UT Oct 05, 2025: Photometry of V527 And

Michael Richmond
Oct 5, 2025

On the night of Oct 04/05, 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 2,460,400.52 to 2,460,400.89. There were no problems with instruments or the weather.

• Dome flatfield exposure times:
  • B: 20 sec yields 8,100 counts
  • V: 8 sec yields 17,300 counts
  • R: 6 sec yields 17,000 counts
  • I: 8 sec yields 20,000 counts
• Focus tests on a single star
  • B: 0.432 leads to FWHM = 2.2
  • V: 0.415 leads to FWHM = 1.8
  • R: 0.415 leads to FWHM = 1.8
  • I: 0.384 leads to FWHM = 1.5

Using all four filters on a single target will either require changing the focus position constantly to achieve the best results, or accepting lower quality in some passbands. Probably a decent choice in most cases is to focus in V-band and leave it there.