My Plan.   It was unusually pleasant and warm fall evening, the skies were clear and the telescopes set up.   Just after sunset, a nearly full moon rose above the eastern horizon, lighting up the sky and my backyard.   It just a few days before the lunar eclipse.  I thought that perhaps only narrowband filters would work for imaging and it would be a good night to test my new L-Ultimate dual band filter.   I picked a somewhat dim diffuse nebula target located within 30° of the full moon, thinking maybe, just maybe, it would work.  I had been looking for targets that would fill at least a third the field of view of the RedCat51 and ASI294MC combination.  Having recently done the Elephants Trunk, Question Mark, and other large nebula, I felt the Lion Nebula, which is a little over 1° in height and width, was worth a try.

The Target.  One of the 312 bright emission nebulae catalogued by Stewart Sharpless, this large area of emission nebula in the constellation Cepheus glows from the characteristic red light of ionized hydrogen.  Thick patches of galactic soot between the lion’s mane and its tale blocking out the light from distant stars behind it.  There was a strong moon glow that was easily removed using PixInsight.  I was surprised that in spite of the full moon, there seemed to be a decent signal in Ha and Oiii.

My Setup.  A 10-year old  Celestron AVX mount with hand controller connected via usb cable to ASIAir Pro.  Guiding performed using ASIAIR Pro software, ZWO 30mm mini guide scope, and ASI120MM guide camera.   The log files from the ASIAir indicate a guiding RMS in RA of 1.02” (0.16 px), in Dec axis of 1.55” (0.24 px) and a Total RMS of 1.86” (0.29 px).  The AVX mount is admittedly a substandard mount for astrophotography and mine still has its ultra-sticky grease from the Synta factory in China.  Perhaps this winter I will tear it apart and super-tune it, which will make balancing so much easier and hopefully improving guiding.  The telecope was a WilliamOptics RedCat 51 with ZWO 2” filter drawer with Optolong L-Ultimate filter and ASI294MC Pro camera set to120 gain, 1X binning, and cooled to -10°C.  Clear skies under Bortle 4 light pollution zone and with a full moon.  Out of total of 85 light frames collected, 71 were cloud and satellite free and used to create this image.  The exposure time for all images was 300 sec (5 min) and they were collected over two nights (12 frames on Nov. 7 and 72 frames on Nov. 9th).   Calibration frames included 60 flats, 60 darks, 60 dark flats.  PixInsight was used for image stacking, calibration, integration and to remove the background gradient (from the moon) and limited color correction.

Conclusions.  Imaging deep space objects during a full moon, even with narrowband filters, is just not my cup of tea.  Is it worth it?  I’ll let you be the judge of that.  With the L-Ultimate allowing 3nm of Ha and 3nm of Oiii to pass, much of that was probably lost to scattering in the atmosphere and drowned out by the light of the moon.  Very little detail and structure is visible in this image.  It was so bright outside those two nights (I could see my shadow), it’s amazing any photons reached my CMOS sensor.But Sh2-132 is a cool target and it was worth my time.  The Lion Nebula will now be on my list to image again under dark skies (no moon) with the ASI294MC with only a UV/IR cut filter.  I will also try this in LRGB with my ASI1600MM and Nikon 300mm lens combo.  I also recognize that my cameras are not well suited with the focal length of the RedCat and are woefully under-sampling the image.

Comments. I am new to this astrophotography thing and welcome your suggestions, thoughts, and advise.   The learning curve is steep, but the nights under the stars are just wonderful and peaceful.  Please feel free to provide comments below.

Clear Skies! ✨🔭