Koehler Urban Astrophotography

Because I found learning calibration challenging during a demo for PixInsight (where horrendous results were obtained initially through simple mistakes), I also started to pay more attention to bias, dark and dark flat calibration frames.  Whereas in Astro Pixel Processor, calibration is so easy that no attention need be paid, in PixInsight the user is down in the weeds looking at data... trying to figure out what's gone pear shaped.  And so, I began to do some searches on the behavior expected for the Canon T3I, whether ISO1600 was (in fact) suitable for lights and darks, whether ISO100 is suitable for flats, etc. This led to an old (2015) page from the  Blackwater Skies Blog  on their PixInsight workflow for the Canon EOS 500D that (similar to other posts) noted that the dark current visible in Canon EOS DSLR cameras is modified before written to the RAW CR2 files to manage the dark current levels.  At one extreme, this may suggest fixed pattern noise is no longer an issue in mod

Continuing a number of days of collection of M81 + M82 on the Meade LX10 SCT with the Celestron 0.63 focal reducer (1250mm @ F6.3), the Canon T3I with Astronomik CLS EOS clip-in filter. This includes collection with M81 & M82 on 2/20 (15x at 100s), 3/5 (112 at 120s) and 3/6 (52x at 300s). Collection on 3/3 was centered on M81 only (114x at 120s). The Orion C10 Newtonian also collected with M81 centered on 3/7 (92x at 120s). Tonight's collection started off with an initial alignment via polar scope that produce a remarkable result of 0.67" polar alignment error in PHD2's drift alignment tool. After manually focusing on Procyon using the live display, performed at 10s capture in the Ekos/Indi focus tool... just to see what metrics it produced.  Procyon itself measured 24.91 but the 5 other stars with measurements included 2.44, 2.99, 2.47, 2.71 and 2.46.  Started processing in a demo / trail version of PixInsight.  After a week's work...gave up.  No usable results. O

Performed some experiments at noon with solar imaging with the venerable Jason Constellation Model 311 and the SVBONY SV305 camera (with solar film clipped into place).  Used AstroDMx Capture as well as Indi/Ekos to grab snapshots as well as SER video files.  Captured flats against the basement LCD tv (white background) and then disassembled the telescope to clean the optics after noting lots of blemishes in the image.  Determined that the dust was actually on the AR coated window on the SV305 itself rather than the telescope.  Attempted to clean this up, but getting all the marks off is likely impossible w/ just a regular glasses cleaning cloth. Afterwards, mounted the giant Orion CN10 Newtonian on the Celestron CGEM and balanced for a second attempted imaging session with Apophis. After getting the system focused (without the Paracorr coma corrector)..which required only one small spacer for the T-mount to the Canon T3I, noted that the skies and this reflector were supporting about 1

Attempt to collect a series of frames for an animation on the NEA 99942 Apophis.  Magnitude ~15.8.  Yesterday night was closest approach. Example video  from a C8 at F7 (obviously far darker skies than the DC region).  Using the Meade LX10 EMC with a 0.63 Celestron focal reducer (1250mm @ F6.3) on Celestron CGEM DX mount with only the Astrodon CLS EOS clip-in filter.  Canon T3I set with a custom white balance for this filter. Used the polarscope for an initial alignment... PHD2 drift align showed 0.66' after after several minutes drift time in the initial azimuth adjustment position (pointed to the meridian and celestial equator). Two sets of posts... one in the  Indi forum  and one in  Cloudy Nights  provided insights on how to update Stellarium with the latest near Earth asteroid (NEA) ephemoride for Apophis.  Used this RA/DEC to slew the mount in KStars/Indi/Ekos and began guiding and collecting 60 second frames at ISO1600.  Guiding RMS settled to around 1.5 to 2". Started