UT Sep 23, 2026: Photometry of QR And

Michael Richmond
Sep 23, 2026

On the night of Sep 22/23 2026, under good-to-excellent conditions, I acquired images of the cataclysmic variable star QR And.

Conditions were good-to-excellent, and I measured the star over a period of about six hours. Tonight, I switched to V-band instead of unfiltered measurements, and increased the exposure time to 90 seconds to compensate. The precision of measurements for the brighest stars in the ensemble was very good -- 0.003 mag -- so I think this is a good combination for future photometry.

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
• V filter, exptime = 90 sec
• images binned 4x4
• guiding with 5-sec exposures, QR And at (882, 870)
• focus position on 12-inch:
  • V = 0.126 yields FWHM 2.1 pixels at T = 58/14

Notes from the night:

• I didn't start observing until about 9:30 PM, 2.5 hours after sunset
• broken clouds at the start of the run, but clear for the final four hours
• bright waxing gibbous Moon in the south during the entire run
• camera at T = -10 C
• used dark frames of 90 seconds to match length of target images
• increasing exposure time to 90 seconds and using V filter yields standard deviation in measurements of the target of around 0.003 mag. It will be easier for people to combine V-band measurements (rather the unfiltered) with those of others, so I'll keep doing this.
• chirping insects grew rather faint by 3 AM as the temperature dropped to 50/10.

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. Broken clouds early, but they disappeared for the final four hours or so.

The FWHM was pretty steady.

The graph below shows changes in the photometric zeropoint of an ensemble solution of the instrumental magnitudes over the course of the run. No evidence for clouds.

Using aperture photometry with a radius of 7 pixels in V 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 V filter was about 0.003 mag: excellent!

Here's the light curve of the target and some nearby comparison stars.

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