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Imaging dim comets like c2022 ZTF

Celestron EdgeHD 8" Optolong L-Pro Acquisition Solar System Comet
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gfunkernator avatar
gfunkernator avatar
Having some trouble getting good data for this comet.  I can only do 15-30” exposures at high gain/ISO.  Anything longer than that produces the comet trail.  I tried to collect about an hour of data but I barely see anything more than the hazy cloud around the comet after stacking.  I also used the L-Pro filter.  Could that be blocking important signal?

I've seen posts on here of this comet and the subs were more than a minute, some cases 180".  I'd like to image it with my c8+asi2600mc just wanted to hear from others on their acquisition techniques.
Engaging
andrea tasselli avatar
andrea tasselli avatar
Having some trouble getting good data for this comet.  I can only do 15-30” exposures at high gain/ISO.  Anything longer than that produces the comet trail.  I tried to collect about an hour of data but I barely see anything more than the hazy cloud around the comet after stacking.  I also used the L-Pro filter.  Could that be blocking important signal?

I've seen posts on here of this comet and the subs were more than a minute, some cases 180".  I'd like to image it with my c8+asi2600mc just wanted to hear from others on their acquisition techniques.

Track on the comet's nucleus and you'll have longer integrations, considering that it moves at 14"/min. I doubt that using a C8 and a 2600MC is a good idea, even at bin 2x. Never mind the high moon.
gfunkernator avatar
gfunkernator avatar
@andrea tasselli 

Track on the comet with short or long exp length in PHD2?  2 seconds should be enough right?  What about the use of the L-Pro filter?  Should I use a filter or no?
Jonathan W MacCollum avatar
Jonathan W MacCollum avatar
No, comet is a broadband target so just use a luminance filter on OSC or RGB (with optional luminance) on mono.  This comet is also not very dim by any means.  I've been doing 30s without issue at f5 and getting plenty of data.  Shoot exposures long enough to get plenty of information but not long enough to get trailing. I personally wouldn't guide on the comet. Guiding on stars lets you get a better/cleaner star separation in post-processing. 
There are different approaches to this of course, so go with what works for you.
Helpful Concise
gfunkernator avatar
gfunkernator avatar
Jonathan W MacCollum:
No, comet is a broadband target so just use a luminance filter on OSC or RGB (with optional luminance) on mono.  This comet is also not very dim by any means.  I've been doing 30s without issue at f5 and getting plenty of data.  Shoot exposures long enough to get plenty of information but not long enough to get trailing. I personally wouldn't guide on the comet. Guiding on stars lets you get a better/cleaner star separation in post-processing. 
There are different approaches to this of course, so go with what works for you.

So are galaxies that's why I asked, wasn't sure if the filter was hurting the snr.  I shoot at f7 on my 8SE (basically the same as C8) with the Starizlna Corrector.

I say dim in comparison to Neowise.  I'll try not using any filter tonight.  30" is too long for my system and this particular comet.  My ed80+Canon eos ra 30" was alright but still quite low snr, that scope is f6, still too slow.  I tried 30" ISO12800 and still could see movement in the comet in one frame.  Ah, I'll figure it out I guess.  I was spoiled by Neowise and how easy that comet was to shoot.
Jonathan W MacCollum avatar
Jonathan W MacCollum avatar
I tried 30" ISO12800 and still could see movement in the comet in one frame.


Ya, it's moving very fast... at your image scale comet guiding may indeed be the best course of action.
gfunkernator avatar
gfunkernator avatar
Jonathan W MacCollum:
I tried 30" ISO12800 and still could see movement in the comet in one frame.


Ya, it's moving very fast... at your image scale comet guiding may indeed be the best course of action.

Gonna try it now.
andrea tasselli avatar
andrea tasselli avatar
Track on the comet with short or long exp length in PHD2? 2 seconds should be enough right? What about the use of the L-Pro filter? Should I use a filter or no?


L-Pro if is really LP dependant in use and what kind of P you've got. You suppress the yellow-green bandpass so you should still get a decent shot at the comet.
gfunkernator avatar
gfunkernator avatar
@andrea tasselli 
I'm noticing that now that I'm taking 2 minutes subs with my ED80 and Canon.  I gave up on using the SCT only because it's a major hassle to get PhD2 guide at the rate that is trying to with the comet tool.  Now I'm guiding on the comet itself and its working.  I'm wondering now that you mention if I should put the filter back on and try to take longer subs.  Get as much as I can.  Right now my histo's at 1/2, I'm trying to get as much as I can in 2min.  Image is baked but the comet looks good. 
andrea tasselli avatar
andrea tasselli avatar
I probably would put it on.