Wednesday, August 8, 2012

So this is why no one else is up here observing

This night was particularly frustrating.  Clear all day, clear at sunset.  An hour later thin clouds forming above us and getting thicker.  We tried to shoot between the clouds for a couple of hours until the overcast was solid.

One OTA with a very bright star, showing the crosstalk ghosts in cells in the same row.
Even so, we accomplished a few things and learned a bit about ODI.  We discovered that the shutter is so good that we can do twilight flats (8 millisecond exposures) while the sun is still up.  This means that you can get good flats for all filters without having to race against the darkening sky.  We worked on video readout for guiding, and, while we didn't get it going, we found and fixed some of the bugs.  This is our highest priority for the rest of the week.  We measured the crosstalk ghosts that result when you observe a bright star, and we found that they are limited to the row of cells in which the bright star appears (see picture).  The ghosts are about 1/10,000 of the original image, so they only show up where the original is saturated.  Finally, we obtained a complete dither sequence so that the pipeline developers can have some realistic data to begin playing with.

Todd and Daniel

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