Rho Ophiuchus Widefield

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 :-)