View here: American Association of Variable Star Observers
Abstract: We request frequent monitoring of the dwarf nova RU Peg to support an approved Target-of-Opportunity (ToO) observing program with the hard X-ray observatory NuSTAR. The goal of the program is to obtain observations of RU Peg during both quiescence and outburst in order to investigate the changes in hard X-ray emission from the accretion boundary layer in this cataclysmic variable system. Rapid identification of the onset of the next few outbursts is essential for triggering the NuSTAR observations within the limited visibility windows imposed by the NuSTAR’s solar aspect angle constraints. We therefore request visual and CCD/CMOS monitoring of RU Peg with one observation per night, beginning immediately and continuing upto January 2027. Observers are encouraged to report immediately to the forum if RU Peg brightens to approximately 12 mag or lower to enable rapid triggering of the ToO observation.
Justification: RU Peg is a well-known dwarf nova exhibiting recurrent optical outbursts approximately every three months. During these transitions, the structure and radiative properties of the accretion boundary layer between the accretion disk and the white dwarf are expected to change substantially. Our approved NuSTAR program is designed to obtain sensitive hard X-ray observations of RU Peg in both accretion states, enabling a direct comparison of the boundary layer properties during quiescence and outburst. The success of this program critically depends on the rapid identification of the onset of outburst; therefore, we request frequent monitoring of this source.