NAME

osorat -- Extract lightcurves from the OSO8 raw rate data

USAGE

        osorat equinox ra dec detector filelist outfile 

DESCRIPTION

This task extracts background subtracted and collimator corrected lightcurves from the OSO8 raw rate data obtained with the CGXSE experiment for a given sky position. The CGXSE on board OSO8 consisted of three proportional counters (2 xenon, 1 argon). Two detectors (B and C) had fields of view aligned with the spin axis in opposite directions. The third, detector A, is offset 5 degrees from the spin axis and is located on the same side as the B detector. The fields of view (FOV) were 5, 3 and 5 degrees for the detectors A, B and C respectively. The B and C were pointed detectors, instead A was a scanning detector. The program uses as input the OSO8 raw rate data files as stored in the HEASARC archive. Each file contains one day of data for the A, B and C detectors. To select the OSO8 raw rate data file which most likely includes a given sky position in the detector FOVs, users should run first the script 'osofindfast'. This determines which detector viewed a particular position throughout the entire OSO8 mission and outputs a file list of filenames, one for each detector, as input for 'osorat'.

Only lightcurves for one detector (A, B or C) can be extracted during each run of 'osorat'. For a given detector multiple lightcurves are output if a source position was observed several times during the OSO8 mission at intervals greater than a week. The output lightcurve excludes data detected below a default detector collimator response. These limits are set in the parameters 'arlima', 'arlimb' and 'arlimc' for the A, B and C detectors respectively in unit of cm**2. Data are also excluded if an overflow is detected in the telemetry stream. The default setting excludes telemetry records (~66 points of 160 ms each ) if an overflow occurs in any of the detectors. Less restrictive data filtering is allowed by changing the parameter 'filter'. The background levels (and errors) are set to fixed values, different for each of the detectors, corresponding to the nominal detectors plus sky as best known. These values can be altered using the appropriate parameters relative to each of the detectors. The time resolution of the output lightcurves is 0.16 seconds. For the detector A the program currently does not account for confusing sources included in the A detector FOV during a spin revolution (~10 seconds), therefore it should be used with caution.

PARAMETERS

equinox [real]

Equinox of the input sky position (default value 1950)

ra [string]

The Right Ascension given in hh mm ss.s or degrees.

dec [string]

The Declination given in dd mm ss.s or degrees.

detector [integer]

Detector number. The program extracts lightcurves for only the one detector specified in this parameter. The parameter values are 1, 2 and 3 for the detector A, B and C respectively.

filelist [string]

The name of the file containing the list of raw rates files (listed as one filename per line). The file list can be created using the script 'osofindfast'.

outfile [string]

The root name for the output lightcurves. The program will output multiple lightcurves if there is an interval greater than a week between observations of the source position. The lightcurves are named by adding a sequential number to the 'outfile' parameter starting from 1.

(binspin) [boolean]

Logical flag to indicate whether the user wishes the data to be binned once per spin revolution. By default this parameter is 'no' and the data are binned at 0.16 seconds. By setting this parameter to 'yes' the data are binned at once per spin revolution, which corresponds to about 10 seconds.

(arlima=10.0) [real]

Only data above the detector area limit set by this parameter are included in the output lightcurves. The area of the A detector is 263 cm**2 and the area limit is currently set to 10 cm**2.

(arlimb=5.0) [real]

Only data above the detector area limit set by this parameter are included in the output lightcurves. The area of the B detector is 76 cm**2 and the area limit is currently set to 5 cm**2.

(arlimc=50.0) [real]

Only data above the detector area limit set by this parameter are included in the output lightcurves. The area of the C detector is 237 cm**2 and the area limit is currently set to 50 cm**2.

(abkg=3.4) [real]

Background value for the A detector given as count per 0.160 seconds.

(bbkg=0.16) [real]

Background value for the B detector given as count per 0.160 seconds.

(cbkg=1.6) [real]

Background value for the C detector given as count per 0.160 seconds.

(abkgerr=0.12) [real]

Background error for the A detector for 0.160 seconds integration time.

(bbkgerr=0.008) [real]

Background error for the B detector for 0.160 seconds integration time.

(cbkgerr=0.08) [real]

Background error for the C detector for 0.160 seconds integration time.

(filter=1) [integer]

Set filtering due to data overflows. The values range between 1-4 with the following meaning. Filter value=1 (default), skip an entire record of data if an overflow is detected for that record in any of the detectors. Filter value=2, skip only one data point if overflow is for that data point in any of the detectors. Filter values 3 and 4 skip either a record or a point if overflow occurs in the detector for which the lightcurve is extracted.

CATEGORY