David Cortner's Slowblog

10/26/2012. Maybe 90mm aperture really is enough. In any event, I should learn to get the most from this before putting back and hip and nice glass at risk to use more.

Amy and I dropped a line from Polaris a few nights ago, and I marked an approximate meridian on the pavement of the cul de sac. (Note to self: err a little to the left when setting up based on those lines.) The Sun doesn't hit the part of the cds I like to use for sungazing until almost noon, but so far the seeing has been better than I am used to later in the day. The images below are typical of the most recent sessions. There hasn't been too much to photograph, so take these as representative of recent efforts (right click and "view image" to see 1024 pixel versions of these). The first photo is of lonely sunspot 1599 which follows more complex active region 1598 by a hundred thousand miles or so. AR1598 threw a couple of M flares and an X1 as it came into view a few days ago. It's quieted down since then, but it's far from dead. The three bottom images show plenty of B flares and a weak C flare lighting it up:

ar 1599

ar 1598

AR1599 (top) and 1598
All are ~ 125 frames out of 850.
Barlow inside the Chameleon adapter (0.33" / pixel)
Baader IR-cut

When the air cooperates, as it did today, single 1GB clips seem to be plenty for good S/N, good resolution, and good tones. 125-150 frames suffice. Of course, under poorer seeing, it might take two or three 1GB clips to get that many clean frames. I still have to really work not to push the data so hard that the finished image is harsh / brittle / over-sharpened.

The optical cement holding the repaired ERF together is as cured as it's ever going to be. The filter looks as if it should work just fine. I may try it out in the 90mm telescope — a few images made with and without the ERF should help to decide whether it's fatally flawed for use in the 152 when I am good and ready to wrestle that beast back into service.

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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.