UT Sep 15, 2026: Photometry of QR And

Michael Richmond
Sep 15, 2026

On the night of Sep 14/15, 2026, under very good conditions, I acquired images of thecataclysmic variable star QR And.

QR And

This cataclysmic variable is the subject of a long-term study by the Center for Backyard Astrophysics.

  QR And    RA = 00:19:49.93   Dec = +21:56:52.1

These observations involved:

• Meade 12-inch telescope
• no focal reducer, so working at f/10
• ASI 6200MM CMOS camera
• clear filter, exptime = 60 sec
• images binned 4x4
• guiding with 5-sec exposures, QR And at (750, 780)
• focus position on 12-inch:
  • V = 0.160 yields FWHM 3.0 pixels at T = 62/16
  • V = 0.139 yields FWHM 3.0? pixels at T = 52/11

Notes from the night:

• mostly clear, with a short period of light cloud near the end of the run
• young crescent Moon set very early, didn't affect measurements
• camera at T = -10 C
• temperature dropped from T = 62/16 at start of the run to 48/8 when I closed at 4:18 AM
• used dark frames of 60 seconds to match length of target images

The picture below shows a cropped image of the field of QR And from Sep 06/07, 2026. The field of view is about 20 arcminutes across.

I've marked the location of several comparison stars, with magnitudes and names taken from the AAVSO's table X43062GE.

  star       name                  B          V         
------------------------------------------------------
    A     000-BBB-469         11.743     10.647
    B     000-BBB-468         12.454     10.928
    C     000-BBB-450         11.951     11.425
--------------------------------------------------------------------------

 

When the target is centered, the finder TV shows this field:

Here's the sky background over the course of the run. Note the small bump near the end.

The FWHM improved slightly as the field rose and crossed the meridian.

The graph below shows changes in the photometric zeropoint of an ensemble solution of the instrumental magnitudes over the course of the run. Light clouds once or twice.

Using aperture photometry with a radius of 7 pixels in clear filter (binned 4x4, each pixel is 1.036 arcsec, so a radius of 7.3 arcsec), I measured the instrumental magnitudes of a number of reference stars and the target. Following the procedures outlined by Kent Honeycutt's article on inhomogeneous ensemble photometry, I used all stars available in each image to define a reference frame, and measured each star against this frame.

Sigma-vs-mag plots show that the floor in clear filter was about 0.005 mag.

Here's the light curve of the target and some nearby comparison stars. I've placed the clear-filter measurements onto the V-band scale.

My measurements can be retrieved from the following ASCII data file. The header and first few lines are shown below for guidance on the format.

# Measurements of QR_And made at RIT Obs, UT 2026 Sep 15, 
#    in very good conditions, 
#    by Michael Richmond, 
#    using Meade 12-inch LX200 and ASI 6200MM. 
# Exposures 60 seconds long, clear filter. 
# Tabulated times are midexposure (FITS header time - half exposure length) 
#    and accurate only to +/- 1 second (??). 
# 'mag' is a differential magnitude based on ensemble photometry 
#    using a circular aperture of radius 7 pix = 7.2 arcseconds.  
#    which has been shifted so AAVSO 000-BBB-469 has mag=10.647 
#    which is its V-band magnitude according to AAVSO chart X43062GE.  
# 
# UT_day             JD            HJD        mag    uncert   airmass
Sep15.03876     2461298.53876  2461298.54389  12.547  0.008    2.272 
Sep15.05189     2461298.55189  2461298.55702  12.523  0.009    2.032 
Sep15.05266     2461298.55266  2461298.55779  12.542  0.009    2.020 

• RIT Obs of QR And, clear filter, UT 2026 Sep 15 (ASCII)

I've submitted these results to the AAVSO and the CBA.