MBCAA Observatory

OV Boo rare outburst

Observed: 15, 16, 29 Mar, 7, 20 Apr 2017

Michel Bonnardeau
16, 17 Mar, 5 Jun 2017

Abstract

Time-series at the outburst of March-April 2017 are reported.

Introduction

OV Boo (SDSS J1507+52) is a cataclysmics system (dwarf nova, probably WZ Sge type), usually around magnitude 19. In March 2017 it was reported in outburst at magnitude 11. It has an unusually short orbital period of 67 min. It is listed in VSX.

Observations

The observations were carried out with a 203 mm SC telescope, a V filter and a Clear filter, and a ST7E SBIG camera (KAF401E CCD). For the light curves, the exposure duration is 60s. For the photometry, the comparison star is UCAC4 713-54077 (GSC 3868-01067) with an APASS V magnitude of 11.482 and an r' magnitude of 11.373. For the unfiltered observations, the r' magnitude is used, as the CCD is mostly red sensitive. The resulting light curves:

Observed with a V filter. Green: OV Boo, Blue: a check star, UCAC4 713-54078, shifted by -1.2 mag. The error bars are the 1-sigma statistical uncertaies (quadratic sum with the comparison).

Still with a V filter. About 0.3 mag dimmer than the previous night.

Still with a V filter and dimmer. The check star is shifted by +0.3 mag.

The object is so dim that I switch to a clear filter to have a better signal. The check star is shifted by +1.3 mag. The eclipses are much deeper as the object get dimmer; their positions are in agrement with the ephemeris of Patterson et al (2008).