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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.


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