Observation by Tracie Heywood: Autumn 2020 eclipse of Eta Geminorum

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Tracie Heywood


Tracie Heywood


2020 Nov 01 - 00:00


2021 Apr 07 - 13:29


Variable star

  • NE
  • 10x50B
Target name

Eta Geminorum


Autumn 2020 eclipse of Eta Geminorum

About this image

This is my light curve showing the autumn 2020 eclipse of Eta Geminorum.

In addition to being a semi-regular variable with a period of 233 days, Eta Gem also shows eclipse at intervals of approx 2984 days (8.17 years).

I don't have enough observations from 2019 and early 2020 to work out where Eta Gem was within its 233-day semi-regular cycle, but looking at the AAVSO V light curve from recent years, it is likely that the most recent SR maxima occurred during Nov-Dec 2019 and July-Aug 2020 (and so it is currently around its latest SR maximum).
Thus it seems that eta Gem had just started to fade from last year's SR maximum when the eclipse started in late Aug/early Sep.
Mid-eclipse probably occurred around early November, a few weeks earlier than would have been extrapolated from the smallish number of previous eclipses of Eta Gem that have been observed.
Working out the depth of the eclipse is tricky, given that Eta Gem was also fading into a SR minimum, but in mid eclipse eta Gem was around half a magnitude fainter than I usually see it in a SR minimum.
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