[vsnet-alert 620] (fwd) Urgent photometry of AR UMa needed

[Taichi Kato <tkato>]

  Forwarded message from the Nova net:

Date: Sun, 08 Dec 1996 23:10:30 -0700
From: rmw@lowell.edu (R. Mark Wagner)
Subject: Urgent photometry of AR UMa needed
To: aavso@aavso.org, nova@nova.la.asu.edu


Colleagues,

We have an approved X-ray Timing Explorer target of opportunity program
to study the high magnetic field AM Her binary system AR UMa in its high
accretion state.  Spectroscopy of AR UMa obtained over the past week by
Gary Schmidt using the Steward Observatory 2.3-m telescope has shown a
brightening of the star by perhaps a magnitude and the appearance of a
rich emission line spectrum which is characteristic of a high accretion
state.

We are in urgent need of some visual or digital magnitude estimates of
AR UMa to supplement our spectroscopy. These observations will help us to
decide whether AR UMa is in the high accretion state.  Previous RoboScope
observations (Remillard et al. 1994; Honeycutt, Robertson, and Turner
1996, private communication) have shown that AR UMa exhibits a bright
optical state which corresponds to the high accretion state when it
becomes brighter than about 14th mag.

AR UMa is located at:

alpha = 11:15:44.9
dec = +42:58:23     (2000)

If anyone can obtain some photometry of the star in the next 24 to 36 hours
we would be very grateful.  High precision is not required.  A finding chart
is in the Remillard paper (ApJ, 426, 288, 1994; Fig 2, plate 5).

Thanks in advance,

R. Mark Wagner (Ohio State U)
Gary Schmidt (U of Arizona)
Paula Szkody (U of Washington)

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