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Optical novae in M31

ATel #1141; D. Hatzidimitiou (Department of Astrophysics, University of Crete, UOC), W. Pietsch (Max Planck Institut f. extraterr. Physik Garching MPE, Germany), V. Burwitz (MPE), A. Stefanescu (MPE), H. Steine (MPE), P. Reig(UOC), G. Papamastorakis (UOC)
on 11 Jul 2007; 15:19 UT
Credential Certification: Wolfgang Pietsch (wnp@mpe.mpg.de)

Subjects: Optical, Nova

Referred to by ATel #: 1146, 1157, 1602, 1790

We report pre-discovery observations and confirmation in Halpha and R of the nova candidate reported in ATEL#1139 and follow up observations of the nova candidate reported in ATEL#1131. The data were taken as part of a monitoring campaign of the M 31 central region for optical nova candidates, using the 1.3m Ritchey Chretien f/7.5 telescope at Skinakas Observatory, Crete, Greece. We used a Roper CCD Camera (SITE 1k x 1k chip with 24µm sq. pixels) with a standard Johnson R and broad (75\AA) Halpha filter.
We confirm the candidate from ATEL#1139 as a nova as it shows up as a bright Halpha source. We determine magnitudes from a photometric solution using R magnitudes of the Massey M31 catalogue for both the Halpha and R images. Our detections were: in Halpha 2007, July 8.053, 18.0+-0.3; July 10.042, 17.5+-0.2; July 11.042, 17.1+-0.1; in R July 9.058, [18.4; July 11.010, 17.7+-0.1. The object was rising in Halpha at least 3 days prior to its discovery in R by Ovcharov et al. (ATEL#1139). We find a position of RA(2000) = 00h 42m 45.89s, Dec(2000) = +41° 18' 04.2" with an accuracy of 0.2". It should be noted that according to our estimate the nova appeared to be 0.9 mag brighter in R than reported in ATEL#1139 for about the same time on July 11.
The candidate M31N 2007-07a (ATEL#1131) is confirmed as a nova as it also shows up as a bright Halpha source. Further magnitudes are: in R 2007, July 9.058, 18.3+-0.1; July 11.010, 18.6+-0.1; in Halpha July 8.055, 16.8+-0.1; July 10.042, 17.1+-0.1; July 11.042, 17.3+-0.1. These data indicate a speed class T2 of about 6 days in the R band for this nova.