GIS Night-Earth Event Lists available in the OGIP Caldb

["Ian M George, Code 668, NASA/GSFC, USA (Usque ad mortem bibendum)" <GEORGE@lheavx.gsfc.nasa.gov>]

          New GIS Calibration Files in the CALDB
          **************************************

A set of new files for the ASCA GIS have recently been installed in the OGIP
caldb at NASA/GSFC: 
	/caldb/data/asca/gis/bcf/bgd/night_earth

A README is provided in the above directory (and appended below) giving 
further information on the creation & use of these files.

Ian M George
NASA/GSFC, HEASARC

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GIS Night Earth Event files (July, 1st, 1994)

     Ken Ebisawa (ASCA GOF, GSFC) &
               Yoshitaka Ishisaki (Univ. of Tokyo)

Files in this directory are GIS night earth event files taken from May 28
1993 (GIS Spread Discriminator ON) to Feb 8 1994 (just before the GIS3 CPU
trouble).

The files night_earth_g2_all.evt and night_earth_g3_all.evt include all the
GIS2 and GIS3 events, respectively.  Other files have events
sorted with the magnetic Cut-Off-Rigidity values with which the data
are taken.
For example, night_earth_g2_10cor12.evt includes GIS2 events which
are taken with the COR range 10 <=COR < 12.  It is known that GIS intrinsic
particle background increases for lower COR values. (see an article
by Kubo et al. in the ASCA News Letter vol 2).

The PHA dependent RTI (Rise Time Invariance) filter HAS BEEN APPLIED
to these data (with the 'gisclean' command in XSELECT).  When these
data are used for BGD subtraction, the data also should be filtered
with 'gisclean'.

The exposure times of the files are the following (the unit is second):

     all         1.3e6     100 %
     cor < 4     7.6e3     1 %
4  <=cor < 6     1.1e5     9 %
6  <=cor < 8     1.1e5     9 %
8  <=cor < 10    1.6e5     12  %
10 <=cor <12     4.0e5     31  %
12 <=cor <14     3.9e5     30  %
14 <=cor         6.4e4     5 %


The count rate of the data are the following:

                G2_center   G2_outer   G3_center   G3_outer
 all cor        6.3e-3      8.6e-3     6.6e-3      8.3e-3
     cor < 4    9.5e-3      1.5e-2     9.2e-3      1.4e-2
4  <=cor < 6    8.6e-3      1.3e-2     9.1e-3      1.2e-2
6  <=cor < 8    6.6e-3      9.8e-3     6.9e-3      9.3e-3
8  <=cor < 10   7.0e-3      9.1e-3     7.0e-3      8.8e-3
10 <=cor <12    6.5e-3      8.4e-3     6.9e-3      8.2e-3
12 <=cor <14    5.3e-3      7.0e-3     5.4e-3      6.8e-3
14 <=cor        4.9e-3      6.7e-9     5.1e-3      6.5e-3

Unit =  cts/sec/cm2
Center = r < 15 arcmin
Outer  = 15 < r < 20 (excluding the calibration source)
GIS 1 pixel = 0.25 mm = 0.24558 arcmin
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