First light: Baader Planetarium Rowe Triplet Coma Corrector for Newtonians - RCC-I

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 started using local terrain (distant trees) and felt it was close, but ran out of adjustment with the focuser when centered on a bright star.  Noted that the Orion CN10 T-mount accessory has zero space between the T-mount and the focuser.  Given the eyepiece adapter was required to use the RCC-I (which has at least 5cm of distance), there's no way.  Gave up for the night.

Tried again on 05/18.  After removing a baffle from the focuser (just popped out, no worries), was able to insert the Baader Rowe RCC-I deep into the focuser and connect it using an M60 to M42 adapter.  Using spacers to emulate the distance used by the VariLock T-2 extension, was able to accommodate the thickness of the M60-M42 adapter (and M42x1 to M42x0.75 male to male adapter) to the Canon T-mount.   

Started setting up around 9:15pm...began working on imaging at about 10pm.  Tested initial rough focus on the moon (~50% full).  Good results with only minor focus adjustment (poor seeing, however...recorded a SER file for posterity within Indi/Ekos).  Next centered on Eta Herculis for fine focusing and drift alignment with phd2.  10 second frames collected for plate solving looked fairly good with reasonable stars across the frame. A few in the lower right of the frame showed elongation, but overall the field looked free of major coma.  Initial polar alignment error with phd2 was large (25' with the declination line trending down).  Shifted closer to the Meridian and the Equator, centering on HD 124224.  After several adjustments, reached a polar alignment of ~3.8'.  

Photo showing the position of the focus tube the next day to illustrate relative focus position with the RCC-I installed in this manner:

Next, centered on M86 and tested several exposure settings while examining DU values for red, green and blue channels within rawtherapee.  Found 180s exposures created background sky values of near 255 for the blue channel, so reduced exposure setting to 120s at ISO 1600.  Set up a job to collect 30 frames for M86 and then slew to NGC 6888 to collect until 4:30am. Sadly, the scheduler reported an odd error (end time before start time) and did not execute the NGC 6888 job.  28 usable frames were collected from M86 and the scope was left parked normally at the end of the job when an altitude of 35 degrees was reached (ending the collection automatically).  Collected 30 flats the next morning on blue sky and 30 dark flats with the OTA covered and pointed to the house.  Processed this initial stack (total integration 3400 seconds, 56.6 minutes) with Astro Pixel Processor using Bayer drizzle set at 1.0x.  This led to pixel spacing of 0.719 arcseconds / pixel...which suggests a 2:1 binning should be used.

Result from this initial integration:

Left the tripod as is and tried again on 05/20.  Very light breezes, moon at 50% and high at the meridian around 10pm. Attempted adjusting the focus to push outwards on the stop to try and see if this corrects a slight out of plane focus error that seems apparent on the 28 frames from 05/18.  Started with initial polar alignment with the polar scope, but found this horribly off in PHD2 with a drift alignment.  Four adjustments required to bring the DEC line flat (tightening on the left (east) azimuth adjustment knob).  

Due to the moon, started a job on M81 (Bodes Galaxy) rather than revising M86.  Astronomik EOS CLS filter in place in the Canon T3I.  After difficulty in getting M81 centered (adjusted acceptable error to 70' after repeated failing), finally began imaging at ~10:50.  Internal guider showed initial RMS of ~2" total.  Collected 58 frames for M81 up until ~1am.  Integration in Astro Pixel Processor (with Bayer drizzle and binning at 2:1 showed this result:

Sadly, integration across the 50 usable frames did not eliminate issues with a sensor out of plane issue resulting in elongated stars in places... highlighting that focuser has too much movement with the RCC-I mounted in the adapter.

While waiting for NGC 6888 to raise, began collecting 25 frames for M101.  Initial integration in Astro Pixel Processor with levels set in the Gimp provided this result for the Pinwheel Galaxy:

Scheduled job for NGC 6888 set for approximately 2am.  Had to manually stop the M101 job and restart the NGC 6888 job due to weirdness (plate solving).  Ultimately, the scheduled job ran until 3:45am when ended due to impending astronomical dawn with ~35 frames collected successfully.  Results in Astro Pixel Processor for the Crescent Nebula:

Collection notes for 05/21.  Temp 73 at 09:30pm with some high level clouds (haze) with more serious clouds coming in around 1am.  During the day, used the collimation laser / Cheshire to study the movement (and misalignment) of the focuser.  Noted that if the focuser is put into position (focused), then locked, and then the focus knob is turned clockwise (looking from the top of the scope down onto the focus knob), this places the laser spot on target.  If locked counter-clockwise, the alignment is forced way off. 

Started with polar drift alignment in PHD2 (didn't bother to check polar scope).  Initial alignment off with the DEC line drifting up.  Tightened on the right to correct in two iterations.  Performed some initial collection on M81 while waiting for scheduled job to start collection at 22:12. Guide RMS was low (<2.5"). Halted before scheduled job started... which launched successfully.  However, follow-on job (M101) scheduled after M81 did not launch.  Again, some weird scheduler bug with error message, "Job 'M 101' completion time (22/05 04:00) could not be achieved before start up time (22/05 22:16)". The job was examined at 12:30am and marked invalid.