Telescope cleaning & collimation test

 03/08/2025 -- Cleaned the corrector as well as the primary and secondary mirror on the venerable Meade LX10 SCT. Also cleaned the surfaces on the Svbony Sv405cc, the UV/IR cut filter and the Starizona SCT corrector III using generic lens cleaning wipes (Costco/Amazon) and the ancient lens cleaning kit blower & brush.  Struggled with streaking and dust... but eventually got to a point where improvement was clear (especially for the SCT corrector and the secondary.  Tested outdoors with the OTA reassembled and found major dust / dirt problems were solved.  Tested collimation against a bright 1st magnitude star and found no issues (thankfully). Defocused pattern looked symmetrical.  Tested using AstroDMX-Capture on the Odroid C4 viewed over Remmina RDC client (using the UV/IR cut filter...broad band imaging). Captured the moon and then switched over to the dual narrow-band (OIII, Ha) filter...since the moon is up at 79% all night.  Attempted to get the Owl nebula (M97) as a test collection with the cleaned optics but struggled to get the OTA into position with plate solving.

Seeing forecast from cleardarkskies captured at 12:10 on 3/9/2025 showing overall fairly clear skies but a large moon impacting darkness.

Ultimately, plate solving failed repeatedly for 3/08, 3/10 attempts to capture light frames.

03/11/2025 -- Clear skies (early) but the moon is high in the sky at 93%...tonight is only usable for testing purposes.  Indi Allsky backyard camera showed a pseudo sky quality metric of ~23,700 in moon mode (gain limited to 75%) at 23:30 (where 4,000 would be a reasonable value w/o the full moon). Fiddled with plate solving settings in Indi/Ekos ... challenging with the dual-narrow band filter in place and poor contrast in the sky. Found a set of parameters that appeared to work.  Also noted the the autofocus routine appeared to be at maximum inward travel without achieving fine focus. Used a laptop and adjusted the primary mirror against a bright star to bring the OTA into focus manually.  Set up M106 in the scheduler as a test object.With temperatures still at 50F at 23:30, used the cooler to put the SV405CC camera down to 0C.  Discovered (after the fact) that as all the various settings were changed across Indi/Ekos to obtain working plate solving and focusing, that the gain in the sequence file for light frame collection had been set to 399 with offset 24 (which is higher than normal...likely noisy).

Seeing forecast from clear dark skies for 03/11 looking grim wrt clouds later in the morning of 3/12 (European model) as well as poor darkness with the giant moon.

Seeing forecast for 03/11/2025 from meteoblue suggesting some clouds (low, medium & high) starting at 02:00. Plus huge moon.

Collected 30x180s dark (gain 399, offset 24), 30x10s flat (gain 284, offset 24) and dark flat (gain 284, offset 24) and bias frames (gain 399, offset 24) on 03/12/2025 using the white LED tracing panel with the stack of neutral density filters.

Ultimately, after processing to remove unusable frames, 43x180s (7740s, 2.15 hours) light frames were processed in AstroPixelProcessor.  The good news is that cleaning the SCT corrector, the primary and secondary mirrors, the Svbony 405cc camera itself... removed the effects of the three large dust bunnies. This was reflected in the master flat...and ultimately in the processed result from collection on 03/11.

M106 captured on 03/11/2025 (moon at 93%) across 43x180s (2.15 hours) of light frames (and calibration frames) with dual narrow band (Ha/OIII) filters.

03/18/25 -- Moon raises at midnight ... so still imaging with dual narrow band filter in place... skies are clear.  Collection before midnight looks optimal with pseudo sky quality metrics of ~5700 (with 4000 being excellent skies over DC).  Double-checked polar alignment after a couple days stowed for wind and rain... and found the mount with a relatively low polar alignment error (w/o any adjustment) of -1.1' after drifting for a couple minutes. Left PHD2 running on drift alignment for 10 minutes and found the reported polar alignment error at -0.15'.  Clearly, no adjustment needed.  Guide errors were low (RMS ~1"). Weewx backyard weather station showed temperatures staying relatively high (49.5F at 22:20) but no wind.  Turned the cooler to 0C on the Sv405cc camera with gain set back to 285 and offset 24. Set the Indi/Ekos camera session to utilize 120s light frames. Set up the Medusa Nebula through 1am and then M106 through 05:30 in the scheduler.  Automated plate solving, auto focus and guiding commenced successfully for the Medusa nebula job with 45 second exposures used for both plate solving and auto focus steps using the dual narrow band (Ha/OIII) filter for narrow band imaging.

Noted guide performance did not recover immediately after the meridian flip (~22:00). Repeated guide failures -- perhaps a problem with the OTA balance on the mount? Stopped the scheduler, parked the mount and restarted.

Indi Allsky backyard camera pseudo sky quality metric and star count for 03/18/2025 from ~18:00-22:00 showing around 5700.

Seeing forecast for 03/18/2025 from meteoblue showing cloud-free conditions and no moon until midnight. Reasonably good seeing conditions also.

Seeing forecast for 03/18/2025 from cleardarksky showing similar rosy predictions for sky conditions until midnight.

03/19/205 -- collected calibration frames. Light frames captured using the stack of neutral density filters with the LCD tracking pad (30x10s) with the Svbony 405cc set to 0C with the cooler (ambient temperatures were in the upper 40's). Gain set to 284 with offset 24.  Dark flat frames, dark frames (30x120s) and bias were collected.

Master Flat exported from ASTAP as a jpg after cleaning the LX10 SCT corrector as well as primary and secondary mirrors (no more dust bunnies).

ASTAP background contour from the image analysis tool applied to the Master Flat from the calibration frames collected on 03/18/2025 (30x10s).

Medusa nebula (35x120s, 1 hour and 10 minutes of collection from 03/18/2025 from 20:14 until 22:49 Eastern) with the dual narrow band (Ha/OIII) filter processed in Astro Pixel Processor. Moon had not risen yet.

03/23/2025 - Removed the Svbony 405cc OSC camera to test the fitting of a new (to me) electronic 8-position 1.25mm filter wheel.  This would require new calibration frames to be collected given a new camera position on the OTA.  

Clouds prevented collection early in the evening... but set up a job in the scheduler for M106 which started at 12:32 on 03/23/25.  However, the moon (at over 40% illumination) was rising at this time...so stuck with dual narrow band filter.  Remarkably, auto focus, plate solving and guiding all proceeded successfully from the scheduler running autonomously and over 90 light frames were collected.  Did note that the gain was mistakenly left at 399 with offset 24.   

Indi / Ekos Analysis module showing metrics (SNR, guide RMS error) along with the collection timeline for the M106 collection on 03/22-23/2025.

During the day (after noon), collected flat, dark flat and new bias calibration frames.  Found that the gain of 150 was needed for the 30x10s flat frames to be on-scale with the light frames collected overnight.  Had the OTA pointed at zenith with the stack of neutral density filters and the LCD tracking panel providing illumination. Used a cushion to block sunlight from getting through the LCD tracking panel (or as stray light) as much as practical.  Found dust / dirt on the stack of neutral density filters...and so cleaned and rotated the stack & LCD tracking panel and collected a second set of 30x10s flat frames (just in case that dust/dirt would impact the light frames). May make sense to use just the second set and discard the first set of 30x10s frames.

03/26/2025 - no moon until after 06:00...only a few clouds... switched back to broad band imaging by swapping out the 1.25" dual narrow band filter for the basic UV/IR cut filter...still awaiting parts for the electronic filter wheel...so this was a manual filter change that will require (yet more) calibration frames for pre-processing. Temperature at ~21:00 at 45F...set the Svbony 405cc cooler at 0C. Indi Allsky backyard camera showed a steady pseudo sky quality metric of ~6700.

Set up PHD2 to check the polar alignment error using the drift alignment test with sigma Hydrae. Initially off by -10.8'. Adjusted the rotary stage from 0.5 to 0.9 on the index.  This resulted in a polar alignment error of -0.2 after over a hundred steps.  Noted a couple small clouds drift by. 

Set the scheduler for M160 and M5 with a sequence file using 60s light frame collection at gain 285 and offset 24. Reset the focus and plate solving modules for 15s collection at gain 285.

Seeing forecast from meteoblue for 03/26-27/2025 showing only a few clouds and no moon.

Seeing forecast from cleardarksky with a similar prediction...but also showing largely cloud free after 01:00.

A single 60s light frame capture of M106 from ~21:40 with a background level of ~13,000 inside the Indi FITS viewer.

After launching scheduler, the focus module, plate solving and guiding calibration proceeded smoothly and quickly. Guide errors started near 2" but fell to ~1.4" after the guider stabilized.

03/27/2025 - No moon but clouds scheduled for ~04:00.  As the sun set, collected 30x10s flat, dark flat and bias frames at gain 185, offset 24 using the LCD tracing panel and stack of neutral density filters with a seat cushion on top to ensure no light penetration through the panel. Then set up M106 and M5 in the scheduler.  At 21:00, the Indi Allsky backyard camera showed a pseudo sky quality metric of ~6400 (had been steady at this value since ~20:35).  Outdoor weather station showed local temperature of 48F with no wind.  Had set the Svbony 405cc at 0C and provided 30 minutes to stabilize after cooling down.

Seeing forecast for cleardarksky (downloaded at 21:10 on 03/27/2025) suggesting clear skies through 05:00, no moon and poor seeing.

Seeing forecast from meteoblue (downloaded at 21:10 on 03/27/2025) with similar predictions.

After noticing repeated challenges with guiding, double-checked polar alignment using PHD2 drift align on the Odroid C4.  Measured a relatively modest error of 2.25'.  Took up backlash and rotated 3 tick marks from high to low.  This was too large of an adjustment... resulting in a polar alignment error of ~-5'.  Took up the backlash and adjusted back from low to high by 1 tick. This brought the polar alignment error down to 0.3'.  Dropped out of PHD2 and relaunched the M106 / M5 jobs in the scheduler.  Found that guiding was still extremely poor.  Parked the mount, cleaned the 9x50 RACI guide scope optics, rebalanced the OTA on the mount as well as counter weights and restarted the jobs. Following this, the first 30 light frames for M106 varied in guide RMS error (starting over 3" and gradually reducing below 2") and the second 30 light frames remained largely below 2". 

By 23:35, the Indi Allsky backyard camera pseudo sky quality metric fell below 5500.