HL Aurigae / HL Aur
Primary minima of the EB type eclipsing binary HL Aurigae / HL Aur observed with the 2" Titan at Somerby Observatory, together with their calculated times of minima using Peranso ANOVA.
All the observations were made with the same equipment, but the star is so faint that the 'correctly' exposed images of 2012 gave so few data points that the light curves appear to have 'kinks' in them. For the 2019 January observations I used much shorter exposures, generating more data points. Although underexposed, the actual curve appears smoother due to the greater number of data points, and the calculated error in the HJD of minimum, about +- 6 seconds, is one third as large as those constructed from the longer exposures, which are about +-22 seconds. [This topic was discussed by Chaplin, Samolyk and Screech, June 2018.]
The corresponding light curve and phase diagram of the above four minima is shown below.
The 'best fit' period for these observations was 0.622504 days. The catalogue period for this star is 0.6225051d (GCVS), 0.6225058d (AAVSO VSX) and 0.6225048d (Kreiner). There is some o-c activity with this star (Kreiner). (Accessed 2020 January 18.)
The following light curve and phase diagram were constructed from photometry of two sets of images taken by remote observatories. The first group, of 8 points, is from images taken with the Bradford Robotic Telescope Galaxy Camera (BRT) between 2015 December 4 and 2016 January 11. The second group, of 32 points, is from images taken with the Open University COAST telescope between 2019 January 4 and 2019 September 9. All images were taken with a V filter.
Combining the minima observed from Somerby with the data from the BRT and COAST telescope generates the following light curve and phase diagram. The Somerby data (unfiltered and untransformed) is in black and the BRT/COAST data is in red.
The phase diagram is repeated below in monochrome.
These are a couple of primary minima I observed visually with my 10" Newtonian from Somerby Observatory.
[ Page updated 2020 January 18 ]