On the night of Sep 06/07 2026, under very good conditions, I acquired images of the recurrent nova T CrB. This star undergoes outbursts at long intervals of 80 years or so. Its next outburst is predicted to occur soon (but then again, it was also predicted to occur during 2024), and so I've joined the crowd who are monitoring it.
Since T CrB is now reaching high airmass at sunrise, and since I'm not making air-mass-dependent color corrections, I will stop reporting B-band measurements to AAVSO for airmass > 2.0. I'll keep reporting V-band, and my graphs on these pages will include the high-airmass B light curve as well.
I also took a first look at the cataclysmic variable star QR And. I may monitor this source for the Center for Backyard Astrophysics.
This recurrent nova brightens by about 8 magnitudes (!), from V = 10 to about V = 2, around every 80 years. Will we see another outburst THIS summer?
These observations involved:
Notes from the night:
The picture below shows a cropped image of the field of T CrB from Jun 14/15, 2024. 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 X40237AAS. Note that the magnitudes listed for stars "A" and "B" have changed from the ones I listed in last year's notes.
star name B V
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A 000-BJS-901 11.096 10.554
B 000-BBW-805 11.779 11.166
C 000-BPC-198 13.049 12.336
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When the target is centered, the finder TV shows this field:
Here's the sky background over the course of the run. Smooth curve means no sign of clouds.
The FWHM was pretty flat.
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), and 7 pixels in B 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-band was about 0.006 mag in V, not bad for high airmass; It was 0.009 in B.
The measurements show that the target is still in quiescent phase.
I've submitted these V-band results to the AAVSO.
This cataclysmic variable is the subject of a long-term study by the Center for Backyard Astrophysics. This will be my first night of observations of this system, mostly to see if I should work on it regularly. (Answer: probably yes, with some modifications to procedure)
These observations involved:
Note to self: switch to using only a clear filter and longer exposures, maybe 60 seconds.
Notes from the night:
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
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A 000-BBB-469 11.743 10.647
B 000-BBB-468 12.454 10.928
C 000-BBB-450 11.951 11.425
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Here's the sky background over the course of the run. Smooth curve means no sign of clouds.
The FWHM was pretty flat.
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), and 7 pixels in B 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-band was about 0.004 mag in V.
Here's the light curve of the target and some nearby comparison stars.
I've submitted these V-band results to the AAVSO and the CBA.