pep alert 3
Special AAVSO Photoelectric Photometry Alert Notice #3
THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
25 Birch Street, Cambridge, MA 02138 USA
Tel. 617-354-0484 Fax 617-354-0665
SPECIAL AAVSO PHOTOELECTRIC PHOTOMETRY ALERT NOTICE #3 (January 28, 2005)
2248+16 IM PEGASI - PLEASE FOLLOW VERY CLOSELY OVER COMING MONTHS
This special PEP Alert Notice is a follow-up to the special Photoelectric
Photometry Alert Notices we sent in September 2001 and May 2004 to request PEP
observers' assistance in monitoring IM Peg in support of the NASA satellite
Dr. Michael Ratner, Harvard-Smithsonian Center for Astrophysics, has asked
us to pay special attention to IM Peg over the coming few months as it
approaches, enters, and emerges from its seasonal observing gap. Your PEP(V)
observations during this very difficult observing period are particularly
important because the automated photometry that has been ongoing cannot be
carried out when the star is so low and in such bright twilight. Even PEP(V)
observations of low precision will be very important and of high value.
Please follow IM Peg as close to the sun as your instrumentation and location
will allow, and then pick up this magnitude-5.7 star again as soon after it
emerges in dawn twilight as possible. IM Peg should be observed once or twice
each night/twilight with a V filter, and the standard procedures used for our
other PEP program stars should be followed. If you are able to make more than
one observation a night/twilight, please try to space them as widely as
possible in time.
Please report your observations to AAVSO Headquarters (firstname.lastname@example.org).
An AAVSO Photoelectric Photometry chart for IM Peg prepared by C. Scovil may
be downloaded from our website
(http://www.aavso.org/charts/PEG/IM_PEG/IMPEG-P.GIF). Please use this chart to
make your V observations. A copy of the chart is also available from AAVSO
Headquarters on request.
Information on IM Peg as a Gravity Probe-B guide star may be found at
Additional information on the Gravity Probe-B mission may be found at
The earlier special Photoelectric Photometry Alert Notices may be found on the
AAVSO website at http://www.aavso.org/publications/alerts/ in the 2001 and 2004
Your ongoing observations of IM Peg, and especially at this time, are
essential to the success of this extremely interesting mission. On behalf
of the Gravity Probe-B scientists, AAVSO PEP Newsletter Editor John Percy,
and me, thank you for your astronomical contribution, and we look forward to
receiving your valuable observations!