Spiral Galaxy M66 repro

gregbradley · #1 28-03-2015, 12:52 PM

I spent several hours last night updating the collimation of my CDK17 using CCDinspector. I thought I had improved but a few images showed it was worse! I stayed up til 1:15am to get it right and got it so its better than what it was (it wasn't bad in the first place and the CDK design is not that sensitive to collimation it would seem). I have also just cleaned the mirrors again (very easy to do) and reflocked the secondary shroud. So all in all the PME, CDK have had some maintenance.

M66. Quite a bright galaxy, a little low to the north.

CDK17, SX Trius 694 at .485 arc seconds per pixel (I don't know how I get away with it at that sampling, its the high QE and low read noise I think). Astrodon Gen 2, PME, 330 point Tpoint Supermodel and guide scope with an STi guide camera with reducer in a Vixen 95 VMC, PemPro PEC curve. The PME with Pempro is running at about 1.5 arc secs of PE.

A beautiful clear night last night but the seeing was a bit rough until midnight.

10 minute subs, all 1x1, -20C, CDK reducer giving approximately F4.5, about 4 hours.
I lost 2 hours the other night that due to low disk space did not get saved - grrrr.

http://www.pbase.com/gregbradley/image/159561387/large

http://www.pbase.com/gregbradley/ima...61387/original

I'll probably add to this as its a nice target but I am surprised how well it came out given the low total exposure. The advantage of large aperture, clean mirrors, F4.5 and high QE plus good guiding and collimation. I saw the sharpness/brightness go up on the focus graph when collimation improved.

Greg.

batema (Mark) · #2 28-03-2015, 12:56 PM

Beautiful image and stunning equipment.

RickS (Rick) · #3 28-03-2015, 01:05 PM

Looks great for a quick one, Greg.

Placidus (Mike and Trish) · #4 28-03-2015, 02:08 PM

Beautiful gentle colour and saturation in the main galaxy.

If I stretch your image and do a tiny bit of wavelet smoothing, I see quite a bit more of the faint outer spiral arm toward 4 o'clock. It's a great image already, but if you clipped the blacks a bit less I reckon you'd bring out even more.

Good work with the collimation. It looks perfect. The collimation screws on our CDK are 3.5 metres above the ground, and it's pretty scary up there in the pitch dark!

Best,
Mike

IanP · #5 28-03-2015, 02:08 PM

Very nice shot of a difficult object, Greg ..

On the right side of the galaxy I can see a satellite (or something) crossing the faint outer “arm” .. that firstly thought was a long spike from the star at the bottom .. I guess you can’t see this stuff on mobile devices ..

gregbradley · #6 28-03-2015, 03:07 PM

Quote:

Originally Posted by batema

Beautiful image and stunning equipment.

Thanks for that compliment. Yes the gear is very good and deserves close maintenance and optimisation.

Quote:

Originally Posted by RickS

Looks great for a quick one, Greg.

I think I'll add to it. Its quite a bright galaxy so its not taking too long to build up a decent signal.

Quote:

Originally Posted by Placidus

Beautiful gentle colour and saturation in the main galaxy.

If I stretch your image and do a tiny bit of wavelet smoothing, I see quite a bit more of the faint outer spiral arm toward 4 o'clock. It's a great image already, but if you clipped the blacks a bit less I reckon you'd bring out even more.

Good work with the collimation. It looks perfect. The collimation screws on our CDK are 3.5 metres above the ground, and it's pretty scary up there in the pitch dark!

Best,
Mike

I am sure there is a bit more in it but I was already starting to see the effects of not enough exposure so I left it at that point.
My CDK is about 2.3 metres up so a short step ladder wasn't too bad. Lots of getting up and down though - about 40 times!

CCDInspector is good but it assumes the camera is dead square. Also the seeing was poor at times last night then improved after midnight. So not ideal. I got it to about 2 arc seconds error. So pretty close. It was at 7.1 arc seconds error when I started and the stars were round anyway.
Also CCDInspector shows only 3 collimation screws in their graphic. The CDK has 4!

Greg.

gregbradley · #7 28-03-2015, 03:09 PM

Hi Ian,

Thanks. That satellite trail would normally disappear with enough subs using median combine. I had several trails in this area. It must be a bit of a satellite highway there! I could Photoshop it out but that may disrupt some of the Galaxy.

Greg

Stevec35 (Steve) · #8 28-03-2015, 08:35 PM

Nice looking galaxy shot Greg

Cheers

Steve

gregbradley · #9 28-03-2015, 09:11 PM

Quote:

Originally Posted by Stevec35

Nice looking galaxy shot Greg

Cheers

Steve

Thanks Steve. I was hoping to add to it tonight but despite the forecast of Clear it looks pretty cloudy outside.

Greg.

gregbradley · #10 28-03-2015, 10:55 PM

I did a minor repro on this, removed a bit more background gradient, got rid of the satellite trail and some subtle selective sharpening.

Same link.

Greg.

strongmanmike (Michael) · #11 29-03-2015, 06:09 PM

Looks like the tune up worked Greg

... looking at the bright stars it looks like they have been worked on to make'em smaller, what did you do to the stars? Decon? Did you apply star shrinking to the fainter stars too? Only ask out of interest because they look good regardless, nice work

I thought you were having star bloat problems with the 684? There are some mixed gradients in the back ground but the lovely soft look works and the faint outer arms are there...but I'm thinking there is more detail in there somewhere though..? Or do you think you have reached the seeing limit on this occasion?

Hope that didn't sound like a nit pick list

it's a really nice image, just musing out loud

Mike

gregbradley · #12 29-03-2015, 07:13 PM

Quote:

Originally Posted by strongmanmike

Looks like the tune up worked Greg

... looking at the bright stars it looks like they have been worked on to make'em smaller, what did you do to the stars? Decon? Did you apply star shrinking to the fainter stars too? Only ask out of interest because they look good regardless, nice work

I thought you were having star bloat problems with the 684? There are some mixed gradients in the back ground but the lovely soft look works and the faint outer arms are there...but I'm thinking there is more detail in there somewhere though..? Or do you think you have reached the seeing limit on this occasion?

Hope that didn't sound like a nit pick list

it's a really nice image, just musing out loud

Mike

Yes I did some work on the stars. I am surprised there are still some gradients as I couldn't see anymore but different monitors probably show up things. More detail is very likely able to be achieved with more exposure. I was happy to get a decent image out of less than 4 hours of data.

Greg.

Ross G · #13 29-03-2015, 09:15 PM

A great looking galaxy photo Greg.

Nice colours and lots of faint detail.

Ross.

gregbradley · #14 29-03-2015, 10:46 PM

Quote:

Originally Posted by Ross G

A great looking galaxy photo Greg.

Nice colours and lots of faint detail.

Ross.

Thanks Ross. I hope to add to the exposure once the moon is gone and clouds part. Then I can bring out more detail once the signal is built up more.

Greg.