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APASS status

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HQA's picture
APASS status

The southern survey is well underway, with about 3000 square degrees of sky covered at least twice.  We're coming into the first full moon period when the telescope is working properly, so I'll probably do less survey fields and more engineering during these nights.  In a month or two, I'll start freeing up the bright time for other projects.  One of my tasks this weekend is to obtain the images of the South Polar field, as these have to be manually obtained - software really doesn't like -90.0 degree fields!

APASS South is working ok, though the mount is more troublesome than I'd like.  It tends to lose its periodic error correction, and the worm gear on this Paramount is old enough and bad enough that PEC is absolutely essential.  There is a workaround, but it requires that I manually start up the system every night, and I cannot guarantee that I'll be available.  The software or hardware has turned off tracking at least once; the first field of a night often has the wrong coordinates; two or three fields during the night might be improperly positioned.  That still gives us about 95% good results, and since it has been perfectly clear at CTIO for the past month, progress is rapid.  The system is currently covering all fields south of -40 dec; at the current rate, we'll start moving north in January.

The southern system optics are working well - the star profiles look good all across the field.  There are typically 30,000 stars per image in these out-of-plane fields; once we hit the LMC/SMC, and in January, the galactic plane, each frame will have more than 100,000 stars.  We get lots of satellite trails near twilight which impact some stars, but when the final 4 visits for each field are performed, these should clean up nicely.

Tom Smith has built new Phidget boxes for both north and south systems, to give us more control over the flatfielding lights.  He'll be sending one box down to CTIO for the technician there to install.

The astrographs for APASS North are due to be shipped to HQ this Friday, and should be undergoing commissioning tests around New Year's at Dark Ridge Observatory.  I expect to see new northern fields by mid-January.

I should be able to do the final analysis for the southern fields over the Christmas time period, and the DR2 release date of "January" looks well in hand.


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