NS Draconis / NS Dra
Light curve and phase diagram of the EA type eclipsing binary NS Draconis / NS Dra, constructed from photometry of 72 images taken between 2017 July 28 and 2018 March 11, and 34 images taken between 2018 December 29 and 2019 September 20, by the Open University COAST telescope. The images were taken with a V filter.
The catalogue period for this star is 50.517 days (GCVS, AAVSO VSX and Kreiner, accessed 2019 December 14). Plotting a phase diagram with this period gives the following result;
The secondary minimum appears thus;
The secondary minimum - all two data points of it - occurs at a phase of approximately 0.62 to 0.65, but the above phase diagram appears inconsistent with an eclipse. These observations give a plot more consistent with an eclipse using a slightly longer period of 50.58d. The corresponding phase diagram appears below, together with an enlargement of minII.
This is consistent with the result published by Otero et al (2006) [NS Dra is listed as GSC 04544-00439 with a listed phase of 0.630 for the secondary minimum.] A phase other than 0.5 for the secondary minimum is due to the eccentricity of the component's orbits around the barycentre.
More observations are needed to give more detailed shapes and phases for the minima.
[This page updated 2019 December 14.]