Staring @ the Sun, 64

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11/22/2012. Another week, another few gigabytes...
I'm cleaning up the computer to get ready for the new year. I caught a sale on 2TB SATA drives and added one to the kit; the Inspiron 17r slowed down too far once too often and I've ordered 8GB of RAM for it while chips are cheap. In the meantime, AR1618 (second photo below) has been spitting out M-flares on a regular basis (only B-level activity is seen here, the last M-flare having flickered out six hours earlier); AR1619 sprawls across multiple fields of view; and something comes around the limb. The limb shot is a mosaic of 2 clips made at gamma 1.8 and processed only once for both limb and surface detail; the others are mosaics of 2 and 4 frames at higher contrast, gamma = 0.5. All with 90mm Orion, etc, etc. The usual cul de sac kit. Right click and "view image" to see any of these larger. I'm not sure why the second frame is so grainy. If it were easy...








04/01/2013. Alas, not an April fool joke. It's been this long since I had the solar kit out. Terrible seeing and too many clouds limited what I could do today. I grabbed this snapshot (only 200 frames, best 80 used here) of new AR 1711 during one brief clear spell mostly to remember how to run the hard- and software. Doesn't it look a lot like a little Mandelbrot set surrounded by all that chaotic plasma?



AR 1711 rotates into view
Orion 90mm objective, Lunt 60Tha, Barlow inside snout
200 x 6ms, PGR Chameleon, best 80.


The telescope is piggybacked on the AT10RC. I'd removed the Robofocus to simplify the telescope over the winter when it had to be used as a portable, tended outfit, so focusing today was by hand. That's usually OK, but in the wind, with so much shimmering air, and without long clear spells, the result was a little soft. Over-aggressive sharpening produced the grainy, gritty image above. A quick look at the images at the top of this page suggests how much expertise needs to be regained. No surprise there. So let's set the bar low and post this to mark the beginning of the new solar year.

After I packed it in for the day, I remounted the focus motor and drive belt. I think they're on there more solidly than before.

There's something off about the B600 blocking filter. The "upwind" side shows what looks like moisture or fungus that resisted all attempts to clean it using the Baader cleaning kit. I removed the mirror from the diagonal (after some messy attempts to remove the filter) so I could clean the back side of the glass. No improvement. Probably a coating defect, per Lunt discussion groups, and probably under warranty. I'm not convinced this has much effect on rays entering nearly normal to the surface -- today's session did not seem much if at all hampered. I'll know more when I get a chance to play with it under steadier air.


04/03/2013. Caught a C1.7 flare in AR1711. Not particularly sharp (looking through increasing haze), but not bad (best 100 out of 400 frames):




04/03/2013. A clear and reasonably steady day with a big sunspot near the solar meridian. This is fun. 2,500 frames, best 250:




I was reasonably pleased with this until I saw what Philippe Tosi did with a C14 and a 0.5A filter ( If I want to play in or near that league, I'll need to get the 152mm achromat working again. I don't particularly want to dismount the AT10RC to make room for it on the Mach1 mount, so I think for the moment it's better to keep refining technique with the 90mm 'scope. We'll see how it goes.




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Except where noted, solar photos are made with a Point Grey Research Chameleon camera behind a Lunt Solar Systems 60mm THa solar telescope double-stacked wtih a 50mm front etalon for an achieved bandwidth of about 0.55 Angstroms. The telescope uses a B600 blocking filter and is mounted piggyback with an Astro-Tech 10-inch Ritchey-Chretien (carefully capped!) on an Astro-Physics Mach1GTO mount. An Acer Aspire One netbook running Point Grey's Flycap software provides camera control and capture services via USB 2.0. Images typically begin as 20 second AVI's captured at 15 fps. 300 frame clips are aligned and stacked using Registax 6 or AVIStack 2.0. The resulting files are processed via wavelet functions in Registax and / or the FocusMagic 3.0.2 deconvolution plug-in in Photoshop CS4. (PixInsight is rapidly supplanting some of those steps.) The imaging train usually includes an Orion "Shorty" 2x barlow screwed into the 1.25-inch prime-focus snout. Exposures are on the order of 4-8 ms with gain set to 10-12 db, or 12-18ms at 0 gain. The barlow is sometimes replaced by an Antares 0.5x telecompressor sandwiched between the 1.25-inch snout and the C-adapter on the PGR Chameleon; this produces a full-disk image (during most of the year) and allows exposures in the 1ms range with slightly less gain. A RoboFocus motor with a timing belt looped around the stock (or, sometimes, a Feathertouch) focus knob enables remote operation.


                   © 2012, David Cortner