I want to photograph comet Lemmon over the next few nights. I’ll be doing it at 900mm with a mono setup. It this point I’m more worried about the data capture end, I’ll deal with the different processing options later. I’m looking for basic advice about guiding, filter rotations and anything else I might need to consider.
Comet imaging
Well Written Engaging
First piece of advice: get the colour camera out, saves a lot of headaches.
Second piece of advice: get the colour camera out, saves a lot of headaches.
Third piece of advice: since you didn't listen, shoot RGB only.
Other stuff:
1. Get that comet's time drift and compare to your typical FWHM; that is the length of the exposures (1.5xFWHM/Drift)
2. Think of interleaving, with at least as much time between exposures as the exposure time (best 2x though)
3. Cycle between the RGB filters for each exposure
4. Go back to the same field in few days and shoot the same total exposure time
5. Guide on the stars, selecting the ones you want and discarding the comet's nucleus
Second piece of advice: get the colour camera out, saves a lot of headaches.
Third piece of advice: since you didn't listen, shoot RGB only.
Other stuff:
1. Get that comet's time drift and compare to your typical FWHM; that is the length of the exposures (1.5xFWHM/Drift)
2. Think of interleaving, with at least as much time between exposures as the exposure time (best 2x though)
3. Cycle between the RGB filters for each exposure
4. Go back to the same field in few days and shoot the same total exposure time
5. Guide on the stars, selecting the ones you want and discarding the comet's nucleus
Helpful
lol, I think I’ll use a color camera….
The shift rate is 0.025” arc sec per sec.
1.5 × 2.5/0.025 = 150 sec.
Looks like there’s plenty of time for my normal range of sub lengths. Given that, it really wouldn’t be a problem to do it in mono….
Imaging with mono is not that difficult, so that it should be avoided by all means . It can be done by mono camera . It is good to have filter offsets known so that no refocusing is needed between changing filters and then you cycle RGB (one R, ong G, one B and then again…) . You may dither within the cycle… and that is all…