Koehler Urban Astrophotography

Installed a 2" Orion  Crayford-Style focuser  to the massive Orion CN10 Newtonian due to wobble and shake with the original rack & pinion.  Additionally, this focuser accepts the Baader RCC I  Rowe Coma Corrector  without needing to be modified and without adapters, custom spacers, etc.   Started setup at 8pm with plenty of light left to level the Celestron CGEM DX mount, stick on the counter weights and the OTA and cameras.  With trees now grown so tall to permanently block polaris, used a best guess approach with the mount in the drive.  After focusing on Epsilon Serpentis, started phd2 to begin a drift alignment.  Remarkably, started at only 15.45' off (without using the polar scope)...just dead reckoning.  After an initial over correction, adjusted to 2.66' after several minutes of drift. Initial frame used for plate solving (before polar alignment) showed strong streaking in the top half of the frame (with long dimensi...

Goal: Grab additional frames of M86 on the CN10... work to try and reduce coma with the existing rack & pinon focuser. Set up around 8:45...  Great skies...zero clouds...no moom (set at 8:30pm)...warn temps (80's)...meteoblue suggests good seeing (green).   Started focusing and drift alignment around 9:45.  Was unable to catch Polaris through the trees with the polar scope.  :<  Leveled the mount and eyeballed north.  Initial drift alignment showed ~85' off (DEC line drifting down).  Focused on Vindemiatrix (Epsilon Virginis) and after tightening the focus lock, tilted the focus tube downwards.  Adjusted azimuth by loosing on the right (east)...and got to 62".  Second adjustment: ~12". Third azimuth adjustment: -1.2".  Internal guider calibrated w/o problem and showed initial RMS of ~2" (with variation across a line spanning RA). Generated two jobs in the Indi/Ekos scheduler...first M86 (3x40 lights) and then HD 197912 (the W...

Goal: install, configure & test out the Baader Planetarium Rowe Triplet Coma Corrector - RCC-I on the Orion CN10 (long tube) 10" Newtonian.   This is an attempt at replacing the Teleview Paracorr (type 1) since my example is ancient, hazy (smoky...amber colored...ich) and results in a 15% increase in focal length.  Early testing with my example paracorr suggested similar light throughput as the (deforked) Meade LX10 EMC 8" with a 0.63x focal reducer (which is sad). A key challenge with the RCC-I in this Newtonian is the focuser.  It comes with a T-adapter...and an eyepiece adapter...neither of which work with this 2" coma corrector...because it needs to go _into_ the focuser.  Sadly, the eyepiece adapter for the focuser brings the camera too far out... and the T-adapter provides no mechanism to mount the coma corrector.   This was confirmed on the first night...which resulted in no images... with no mechanism to reach infinity focus.  Had...

Collection notes from 05/05.  No moon.  Some breezes. No clouds.  Temps in the low 60's. Seeing described as very poor on meteoblue (40+m/s) and Cleardarksky.com.  Tripod re-positioned over previous location (grass marks from vibration pads).  Initial polar alignment through the polar scope was a bit difficult... lots of branches.  PHD2 drift alignment (with NGC 4438 centered) showed ~2' (3px) error after several minutes of drifting.  Once again, polar scope works on the first attempt.   First collection with the Zwo Asi 120MC-S following firmware upgrade and the Cosmicar 50mm F1.8 lens was refocused (put the line under the 7).  Also readjusted centering using Denebola (also adjusted ST80 focusing w/ the Canon T3I).  Was successful in getting alignment between guide camera and Canon to within 128 arcseconds.   Two jobs scheduled: NGC 4428 until 03:00 then NGC 6888.  Guiding was tough... switch to using ST4 cable and b...

Started a mult-session collection on 03/26 (52) and continuing on 04/15 (47), 04/16 (109) and 04/19 (~20) against Markarian's chain  with the venerable Orion ST80 using the generic dual narrow-band filter , clear Astronomik EOS clip-in filter (for consistent focusing with the EOS CLS clip-in filter) and Canon T3I (astro modded for Ha sensitivity).  180s collections used for each (except for 3/26 at 300s) and flats collected against morning blue sky when needed based on re-focusing (03/26, 04/16).  Canon configured with UTC time.  Based this collection in Kstars/Ekos/Indi by centering on  NGC 4438 . For this processing, utilized both 60x180s and 30x300s darks as well as 130 bias (all at ISO1600) frames for calibration.    Collection notes from 04/19:   Ran entirely on the Odroid XU4 via remote desktop protocol (rdesktop client with compression) to simulate a remote location and provide some robustness for network / wifi drop-outs. ...

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 lo...

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....