AZ Cassiopeiae / AZ Cas
Light curve of the EA/GS+LC type eclipsing binary AZ Cassiopeiae / AZ Cas, from photometry of 313 images taken with the Open University COAST telescope between 2017 September 22 and 2023 March 25. All images were taken with a V filter.
An enlargement of the primary minimum appears below.
The quoted time of this primary minimum, HJD 2459712.6 +-3.5 days, was calculated by Peranso. However, given the low number of data points for the minimum itself, as well as for the maxima on either side of it, I think the precision might be a little optimistic.
This star has catalogued periods of 3403.6 days (GCVS) and 3403.85 days (AAVSO VSX) (accessed 2023 May 15).
The 'dip' at approximately phase 0.76 is probably not an eclipse (the system has a highly eccentric orbit with e=0.55 Cowley 1977), but is more likely to be the result of variability of the red supergiant component (see type LC ref GCVS) . This is a complex system (see Cowley et al 1977 and Tempesti 1979) and does typically show variation between primary minima. Its spectrum is given by the GCVS as M0eIb+B0-B1V and by the AAVSO VSX as F8-M0elb+B0/B1V [accessed 2023 May 14].
More observations needed, and fingers crossed for the next primary minimum in 2031!
[This page updated 2023 May 15]