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M81 and M82
Posted: Tue Mar 24, 2020 10:32 pm
by bobharmony
I got out on Saturday night for an
AP session. It was clear (obviously
) and rather cool with a brisk breeze. I have been planning to capture M81 and M82 for a while and got out as early as possible. I was set up by 8:20 local time and collecting data. I wound up with 85 three minute subs and in the end stacked 70 of them with 70 darks I collected in December, 81 flats, and my trusty master bias frame. Only one sub needed to be dropped due to tracking issues, the others were taken in the light bubble on my northern horizon and had too bright a background.
Guiding was fantastic again with RMS running .20-.30 arcsec in both
DEC and
RA and hovering around .40 overall. This is the second consecutive session with RMS error in this ballpark. The only change I made that is common to these two sessions is removing the vibration dampening pads from under the tripod legs. Is this what caused the improvement? I can't say, I just report my observation.
For a change, I got my best result from
StarTools by not binning. Maybe the seeing was better than usual, and maybe that contributed to my excellent guiding results.
In any case here it is. Comments and questions are welcome.
Bob
Re: M81 and M82
Posted: Tue Mar 24, 2020 10:35 pm
by helicon
Fantastic image Bob. Thanks for sharing it.
Re: M81 and M82
Posted: Tue Mar 24, 2020 10:44 pm
by Juno16
Very nice image Bob! Your excellent guiding and lots of subs really paid off.
No binning? Hmmm. Interesting. Never tried that. Did the lack of binning significantly slow Startools?
Your guiding is amazing. Stars look great. You really had an excellent evening of imaging! Really feels good when that happens!
Re: M81 and M82
Posted: Tue Mar 24, 2020 10:52 pm
by The Happy Parrot
Beautiful image, especially for a visual only type like me. It helps to see what they actually look like when you are star hopping.
Re: M81 and M82
Posted: Wed Mar 25, 2020 3:28 am
by bobharmony
Juno16 wrote: ↑Tue Mar 24, 2020 10:44 pm
Very nice image Bob! Your excellent guiding and lots of subs really paid off.
No binning? Hmmm. Interesting. Never tried that. Did the lack of binning significantly slow Startools?
Your guiding is amazing. Stars look great. You really had an excellent evening of imaging! Really feels good when that happens!
Did not binning slow things, Jim? Oh, yes. But it was worth it in the end. I did my usual bin to 35% first and tried to pull out any detail with HDR and deconvolution. M82 was particularly hard to get anything from, just a small smudge in the central portion of the galaxy. I went to 50% and got a little more. At full size I didn't have to do any deconvolution at all. The detail just popped out and I was able to get a bit more using HDR "reveal core". I was much happier with that. I'm thinking of going back to the Rosette one more time and trying it without binning to see what happens.
Bob
Re: M81 and M82
Posted: Wed Mar 25, 2020 3:35 am
by Juno16
bobharmony wrote: ↑Wed Mar 25, 2020 3:28 am
Did not binning slow things, Jim? Oh, yes. But it was worth it in the end. I did my usual bin to 35% first and tried to pull out any detail with HDR and deconvolution. M82 was particularly hard to get anything from, just a small smudge in the central portion of the galaxy. I went to 50% and got a little more. At full size I didn't have to do any deconvolution at all. The detail just popped out and I was able to get a bit more using HDR "reveal core". I was much happier with that. I'm thinking of going back to the Rosette one more time and trying it without binning to see what happens.
Bob
Bravo on experimenting! Really paid off!
I will give that a try hopefully soon. Not too optimistic because my seeing is usually poor and the
lp is at a disturbing level, but won’t hurt to try!
Re: M81 and M82
Posted: Wed Mar 25, 2020 12:46 pm
by Jockinireland
bobharmony wrote: ↑Tue Mar 24, 2020 10:32 pm
I got out on Saturday night for an AP session. It was clear (obviously
) and rather cool with a brisk breeze. I have been planning to capture M81 and M82 for a while and got out as early as possible. I was set up by 8:20 local time and collecting data. I wound up with 85 three minute subs and in the end stacked 70 of them with 70 darks I collected in December, 81 flats, and my trusty master bias frame. Only one sub needed to be dropped due to tracking issues, the others were taken in the light bubble on my northern horizon and had too bright a background.
Guiding was fantastic again with RMS running .20-.30 arcsec in both DEC and RA and hovering around .40 overall. This is the second consecutive session with RMS error in this ballpark. The only change I made that is common to these two sessions is removing the vibration dampening pads from under the tripod legs. Is this what caused the improvement? I can't say, I just report my observation.
For a change, I got my best result from StarTools by not binning. Maybe the seeing was better than usual, and maybe that contributed to my excellent guiding results.
In any case here it is. Comments and questions are welcome.
Bob
Hi Bob, thats a great image. Can I ask which scope you used for that?
David
Re: M81 and M82
Posted: Wed Mar 25, 2020 2:49 pm
by bobharmony
Jockinireland wrote: ↑Wed Mar 25, 2020 12:46 pm
Hi Bob, thats a great image. Can I ask which scope you used for that?
David
Thanks, David. I used the C6N for this. The ST-80 is dedicated as a guidescope for the most part. This image is slightly cropped, more to remove stacking artifacts than for any other reason.
Bob
Re: M81 and M82
Posted: Wed Mar 25, 2020 2:52 pm
by Dragonsfire
Very Nice Job Bob
Re: M81 and M82
Posted: Wed Mar 25, 2020 5:45 pm
by MariusD69
Wonderful! Well done, Bob!
Re: M81 and M82
Posted: Wed Mar 25, 2020 7:52 pm
by STEVE333
Nice capture Bob - Those two make a lovely compliment to each other.
I envy your guiding, I'm happy when my total RMS is at 1" or under.
Steve
Re: M81 and M82
Posted: Wed Mar 25, 2020 11:10 pm
by jthommes
Well done Bob. Nice to have great conditions and get a great image.
Re: M81 and M82
Posted: Thu Mar 26, 2020 3:07 am
by bobharmony
STEVE333 wrote: ↑Wed Mar 25, 2020 7:52 pm
Nice capture Bob - Those two make a lovely compliment to each other.
I envy your guiding, I'm happy when my total RMS is at 1" or under.
Steve
Thanks, Steve. I'm not exactly sure why guiding has gotten so much better lately, but I'll take it
Previous to this latest run of good result, I would typically get
DEC around .60-.70,
RA at 1.00 and total RMS in the 1.3 range, so this has been a nice improvement. This result coincides with incorporating
APT into my routine instead of BYEOS, but I am at a bit of a loss as to how that would affect guiding results. Looking into it a little more, it also coincides with your recent study and formulation of dithering amount. I may have incorporated that into the multiplier I am using in
APT. I will have to see how old a guidelog I can find and see if my average dither amounts are smaller with
APT than they were with BYEOS. I am still getting good control of walking noise, so it appears to be an acceptable amount of dither.
Bob
Re: M81 and M82
Posted: Thu Mar 26, 2020 6:23 pm
by Astrovetteman
Great image Bob!! Glad you got your guiding issues ironed out. Your stars are perfect and you got some GREAT detail in this one!!
Excellent Image!!
Tom
Re: M81 and M82
Posted: Fri Mar 27, 2020 11:37 pm
by JohnP_1
Looks great Bob! Saturday was indeed nice for a while that is. Cold as ice though. The clouds rolled in later on shutting everything down for me. I went after M81 myself the next day. I love the detail you grabbed. Well done.
Re: M81 and M82
Posted: Sat Mar 28, 2020 12:20 am
by chartram
Bob,
Fantastic image sir- and those stars indeed as tight as can be and the framing is wonderful! I do have one comment, I wonder if it might just be this area of the sky because I had the same issue Wednesday night... your image is a little heavy in red. I would suggest backing the red off in the histogram, but only just a bit. Still an amazing image- well done Bob! Hope you and yours are staying safe and well!
Mike
Re: M81 and M82
Posted: Sat Mar 28, 2020 3:30 am
by bobharmony
chartram wrote: ↑Sat Mar 28, 2020 12:20 am
Bob,
Fantastic image sir- and those stars indeed as tight as can be and the framing is wonderful! I do have one comment, I wonder if it might just be this area of the sky because I had the same issue Wednesday night... your image is a little heavy in red. I would suggest backing the red off in the histogram, but only just a bit. Still an amazing image- well done Bob! Hope you and yours are staying safe and well!
Mike
Thanks, Mike. I actually had to back the blue down a bit in post processing. That might have left things a bit high in the reds. For me the circumpolar region is tough as I live just south of Hartford and I get the most sky glow in that direction. I may give this another try by stacking 10 less (or so) subs from early in the evening and see if that improves the color without loss of detail. It is always a balancing act to get things just where I want them!
Bob
Re: M81 and M82
Posted: Sat Mar 28, 2020 3:43 am
by chartram
bobharmony wrote: ↑Sat Mar 28, 2020 3:30 am
chartram wrote: ↑Sat Mar 28, 2020 12:20 am
Bob,
Fantastic image sir- and those stars indeed as tight as can be and the framing is wonderful! I do have one comment, I wonder if it might just be this area of the sky because I had the same issue Wednesday night... your image is a little heavy in red. I would suggest backing the red off in the histogram, but only just a bit. Still an amazing image- well done Bob! Hope you and yours are staying safe and well!
Mike
It is always a balancing act to get things just where I want them!
Bob
True statement. It’s an insane balancing act! The amount of things that have to go right both on the ground and in the sky for us to get just one good sub is... well- astronomical!
Re: M81 and M82
Posted: Sun Mar 29, 2020 11:14 pm
by bladekeeper
A really nice image, Bob!
Re: M81 and M82
Posted: Mon Mar 30, 2020 1:19 am
by Baskevo
This is a great image, Bob! It is funny, I have been going after M81 myself, and noticed my guiding is incredible when pointed in that direction--same as yours, in the .3 - .4 RMS error range for each axes. I wonder if it is the direction we are facing or something...
Anyway, your image looks incredible! Thanks for sharing!