>
> Hello,
>
> I am wondering about the properties of possible trails along the readout
> axis in ACIS images.
>
> The issue is that in an image we have found what appears to be a real
> trail behind a point source, however it is along a column of S3, which is
> the readout axis. We're wondering what the expected properties of
> instrumental trails are so that we can compare with the data.
>
> The trail is behind a faint but very significant point source and we have
> verified that it is not an aspect problem ie the events from the trail are
> distributed evenly in time during our 20 ks observation.
>
> Vicky
>
> *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
> Victoria M. Kaspi
> Associate Professor
> McGill University
> Physics Department
> Rutherford Physics Building
> 3600 University Street
> Montreal, Quebec
> Canada H3A 2T8
>
> Phone: 514-398-6412
> Fax: 514-398-3733
> URL: http://www.physics.mcgill.ca/~vkaspi
> *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
>
>
>
Vicky,
Thanks for the question about the ACIS transfer streak. There's
a description of the phenomenon in section 6.12.4 of the POG,
which gives the crucial number: ACIS is read out at 40 microsec
per pixel. The ratio of this number to the frame time for your
observation (often 3.2 sec, but user-selectable) gives the ratio
of the number of photons in the main image to those *per pixel*
in the transfer streak. The streak should also, within errors,
have a constant brightness vs. chipy.
cheers,
Dick Edgar
This archive was generated by hypermail 2b29 : Thu Dec 13 2012 - 01:00:05 EST