The Starry Night, 150

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Autumn Begins!

9/13/2015. A strong cold front dropped temperatures into the 40's and brought the first clear skies since forever -- in fact, some of the clearest since last winter. I took the G11, the AT65EDQ, the power-sipping Asus, and the 50mm guider up to the cul de sac. Consider this a rehearsal: if this kit works in the cul de sac, it will work at Doughton Park, and it will work at Datil Well too.

I made a couple of trips back down from the faux wilderness to doublecheck charts (and to pick up forgotten widgets). Might want to come up with some acetate overlays for the Skalnate Pleso and for U2000 maps (remember those?). It would let me check targets and devise starhops without increasing demands on the computer.



"My God! It's full of stars!"
M22 and environs: this may be more stars than I've ever shot in one frame: Four globular star clusters and drifts of stars near the galactic core (which is just off frame right). This is a stack of 18 180-second exposures (54 minutes total, tree limited) with a Canon 6D @ ISO 1600
AT65EDQ on G11, Guiding via PHD Guide

Click the image for a bigger version. (Just do it. It's worth it.)


The guider ran out of in-travel just outside focus though it came close enough to serve nicely. (In the morning, I removed a millimeter from the 1.25-inch holder on the tailpiece of the guide OTA -- there's room to remove more and room to remove much more if I am willing to retap and rethread some set screw holes).

The 9x60 straight-thru finder simply doesn't clear the rest of the kit enough to allow my head to fit where it needs to be to use it. With the compact penguin legs under the G11, the angles are especially contortionous. (I considered many fixes, but the easiest was just to fit an Orion RACI finder on the AT65EDQ's tube rings.)

I wanted to leave the kit in the cul de sac overnight for a longer run on M31, but to go as long as I wanted, I needed a way to shut down the computer automatically and cut off power to the mount. Shutting down the computer is for power conservation. That will matter more when far out in the field than it does here. Shutting off the mount would be nice because at moderately northern declinations, the camera will eventually intersect the pier. Staying up all night just to turn it off seems a waste of good consciousness.

I walked down and found software to manage delayed computer shutdowns, and for the mount, I messed with the timer I bought a couple of years ago to use in the backyard. The software works like a charm; the hardware timer is every bit as complex as I remembered. It's vast overkill for this purpose. So I ordered a spring-driven 12-hour power-off timer from Amazon. It's made for AC, but in the low voltage regime, juice is juice and it should work just fine. I hope to put into service Tuesday night. Rather than sit up later gathering light from a galaxy far, far away, I practiced tearing the kit and was done by about 2:45.

Couple of successes, but also a couple of disappointing images: the Alpha Persei Association and NGC 7000 were not much to see. Alpha Persei needs more exposure (I only did 3 subs, figuring the stars were bright; true enough, but the sky is not, and that's where the noise has to be knocked down, no?). I whiffed twice on NGC 7000: I missed to the north and fouled up the focus. S'OK: this week's forecast is remarkable. Three or more cold and sparkling nights are in the offing.


9/14/2015. Improvements. Guider focus is better, but still not perfect -- in the morning, I took off another silly mm or perhaps a bit more -- but as it was good enough last night, it is better tonight. I started with another cut at NGC 7000, the North America Nebula. This time I oriented the camera E/W. The nebula would be better shown N/S, but this way I get to enjoy the wide, wide view: Deneb is in the corner of the frame! (And I still missed, but I got enough to see that this will work well.) I've set up on the western fringe of the cul de sac to catch targets coming up in the NE, a real novelty for me. The RACI finder does not appear to have sufficient adjustability to be well-aligned with the OTA. Some tweaking to do there (damn straight: the next day, I removed it from its stock collimating tube / shoe mount and put it on an X:Y slow motion mount with grey tape; looks crude, works great).

I got it in my mind that dew was going to be an issue tonight, so I improvised dew shields for the main instrument and for the guider. The next day, I replaced the cobbled up (aluminum foil) dew shield on the guider with a cobbled up (PVC) version. The AT65 objective is set within a substantially larger cell, so the short piece of flocking I rolled up and inserted there (where it stays under its own springiness) will suffice.

About eleven, I slewed east to continue yesterday night's M31 exposure. I have about six hours of motion available before the camera strikes the pier, but I'm not waiting up quite that long. Wish I had that timer tonight. Tomorrow, weather, Amazon, and the Post Office willing, I'll try an overnight session on something.

With a two-night total of 4h15m in the can for M31, I called it a night and packed away the toys.


M31 with Guidepost Stars Nu and 32 Andromedae
85 x 180s (4h 15m) same outfit as above
Click the image for a bigger version.


9/15/2015. A third clear night! The timer is here, wired up, and proven on the dining room table. One issue: you can't reduce the time once you've set it. That is, if you set it for four hours, four hours it will be unless you'd rather have five or six or ten or twelve. Two is right out. So be careful. It's very quiet; the timer ticks like a watch rather than buzzing like a rattlesnake. This is good.

Tonight's plan: NGC 7000, then Alpha Persei, then the Pleiades while I sleep. What are the odds?

After Alpha Persei, I elected to kill some time with M52 and the Bubble while waiting for the Pleiades to rise, but I had forgotten the challenges of starhopping up north under a lackluster sky. I wasted some time wandering around in the wilderness looking for M52 in the 8x50 finder. Then I added the Double Cluster to the night's program. I changed the camera battery, set the new timer for ~4 hours and put it between the battery and the G11. I set the camera to do ~80 frames, told the computer to shut down in the morning twilight, and got some sleep. (Note: when switching over to the timer, remember to turn the G11 off first, plug it into the switch, turn the G11 back on, AND RESET THE RATES.)

Clouds started blowing through --unanticipated by Clear Sky Clock -- about 2:00. I had to toss more than half the Pleiades frames owing to clouds, but all the hardware worked like a charm.

Notes from tonight: pack a magnifier for focusing with Live View (ordered some cheap high diopter reading glasses) and use a second SD card so I can see what I've got while leaving the camera to go about its business.



Except where noted, deep-sky photos are made with an SBIG ST2000XM CCD behind a 10-inch Astro-Tech Ritchey-Chretien carried on an Astro-Physics Mach1GTO. The CCD is equipped with Baader wide- and narrow-band filters. The internal guide chip of the CCD most often keeps the OTA pointed in the right direction (I'll let you know when an OAG or guidescope takes its place). Camera control and guiding are handled by Maxim DL 5.12. The stock focuser on the AT10RC has been augmented with Robofocus 3.0.9 using adapters turned on the lathe downstairs. A Canon 6D and a modded 50D find themselves mounted on an Orion 10" F4 Newtonian or carrying widefield glass on an iOptron Skytracker. Beginning in May 2013, PixInsight has taken over more and more of the heavy lifting -- alignment, stacking, gradient removal, noise-reduction, transfer function modification, color calibration, and deconvolution. Photoshop CS4 et seq and the Focus Magic plugin get their licks in, too.


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                   © 2015, David Cortner