HEAO-1 Software: Example 1 - Extracting a Lightcurve

To extract a lightcurve from the raw rates data, use the task a2source (step 1) and a2lcurve (step 2).

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)=01h 15m 45.7s, 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

The above listing contains raw data files for both 1.28 sec and 5.12 sec accumulation modes.

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

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