The Devils Mask

[strongmanmike]

Got some clear skies over the New Moon and along with finishing off a bigger project, decided to hit the very cool trio of small galaxies in Pavo known as the Devils Mask (because viewed in a certain orientation, together they look a bit like an evil face).

The conditions were favourable for a good whack of the capture time with FWHM measured in raw subs, using MaximDL, ranging between a good 1.7" to a pretty soft 2.3". To get the best detail out of the small 2 arc min sized galaxies, I used about three hours worth of the best subs (FWHM < 1.9") for the main galaxy trio region and the whole 4.1hrs Lum with FWHM < 2.2"(and scrapped the rest) for the full field.

At 190 Million light years these babies are pretty small, each only 2 arc min in size, so I am pushing the limits of an 1120mm FL F3.8 Newt trying to capture fine detail in such a small object but the conditions never the less allowed for a respectable result again on what is a challengingly small target using an image scale of 0.84"/pix :thumbsup:

All capture details are under the images

The Devils Mask: Pbase (https://pbase.com/strongmanmike2002/image/174788484/original) and Astro Bin (https://www.astrobin.com/full/e4wxku/0/)

Go for a surf around countless galaxies in the full frame full res HERE (https://pbase.com/strongmanmike2002/image/174788483/original)

Cheers

Mike

[alpal]

Hi Mike,
that's an impressive picture - well done.


cheers
Allan

[Startrek]

Mike,
Another one of your unique excellent Galaxy images
Well done !!

Cheers
Martone

[Dave882]

wow Mike that exceptional. Plenty of fine detail and the colour is natural and just gorgeous. I sometimes imagine if we could zoom in to some of those background beauties - what treasures we could find. That spiral galaxy on the far left is really interesting...

[strongmanmike]

Cheers Allan, Martone :thumbsup:

Yes I agree Dave, certainly HST has zoomed in on quite a few of, what we would call background galaxies...and made them look like our foreground ones, that's for sure :thumbsup:

Mike

[alpal]

Hi Mike,
well - it seems like Hubble zoomed in on only two of them here:
https://fr.wikipedia.org/wiki/NGC_6769#/media/Fichier:AM_1914-603_(Color).png


Also - the 2 other bright galaxies in your image are:
IC 4845 and IC4842.
https://cseligman.com/text/atlas/ic48.htm#ic4845
https://cseligman.com/text/atlas/ic48.htm#ic4842


wide field annotated here:
https://www.astrobin.com/suu8is/


A further note:
we are also in a cosmic dance as part of 3 galaxies:
Milky Way, Andromeda M31 and Triangulum M33.



https://earthsky.org/clusters-nebulae-galaxies/triangulum-galaxy-m33-a-binocular-challenge/






cheers
Allan

[GUS.K]

Thanks for sharing Mike, great capture. I spent Friday night observing this and other galaxies in Pavo through my 18 inch scope.

[strongmanmike]

Interesting stuff Allan, be cool to see our night sky with three large galaxies spread across it, huh? That HST shot is so cool huh? Wonder what civilisation/s will get to witness that?:thumbsup:



Cheers Ivan, yeah I have an 18" Dob (https://pbase.com/strongmanmike2002/image/173397228/original) too, under excellent skies, had several observing sessions with it but haven't looked at this trio though?...must remember to take a peak this season, I'm sure it will be worth it, thanks for the prod :)

Mike

[TrevorW]

Now that does look like a Devils mask when you orientate the image correctly :)

[rmuhlack]

Nice work Mike. It looks like this latest effort has provided a deeper and more detailed result compared with your 2013 image.

[strongmanmike]

Indeed :thumbsup:



Yes, a consistent improvement is evident between my current and previous sites, both in terms of seeing and contrast as well as achievable depth per unit time, it's great. The seeing conditions for this one weren't even the best I get, fairly regularly now, so I am getting annoyed every time the seeing isn't less than 1.7" now (my most frequent measurement in raw subs) :mad2:... I want it ALL the time now!! :lol: :thumbsup:

Mike

Mike

[gregbradley]

Great result Mike.
Lots of detail in a dim target.
Greg.

[strongmanmike]

Thanks Greg, I have decided I need a 17" CDK :confuse3: :evil:

Mike

[petershah]

I love this Mike....beautiful colour balanced

[strongmanmike]

Thanks Pete, it's a cool trio :thumbsup:

Mike

[gregbradley]

haha. Mine is up on the PME ready to be used.

Greg.

[alpal]

Hi Mike,
A 17" CDK - that's a lot of money.
You could start a whole new thread on that?
Some quick calculations not taking into account secondary obstruction sizes - which I suppose you have already done?
The 17" at f6.8 will be 38% slower than your 12" f3.8 Newt.
Focal length = 2936mm.
With the CDK Focal reducer = 0.66.
Focal length = 1813 mm -
speed 43% faster than your Newt.
Using your camera at 4.54 micron pixel size - the ratios are:

With Newt FL = 1158 mm = 0.81 arcsec/pix.
With CDK at FL = 2936 mm = 0.32 arcsec/pixel.
With CDK reducer FL = 1813 mm = 0.52 arcsec/pixel.

Conclusions.
using the principles of the Nyquist sampling Theorem.
The full focal length of 2936 mm would confirm once and for all
if you are getting less than 1 arc second seeing.
The 0.66 reducer would allow you to take images faster than your Newt now.
You could run a much larger camera sensor without vignetting.
The 10" back focus of the CDK would allow you to install adaptive optics
which would take full advantage of the seeing.
Would you break the 1 arc second barrier?
Would you get some pictures as good as CHART32 on some nights?

cheers
Allan

[gregbradley]

Don’t think it works that way Al. Look at F ratio myth. Aperture rules.

Greg

[Leo.G]

Beautiful image Mike!

[alpal]

Greg,



Yes I know,
if you are imaging a small galaxy then with a lower f ratio that galaxy will appear smaller but be brighter given the same time -
so it's a trade off.
I look at it as concentrating the photons into a smaller area.
You also get a wider field of view.

Plenty of thoughts here:
https://www.cloudynights.com/topic/409775-busting-the-f-ratio-myth/


cheers
Allan

[rmuhlack]

this old thread (https://www.iceinspace.com.au/forum/showthread.php?t=136008) from Shiraz (Ray) is probably relevant to the discussion here

[gregbradley]

To be honest Allan, what you said is what I have experienced using both types of scopes - CDK 17 and RHA F3.8. Both image fast with these new 91QE cmos cameras. The main difference is the magnification of the image.
That's why I started taking my RHA to my dark site. It gets a fast wide image at dark skies.

Mike's image highlights the flexibility of a 12 inch F3.8 system with accurate optics.

Greg.

[strongmanmike]

As Greg says, if one can only have one telescope the 12" F3.8 is very versatile, not to mention affordable, compared to a 16"/17" CDK/RC and 0.84"/pix image scale is certainly adequate for many applications, but about half that would be great to take better advantage of the more consistently good seeing up here and increase the sampling for traditional deconvolution to work its magic. To have optics free of astigmatism would help too :rolleyes:..probably lift the resolution a similar order of magnitude again that the improved seeing has :doh:

Mike

[alpal]

Hi Mike,
there's nothing wrong with Newts - they give impressive results.
I was always scared of RCs and other designs because of the
collimation problems people seem to have.
The big advantage of RCs etc to me is the back focus which would allow
for adaptive optics to take it to the next level.
No matter how good your mount is those stars will still dance around
and the adaptive optics takes care of that.
Also the spot sizes off axis are better - I think - for RCs
so you could use a full frame camera for a wide FOV.
Unfortunately: a high end scope, adaptive optics and the
latest high QE full frame cameras represent an enormous price tag.


cheers
Allan

[alpal]

Hi Greg,
you've been spoilt with premium scopes. :)


cheers
Allan

[alpal]

yes - it's very relevant - thank you.


cheers
Allan

[strongmanmike]

It's a good synopsis huh?

Mike

[alpal]

From what I've read it's very good although
I haven't read every post there.
I still think my calculations are a good guide.

cheers
Allan