Henric Krawczynski <krawcz@astro.yale.edu> asked:
> Dear Colleagues
>
> I wonder if you have information on the following problem. I have an ACIS
> S imaging observation with a very strong source (standard data taking
> mode). The excess, strongly affected by pile-up, has a "doughnut"-shape,
> with an event deficit just in the center of the excess. Probably one might
> estimate the source brightness from the "streaks" above and below the
> source. Do you have any information about the "effective exposure time for
> pixels along the streaks" relative to the exposure time in normal data
> taking mode?
>
> Yours,
> Henric Krawczynski
The transfer time in the normal observing mode is 40 microseconds per pixel.
This plus a bit of thought will lead to a proper exposure time in the
transfer streak. Another ingredient, of course, is the source structure
(which sounds like a point source from your description). This may
be documented in more detail somewhere, but I can't put my hands on
it in a half hour of searching. Mark Bautz gave a talk on it at
the 1997 meeting of the AAS High Energy Astrophysics Division; and
it's mentioned in passing in section 6.12.4 of the Proposer's Observatory
Guide, Rev 2.0 (p. 97).
Questions like this will reach a larger audience (than 2 or 3 members
of the calibration group) if you send them to the mailing list 'chandra-users@head-cfa.harvard.edu'. I'm copying them on the
question in case someone has a better suggestion.
Richard Edgar
-- ============================================================================= Richard J. Edgar edgar@head-cfa.harvard.edu | "It all depends, of course, Harvard-Smithsonian Center for Astrophysics | upon whether or not it depends 60 Garden St., MS 70, Cambridge, MA 02138 | or not, of course, if you take phone: (617)495-7249; fax: (617)495-7356 | my meaning." --John Woolley
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