RBA Premium Astrophotography

Rho Ophiuchus Widefield

Posted: May 15th, 2010



The area of Rho Ophiuchus, Blue Horsehead and Sharpless 1 - The head (and "shoulders") of the scorpion constellation - is without a doubt "the mother of all pretty pictures", and in this 3x4 mosaic I tried to show them all of them in a family portrait.

The image is a 3x4 mosaic with the FSQ+reducer+STL11k captured over 4 nights (plus 800 more miles in my SUV!!).

The interesting thing is that each frame is only 3x5 minutes of luminance, bin 2x2 (see details after this writeup). I am very very surprised to get this quality with so little data. I know binning reduces read noise but I wasn't expecting this...

I would have not done 3x5' and bin 2x2 if it wasn't because when I planned this FOV I didn't calculate it right so I thought I needed a 2x3 mosaic. It was when I was at DARC and ready to start when I realized I screwed up, and after 5 minutes of "what the heck I'm going to do now" I decided to still go for the entire luminance in one night, and do 3x5' 2x2 per frame instead of 3x10' 1x1 as I had originally planned. Either way I think that the short exposure times played on my favor, keeping the stars under control in an area that has more stars than background!!

Eric Zbinden was right next to me that night. He can confirm the madness I was in for the whole night: since I don't use automation software (CCDCommander, etc) I had to switch to a new frame every 15 minutes, and since I also don't do platesolves, I had to make sure each new FOV would match the right area (manually slewing with TheSky6's mosaic tool cannot be trusted 100%). Good thing I didn't need to rotate the camera between frames for this composition!

Even with that, the last two frames were bad, as the sky was already clearing that night, so on Tuesday 18th, I headed out again, and after taking those two frames, since I had time that night to keep going, I started with the color, and after seeing the results with the lum, I went for marginal data as well.

But I knew Tuesday wouldn't be enough, and it wasn't, so I went out again on Wednesday (there's some bright stuff called Moon which is setting rather late these days but still giving 3+ hours of darkness). But late on Wed I was getting tired, and rather than risking falling asleep at the wheel on the way back home, I packed and went home short two RGB frames.

So I went out on Thursday, again. I headed to Montebello (tired of driving so much) but when I got there it was all foggy, so I drove all the way near to Dinosaur Point, which was SO WINDY I had to retreat and I setup not far from the Hwy 152 entrance to Henry Coe but away enough from the road so the cars lights wouldn't be a bother, and there I captured the last two color frames, and went home.

Full disclosure: the areas around Antares and the blue horsehead use color from the two images of those areas I took last year. Likewise, the blue horsehead has luminance from that image as well. It looks better despite I actually lost some resolution. Also, at some point in the processing I "killed" the color in small all stars, so they're all white except the big ones (and the color in the big ones is blown out), so I may go back to this image and be careful with that!

Frame adaptation was very challenging, and the reason I decided to use Photoshop instead of PixInsight for that, as it gave me more freedom to do it, by using layers and manually defined masks, as even after applying background models to each frame to correct gradients, although signal strength was similar, no two frames shared an even background illumination across the overlapping areas, so I would stretch each frame looking for a visual match, and re-stretch using painted masks to correct seam differences. Although I usually try to stay away from painted masks (it's not a religious thing, I simply have more fun using luminance-based masks) in mosaics like this one with somewhat marginal data, I just can't get away with using more strict frame adaptation techniques.

So that's the story. 800 miles and a very unhealthy "schedule" for a pretty picture. I'm seriously considering switching to another hobby, like reading on bed or something :-)

 



:: 15 Comments

Comments

Christoph Kaltseis (Contact, Page), May 24th, 2010, 2:05
Hello from Austria!
Very nice image! I have done some areas 2008 at La Palma and this oveviwe is very nice! From my home it is not able to take this region.
CS, Christoph

Bob Polcyn (Contact, Page), May 24th, 2010, 5:34
I've browsed all of your website -- all of it of the highest quality.
I particularly like your widefield work. Thanks for sharing.
Exceptional!

Bob Polcyn

ZOILA MIRANDA (Contact, Page), May 24th, 2010, 7:28
MI mas grande alegrķa al tener que felicitarte RBA por esta nueva APOD.

RIch Wilbourn (Contact, Page), May 24th, 2010, 7:28
Beautiful work on the Rho Oph wide field. Really like your suble use of color.

RBA (Contact, Page), May 24th, 2010, 8:05
Thank you so much for your comments, Christoph, Bob and Rich!

Gracias Zoila! ;-)

Vlad Lazanu (Contact, Page), May 24th, 2010, 11:52
Truly fascinating!
Congratulations, Rogelio, for all these stunning pictures you share with us! Thank you!

Vlad Lazanu - ROMANIA

Chuck Mountain (Contact, Page), May 24th, 2010, 14:33
Your photography of the beauty of the heavens is both technically adept and aesthetically pleasing. I have used Hubble photos for several of my digital art pieces, but your work achieves a higher and more consistent sense of wonder than Hubble's. Thanks for displaying them. I may contact you for commercial use of some of the photos in the future.

RBA (Contact, Page), May 25th, 2010, 0:52
Chuck and Vlad, thank you for stopping by and your kind words!!

Bill Logan (Contact, Page), May 27th, 2010, 14:53
This has to be the best digital image that I have ever seen, bar none. Truly magnificent!

RBA (Contact, Page), May 31st, 2010, 21:13
Thanks Bill!

kim ui li (Contact, Page), August 16th, 2010, 6:59
Hello!
your photo is very Beautiful!! :->
I'm poor at English..but like for seeing a star.
I will often visit here^^ bey!

Frans Lalleman (Contact, Page), February 16th, 2012, 0:20
Very inspiring website , I really love your wideshots.
Your imaging night outs read like a boys book ,
Best regards from the Netherlands
Frans

mehar pari (Contact, Page), May 25th, 2012, 22:17
Beautiful work on the Rho Oph wide field. Really like your suble use of color.

Greg Parker (Contact, Page), May 6th, 2013, 7:19
Completely and utterly - totally outstanding!! Great work Rogelio :)
Greg

Massimo Rodolfi (Contact, Page), July 27th, 2014, 6:46
Sometimes, me too, I think to change hobby. When the program that your using is doing what he likes, when you've just finished to center and focus a difficult object and in the dark you pull a cable and move the mount, and all the rest that makes astrophoto an hard job. But in the end, the sky's too beautiful, like the pictures that you take. So, as Peter Gabriel said in one of his songs:'...don't give up, cause you have friends...'

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