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Contains:  IC 4605, NGC 6144, rho Oph nebula, IC 4604, IC 4603, M 4, NGC 6121, The star 22Sco, The star Antares (αSco), The star ρOph, The star Al Niyat (σSco), The star οSco
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From Antares to the Rho Ophiuchus Cloud Complex, 


            Sven Hoffmann
From Antares to the Rho Ophiuchus Cloud Complex

From Antares to the Rho Ophiuchus Cloud Complex

Technical card

Resolution: 3904x3992

Dates:Sept. 10, 2018

Astrodon B Gen.2 E-series: 7x60" -25C bin 2x2
Astrodon G Gen.2 E-series: 7x60" -25C bin 2x2
Astrodon L Gen.2 E-series: 14x120" -25C bin 1x1
Astrodon R Gen.2 E-series: 8x60" -25C bin 2x2

Integration: 0.8 hours

Darks: ~12

Bias: ~12

Avg. Moon age: 0.86 days

Avg. Moon phase: 0.83%

Bortle Dark-Sky Scale: 1.00

Mean FWHM: 3.00 job: 2251244

RA center: 246.848 degrees

DEC center: -24.869 degrees

Pixel scale: 3.500 arcsec/pixel

Orientation: 178.713 degrees

Field radius: 2.714 degrees

Data source: Own remote observatory


Well this is something special for me. I always wanted to capture this region in high quality since I saw images of it. Unfortunately this is next to impossible from Germany. We are just so high up and the capture opportunities so limited that I had to make use of a remote service for it.

My experiences with itelescope

I had used itelescope for a test image before in the past, so I kind of knew my way around. In addition I learned a lot about in the past 2-3 years. The most difficult part about this image capturing is that there is nothing like the mosaic and framing wizard in SGP, so you need to enter the coordinates by hand and in the right system and format (they use J.2000).

The system used is T8 in Siding Springs Australia because this puts Antares almost at the zenith at the beginning of the night right now.

The data quality is pretty much what you can expect from the system and exceptionally good. I calculated the etendue beforehand and knew that little time would be more than enough. Having no light pollution really helps. I have to be honest though. I started my astrophotography journey with CMOS, so the raw data from the 16803 looks horrendously bad because of all the column defects. Unfortunately itelescope does not provide a defect list so you end up cleaning this up by hand. Ugh!

I was disappointed that no flats were provided even though they were saying on the website that a full set of calibration files would be provided. Luckily it did not impact the image much. The system and sensor appear to be clean so there were no dust motes or anything. But still I would have liked even field illumination correction by flats.

I encountered one hickup during my capture. The roof closed during my session because of wind and I got an email that my reservation ended and I had been logged off. That was far from it. The system just continued capturing and I was billed for the "darks". Good thing they have excellent support and you can get a refund for situations like this directly from the website and get the points back immediately. That is a huge thumbs up from me. It would be even better if that scenario would have been covered by automation though.

In addition it was reassuring to me that even a 45.000€ setup has problems. The correction of the FSQ 106 is not good enough to cover all corners of the 16803, which I suppose is just a limit of physics in the end. In addition there is slight tilt in the system. I'm writing this to dispell some illusions :) Everybody will need to work very hard to get to a well working setup. Throwing money at the problem will most likely eliminate a lot of tinkering but not all of it to get to "perfect" images. Obviously it also depends on your standards.

For those interested: I paid about ~100$ for the 50 minutes of exposure time and the only downside was the limitation of usable rejection algorithms because of the low sub count on the color images.



Sven Hoffmann
License: None (All rights reserved)

Sky plot

Sky plot


From Antares to the Rho Ophiuchus Cloud Complex, 


            Sven Hoffmann

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