Some Early December Images

These images were acquired in the increasingly sprawling and light polluted city of Frederick, MD. The Whittier neighborhood borders a red and white zone which called for 15 to 20s subframes. Each target was imaged for 180 subframes for cumulative exposure times between 45 and 60min. Equipment: Celestron 8/AVX Mount, Starizona Night Owl with Light Pollution Filter, ZWO ASI294MC Pro. 

M31 Andromeda Galaxy

M42 Orion Nebula

NGC2024 (Flame Nebula), NGC2024, B33(Horsehead Nebula)

NGC7789(Caroline's Rose open cluster)

NGC281(Pacman Nebula)

I recently watched Robin Glover's excellent talk on deep sky imaging with one shot color cameras. I also read his SharpCap forum write up on setting the exposure time for a site's sky brightness. Robin also gets into the mathematical justification in the write-up which I like. It seems that for my typical F/4 configuration with the Starizona Night Owl focal reducer, exceeding 30sec sub frame exposures offers no signal to noise benefit. This is a real eye opener. Instead, best practice is to collect as many sub frames to achieve a certain total exposure time. For example 120x30sec exposures for an hour. These concepts were played with the six images below from the most recent two imaging sessions. 

NGC 281 (Pacman Nebula)

NGC 6992 (Eastern Veil Nebula)

NGC 7635 (Bubble Nebula)

Messier 13 (Hercules Globular Cluster)

NGC 7023 (Iris Nebula)

NGC 7380 (Wizard Nebula)

A Couple of Globular Clusters (5/15/2021)

Messier 3 and Messier 52 captured in May. Celestron 8 on Celestron AVX mount, Starizona Night Owl, ASI294MC Pro. Exposure 30 x 30s. Guided by Orion Magnificent Mini Autoguider. 

Messier 3

Messier 52

 

Wow, I haven't posted here since April 12. So, I'll be catching up with some of the my better DSO images acquired over the last five months. A really fun thing about this hobby is when despite owning your hardware for five years you learn a couple of things that make a significant difference. First I recently realized that after doing an All Star Polar Alignment I should realign on the Polar alignment star for better go to pointing accuracy. Also helpful is to display the polar alignment before adjusting it.  The signs of the displayed angles tell you which way to move the tilt and azimuth if the star has not in your finder's field.

The following were acquired 5/14/2021 and averaged from 10 x 2 min exposures using Celestron 8/Starizona Night Owl 0.4x focal reducer and ASI294MC Pro. 

Messier 51 (The Whirlpool Galaxy)

 

Messier 63 (The Sunflower Galaxy)

NGC 4631 (The Whale Galaxy)

 

Galaxies Despite the Forecast

The NOAA partly cloudy forecast for Harvard, MA on Thursday 4/8 was not optimistic but Clear Sky Charts showed clear skies with average transparency for the night. My local skies were clear so I decided to gamble on the 45 mile trip to Harvard for a night of Coma Cluster galaxy imaging. For the most part the gamble paid off. All images below were averaged from 16 one minute subframes. While experimenting with image processing I found that applying noise reduction immediately after expanding the histogram to brighten the image makes the histogram more manageable. I'll consider elaborating in a future post.

Messier 49 - Giant Elliptical Galaxy

Messier 60(top) & Messier 59(bottom)

Messier 61 - Barred Spiral Galaxy

Clockwise from top Messier 86, NGC4402, Messier 84, NGC4387, NGC4388

Messier 88

Messier 89 (center)

Messier 90

Messier 98

Messier 99

Messier 100

NGC3521

Galaxies

By all measures this should have been a good galaxy season imaging night; clear, light winds, average transparency and seeing and not too cold at Harvard, MA. Setup and polar alignment went well. The auto-guider was working great. Everything was ready by 8:50 PM in time for my three hour imaging session. Of the 14 galaxies on my target list I managed to image eight by midnight. I considered going past midnight but my chilled fingers and toes said no. That yield was acceptable. Unfortunately I was off my mental game. In several cases I used the wrong exposure dark frame during sub frame acquisition. An inordinate amount of image processing with Paintshop Pro 2021 was necessary to produce the images below. If given another good galaxy season clear night I'll try to finish aforementioned target list while adding a few more. Equipment used: Celestron 8 with AVX mount, Starizona Night Owl 0.4X focal reducer corrector, ZWO ASI294MC Pro camera.

NGC2403

NGC2841

NGC2903

Messier 65 (top) and Messier 66

Messier 85 (bottom) and NGC4394

Messier 95

Messier 96

Clockwise from top Messier 105,NGC3389, NGC3384

Into Spring

Spring has arrived, so I've decided to get a jump on galaxy season. One non-galaxy target, overlooked by me in the past, is the gaseous nebula NGC2174. It was during an earlier open cluster imaging night that I noticed its nebulosity while imaging its associated open cluster NGC2175. Imaging wasn't under the best conditions, the heavily light polluted count of Frederick, MD, so I'll likely revisit NGC2174 in the future. It appears below along with five galaxies. All imaging was done at F/4 with a Starizona Night Owl focal reducer/corrector. Am, I glad I acquired this accessory before the SARS Covid-2 pandemic as it's been out of stock for months.  NGC2174 and NGC2175 were averaged from 60s sub frames. The galaxies were averaged  from 120s sub frames.

NGC2174 (gaseous nebula) and NGC2175 (open cluster)

M94 (galaxy)

M106 (galaxy)

M109 (galaxy)

NGC2403 (galaxy)

NGC2841(galaxy)

Short Cold Night at Harvard

The December 8 forecast was to be in around 32 by 9PM I decided to keep the night short. Astro-twilight was about 6:05 PM so I  arrived at the town of Harvard parking dark site around 4:30PM. Setup and all star polar alignment went smoothly. I deviated from the original target list dropping  M31 and NGC 1342 while adding M77 and NGC 2024. I probably should have stuck with NGC1342 instead of M77 which would be better imaged at a longer focal length. A combination of the dew hood and an ~8 mph breeze from the north challenged the auto-guider. And, having forgotten to bring my balaclava head covering the wind chill challenged my face during tear down at the end of the night. Fortunately I did remember to bring gloves and hand warmers. The five targets imaged appear below. Additional notes follow the images.

IC 5146

Messier 33 - Triangulum Galaxy

Messier 77(NGC 1068)

NGC663

NGC2024 (Flame Nebula)

All imaging was done at F/4 (800mm) with Celestron 8 AVX + Starizona Night Owl focal reducer corrector + ZWO ASI294MC Pro. Image area reduced to 3104x2116 pixels. Imaging temperature -10C. Of note, optical configuration was kept assembled and dark frames acquired the following day. Processing was with Autostakkert! I decided to experiment with acquiring dark frames with camera rotated slightly clockwise and counterclockwise from original. These were found to have little effect on post processing. For this reason I will likely acquire flat frames after the night of imaging with a reassembled optical configuration. I'll also return to the Orchard site which has less of an issue with passing cars.