U Cephei / U Cep
Light curve and phase diagram of the EA type eclipsing binary U Cephei / U Cep. These were constructed from photometry of 50 images taken with the Bradford Robotic Telescope Cluster Camera (BRT) between 2014 September 3 and 2016 January 13 through a tri-colour green filter.
The mid part of a primary eclipse was observed from Somerby Observatory with the 2" Titan, stopped down to 30mm (to compensate for the brightness of the star), on 2019 February 10. The images were unfiltered.
The mid part of a secondary eclipse was observed from Somerby Observatory with the 2" Titan, stopped down to 30mm (to compensate for the brightness of the star), on 2022 October 17. The images were unfiltered.
This is a semi-detached interacting binary. Irregularities in the light curves are due to the effects of 'mass transfer events' into an optically thick disc around the gainer component of the system (AAVSO VSX). Also, for earlier research see eg Olson 1981.
All of the above observations were combined into a single light curve and phase diagram. The BRT observations are in black, and the Somerby observations are in red. The two minima, which were observed without filters, were 'transformed' to more closely match the BRT observations, which were made with a tri colour green filter. Note that these transformations were NOT rigorous, they were simply done 'by eye' in order to more closely agree with the catalogue values for the light curve in order to give a general idea of the shape. The duration of the minima is about 9 hours (AAVSO VSX).
Below is a copy of the above phase diagram but in monochrome.
The catalogue period for this star is 2.493091d (GCVS), 2.493087d (AAVSO VSX) and 2.493093d (Kreiner). There is significant o-c activity with this star (Kreiner). (Accessed 2022 October 20.)
[This page updated 2022 October 20.]