On the night of Oct 28/29, 2025, under very good conditions, I acquired images of the eclipsing binary star V527 And. One of my capstone students is studying the star, and we're trying make a complete light curve.
I took images in BVRI from about JD 2,460,977.48 to 2,460,977.80. The skies were clear and dark, once the first-quarter Moon set around 10:30 PM.
There was one minor problem with the camera: at some point around 11:38 PM, it entered a state in which it terminated all exposures after about 1 second, saving a COPY of some previous image data over and over again; it didn't actually read the chip. This is a dangerous error, because a casual glance at the MaximDL display will show what looks like an ordinary image; the only giveaway is the rapid-fire sequence of image numbers. Fortunately, I paused the sequence to re-focus at 11:46 PM by coincidence, noticed the problem, and fixed it by
The problem did not recur for the rest of the run (about 4 hours).
The I-band images show a VERY low sky level, just 2-6 counts in a 40-second image. That seems strange, as the other filters yield sky background levels of 30-to-50 counts in exposure times of similar length. The photometry from these I-band images seemed reasonable, if a bit lower in S/N than the others, but I want to check the sky levels in I-band carefully the next time I observe.