Happy 2023 from the Terrace

The condo association gave me an early Christmas gift cutting down the sky obscuring dying tree outside my terrace. Trees across the way still block my light polluted skies. Nonetheless, I now have a descent strip of sky between 20 and 45 degrees altitude to work with during Orion season. I'll still make trips to my favorite darkish site in Harvard, MA but this will cut down on my carbon footprint as well as freezing toes during winter months. An additional benefit is access to WiFi allows me to monitor the scope using Chrome remote desktop. I'm pleasantly surprised with NGC2359 acquired with 15s subs which I first imaged with 60s subs last April from the McCoy's landing darkish site.  I'll definitely revisit NGC2359 between now and April from the terrace. 

The experiment with finder only All Star Polar Alignment has worked better than expected. Typically, I have only needed the two alignment stars plus two calibration stars after rough alignment with Polaris which is not visible from my south facing terrace. Typically less than 2 degrees of azimuth and less than 1 degree of altitude correction have been needed to correct for axis deviation from polar alignment. Thus far the Celestron AVX GoTo puts targets in the NightOwl  field of view (FOV). To center faint targets I just use Precise Goto which puts a bright star in the field which when centered in the FOV and centers the target with an offset.  Below are targets acquired on 12/27/2022 using 60x15s or 120x15s exposures.  Update: M42 reprocessed for reduced contrast and saturation.

M77 Irregular Galaxy

NGC 1788 Reflection Nebula

Left to Right: NGC2024(Flame Nebula), NGC2023, Horsehead Nebula (B33)

NGC2359 (Thor's Helmet) -- To be revisited

Orion Nebula (M42) again 😂

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!! 😀

Comet C2017T2, IC405, IC410, M33, NGC281, M42, NGC7635

Here are a few recent images acquired this 2019 winter. All were acquired at F/4 using the recently with Celestron 8+Starizona Night Owl FR+Orion SkyGlow Astrophotography filter. Camera: ZWO ASI294MC Pro, Mount: Celestron Advanced VX, Guider: Orion Magnificent Mini Autoguider. 

Look closely at Comet C2017T2 and you might notice the glow slanting down to its left. That's residual glow not zeroed out by the flat frame. Vignetting from the Night Owl is very aggressive and tough to zero out.  

Using SharpCap 3.2 I have found collecting flat frames at a narrow range of different exposures that give a histogram just above and below the "above 20%" criterion should provide a flat frame that does a good job zeroing out vignetting and artifacts. *

* More recently I have found a 20% to 80% histogram range, as recommended by SharpCap documentation works best. 

Update:03/13/2025 M33 reprocessed 

Comet C2017T2 PANSTARRS -- 15x60s @bin2

IC410 -- 6x300s @bin1

M33 (180s exposures)

IC405 -- 6x300s @ bin1

NGC281 -- 10x180s @bin1

M42 -- 25x8s @bin1

NGC7635 -- 6x300s @ Bin1

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.