HETGS Line Profiles

Caveats on Using the LSF Library

Caveats on using the LSF library

The users must be aware of five caveats on using the LSF library:

The library works the best for the point source placed on the nominal aim point for science intrument,
in CIAO/tg_extract tool, set the keywords: $abs|min\_tg\_d| = max\_tg\_d,$ so that the extraction region is centered around the tg_d value = 0.0 deg (see Figure 6 below):

Figure 6: Caveat on the extraction region. Because of the way that EEFRACS is numerically derived, the extraction region must be centered at tg_d = 0.0 deg.
extraction widths should be greater than 2 ACIS CCD pixels (or 0.00014deg),
pixel randomization in tg_resolve_events must be set to 0.5pix (defined as default),
the LSF library support +1 order only, though the library seems to work O.K. with -1 order as well(*) as other higher orders.

(*) Not explicitly true for HEG as one of the HRMA mirror shell is misaligned appreciably.

The next section demonstrates the validity of the LSF library.

Previous: LSFPARM library Next: Validation

This page was last updated Dec 4, 2002 by Bish K. Ishibashi. To comment on it or the material presented here, send email to bish (at) space.mit.edu.