NGC 3817

[Rodd]

I t has taken me a long time to get back to it.  I finally decided to go with the C11Edge for galaxies over the TOA 130.  It is, after all, the reason I bought it.  I am glad I was able to quell refractor fever.  Normally, it is a decent countermeasure to aperture fever, but in this case, I think it was the right decision to go with aperture.  It has been cloudy almost perpetually, with clear nights that are forecasted deteriorating into cloud banks with the coming of darkness.  Fortunately, I used the OAG from the FSQ to the C11 instead of the Celestron AOG.  This meant that the guide cam was perfectly focused immediately.  I didn't have to touch the guide cam focus.  Another benefit in using the ASKR OAG is it is much thinner, so my sensor is actually very close to 146.5 mm from the objective--which is the design spec. 

I decided to start with NGC 3218, which is one of my favorite galaxies.  I had shot this same target, same filter same camera same scope last year but could not complete it due to seasonal progression.  I tried combining the data from last year and noticed something I had not seen before--the stars had spike artifacts.  I am not sure if this was because of  faulty distance, or wind, but the image is much better over all without the old data.  Shame to, because instead of 7.8 hours, I now only have 2.8 hours.  The FWHM was slightly better in the old data (2.2 vs 2.6), but I attribute that to 1/5 seeing and windy conditions.  This time, I inspected all subs and found that about 20% had wind artifacts.  I did not inspect last years data the same way and suspect it has wind artifacts as well.  I only have the stack, so it is what it is.  

Anyway--here is my first data from the C11Edge with the sensor at the right distance.  Its only 84 120 sec red subs, but it shows promise.  Considering this image is bin 3, resolution was pretty decent.  With bad seeing and wind, I think a FWHM of 2.6" is not too bad.  My sky is poor--lots of LP and low transparency, so its hard to achieve a nice background without clipping.  This stack has 2.8 hours.  maybe I will collect more red for a 5 hour stack.  5/5/5/7 for 22 hours.  I don't think this galaxy has appreciable Ha.  If anybody knows otherwise, let me know and I will happily collect some

C11Edge with .7x reducer and ASI 1600.  Red: 84 120 sec, Bin3