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Q&A: Chandra Mission
Q:
Why don't you have more public pictures available? I am assuming
that hundreds of black hole candidates, quasars, the core of our
own galaxy, pulsars, neutron stars, supernovas, etc...have been
imaged already and not released.
A:
The images are coming. However, they don't just come down from
the telescope in their full glory, and there are not thousands
of them. Only a few, actually. They come down as a data stream,
which is converted to an event file, which includes all sorts of
information that is mixed together. To get an image, the
scientists first have to figure out where the telescope was
actually pointing, since it moves around during the observation.
This is done by tracking fiducial lights on the spacecraft and
the positions of well-known stars. The spacecraft motion is then
taken out using a computer program. Then the background noise
due to the detectors, cosmic rays and the diffuse X-ray
background must be subtracted out. Finally, the scientists
select the energy band they want to look at to get the
information they want, and then the images have to be put in a
form for publication on the web. During the approximately three
and a half weeks that we have been calibrating Chandra, only
about a couple dozen sources have been observed. Most of these
observations have been out of focus, and off the axis of the
telescope to test the instruments and the mirror, so they don't
make good images. Some of the others are point-like, so they are
not too interesting. However, there are several beautiful images
that haven't been made public yet, and be assured, we are
working hard to get them out as soon as possible.