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Finally ... some success with EEVA


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This was the third session with the Altair GPCAM2 327C camera and the Photoline 72, and finally I had some success!

The secret seems to be to make sure I have the DSO in frame by winding up the gain to maximum, using auto stretch, and if necessary, checking the image on Astrometry.net.

I used the alignment from the previous night which was still good, and controlled the mount entirely with the SynScan software so that I could nudge the alignment more easily.

I focussed the scope on bright stars using the Bahtinov focus mask a few times during the session, mostly when I had switched in or out a filter, but once part way though the session when the focus had drifted. This was easy and quick to do. When the focus had drifted the SharpCap focus detection function was showing this.


This time I decided to start with a bright small DSO that would easily fit into the field of view and get things right with this target before moving on to another.

I set the exposure to 1 second and the gain to maximum (10,000) and this was enough to show a smudge where M27 should have been located which became more visible with auto stretch. Looking at the surrounding star pattern confirmed it. The smart histogram function suggested an exposure time of 10 seconds, a gain of 200 and a black level of 24. Leaving the gain at maximum but adjusting the exposure time to 8 seconds allowed me to see shape and colour in each image of M27 that the camera was taking. Then I started stacking and the image improved further. Auto stretch of the stacked image improved things a little, as did some further manual tweaking.



I could not find this, even after submitting a snapshot to Astrometry.net.


This had looked pretty poor the previous night so I tried again. Same procedure, starting with short exposure and maximum gain then switching to 8 seconds, 200 gain and 24 black level for live stacking.

The stacking histogram needed some manual tweaking and this was easier with the horizontal axis set to logarithmic. The image was a lot better than last night.


NGC 6992 East Veil

By now I was feeling ambitious and thought I’d try for the Veil. The mount didn’t bring it into the field of view but Astrometry.net confirmed I was pointing just to the right and when I slewed the scope over, the smudge of the East Veil came in to view at high gain.

I took images with the UHC filter and with the OII filter. The UHC image was brighter with more detail but quite a lot of noise. The OIII image showed less contrast and colour but more detail of the structure.

With the OIII filter …


I've been wanting to see the Veil since I first bought a scope last year so this was very exciting! Next time I plan to use the DSLR to try to see the whole thing.


Right at the end of the session I tried again for Jupiter. This needed a short exposure of 17mS and minimum gain (100) and it couldn’t be stacked so the image was not great. When I zoomed in it was grainy but I could see the North and South cloud bands and the Great Red Spot (for the first time).


Overall EEVA does let me see much more but the improved images take a few minutes to appear so are not close to live and there is more fiddling about than with straight visual. It is also harder to find objects because there is no way to zoom out by swapping eyepieces. Nice to be inside though, and not have to worry about light pollution or dark eye adaption.


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