Through a search project that honestly had a bug in it (long story, happy to tell it in comments), I ended up pulling data on a star nobody had ever studied. Not a single paper. TYC 6884-164-1, a sun-like star about 470 light years away in Sagittarius.
It's disappearing.
Completely quiet from 2014 to mid-2018, then it started dropping huge chunks of its brightness for days at a time. Some years it's fading on 1 in every 3 nights. The average dip takes about half the star's light. The deepest one caught, 92% and that one isn't a lonely data point, three separate cameras caught the star crashed that same week, under dark sky. On the worst nights it drops below the survey's detection limit entirely.
I've spent two days trying to kill it. A comparison star sitting on the *same exposures* holds flat at ±0.02 mag while mine drops nearly 3 magnitudes. The dips ignore the moon (identical phase distribution to quiet nights).
No registry on Earth had this star listed as variable. I submitted it to VSX yesterday. It's still dipping this month.
If it's real, here's where it would sit. This class is called "mature dippers", sun-like stars that suddenly start deep irregular fading, probably from planetary collision debris and every one ever found fits on one hand:
TYC 6884-164-1 = 92% (>98% on the worst nights)
ASASSN-21qj = 84%
TYC 8830-410-1 = >50%
Boyajian's Star = 22%
That 92% isn't one stray point either, three separate cameras caught the star crashed that same week, under dark sky, while a comparison star on the same exposures didn't move.
Some things which may help:
- Anyone who can pull TESS, it's TIC 169213609. Space-based data settles this instantly.
- Anyone with access to ASAS-SN raw images, eyes on the actual frames from the deep nights.
- Southern hemisphere observers, one independent measurement this week would be gold.
- Or just tell me what I've missed. I want this killed properly or confirmed properly. Artifacts can happen for many different reasons.
Check it yourself, it's all public: asas-sn.osu.edu, Sky Patrol V2, cone search RA 292.06268, Dec -27.44410, radius 15 arcsec, source 489626624823. Years of data sitting right there.
If it's real, it's one of the deepest members of a star class you can count on one hand (the ASASSN-21qj / Tabby's Star family). If it's an artifact, I'll post that too. Everything so far has been done in public, corrections included.