GraXpert game changing freeware.

A number of weeks ago I stumbled upon a game changing piece of freeware, GraXpert. GraXpert's algorithm analyzes your deep sky image distinguishing stars and nebulosity from back ground sky and generates a background that eliminates gradients and reduces light pollution. A standalone app GraXpert is easy to use while offering settings that allow you to tweak the algorithm for better results. Prior to downloading this awesome piece of free software dealing with gradients, inherent to my  ASI294MC Pro was a bit tedious. With GraXpert you just load the stretched image*, create the grid, calculate the back ground and save the processed image. That's it. You can adjust the sensitivity of the grid creating algorithm to background intensity and you can move, add or delete grid points to distinguish nebulosity from the background. Aside from reducing my workload the colors in my images have improved. Some recent images follow. Thor's Helmet nebula was actually imaged from my 3rd floor balcony in my heavily light polluted south of Boston suburban skies with 120 15s sub exposures. 

*Stretching the histogram in Paintshop Pro seems preferable to the GraXpert stretching routine which seems to throw away black side data. 

Comet C2022E3 ZTF (2/15/2023)

Comet C/2022E3 ZTF  (2/8/2023)

Comet C2022E3 ZTF (1/30/2023)

Comet C/2022E3 ZTF (1/27/2023)

IC443, Sharpless 248, Jellyfish Nebula--Supernova Remnant. 

M42 Orion Nebula

M48 --Open Cluster

Flame Nebula (NGC2024) , NGC2023, Horsehead Nebula(B33)

NGC2264

NGC2353 Open Cluster

NGC2359 (Thor's Helmet Nebula)

M46(NGC2437) Open Cluster + Planetary Nebula NGC2437

NGC2232 Open Cluster

Messier 50 Open Cluster

Alignment and Guiding Experiment

After setting up the telescope I usually do a Celestron AVX all star polar alignment (ASPA) using the visual finder for rough centering then fine centering on the computer screen with the ASI294MC Pro. I thought this might be bit of overkill considering the use of the Orion Magnificent Mini Autoguider. I setup the scope on my 3rd floor patio, as lousy a place for viewing considering no access to Polaris and a tree limited view. The ASPA was performed using the visual finder only starting with  rough north alignment. Jupiter, Saturn were used for alignment and Fomalhaut for calibration star. I usually use two alignment and four calibration stars in the field. Surprisingly only 7' altitude and 7' azimuth corrections were required. Pointing accuracy was less accurate than typical but was good enough to put target on the camera sensor. I had not checked the alignment of the finder with the optical train. This was good enough for M42 but not for NGC2023 so I used precision go to which uses a bright star as a waypoint to the faint target. M42 and NGC2023 with the Flame Nebula and Horsehead Nebula imaged that night appear below. Update: M42 reprocessed for reduced oversaturation.

M42

NGC 2023(center)with Flame Nebula(left) and Horsehead Nebula(right)

Update: A pleasant  start of Orion season surprise. Condo association removed twelve dead trees surrounding my building including the tree right in front of my terrace. Likely the association was prompted by the coming bomb cyclone that will hit Greater Boston with heavy rain and high winds. More sky!! 😀

Another 5AM Orion Nebula

Similar to October 22, I decided to image M42 from my mostly tree blocked patio at 5AM in what amounted to a practice session. Ultimately I want to acquire an M42 good enough to enlarge, frame and wall hang. Similar to previous patio adventures the scope was rough aligned the night before on Mars and three other stars; two for calibration the put in hybernation. I was awakened by the flip phone alarm at 4AM well before M42 cleared the #%@&ing tree.

I decided to image at the ASI294MC Pro's full frame, 1x1 binning and at 120 gain. I would use the best frames from sets of 30x15s and 30x30s. Cooling was set at -10C. I not aggressive in cooling to limit taxing the cooler and the battery. Flat frames were acquired later in the morning after the scope hand warmed up. Stacking with Autostakkert!3 and processing with Paintshop Pro 9 resulted in the following.

Not bad. I don't consider this quite frame worthy but it's close. The problem is the haloing around the bright stars which might derive from my use of a light pollution filter just in front of the camera or from the protective glass in front of the sensor. That said, I'm really impressed by how well the auto-guider does considering my rough alignment on the patio. I really look forward to a few rare mid Atlantic clear, moonless nights with good seeing where I can go to one of my darkish sites to put this system through its paces.