The Starry Night, 125

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10/22/2014. Another sparkler. I wanted to do a mosaic of M31. It keeps spilling over the edges of the 6D's chip. Ideally, I'd want four frames, but tonight I will settle for two. Subs tonight are 150s. So in addition to nightly flats, I began with fresh darks and bias frames. I'm still having to calibrate and guide at 2x sidereal (I wonder what would happen if I calibrated at 2x but guided at .5x, perhaps with elevated aggressiveness settings). Tonight I am repeating last night's settings with the mount modestly out of balance to the east. At 2x, RA will still reverse from time to time, so this may not be the fix I want. [Looks good.] But... one variable at a time.

morning afterThe STV tried to select the center of M31 for guiding which did not work out well. I switched it into manual mode to select a guide star (1000-1300 brightness) which did work out [you could've increased the exposure some, y'know?]. I also reduced aggressiveness on the more active axis to prevent overshoots and ran PEC calibration on the G-11. All this, or some of it, seemed to help significantly: average corrections came down from a little over 3 arcseconds to under 2. That'll do.

What? Still no guided astrophotos for show and tell. Well, uhm, no. Time is too short this morning to work up any of last night's images for show and tell, but the takeaway is simple: the STV makes a new mount of my 22 year old G-11; it carries the 10-inch Newt beautifully.

Tonight's fail: I bumped the camera, evidently harder than I thought, while resetting the field for the second part of the M31 mosaic. The second set of images is beautifully guided (so maybe the imbalance to the east is the key) but hopelessly defocussed.

The morning after: 75 minutes of M31 (in 2m30s gulps) required only 1h45m for PixInsight to calibrate, register, and stack. Likewise, a 30m stack of a dozen 150s exposures of IC 59 and IC 63 made while waiting for M31 to clear Bird Feeder Tree took 45m to process. With subs of somewhere around 180s, processing and exposure times are equal, for whatever that's worth. Also, maybe this sky will permit 300s subs at ISO 1600 after all.

Improvements on the way: A timer and multiple 12v outlets (to get some sleep and to preserve batteries), a log carrier (to help Dewey the long dog up and down stairs), a couple of 6-wire splitters (so I can use a hand control to adjust the G-11's aim without unhooking and rehooking the guider) are on the way. Like the laptop desk (to hold the STV), it's small stuff that together should make (another) big difference. We'll see by the end of next week.


10/23/2014. Off to Mount Pisgah, the NPS campground across the Blue Ridge Parkway from the Mount Pisgah Inn for RV practice and a partial solar eclipse, some good dining, good scenary and excellent company. Also scouting for stargazing venues because sooner or later before going West, the 10-inch must hit the road. But not this time -- this time we'll find out how well we can travel with Dewey and Raymond.



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 LRGB and 7nm H-a filters. The internal guide chip of the CCD most often keeps the OTA pointed in the right direction (I'll let you know when a Meade DSI and a separate 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. Maxim performs image calibration, alignment, and stacking; Photoshop CS4 and FocusMagic 3.0.2 take it from there. Gradient Xterminator by Russell Croman and Astronomy Tools by Noel Carboni see their share of work, too. Beginning in May 2013, PixInsight has taken over some of the heavy lifting for transfer function modification and deconvolution.


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                   © 2014, David Cortner