xrt_lalit930330.ear

caldb/data/asca/xrt/bcf

SUPERSEDED (see Section 2.2.3)

XRT effective area dataset constructed by the OGIP Calibration Database on 1993 May 10 from a series of ASCII files provided by Lalit Jalota of the NASA/GSFC ASCA mirror team from his ray tracing calculations of 1993 Feb/March.

The effective area dataset consists of a regular (6x6) 2-dimensional grid in ALPHA-BETA space, where ALPHA & BETA are cartesian coordinates in the focal plane, with 4 arcmin spacing. Due to the symmetry of the telescopes, only one quadrant of one telescope is mapped.

Lalit Jalota (NASA/GSFC XRT Team) as ASCII files, reformatted to OGIP standard by Ian M George.

HDUDOC/VERS = CAL/GEN/92-019/1.0.0
(see CAL/GEN/92-019, available on-line as postscript and html versions).

No information supplied to the CALDB.

• WARNING: This dataset is known to have the following problems:
  • One of the original ASCII files was missing (at ALPHA=4, BETA=8 arcmin)
    This FITS dataset was therefore created using the symmetric ALPHA=8,BETA=4 arcmin dataset it its place.
  • One of the original ASCII files (at ALPHA= 20, BETA=16 arcmin) contained NAN (not a number) values throughout.
    This dataset contains the value -99 within the FITS file
    EXTREME CAUTION IS THEREFORE REQUIRED AROUND THESE COORDS
  Lalit has promised to re-supply copies of the relevant ASCII files and the dataset will be updated asap
• No s/w currently exists to automatically access these datasets should an effective area for off-axis position in one of the other 3 quadrants be required.
  A Virtual calibration file & associated task is required.
• Similar datasets listed in Sections 2.2.1 & 2.2.3.