NGC 6857 Emission Nebula

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menardre
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Joined: Tue Jan 17, 2012 6:09 pm

NGC 6857 Emission Nebula

Unread post by menardre »

While working with SkyTools4 (Imaging) I found NGC 6857 nebula situated in Cygnus. Currently, Cygnus is situated in a good part of the sky allowing for longer exposure times. So I decided to give it a try. I re-configured my setup to use 11 inch SCT with focal reducer, Falcon rotator and ZWO ASI2600 OSC. I also used IDAS NB-1 nebula filter in-between the rotator and the camera. I did not think that I impacted PHD2 guiding so I decided not to perform a calibration. That was probably the wrong decision.

The setup worked perfectly all night. I was able to acquire 77 images of 4 minutes with 0C, gain 100, and 2x2 binning. I reluctantly moved up to 4 minute exposures due to the NB-1 filter. SGP handled everything completed unattended. I also found that edge-to-edge focus was still good with the backfocus distance in my setup.

Upon analysis with Pixinsight I found that the first several images had some star streaking (really oblong stars). It was not until the scope was overhead that guiding eliminated the oblong stars. I believe this may be due to poor calibration. I will know better next time, especially since doing a calibration only takes a couple of minutes --- much better than wasting hours with poor quality exposures.

So I ended up with only 37 images that were used for stacking (Pixinsight calls it 'integration').

MGC 6857 is an emission nebula however there is very little published information on the nebula.

As we all say, astrophotography is a learning experience.

Roger
NGC 6857 Nebula.jpg
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Roger M.
Celestron CPC1100 EDGE, Stellarvue 130T refractor dual mounted on iOptron CEM120 on permanent pier mounted in Observatory. Imaging camera ZWO ASI2600 OSC, guide camera Lodestar or ZWO ASI290MM.
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menardre
Vice President
Posts: 886
Joined: Tue Jan 17, 2012 6:09 pm

Re: NGC 6857 Emission Nebula

Unread post by menardre »

I checked my scope today and found that the setup is way out of balance, which is probably the reason why my last imaging session had much better tracking at higher angles where the balance was more even.

I spent about 1/2 hour rebalancing. My rig is difficult to balance since I have a dual scope setup which requires balancing in 3 axes. Also the scopes are heavy so making small adjustments is difficult... mostly trial and error.

My next imaging session I plan on trying NGC 7013 which is a galaxy next to a nebulous area in Cygnus. This object will not clear my Eastern trees until about 10PM so it will be a good test.

Roger
Roger M.
Celestron CPC1100 EDGE, Stellarvue 130T refractor dual mounted on iOptron CEM120 on permanent pier mounted in Observatory. Imaging camera ZWO ASI2600 OSC, guide camera Lodestar or ZWO ASI290MM.
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