ascalin HEADAS help file

NAME

ascalin -- Calibrate ASCA Science File to produce linearized detector coordinates, gain corrected PI values, and aspected sky image.

USAGE

1. Aspect Science File to mean pointing during file time:

            ascalin datafile calfile tempofile attitude ATT

2. Aspect Science File to RA/DEC_NOM keyword values:

            ascalin datafile calfile tempofile attitude KEY

3. Aspect Science File to user selected RA/DEC:

            ascalin datafile calfile tempofile attitude USER RA DEC

4. Fixed aspect using Euler angles E1/E2/E3:

            ascalin evtfile calfile timfile EULER E1 E2 E3

where,

datafile = name of event file to be processed
calfile = name of teldef file (or DEFAULT, CALDB)
tempofile = name of gain history file (or DEFAULT, FTOOLS, NONE)
attitude = name of attitude file (or DEFAULT, EULER, NONE)
pointing = method to determine aspect point (KEY, USER, ATT->file mean)
RA,DEC = aspect point, if pointing = USER
E1,E2,E3 = Euler angles to use if attitude = EULER

DESCRIPTION

Program to calibrate the ASCA data; ASCALIN transforms the raw telemetry values to physical values. The results are written out to the input Science File: DETX, DETY (detector coordinates), X, Y (sky coordinates), and PI columns. The transformations are defined by the appropriate Telescope Definition File (teldef file), Temporal (Gain) History File, and Attitude File.

ASCALIN works on SIS FAINT, BRIGHT, and BRIGHT2 mode data, and all GIS PH data mode configurations.

The sky reference point for the aspecting may be selected from either the Science File RA/DEC_NOM nominal R.A. and Dec. keywords (pointing=KEY), a given input value (pointing=USER), or the file average defined as the Attitude File mean R.A. and Dec. during the Science File stop and start time (pointing=ATT).

The option is available to perform a 'fixed aspect' using a set Euler angles to calculate the sky X, Y binned R.A. and DEC. coordinates for each event (attitude=EULER).

Another option (attitude=NONE) is available to update the PI channel without re-calibration the spatial coordinates. The parameters gainnorm and gainoff allow for an overall gain and offset adjustment to the PI scale for both the SIS and GIS. The intent is that you can simply put in the numbers from fiddling with the gain command in XSPEC.

The names of calibration files may be enter by various means. The most direct way is the give the complete file name and path for the prompted parameters. If the CALIBRATION DATABASE is set up at your site, and the requested file is available, the CALDB option will automatically return the correct file name and path. The FTOOLS option will return the default file stored in the FTOOLS REFDATA area, if available. Site wide defaults calibration files names can be stored in the default parameters (see below) and invoked using the DEFAULT option.

A convenient option is available to determine the correct attitude file. If the DEFAULT option is invoked the attitude file name will be deduced from the FRF name stored in the science file. This filename will be appended to the path stored in the defATTpath parameter. This is useful if there is a common directory with all the attitude files.

Don't forget that for some merging programs to work correctly (e.g. XSELECT), all science files for a particular sequence must be aspected to the _same_ celestial location.

See ATTITUDE help file for additional details.

PARAMETERS

datafile [file name]: The ASCA science file to be processed.
calfile [file name]: The Telescope Definition file appropriate for the Science File instrument. If 'caldb' is entered, the appropriate CALDB file will be used, if available. If 'default' is entered, the appro- priate default file name stored in the default parameters will be used.
tempofile [file name]: The Temporal History file appropriate for the Science File instrument. If 'default' is entered, the appropriate default file name stored in the default parameters will be used.
attitude [file name]: The Attitude File. If 'euler' is entered, a 'fixed aspect' will be performed using the prompted Euler angles. If 'default' is entered, the path name stored in default parameters will be app- ended to the attitude file name stored in the file header. If 'none' is entered, then ASCALIN will leave the spatial coordinates intact and recalibrate the PI channels.
pointing [string]: The pointing choice: KEY/USER/ATT (see text above).
ranom [real] (prompted for if pointing=USER): The aspect sky point R.A. (center of image array)
decnom [real] (prompted for if pointing=USER): The aspect sky point DEC. (center of image array)
eulerphi [real] (prompted for if attitude=EULER): The aspect first Euler angle phi.
eulertheta [real] (prompted for if attitude=EULER): The aspect second Euler angle phi.
gainnorm [real] (hidden parameters): A overall gain scale correction to the PI channel values. Normally should be set to 1.0. This is a dimensionless number, which is compatible with the output of the gain command in XSPEC.
gainoff [real] (hidden parameters): A overall gain scale offset correction to the PI channel values. Normally should be set to 0.0. This units are keV, which is compatible with the output of the gain command in XSPEC.
xxxcol [string] (hidden parameters): The various appropriate science and attitude file column names.
verbose [logical] (hidden parameters): The verbose flag: run time information updates.
verbose [logical] (hidden parameters): The history flag: obsolete.
defxxxfile [string] (hidden parameters): The various appropriate Telescope Definition and Temporal (Gain) History file names.
defATTpath [string] (hidden parameters): The path pointing to the Attitude file.

EXAMPLES

1. Aspect science file using RA/DEC_NOM values for pointing. Use default values for calibration file locations (if applicable to site and set up properly in the parameter file, as explained above):

               ascalin datafile caldb ftools default ATT

2. Aspect science file to mean file pointing:

               ascalin datafile teldef_file gain_history_file attitude_file ATT

3. Use default files and aspect science file to user RA/DEC:

               ascalin datafile default default default USER 90.9 65.2

4. Use default files with Euler angles:

               ascalin datafile default default EULER 90.9 24.8 1.0

BUGS

Compatible with FRFREAD version 2.995 and higher.

Please report problems to gotthelf@gsfc.nasa.gov.

AUTHOR

Eric Gotthelf.