[vsnet-alert 109] AL Com periodic waves

[jop@carmen.phys.columbia.edu (Joe Patterson)]

Photometry of AL Com on April 5/6 by David Harvey at the Center for Basement
Astrophysics-West (35 cm, unfiltered SBIG ST-6 CCD) reveals periodic waves
with P=81.8+/-1.4 min, with substantial power also at the first and second
harmonics.  These are likely to be some version of "superhumps".  The
amplitude was 0.1 mag, but may grow in the days to come. The waveform was
highly variable and suggested the possibility of multiple (noncommensurate)
periods.  Finding the correct periodic structure in these cases depends
crucially on amassing a DENSE data stream, and we eagerly seek collaboration
with observers who can contribute time-series photometry of this star
(V-band or unfiltered).

Joe Patterson
Dept. of Astronomy, Columbia Univ.
New York, NY 10027    USA
Tel. (212)-854-3276
FAX (212)-316-9504
e-mail: jop@carmen.phys.columbia.edu

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