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Lunar occultation of double star SAO 79686


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About this observation
Alex Pratt
Time of observation
12/04/2019 - 23:50
SAO 79686
Observing location
C11 @ f/10
Watec 910HX video camera
Losmandy G11 mount
IOTA-VTI GPS video time inserter
1/50th sec exposures
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I seem to get poor quality skies around First Quarter, or the Moon is scraping along the horizon or hiding behind local obstructions, so it was a welcome change to have a run of clear nights earlier this month with the Moon riding high. I was able to record and time a couple of dozen lunar occultations, including light curves of some double stars and Kepler2 targets. 

Occult4 software predicted that double star S79686 would display a dip in brightness lasting for 0.7s, being caused by the 0.7" separation between the star's components. The attached light curve was analysed using Limovie, giving an estimated step duration of 0.722s. It shows that the brighter component was first to be occulted by the Moon.

Assuming a combined magnitude of 9.1, the estimates mags are 9.5 and 10.4. The 1991 values in the IF catalogue give 9.6 and 10.0, also 9.8 and 10.4.

An occultation of this star was recorded a year ago by Dave Herald (AU). Assuming there is little change in its orbit over 12 months, Brian Loader (NZ, IOTA's double star coordinator) combined our data and obtained provisional estimates of: separation 0.876" and PA 141.74 deg. (The IF values from 2008 are:- 0.708" and 139.9).

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