M94 and M106

3/7/24 -- first moonless, cloudless night with workable temps. Attempting to capture M94 high in the north sky from the Meade LX10 EMC with UV/IR cut filter, Meade 0.63 focal reducer and the Svbony 405cc camera. Set camera temp to 0C and using 0 gain and 0 offset.

Telescopius simulator result for M94 using the SCT with the 0.63 focal reducer and the SV405CC camera.

Telescopius M95 altitude plot for 03/07/24.

Cleardarksky forecast for 3/7/24 for Montgomery County showing fairly clear skies and reasonable seeing expected after midnight.

Meteoblue forecast for 03/07/2024 for Silver Spring illustrating clear skies expected for the evening.

Before mounting the OTA and counterweights, checked the mount as level and utilized the polar scope (due to a clear view of Polaris through the backyard tree -- a rarity). Adjusted the altitude up slightly and did a sanity check to ensure ~39 degrees. Initial alignment measured with PHD2 from the Odroid was ~ -11 after several minutes of drift.

Used the Bahtinov mask to focus on a bright star in the vicinity of M94 with several minor adjustments back & forth. This process did not provide satisfying appearing stars and more adjustment without the mask was required. :<

10 second exposure with the Svbony SV405cc using a Bahtinov mask for focus adjustment (shown inside the indi/ekos focus window).

Set the Svbony 405cc cooler to 0C given a predicted low temperature of 5C. Started a job in the scheduler for M94 using a sequence file capturing 40x lights at a time with 180s exposures. After several minutes of collection, guiding errors were ~3".

Indi Allsky camera analysis up to 11:39pm on 3/7/24 showing a pseudo sky quality metric falling to ~5000 with a full 15 second exposure.

Indi Allsky camera analysis up to 11:39pm on 3/7/24 showing the count of stars visible in the scene with a full 15 second exposure.

Ultimately collected over 60 light frames, however clouds entered the skies at around 03:30 with the indi-allsky camera showing steady decrease in quality starting at that point. In the AM, collected darks starting around 4:30am (when skies were overcast) as well as bias frames. Then at 6:30 collected flat (using a light panel...very short integration times) and flat dark frames.

Indi Allsky Camera exposure times overnight.

Indi Allsky camera star counts showing overcast skies by 4am.

Indi Allsky camera pseudo sky quality metrics showing problems starting at 03:30.

Indi-Ekos Analysis window for collection overnight on light frames for M94.

Processed the 54x180s light, 40x180s dark, 40 bias, 40 flat, and 40 dark flat frames using AstroPixelProcessor 2.0.0-beta22. Found issues at the edges of the frame from amp glow requiring a crop. In reading about amp glow issues in cloudnights, noted reports of problems with calibration frames with the IMX294 camera -- particularly recommendations to capture flat frames using a long exposure mode due to differences in how the amp glow manifests in low exposure vs 1-2 second+ exposures. Would also appear beneficial to use at gain of at least 120 to shift the sensor to HCG mode.

Processed with and without a 2x bin using the same post-integration workflow (crop, background calibration, star color calibration) to compare results.

Inset showing detail from the 2x binned case

Inset showing detail from the unbinned processing result from AstroPixelProcessor.

03/11/2024 -- A second evening of relatively clear skies (poor seeing) and very little moon led to an attempt to gather additional light frames against M94...with the hope of gaining the dim external ring of stars for this galaxy.

Forecast for 3/11/2024 from cleardarkskies showing marginal seeing and transparency expected.

Forecast from meteoblue for Silver Spring MD showing few clouds through 5am and poor seeing.

The OTA & mount were left out and covered...lots of rain and lots of wind. Double checking the polar alignment showed -4.75" after several minutes in the drift alignment tool in PHD2 running on the Odroid...no need to adjust. Used the opportunity (with Procyon centered) to double check focus...again using PHD2 with both the RACI 9x50 finder to the Zwo ASI120MC-S as well as the primary Svbony 405cc. Found this acceptable with the finder, but not simple with the primary camera through the OTA.

Examined a range of test images while guiding with new camera settings for gain (125) and offset (5). Starting with 180s exposure, found many stars completely saturated. Dropping to 120s, still found many stars saturated...and noted a median ADU value of ~4600. Dropping still further down to 60s...still many saturated stars and a median ADU of 2453 out of 65535. From a posting on stargazers lounge, noted advice to attempt to reach a signal level in a star-free background region of a sub of 4-5x the noise level (ADU) of a bias. This is challenging, since the existing bias frames have near 0 as mean... even the dark frames (collected at 180s) have few counts (~15) since these were collected at zero gain. A new set of bias and dark frames will likely be needed at a gain of 120 and offset of 5 (today's settings). An additional insightful thread on exposure times found here in the astrobin forum.

In any event, started a job on the scheduler for M 94 for 120sx40 lights repeating until 5am. Initially the Indi / Ekos scheduler refused to start the job...simply suspending it until tomorrow. Restarted Kstars/Indi/Ekos without connecting to the Odroid and set the scheduler connect to the Odroid profile ...and this worked. After examining these 120s frames in ASTAP, noted significant signal levels in background regions (~5000 ADU). Stopped collection after 22x120s light frames and restarted the job with 60s exposure time.

Noted significant time spent dithering. Adjusted settings in the Ind/Ekos guide tool to dither after after 2 frames vs after every frame at the start of 60s light frame collection. At ~4am, started collection for 120s and 60s dark frames as well as bias frames with gain at 120 and offset 5.

Indi-allsky camera pseudo-sky quality metrics for times up to ~11:40pm on 03/11.

Indi-allsky camera star counts for 03/11 up until ~11:40pm.

Performed an initial processing run with AstroPixelProcessor on the combined 120s and 60s lights, darks and bias frames with the master flat and master flat dark (and matching master dark and master bias) from 03/07. This did not produce a useful flat field correction...and the integrated result (while showing good contrast on the galaxy) was definitely suffering from focus problems. :<

AstroPixelProcessor integration from 140 frames collected starting on 03/11/24 (24x120s with 118x60s with gain of 120, offset of 0 and the SV405cc cooled to 0 centigrade) with flats collected on 03/12/24, 40x120s and 40x60s dark and bias frames.

AstroPixelProcessor analytic results plot for the 24x120s and 118x60s light frames from 03/11/24. Note the shift in noise and sky background statistics for the first 24x120s frames vs remaining 118x60s frames.

03/12/2024 - Additional clear night for capturing & experimenting with M94. Started with phd2 running on the Odroid to check polar alignment. PHD2 session started with an insistence on performing a calibration... Following calibration, PHD2 showed an error of ~30" (pre-meridan flip). Loosened on the right (tightened on the left) side of the mount (when facing the front). Meridian flip interrupted this process...switched from procyon to delta hydrae...

Initial drift... 23"...loosen on the right. Bad result...29. Tightened on the right. Very bad. 49. Loosened (alot) on the right. Ended up at -1.5". Next, adjusted focus using the Indi/Ekos focus tool. Initial adjustment - turn to the right...Bad result... turned back to the left. Gave up...switched to AstroDMX-Capture running on the ROG STRIX connected directly to the SV405cc. This provided an interactive mechanism to adjust and view focus. Worked the SCT focus back and forth to find an optimal focus. At this point (23:00), sky conditions appeared worse and some high level clouds were visible. :<

Cleardarksky forecast for 03/12/24 suggesting markedly better skies than yesterday night.

Meteoblue forecast for Silver Spring MD for 03/12/24.

Initial (21:00) Indi-Allsky camera pseudo sky quality metric of ~7,000 suggests the skies are not as clear as 03/11, however.

Light frame collection (60s, gain 120, offset 5, temperature 0c) started at ~23:23). Initial guiding showed total RMS of ~2.5". 146x60s light frames were collected total overnight.

In the AM performed a quick experiment to attempt to gain longer integration times for flat frames after seeing some recommendations online for the IMX294 CMOS detector in the SV405cc camera. Using the light panel on lowest setting, inserted a large cutting board between the panel and the OTA. This did not make a significant enough difference in integration time (goal...longer than 1 second) on low gain (0) setting. Ended up collecting 20 flat frames at a longer (but still not long enough) integration time... with the cutting board / light panel combo with the OTA pointed at zenith.

Initial results in AstroPixelProcessor with just these light frames and flat frames (but without matching flatdarks ...used flatdarks from 03/11 with much faster exposure settings...so not optimal) show significant mis-match between the light frames and the master flat with significant vignetting remaining. A heavily cropped and processed integration (8220 seconds total):

M94 using 146x60 light frames collected on 03/12/24.

AstroPixelProcessor analytical results for the 146x60 light frames collected over 03/12/24.

03/13/2024 (Weds). An additional clear night...higher temps and a sliver of the moon (but low in sky already by 21:00).

Cleardarksky forecast for 03/13/24 with reasonable conditions.

Meteoblue forecast for 03/13 for Silver Spring showing no clouds and reasonable seeing.

Attempting M106 when M94 was initial too low in the sky. Started by double checking alignment and focus. Focus from the OTA with the SV405cc was still tight. And PHD2 showed an initial alignment of ~-7"...but the internal Indi/Ekos guider was calibrating but failing to guide. Restarted PHD2 to take a second look. This showed exceptionally low polar alignment error of -0.62" after a minute of guiding... growing to -3.3 after several minutes of guiding. Once re-aligned to M106 and calibrated, the internal guider in Indi/Ekos returned to sanity and showed a guiding RMS of ~3" with 2s captures from the 9x50 RACI using the venerable Zwo ASI120MC-S.

Indi Allsky camera star count for the evening of 03/13/24.

Indi Allsky camera pseudo sky quality metric for the evening of 03/13/24 showing good readings of ~5700 by 23:15.

After collecting the first 85x60s light frames, switched M106 collection to 120s exposures for the remainder of the evening effort....starting around 23:49. Sadly, come morning, the Kstars / Indi / Ekos capture application was no where to be found on the desktop. At around 1:43am the application appeared to have crashed after 127x60s light frames were collected for M106. Collected flat frames using just the light panel on lowest level with the SV405cc set to 0 gain as well as dark flats.

03/14/2024 (pi day) -- poor skies expected with plenty of clouds....ending the collection streak.

Did perform a quick flat experiment. Using the large light panel on lowest brightness, sandwiched a black garbage bag between the panel and the OTA. This provided opportunity to experiment with flats collected at 1.5s exposure times with a gain set to 120 and offset of 5 to address a hypothesis (rumors in online forums) that long exposure times are beneficial for this CMOS chip. Collected a corresponding set of flat darks with the same settings but with the OTA cover installed.

03/16/2024 -- good skies early, but lots of moon (43%)... and clouds rolling in later in evening ... making for a poor opportunity for more wideband imaging. For a lark, pulled off the telescope cover and did a polar alignment with PHD2. Off by -60"... several adjustments later and sub-2" alignment was achieved. Started collection against M106 around 10:06pm. Indi-allsky camera showed a pseudo-sky quality metric of ~15,000... compared to a reading of ~5000 for a good dark sky over Silver Spring MD. Guiding calibration succeeded with a nice plot... and guide errors were low at ~2" RMS. Oddly, initial inspection of the third light frame in ASTAP showed R, G, B digital numbers of around 2,000 counts in the background regions with the M106 galaxy visible... and did not appear dramatically different than light frames from 03/13 at 10:40 showed ~2000 for RGB at pixel location ~2000,1000 (also collected at 60s exposure with gain of 120 and offset of 5). After capturing 30x60s frames, switched to 120s light frames. Clouds entered the sky around 23:40, sadly, with 52 light frames captured (22x120s). Ended collection, turned off the camera cooler, parked the mount for the evening.