New SIS matrices for AO-2 simulations

["Charles Day, ASCA GOF, NASA GSFC" <DAY@heagip.gsfc.nasa.gov>]

There is now a new set of SIS response matrices for ascertaining the
feasibility of ASCA AO-2 proposals.  They have been created from the
in-flight calibrations and are the best available as of 20 December 93.
The matrices can be obtained via anonymous FTP at:

   legacy.gsfc.nasa.gov

in the directory

   asca/nra_info/responses/sis


Please bear in mind the following points:

 o Since these matrices are just for simulations, only one combination
   of SIS and chip is given, namely SIS0-chip1.

 o The matrices have 512 channels and are in FITS format.

 o The four matrices correspond to four different positions on the chip:

      s0c1_1ccd.rsp ..... default pointing position in 1-CCD mode
      s0c1_2ccd.rsp ..... default pointing position in 2-CCD mode
      s0c1_4ccd.rsp ..... default pointing position in 4-CCD mode
      s0c1_center.rsp ... center of chip

   They differ from one another in their vignetting. Roughly, the 4-CCD,
   2-CCD, 1-CCD and center positions are 4, 5, 7 & 7 arcmin off axis,
   respectively.
   
 o If it's not too late, please do your AO-2 simulations with these new
   matrices. However, proposers will not be penalized if they use the
   old, AO-1 matrix: the main difference between the old and the new is
   that the new ones have a bit less effective area - not enough in most
   cases to affect feasibility.

 o AS FOR AO-1, PLEASE REMEMBER TO DOUBLE THE INTEGRATION TIMES IN YOUR
   SIMULATIONS TO ACCOUNT FOR THE FACT THAT THERE ARE TWO SIS CAMERAS.
   For example, to simulate a 30 ks observation, you should integrate with
   these matrices for 60 ks.

Charles Day, ASCA GOF