M94 - The Cat's Eye Galaxy

[PhotoGav]

M94 - The Cat's Eye Galaxy

 

Messier 94 is a spiral galaxy about 16 million light years away in the constellation of Canes Venatici. It's a weird one, as you can see it doesn't look totally normal; there are three distinct rings to the galaxy: an evidently active inner ring with obvious regions of star formation, an hazier diffuse outer ring and a darker ring separating them. So, what's going on here then? Good question! There is much speculation as to how this has all formed, but the best theories seem to involve a distortion of the inner oval. The term 'pseudobulge' is used, here is further info from Wikipedia: "A classical spiral galaxy consists of a disk of gas and young stars that intersects a large sphere (or bulge) of older stars. In contrast, a galaxy with a pseudobulge does not have a large bulge of old stars, but instead contains a bright central structure with intense star formation that looks like a bulge when the galaxy is viewed face-on. In the case of M94, this pseudobulge takes the form of a ring around a central oval-shaped region.". That's clear then!

Technical Details

Capture: Celestron EdgeHD 8" with QSI 683-WSG8 and Astrodon 31mm filters on a Mesu 200.
Processing: APP and PS CC.

RGB = 25 x 600s Each
L = 29 x 1200s
TOTAL = 22 hours 10 minutes

Thank goodness for a series of clear nights over the last few weeks and the joys of an observatory. The data collection has been a fairly slow process, but I am happy with the resultant image. I think that the Mesu 200 has definitely improved results with the long focal length Edge 8", giving me a guiding RMS of around 0.3" to 0.5", still below the theoretical required value of 0.25", but way better than my HEQ5 which managed in the region of double the Mesu at best. The Edge is still a pain to use though, focussing being my main bug-bear these days. SGP seems to be having a bit of a wobble in that area. I still yearn for a long refractor, but I am happy to make do with this set-up until that materialises! I should probably put the reducer back on and shorten the focal length a bit to gain a bit more guiding forgiveness. I do like the 2000 mm focal length for galaxy season though...!

I look forward to your thoughts and comments on this one.

CS!

[souls33k3r]

You brave brave man, imaging at F/10 but the image was well worth it in the end mate. Absolute stunner.

[Laurin Dave]

Very nice Gav..  you have every reason to be happy!

Dave

[JamesF]

Yes, well worth the effort, I'd say.

James

[Craney]

1 hour ago, souls33k3r said:

You brave brave man, imaging at F/10

.... at  2000mm Fl.... and with 20min exposures.....    very impressive.    

[PhotoGav]

Thank you for your positive feedback folks. Yes, 2032mm FL and 20 minute L subs... Long live the Mesu!!

[Craney]

20 minutes ago, PhotoGav said:

Long live the Mesu!!

... any going cheap....??

 

[tomato]

Very nice, you can clearly  see how the galaxy gets it's popular name from this image.

And you don't disappoint, plenty of tiny distant galaxies to wonder at.

[Barry-Wilson]

Very well done indeed Gav.  Great capture and processing skills for the faint outer ring of stars.  This really is a difficult target and you have executed it with aplomb ?.

Your enthusiasm for our hobby shines through yoour write up and I am so pleased that the Mesu is performing for you.

[ollypenrice]

On 04/04/2019 at 18:20, PhotoGav said:

M94 - The Cat's Eye Galaxy

 

Messier 94 is a spiral galaxy about 16 million light years away in the constellation of Canes Venatici. It's a weird one, as you can see it doesn't look totally normal; there are three distinct rings to the galaxy: an evidently active inner ring with obvious regions of star formation, an hazier diffuse outer ring and a darker ring separating them. So, what's going on here then? Good question! There is much speculation as to how this has all formed, but the best theories seem to involve a distortion of the inner oval. The term 'pseudobulge' is used, here is further info from Wikipedia: "A classical spiral galaxy consists of a disk of gas and young stars that intersects a large sphere (or bulge) of older stars. In contrast, a galaxy with a pseudobulge does not have a large bulge of old stars, but instead contains a bright central structure with intense star formation that looks like a bulge when the galaxy is viewed face-on. In the case of M94, this pseudobulge takes the form of a ring around a central oval-shaped region.". That's clear then!

Technical Details

Capture: Celestron EdgeHD 8" with QSI 683-WSG8 and Astrodon 31mm filters on a Mesu 200.
Processing: APP and PS CC.

RGB = 25 x 600s Each
L = 29 x 1200s
TOTAL = 22 hours 10 minutes

Thank goodness for a series of clear nights over the last few weeks and the joys of an observatory. The data collection has been a fairly slow process, but I am happy with the resultant image. I think that the Mesu 200 has definitely improved results with the long focal length Edge 8", giving me a guiding RMS of around 0.3" to 0.5", still below the theoretical required value of 0.25", but way better than my HEQ5 which managed in the region of double the Mesu at best. The Edge is still a pain to use though, focussing being my main bug-bear these days. SGP seems to be having a bit of a wobble in that area. I still yearn for a long refractor, but I am happy to make do with this set-up until that materialises! I should probably put the reducer back on and shorten the focal length a bit to gain a bit more guiding forgiveness. I do like the 2000 mm focal length for galaxy season though...!

I look forward to your thoughts and comments on this one.

CS!

What a cracker! Well done that man. Lovely job on all counts.

On 04/04/2019 at 18:30, souls33k3r said:

You brave brave man, imaging at F/10...

Why? Where would the extra photons come from with a focal reducer? http://www.stanmooreastro.com/f_ratio_myth.htm

Olly

[Star101]

Very nice image Gav.

I know imaging at f/10 is slow going but when you produce such a fine image as this. WOW, all that time and effort looks definitely worth it in my eyes.

I love the detail you have captured. 

Well done.

[ollypenrice]

27 minutes ago, Star101 said:

Very nice image Gav.

I know imaging at f/10 is slow going but when you produce such a fine image as this. WOW, all that time and effort looks definitely worth it in my eyes.

I love the detail you have captured. 

Well done.

Again, why is F10 slow? My friend Marc's telescope is F8 and saturates the chip in two minutes. It's a big scope though...

Olly

[Star101]

Just now, ollypenrice said:

Again, why is F10 slow? My friend Marc's telescope is F8 and saturates the chip in two minutes. It's a big scope though...

Olly

I'm not sure Olly. Maybe its the imaging chip! 

The problem I have explaining this is, I rarely image the same objects at f2 and f10.

I would be happy for someone to tell me different and explain why! 

In WB, if I image at F10 I can leave my Atik 4120 CCD imaging subs at 300s with no problems apart from some slightly bloated stars (not sure if that's the SCT or the small pixel size 3.1um of the Atik chip, or both). When I use Hyperstar at F2, after 120s the sub image appears over exposed. I have tried 300s at F2 and the image suffers LP and overexposure.  

I know If I want decent images,  at F2 I can get some great images, for me, using say, 10 x 60s subs. Whereas at F10 I will need 10 x 300s.  At F10, 60s is usually very dark.

Maybe an experiment is needed?

30 mins on a given target at any sub length at F2 and F10, compare resulting image

 

 

[PhotoGav]

Thank you for your encouraging comments @tomato, @Barry-Wilson, @ollypenrice & @Star101. It is hard, if not impossible, not to be enthusiastic about glimpsing 16 million years into the past and seeing such weird and wonderful detail in a strange galaxy, from the comfort of my sofa and back garden! My family just think I’m obsessed...

Interesting comments about f/10 imaging, reducers and photons. As Olly says, how can a reducer make any difference to the number of photons that enter the same size aperture. I suppose the perceived increase in speed comes from those same photons being concentrated onto a smaller number of pixels in the camera by the reducer?

I am thoroughly enjoying the improvements brought about to my long focal length imaging by the Mesu200. I was given very good advice on here about which mount to go for when considering an upgrade and I was lucky to grab the Mesu from Astro Buy & Sell from a very honourable seller.

Now I just need to eliminate these darn clouds...

[tomato]

A purchaser of a second hand Mesu, that’s like winning the lottery.☺️