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2013_02 _920

A surprise clear night!

I didn’t expect it to clear off tonight but it has!  It’s been raining all day – some colder weather moving in.  Got on target with Rig#2 on BK Lyn by around 8:15pm.  I may or may not fire up Rig#1 tonight – if I stay awake long enough I’ll make another pass at Rowen Poole’s suspected T Tau star.  There may be some short periods of clouds – it literally cleared just as I acquired BK Lyn.  UPDATE – as of 10:30 wind has come up a lot, from the north, looks like the cold front is passing.  UPDATE2 – clouds rolled in at around 1:15am.

Software Development

As it’s been cloudy the past few days I’ve begun in earnest to write a new aperture photometry “package” in IDL that will use optimal or variance-weighted extraction.  As of tonight the program finds all stars in a field, does aperture photometry on each star found, and, once an entire night’s data has been processed it solves for x & y shifts to map star positions in the first image onto each subsequent image.  The core programs I’m using are the IDL implementation of DAO{HOT’s FIND and APER routines, plus my own Match_Stars routine.  Tonight I had planned to start working on how I’m going to select the PSF stars which will be used to build the variance mask for each image.

Gear Update

It appears the new ST8xme camera is working very well, it’s cooler seems to be better than ST8xme#1, and read noise is slightly better.  I’ve updated the MIRA script that inserts header keywords and such (PreProc.lua) to include the three configurations for the new camera.  Truth is, that code will be moved over to IDL very soon.

I got an email from the USPS saying that the pier top plate for the AP1200 is shipping – a few weeks faster than I’d expected!  So now I need to get a dovetail saddle (ordered the DOVELM162 from Astro-Physics today) and to get some counter weights.  It appears the least expensive option I have for purchasing new weights is around $700 for 60 pounds.  So for now I’m going to see if I can use the CGE counterweights.  I called Chet at Grizzly Services and he quoted me $85 an hour to bore out the current 1.25-inch center hole to 1.875-inches.  The only question is whether the tightening screw will still be securely set enough to hold the weights to the counterweight shaft without any movement.  The only other question is whether the standard Celestron dovetail is a match to the Losmandy  “D” specification – which I always thought was the case until reading a note on the Astro-Physics website saying that, for a while anyway, Celestron’s dovetails were not matched to the “D” plate specification.  We’ll see – if not I’ll need to order a D plate from Losmandy – another $160.

Tree Limits

A little less than two hours after meridian crossing for BK Lyn.