M2 is the science scope (the 12.5″ with the SBIG ST-8XME), and it’s been offline for over a month now due to camera issues. All the images from the camera had horizontal stripes across them, and successive images had the bands in different places. Most of the suggested reasons for something like this had to do with electronic interference due to the shape/size of the bands and the face that the bands were moving. Since they didn’t show up in the same place twice there was obviously nothing wrong with the sensor itself. I ruled out any other potential sources of weirdness from the rest of the imaging train by testing this on a bias image.

The evil bands

We tried everything we could think of to eliminate the issue:

  • Changing USB cables
  • Trying every USB port on the computer
  • With/without using a USB hub
  • Trying a shorter USB cable
  • Trying a different computer
  • Trying it with all other equipment turned off
  • Making sure no cables were touching
  • Making sure the power supply was plugged into a grounded outlet
  • Trying a different grounded outlet…

The only thing I couldn’t try was testing it with a different power supply, but by that point it was time to send it in to SBIG. Turns out the issue was a wiring issue with the fan, but while it was there they also found and repaired an air leak under the heat exchanger. I’ve had issues in the past with the sensor frosting up easily even under moderately humid conditions, so this was probably the culprit causing that. Usually when that happened I would just image at a higher temp for the night and turn on dew heater straps – it didn’t happen often enough for me to think it was an issue, plus I wasn’t the original owner of the camera so I don’t know if it was any different when it was new.

They baked the camera, recharged the dessicant plug, and cleaned the sensor, so it’s coming back in much better condition than before. Since the scope is remote I don’t have a chance to bake the dessicant plug, although I hadn’t worried about it too much since it’s currently in a much drier area than it was when it was outside the house. I’ll also have to retake all my flats since there won’t really be any dust on the sensor, but that’s a pretty good reason to have to retake flats. 🙂 Should probably be doing them more often anyway…