Howling at the Moon, 4

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9/3/2010: I made myself a lot of work by sleeping in an extra hour. My feet hit to floor at 6:50, and I had the telescope focused and the computer taking data by 7:10. The sky was much lighter than yesterday, and the the lessened contrast of the Moon against that lighter sky leaves less room for signal.

I used an alternate Barlow arrangement: the threaded nosepiece I use for solar imaging inserted into the 2-inch TeleVue Barlow. The FeatherTouch goes between the diagonal and the big barlow. This arrangement uses most of the available backfocus; the A-P focuser is only slightly extended. I believe this eliminates the glare I was contending against the previous two mornings, but the EFL is lower (about 3m rather than 4.5m, hence F24 rather than F35). I'll need to get some or most of that back. I changed the gamma of the capture routine to 0.5 as a means of coping with blown-out highlights. For some reason, the auto-exposure settings tended that way this morning. All images are constructed from 500 frame AVI's.

I stored the morning's data on the USB pocket drive, so it was a casual thing to move it all to the desktop. In fact, by 8:00, I had the telescope covered, drives off, and Registax chewing on 3-4 gigs of fresh moondust. Yesterday while gathering pieces for today's effort, I leaned against a bookcase and hyperextended my right index finger. There was this unsettling *pop* and I knew instantly that I'd broken, sprained, or otherwise something in that hand (probably the knuckle). This makes typing interesting, coffee carrying fascinating, and mounting and dismounting irreplaceable optical tubes positively entrancing. As luck would have it, the exact motion required to turn a focusing knob is what my right hand Will Not Do. Just call me Lefty.

Anyway, the thought of sunset on Sinus Iridum got me up this morning, so let's start with that image (an image of the ice pack on my right hand is mercifully omitted):



Evening shadows in the Bay of Rainbows. The summit of Cape Laplace in the darkness at left.



Gassendi's interior structure is much more evident as sunset approaches. Noise from my having to work with the lower contrast is also more evident in this image. Lesson taken: you really do want the Moon in a dark sky. When this cannot be avoided or when the shorter light path of lower zenith angles is needed, try a red filter.



After I got the best data I could of the two subjects I intended to shoot this morning, I went hunting for targets of opportunity. Here's a view of Wargentin (intersection of the two white markers) which is everyone's favorite lunar sport: a crater damn near filled with debris, lava, or pyroclastic material. Note the low western rim catching sunlight, the raised eastern outline standing some distance above the plains below. The twio largest craters in this view are Schickard (lower left of Wargentin) and Phocylides (upper right). Elongated Schiller is cut by the right edge of the frame.

In retrospect, this would have been a good day to try 12-bit data capture again to see if the extra bit depth gave me enough extra streps between pale white and blue to make a difference. A red filter would be nice to try under these conditions, too.


9/4/2010: No imaging but good progress today anyway. The Nikon F - C-mount works beautifully (bought a Nikon-made model on eBay for the price of a cheap knockoff, mint in the box, for 12 cents on the dollar), and have got streaming video worked out. Nikkor lenses work great on the Chameleon and I should have several new extension options with Barlows. The ability to stream straight to disk without buffering in RAM means I will no longer be limited to 500 8-bit frames and fewer 12-bit frames per AVI (limits imposed by memory available in the netbook). The C: drive will capture at slightly more than 15 fps. I'll try the USB drive next, but at worst I can buffer on C: and copy at leisure. To stream: set the click box that calls for streaming to disk and then press F9 to record, as usual, F9 again to stop. (I had been reading the screen prompt to mean click the red dot to stop, suggesting that maybe streaming began as soon as I hit OK. No: set up the filename, click OK, and then F9 is the only control in play. Now bring on Jupiter and some of those narrowband solar details.

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                   © 2010, David Cortner