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M33 - The Triangulum Galaxy

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#1 srosenfraz

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Posted 02 January 2013 - 08:30 PM

M33 is the third largest galaxy in our Local Group of galaxies which includes M31 (the Andromeda Galaxy), and our own Milky Way Galaxy. Visually, the galaxy is quite large - about 70' x 40'. This makes the galaxy about 3 times larger than the full moon. However, unlike the Full Moon, M33 has a very low surface brightness, so it is quite challenging to see as well as to photograph:

Posted Image

High Resolution Version and more image details available at http://www.astronome...php?c=113&p=475

This image was made from several stacks of data captured on 7 nights over the last 2 years. Last year, I gathered 231 x 3 minute subs (11 1/2 hours) of RGB @ ISO 1600 with a Canon 20Da using a Celestron orange tube C-8 with Celestron focal reducer at f/6.3 (1260mm). Guiding was with an 80mm Astro-Physics 80mm f/11 refractor, Orion SSAG, and Phd Guiding. With this year's data, I added 188 x 3 minutes of RGB (9 1/2 hours) at ISO 1600 plus 40 x 10 minutes of Ha (6 2/3 hours) using a 6nm clip filter captured to a Gary Honis modified (Baader mod) Canon 450D. Imaging scope was the same orange tube Celestron C-8 with Celestron focal reducer at f/5.8 (1160mm). Guiding this year was via an ONAG On-Axis Guider, Lodestar autoguider, and Phd Guiding.

This year's RGB data was focused for the outer edges of the galaxy as well as the center of the galaxy, and I used focus stacking to combine these sets of data for sharper focus across the FOV. Ha data was used to highlight the Ha regions within the galaxy.

As always, thank you for looking!

#2 shawnhar

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Posted 02 January 2013 - 08:35 PM

Nice!

#3 TimN

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Posted 02 January 2013 - 09:07 PM

Very nice! Lots of great detail.

#4 rob77

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Posted 02 January 2013 - 09:55 PM

Outstanding

#5 astroricardo

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Posted 02 January 2013 - 11:23 PM

That's pretty awesome, and it is a tough one that's for sure

#6 Skyshooter

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Posted 02 January 2013 - 11:59 PM

Wow, that's spectacular! Your patience and processing abilities are admirable...

CLS
Ed

#7 willem123

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Posted 03 January 2013 - 12:44 AM

SC0TT ROSENFRAZ = CLOUDY NIGHTS DSLR GALAXY EXPERT!


-----------------------
Skywatcher 120 ED pro refractor; SW EQ6 Synscan mount
Celestron Nexstar 8SE SCT; Tasco 90mm refractor
Modified Canon 1100D (T3); Canon 550D (T2i)
Canon 10-22mm lens; Canon 18-55mm lens
Sigma 120-400mm lens
Celestron Nexguide.

#8 carlo rocchi

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Posted 03 January 2013 - 05:54 AM

Wow... really great!!!

#9 johne

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Posted 03 January 2013 - 07:24 AM

Beautiful image of M33. Well worth the many hours of exposure and processing effort. That is one I would print, frame and hang. :)

#10 bouffetout

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Posted 03 January 2013 - 08:23 AM

Awesome !

#11 FloridaObserver

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Posted 03 January 2013 - 08:37 AM

More proof that data is king (in addition to top quality processing). Thanks for the inspirational image.

#12 Orion58

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Posted 03 January 2013 - 08:54 AM

Well done Scott!

#13 srosenfraz

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Posted 03 January 2013 - 02:07 PM

Thank you very, very much everyone for your very nice comments - I truly appreciate it.

#14 lukasik

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Posted 03 January 2013 - 07:22 PM

Hoo-wheee! That's eye-popping Scott - great job!


Regards,

Bob

#15 nive

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Posted 04 January 2013 - 05:25 AM

Good Job

#16 Nils_Lars

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Posted 05 January 2013 - 12:43 AM

Tons of details in M33 here Scott , you got into the outer wisps pretty deep too.

#17 srosenfraz

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Posted 05 January 2013 - 02:11 PM

Thank you so much Bob, Nils, and Erik.

#18 vmsguy

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Posted 05 January 2013 - 02:35 PM

Wow, very nice image.

27 hours of data. The most I've tried to combine is around 6 hours.

Now that I've started guiding, I need to dust off my C8 after seeing results like this.

Brent

#19 northernontario

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Posted 05 January 2013 - 02:47 PM

Are you sure you didn't hijack the Hubble Telescope :question:

That's one nice picture. :bow:

jake

#20 fco_star

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Posted 05 January 2013 - 10:31 PM

Scott, your picture is gorgeous !!
Hi from latitude 0

#21 Darren1968

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Posted 06 January 2013 - 04:16 PM

Gotta be one of the best DSLR M33's that I've seen.

Very nice!

Darren

#22 mpgxsvcd

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Posted 07 January 2013 - 01:47 PM

Great image. Thanks for sharing.

#23 Erk1024

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Posted 07 January 2013 - 06:15 PM

This is a lot of imaging time, processing work, and a great result! ;)

#24 Peter in Reno

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Posted 08 January 2013 - 06:27 PM

Hi Scott,

You are one of the very few I know of that uses ONAG. I checked all of your images using ONAG and they are all excellent.

December 2012 issue of Sky & Telescope has a very positive review about ONAG. The author mentioned that he saw some kind of ghost reflection when a bright star was at or near center of the image but the reflection disappeared after he moved the bright star a little bit off center. He could not prove the reflection was caused by the cold mirror of ONAG. Have you ever notice any kind of refelctions like the author described?

I have been eyeing on ONAG. I like the idea of guiding on a star near the center of the DSO. It makes me wonder that there would be less noticable star trails around the center due to field rotation if the guide star was at the center of DSO in case the polar alignment was less than ideal.

I have been using Hutech OAG/Lodestar with C-8 EdgeHD at 2000mm focal length with great success. I give Lodestar more credit because it's so sensitive that it finds at least one suitable guide star in OAG's guide port FOV without ever hunting for one. I am wondering if I would get better guiding results with ONAG than OAG since guide star can be at the center of DSO instead of off-axis.

Thanks,
Peter

#25 srosenfraz

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Posted 08 January 2013 - 09:10 PM

Hi Scott,

You are one of the very few I know of that uses ONAG. I checked all of your images using ONAG and they are all excellent.



Thank you very much, Peter.


December 2012 issue of Sky & Telescope has a very positive review about ONAG. The author mentioned that he saw some kind of ghost reflection when a bright star was at or near center of the image but the reflection disappeared after he moved the bright star a little bit off center. He could not prove the reflection was caused by the cold mirror of ONAG. Have you ever notice any kind of refelctions like the author described?



I haven't noticed anything like that, but I can't recall having tried to image anything with an unusually bright star near the center of the FOV. So, I don't think I could say it wouldn't happen. I've imaged a lot of objects with it, so I can say that whatever internal reflection problems it may potentially have don't affect the vast majority of targets.


I have been eyeing on ONAG. I like the idea of guiding on a star near the center of the DSO. It makes me wonder that there would be less noticable star trails around the center due to field rotation if the guide star was at the center of DSO in case the polar alignment was less than ideal.

I have been using Hutech OAG/Lodestar with C-8 EdgeHD at 2000mm focal length with great success. I give Lodestar more credit because it's so sensitive that it finds at least one suitable guide star in OAG's guide port FOV without ever hunting for one. I am wondering if I would get better guiding results with ONAG than OAG since guide star can be at the center of DSO instead of off-axis.



To the extent that you have some misalignment causing field rotation, having a guidestar at the center would generally be preferable for preserving more of the FOV. A significant percentage of the objects I usually image don't fill the entire FOV. If I had field rotation, rotation about the center (where my target is) would mean that it would generally be sharper than if my center of rotation was towards the corner of the field. So, I think your hypothesis is accurate.

That having been said, one of the big advantages to the ONAG is that it allows you the entire FOV to choose a guidestar. As a result, I don't always use a star near the center of the field. I usually look for a reasonably bright star (anywhere in the FOV) and then move the guider stage to find that brighter star.

Of course, I'm not concerned about field rotation because my scope is permanently mounted. I think the aspect of having a centered guide star would be more attractive to me if I were constantly taking my scope in the field and trying to do new PA each time.

I agree with you that the Lodestar definitely helps with guide star choice. The difference in star brightness between my Lodestar and the SSAG is quite remarkable.

As far as what improvement you might yield from an ONAG over your Hutech OAG - I think you've correctly identified the potential advantage (centered guide star). If you're commonly seeing field rotation in your images, then the ONAG could help (alternatively you could spend more time during setup with your PA, but that could mean lost imaging time). If you were considering going from a guide scope to an OAG or an ONAG, I wouldn't hesitate to recommend spending the extra $$ for the ONAG. If the Hutech OAG is working well for you, I'm not sure if you'll see much advantage (other than the field rotation). The one other big advantage to the ONAG is that its MUCH easier to find guidestars than an OAG. But, if you've already mastered that technique, it may not be as useful for you.

Hope this helps.






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