Antares – Rho Ophiuchus Region

Antares – Rho Ophiuchus Region, June 11-12, 2021,Torrey, Utah

The Antares – Rho Ophiuchus is low enough in the southern sky that I have to catch it while it is as high as possible but before it creeps behind the wall of my windbreak. It is a wide field area so instead of using the camera and scope in the observatory, I set up my modified Canon Rebel with a Canon L zoom lens on my Losmandy G-11 mount on the outdoor cement pier. Almost a year earlier I had set myself a tickler to look for an opportunity to capture this image while it was in the right part of the sky. I really should have just set up in the driveway on the tripod, like I did in the good old days, where I would have had a much longer view without obstruction. But I keep coming up with low objects I want to shoot and I keep having to use the tripod to find a place where I can reach them. Since I didn’t build the outside pier and windbreak for nothing, I used it this time, dammit.

The big surprise was the coma effect on the stars in the corners. I didn’t expect that from an L lens. Makes me appreciate the quality of the glass and configurations of the telescopes I use more. Next time I will stop down at least one stop. I also tried to use a nifty piece of freeware in processing called Dark Master which matches the temperatures of the dark calibration frames with the temperature of the light frames. But instead of helping, it introduced some serious artifacts. I was doing something wrong so I just skipped the darks and used flat and bias calibrations.

It is a crazy gorgeous region in the sky and while I may not have done it complete justice, I’m glad to have it in my gallery.

• Location: Torrey, UT
• Exposure: 2 hours 45 minutes, 5 minute subs
• Lens: Canon EF 24-105mm f/4 L IS USM at f/4
• Mount: Losmandy G11
• Autoguider: Orion Starshoot
• Guide-scope: ShortTube 80mm f/5.0 refractor telescope
• Camera: Gary Honis full-spectrum modified Canon T1i (500D)
• White Balance: Daylight
• Mode: Raw
• ISO: 800
• Acquisition and guiding software: BackyardEOS, PHD2 Guiding
• Calibration: Deep Sky Stacker (no darks)
• Processing: Photoshop CS5

3 thoughts on “Antares – Rho Ophiuchus Region

  1. Ggreybeard

    A wonderful capture, Mark. I looked at it and thought maybe you had created a mosaic (using your telescope). It didn’t occur to me that you had used a DSLR! You can be proud of this one!

    🙃

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