IC4603/4604 and a Portion of the Rho Ophiuchi Cloud Complex in LRGB
date: June 11, 2021
Cosgrove’s Cosmos Catalog ➤#0073
The Rho Ophiuchi Complex as taken by the Askar FRA400 Platform. (click image for full resolution via Astrobin.com)
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About the Target
The Rho Ophiuchi cloud complex is a dark nebula of gas and dust that is located near the star Rho Ophiuchi of the constellation Ophiuchus. At an estimated distance of 460 light-years, it is one of the closest star-forming regions to our Solar System. This region is quite large, covering an angular area of the sky that measures 4.5 x 6.5 degrees in size.
About the Project
This is the second image I have processed from those acquired during the stretch of clear skies we had from June 4th-6th. This one is from my new portable rig with the FRA400 72mm F/5.5 scope. This is a much wider field than I can normally work with, providing coverage of 3.6 x 2.7 degrees - but even with this scope, I can only image a subset of this huge region.
Why did I choose this target? Well, early summer pickings are a little on the thin side. We are on the tail end of Galaxy Season (very small targets) but we are too early for the rich set of summer targets - so right now the target list is a little weak. The next problem is my restricted field of view. I had to be a target that I can see in the gaps between my extensive tree lines.
This target only shows itself for about two hours a night so I planned on getting at least 3 nights of data.
I chose 2-minute subs, as I always had gotten good results on the ASI1600MM-Pro camera with this. This was a mistake - with the faster optical system, bright stars were not just saturated, they are being blown to hell and back again! Oops. Won't do that again!
I also found that I had some clouds moving through for the first two nights and after culling bad frames, I ended with about 4 hours of integration, rather than the six I had targeted. The ones that were left had a variety of contrasts levels as there were still some very thin clouds passing through. So I decided to keep them and see what happened.
The result was….. Just OK. The bright stars are blown out and the darker regions still have a lot of noise even with careful and aggressive noise reduction processing. The colors are not as clear as they would be with more integration. But you learn with each image and this one had many things to teach me.!
The good news is that the tracking looks reasonable. I was getting RMS errors of 1.25 arcseconds most of the time with some exceptions into the 1.8 domain - and given the pixel scale of this system is about 2, this seemed good enough.
The Annotated Image
Annotated image created with Pixinsight’s Imagesolver and AnnotateImage scripts.
The Location in the Sky
More Information
Wikipedia: The Rho Ophiuchi Complex
Capture Information
Light Frames
The number of frames is after bad or questionable frames were culled.
36 x 120 seconds, bin 1x1 @ -15C, unity gain, ZWO Gen II L Filter
31 x 120 seconds, bin 1x1 @ -15C, Unity gain, ZWO Gen II R Filter
28 x 120 seconds, bin 1x1 @ -15C, unity gain, ZWO Gen II G Filter
29 x 120 seconds, bin 1x1 @ -15C, unity gain, ZWO Gen II B Filter
Total of 4.1 hours
Cal Frames
30 Darks at 300 seconds, bin 1x1, -10C, gain 100
30 Darks at 90 seconds, bin 1x1, -10C, gain 0
30 Dark Flats at Flat exposure times, bin 1x1, -15C, gain 0
Flats done separately for each evening to account for camera rotator variances:
30 L Flats
30 R Flats
30 G Flats
30 B Flats
Capture Hardware
Scope: Askar FRA400 73MM F/5/5 Quintuplet Astrograph
Guide Scope: Sharpstar 66EDPHII
Camera: ZWO ASI1600mm-pro with ZWO Filter wheel with ZWO LRGB filter set,
and Astronomiks 6nm Narrowband filter set
Guide Camera: ZWO ASI290Mini
Focus Motor: Pegasus ZWO EAF 5V
Mount: Ioptron CEM 26
Polar Alignment: Ipolar camera
Software
Capture Software: PHD2 Guider, Sequence Generator Pro controller
Image Processing: Pixinsight, Photoshop - assisted by Coffee, extensive processing indecision and second-guessing, editor regret, and much swearing….. Given the problems on this image, more than the usual whining….
This is my third telescope platform - this one is specifically designed for portability and travel.