOVERY SCALARS   1  2  3  4
 SCAN ANGLE LIMITS      0.000   360.000
 BACKGROUND TYPE  1
 Creating smcx1_rate1.lc

## SUCCESSFULLY CREATED LIGHT CURVE :           smcx1_rate1.lc
 
 Average bkgd for light curve    20.98 cnts/s
 with Root Mean Square Deviation     0.60
 for   31 raw data files for which bkgd was measured
 
 Diff btween avrge & MODEL bkgd for lc     0.76 cnts/s