Discovery of the optical variability of Nova V2491 Cyg

ATel #1514; A. Baklanov, E. Pavlenko (Crimean Astrophysical Observatory), E. Berezina (Kazan State University)
on 9 May 2008; 12:04 UT
Credential Certification: E. Pavlenko (pavlenko@crao.crimea.ua)

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We observed Nova V2491 Cyg (IAUC 8934 , CBET 1334 , ATEL #1473, #1475, #1478, #1480, #1485) during 6 nights (April 21, 23, 25, 29, 30 and May 01, 2008) using CCD ST7 with Cassegrain 38-cm telescope of the Crimean astrophysical observatory in V and R (Johnson) spectral band. The exposure time was 20 sec in each filter. The durations of observations every night was close to 3.5 - 4 hours. 6 comparison stars in the vicinity of Nova were used. The accuracy of the single measure of brightness was 0.008 mag in R and 0.10 mag in V.

We found the light variations occured synchronously every night in V and R with period of 0.09580(5) day and amplitude 0.03 - 0.05 mag (although the one-day alias period, 0.10595 day could not be ruled out).

Example of some nightly light curves: http://i046.radikal.ru/0805/d9/c3756885b6eb.jpg
Fourier periodogram: http://i036.radikal.ru/0805/fb/80236b8bcd8a.gif
Data folded on period 0.09580 d http://i049.radikal.ru/0805/bb/82b56c60e2bb.gif