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Friday, June 14, 2019

More Aladin on a rainy day - Gaia Alert 16bao

Update 17 Jun 2019: Some folks on /r/KIC8462852 think this is probably an eclipsing binary, and they make a decent case, but I still have questions.

Am I really onto something here? Well, let's just look at the facts as I can dig them up and see where it leads.

The star first came to my attention as the source of Gaia Alert 16bao which I have been following for some time now. Gaia has photometric data for this star (I'm pretty sure it's a star, as I can discuss later) going back to October of 2014, and the latest available is May of 2019 as of this writing, for a total span of 1674 days.

Here is the light curve from Gaia alert 16bao:

What we see are as many as 6 sharp dips over the course of about 800 days, and the rest of the time the brightness of the star is about steady. The deepest of this dips is about 1.7 magnitudes, which is very deep - about 79% dimming for a short time - over about 20 hours before recovering over about 10 hours. The sharpness and irregular spacing of the dips is reminiscent of Boyajian's Star. The dips are too deep, aperiodic and irregular for an eclipsing binary.

The Gaia alert gives the J2000 coordinates as RA=297.72688 degrees , and Dec = 23.55513 degrees. We can plug this straight into Aladin Sky Atlas to see what's there.  Right away we can learn several things.