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--- on_sky_testing [2026/06/02 21:13] – holtz
+++ on_sky_testing [2026/06/03 13:25] (current) – holtz
@@ Line 17: / Line 17: @@
 - took pixel flats with liquid cooled QHY600. This was achieved using a LED penlight wrapped in some bubble wrap and inserted into the upper light feed without moving anything in the spectrograph. Took 101 .0005s exposures
+- checked lower dome, which wouldn't open, even though it hasn't been used since Ben last looked at it and claimed it was fixed and working. Perhaps there is some thermal effect. When it gets in this tightly wrapped state, a screwdriver can be inserted in the right side to push the spring loaded catch down, after which you can pull on the cable/push shutter to loosen the system, after which it worked. Experimented with software for safe use of lower dome shutter. When it does fail, it always seems to be in that it won't open, but closes fine, so perhaps the episodic failures are not a show stopper (Bill suggests that running the motor and having the couple slip won't damage the coupler). Otherwise, software seemed to work ok, although there was one instance where, after opening, software thought is was closed, so automatic closing didn't proceed as it should have. Probably should triple-check this!  Implemented some new supported actions in dome driver to allow for easier testing by setting open/close time for both shutters to a shorter value so that they don't have to go all of the way.
+- at end of run, inspected calibration frames and see apparent drop in flux from previous week, especially in flats, but also in ThAr, with drop in both cal channel and direct channel. Lots of investigation followed, determined that fluxes can change with reseating of fiber in cal source, although still couldn't recover previous fluxes. Did fiber inspection and cleaning using APOGEE fiber microscope and cleaning device (with assistance from Jimmy Davidson), found some of the fibers pretty dirty, but didn't make dramatic changes in flux. Flipped the bifurcated fibers as one test. Direct fiber still much brighter in flats, but not nearly so much in ThAr? Final tests suggest significant change in flats but less in ThAr? Not clear what is going on, but maybe the illumination in the cal source is sufficiently non-uniform to make small changes in fiber placement significant, especially for quartz lamp? But swapping bifurcated fiber didn't seem to change the relative brightness dramatically. Maybe some issues with quartz lamp?
 ====April 2026====