Quote:
Originally Posted by Paul Haese
Cracking data collection there Mike and Trish. Smooth image with good detail. Colour is nice in the galaxy. Star forming regions look cool and like you say heaps of galaxies in the back ground. Well done.
There is some odd red dots in the image though. One in the actual galaxy and one just to the upper right of it.
Overall another interesting image. 1 hours subs.  |
Thanks, Paul!
Finally figured out what those red blobs are. They plagued the Yoda image (resolved with lots of H-alpha), and now this. There were some tiny nano-bits of translucent spludge (spider slime or something repulsive) on the red filter, and starlight was illuminating them. Even though the translucent blobs were fixed on the filter, and we move the camera by many pixels between shots, the red blobs moved with mostly with the stars, not the chip. That meant it took a long time for us to suspect the filters.
The camera + filter wheel + guider weighs about 10 kg, was 2.5 metres up in the air, comes off as a single unit (after undoing 4 bolts), and is at an awkward angle, discouraging safe removal. Yesterday we positioned the scope to be pointing at the zenith, made a giant stand to go under the camera combo, removed, disassembled and cleaned the filter set. Found the main blob and some others. We could see more dust landing on it, even while we worked. But now we understand what was causing it, and have a system, we should have less trouble in future.