NGC6744 2nd light AP RHA

[gregbradley]

This is the 2nd image I took with the AP RHA. I used a Trius 694 and this is an LRGB image 5 hours 10 minutes.

PMX, MMOAG, SBIG STi guider. The Trius has a tilt/tip adapter on it and it was off from a previous engineering experiment on another scope. I adjusted it after the bulk of this image was taken and it was a lot better. Still not 100% there but better. I have since gotten some engineering shim material and will be using CCDInspector to square up the cameras and scope for the next trip. Also installing a top dovetail plate to the rings to increase rigidity, moving the Versaplate of the PMX up the mount a bit so that all 3 anchor screws hold the scope in place instead of the current 2. Plus I should have the FLI Atlas and a solid adapter from the scope backplate to the Atlas operational next week. A 5/7 filter wheel is coming as well so I never need to change filters. I have also now repaired my existing filter wheel chain so it the filter changes should stay in alignment now. That was stopping me from doing a longer widefield image last trip which is where this scope is going to be strongest. So its clean the filters, set and there should be clean filter changes. I also repaired the existing filter wheel where 2 screws were missing which could have caused minor flex. Minor flex will show up with this scope. Its all part of the fun tweaking a new system getting it up and running perfectly.

NGC6744 is a galaxy I have imaged several times. Its a bit of a hard target as its somewhat dim compared to the background. I was pleased to see how solid each luminance subexposure was. Much stronger SNR than I would normally get. Very encouraging to see the 12 inch F3.8 system in action. Conditions were good the first night and so so the next.

NGC6744 is considered to be most likely very similar in appearance to the Milky Way with its spiral arms and its central bar. I would guess the Milky Way is more dusty though.

http://www.pbase.com/gregbradley/image/159907851/large

Also the advantage of keeping earlier image data intact. I have combined earlier data from at least 2 other scope and 2 different cameras with the RHA data. It may even be 4 different telescopes and 4 different cameras -I forget if I added CDK17 and Proline 16803 data in this from an earlier mix.

But its at least 7 years and 12.5 inch RCOS and SBIG STL11, Takhashi BRC 250 and FLI Microline 8300 and AP RHA 305 and Starlight Express Trius 694! A total of 25 hours.

http://www.pbase.com/image/159964293


Greg.

[IanP]

Great shot, Greg :thumbsup:
Your new “beast” gives you a lot of magnification at low F.
BTW: Where did the “halos” around bright stars come frm :question:

[SpaceNoob]

Very cool Greg, that setup is a winner! Nicely processed and Looking forward to seeing more.

[RobF]

A tough target Greg, so it definitely shows the photon-sucking and resolution power you're wielding nicely. Sounds like you're reeling in the engineering tweaks too.
You must be pleased to be getting decent images throughout "commissioning".

[alpal]

Nice pic Greg,
& as you say -
you can even make improvements on that.

cheers
Allan

[Stevec35]

That's a very pretty NGC 6744 Greg. The RHA is showing its potential.

Cheers

Steve

[jase]

An improvement over Cent A, Greg. The scope sure sucks in the photons showing the faint outer regions of those faint spiral arms. Image looks a touch soft to my eyes. I'm expecting the focus to snap with such an instrument but perhaps the conditions you note worked against you. If this image is a glimpse of what's to come, I'm getting pretty excited. No doubt you are too. Well done.

[Placidus]

Beautiful result, Greg. The long exposure did the trick. Gorgeous colours.

[gregbradley]

The small Sony chip gives a digital amplification.

The halos are from the camera. I think if I add a star mask earlier in the processing when stretching it may reduce that.



Thanks Rob. Whilst it would be nice to not have to do anything out of the box all scopes have their needs. Fast scopes obviously need things to be squarer than slower scopes.



Thanks Chris. I think the smaller pixels of the Trius camera match the scope well. I notice Roland uses a QSI 683 when he images with the Honders. The Proline will be great for widefield images where you don't really see the undersampling unless you zoom in 400%.

Greg.

[gregbradley]

I think ideally I go for about 8-10 hours with that camera on the Honders. That should give quite a strong signal to noise ratio. Widefield potentially shorter.



The touch of softness is probably focus not exact, windy poorish conditions plus autoguiding could have been better as I need a new TPoint and refined Polar alignment. There is slight drift between subs which I suppose is good for dither but shows PA is a bit off.



Thanks Mike. I also am working on a 25 hour version which is taken over 7 years, 3 scopes and 3 cameras. Its much the same but a bit deeper and more saturated colour.

Greg.

[marco]

I would say one of your best shot so far Greg, very nice one, the RH looks a great scope indeed. I believe it is due to the JPG compression (it happens often to me too), however I see the black point is clipped, perhaps you could give it a check..
Clear skies
Marco

[gregbradley]

Thanks Marco. High praise. I probably will add more data to this next trip so I can check the black point. The current histogram shows it as OK but perhaps bit got clipped along the way. Its easy to do.

Greg.

[Geoff45]

Very nice Greg. The colours are really beautiful.
Geoff

[gregbradley]

Thanks Geoff.

I'll post the 25 hour version after one minor fixup. Colours are a bit more saturated in that one. When you get good data, post processing is so much easier.

Greg.

[RickS]

That's a great result, Greg. Looking forward to the 25 hour version...

Cheers,
Rick.

[gregbradley]

Thanks Rick. Here's the 25 hour version:

http://www.pbase.com/gregbradley/image/159964293

Greg.

[alpal]

Hi Greg,
the links says:

Must login as gregbradley to view this image.

cheers
Allan

[gregbradley]

Sorry done it again. Fixed.

Greg.

[alpal]

Hi Greg,
it's looking good but I checked it out in Photoshop
& the stars are not quite perfectly round -
they are a little bit wooly - and taper off in one direction
mostly towards 5 o'clock.
maybe the collimation is slightly out? -
I wouldn't know what it is really - with such an advanced scope.
Maybe a look at the RAW FITS would help?
Have you put CCD inspector on it yet?

cheers
Allan

[gregbradley]

There was some guiding error plus the camera was not square
I squared it up more and the next session was a lot better
Still a bit more tweaking is needed and I got some shiming material for that and yes I do use CcdInspector but I dont know how reliable it is as one image it will say one thing and then something different on the next.So I suppose you need to look for an average of the results.
The scope does not collimate as the optical components are fixed
Greg

[dvj]

Your sky backgrounds are generally very black Greg. I can't say they are clipped, but right on the edge.

[gregbradley]

Yes I have to watch that.

Greg.

[Rex]

Beautiful image Greg, really nice colours in this one.

[gregbradley]

Thanks Rex. I was definitely happy with this one. Especially for the relatively low number of hours it took.

Greg.

[Placidus]

Greg, that 25 hour shot is seriously deep. We've not done it with the Aspen, but an older STL11000 shot with 11hrs luminance plus colour on the 20" does not show anywhere near as much of the outermost spiral arm. Well done.

[gregbradley]

Yes that arm is pretty faint. There is also some CDK17 data in that - about 5 hours. So its 4 scopes and 4 different cameras over 7 years!

I do like NGC6744!

Greg.

[rustigsmed]

nice work greg, I too am a fan of this galaxy, awesome work with the outer arm too!

Russ

[gregbradley]

Thanks Russ.

Greg.

[Ross G]

A great looking galaxy photo Greg.

Impressive detail!

Ross.

[gregbradley]

Thank Ross. I was happy with it and how quickly the image built up. Also how well it takes processing. The signal to noise ratio seems a lot better than normal.

Greg.