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An OH/IR makes a (faint) appearance?

Matthew Templeton's picture
Matthew Templeton
Online
Joined: 2010-03-12

This morning, the MASTER transient group published ATel #4560 announcing optical detection of a source coincident with the OH maser OH 63.3 -10.2.  This is a bright infrared source, but is (mostly) invisible in the optical.  Most (all?) of the OH/IR stars are pulsating like Mira stars, but have so much extinction from circumstellar dust they're invisible.  This one has put in a brief appearance for MASTER, getting caught at an unfiltered magnitude of 17.3 on 2012 November 6.5524 (2456238.0524).  According to Podvorotny et al., the object was detected on a Palomar red plate on 1992 August 31, but not on 1990 September 15.

Coordinates for the MASTER OT are 20 28 57.00, +21 15 33.2.  Coordinates for the 2MASS source known to be associated with the maser are 20 28 57.10, +21 15 37.0.  They are almost certainly the same source.

This will be a target for large-aperture telescopes, and will be very (very, very) red.  I've submitted it to VSX now, and I'll post a name once it's been approved and assigned an AUID.

This star is now in
Matthew Templeton's picture
Matthew Templeton
Online
Joined: 2010-03-12

This star is now in VSX.

The name to use is "MASTER OT J202857.00+211533.2".  It is faint, so it might be tempting to go unfiltered, but filtered observations (as in Ic or Rc) would be far more useful.  This object's period and behavior is almost totally unknown, so a patient observer willing to make occasional observations of this field (going down to 18 or fainter) over the coming weeks and months would be doing something new.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484