The Starry Night, 131

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12/12/2014. A pair of Geminids in the western sky opened my efforts to photograph this year's shower. In the evening, I left the 6D with a 16mm Nikkor fisheye shooting 30-second frames while Amy and I watched "A Christmas Carol."

2 geminids

Geminid Meteors
Canon 6D, 16mm Nikkor Fisheye
ISO 6400 F3.5, meteors from two frames merged
"De-fished" using PTLens


"View Image" for a larger version. One looks like an Iridium flare, but Heavens-Above showed none in my sky last night. After Scrooge's epiphany, I took more toys (tracker, 24mm lens) up the driveway and watched for more meteors while the camera took frames of the high southern sky (24mm F4, ISO 3200, 30s). Herewith a mystery: I saw a first magnitude meteor sail right through the middle of one frame. But I see no hint of it in the file. How bright must those two captured above have been?

Tech note: the 16mm Nikkor and its adapter reach infinity focus on the Canon near the "7" in the "0.7" mark on the focus ring.


2014/12/13. The 14mm F2.8 Rokinon is a meteor funnel compared to the 16mm F3.5 fisheye I used yesterday, I saw two of the meteors captured in the frame below, and they were 3rd, maybe 2nd magnitude (near center). I did not see the brilliant meteor at lower left, alas, but it must have been mighty. Next time, take even more care to nail the focus. It was just a little off tonight -- the first sequence of the evening was considerably better in that regard than the last.


4 gems

Four Geminids
Canon 6D, 14mm F2.8 Rokinon @ F2.8
ISO 1600, 30 second subs
iOptron skytracker


Really, look at the underlying image which is 1280 pixels wide, to see all four meteors clearly against a darker screen background. Once again, I knocked off at moonrise.

The frame after the one that caught the fireball includes a nice puff of meteor smoke (as well as the faint meteor due west of Orion's belt). I found a fifth meteor, fainter than these four, in another frame but it is not worth mapping it in. That said, I'm considering reshooting the starfield in focus tonight and reassembling the composite. The difference may be imperceptible in web-sized renditions.


2014/12/14: Dunce. I am one. For months, I have complained bitterly about the clutter in the 6D's LiveView screen that makes it impossible to find and focus on faint targets in the dark. Like stars. Woncha try pressing the "info" button while in LiveView to see if it changes the info displayed? Does. Three presses and you got a clean screen. Zoom (5x and 10x virtual loupes) still works. Got any more excuses for fuzzy stars?


2014/12/15. Another few hours in Geminid season. I put the camera out about 10:15 and let it run until almost 1:00. I only caught two new meteors. I rebuilt the sky using the five from yesterday (I added the one I found late) and these two new ones. It's a quick assembly and the positions may not be perfect. Still, it's pretty close.

You'll need to look at a higher-res version to find them all (one that ends near Rigel is very faint).


7 gems

Seven Geminids
Canon 6D, 14mm F2.8 Rokinon @ F2.8
ISO 1600, 30 second subs
iOptron skytracker


While I was assembling the composite, an immense truck pulled up in the driveway. No! It was an earthquake. The USGS says it was small (mag 2.9) but close (12 mi S of Newland, on Camp Creek on the Avery / Burke county line, about 25 miles away). Later: USGS updated this to mag 3.0, 15 km north of Lenoir --near Buffalo Cove -- 13.2 km deep.

Two lessons for the night: dew was a problem late, and the third quarter Moon would not have been a serious impediment had I decided to continue. (Also, that is one wide lens: from well south of Orion to well north of Auriga in a single frame, and that's a crop from a horizontal composition!)


Later that same day: I installed O-III and S-II filters in the next available slots in the CFW-10. I haven't updated Maxim yet, and I note this here to remind me to do that. That completes what I think of as a full set of Baader imaging filters. Think of this as the antithesis of the simple widefield DSLR astrophotography I've been doing lately. Two open slots remain. What else would be useful? Maybe a very narrow H-a? A near-Ha "continuum" red for star suppression? I think the wheel is too far from the sensor to let me cobble up an occulting spot. The near-IR filter and green continuum filters are pretty much planetary and solar filters respectively so they have no business in the CCD. Is a completely open slot useful? There's no reason to fill up the wheel; still less is there a reason to be in a hurry to fill it.

The next day: both computers that sometimes control the SBIG camera have been updated with the new filter information. Officially, slots 1-8 are: C, L, B, G, R, Ha, OIII, SII. Don't know why I reversed the customary order of RGB, but it makes zero difference.

Housekeeping: the generic image repository I've been using ( is retired. The hosting company for almost all my sites increased the disk allowance sometime in the last few months, and I just noticed. Likewise, I can now host more sites under my primary account, so I will be relocating some of the sites currently stored on the old Charlie Masison server to this one. Put it all together and it amounts to close to a $500/year saving! I'll be mending broken links for a while, and ll need to rebuild and relocate the index. (Done, but some pages aren't found; look for "Pisgah" for example.) Still, it's a good deal all around.


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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                   © 2014, David Cortner