Skip to main content

Web Publications


			ASSOCIATION OF VARIABLE STAR OBSERVERS 
			25 Birch Street, Cambridge, MA 02138 USA
			BITNET: aavso@cfa8 SPAN: nssdca::cfa8::aavso
			Tel.617-354-0484	FAX 617-354-0665


SPECIAL AAVSO ALERT NOTICE TO PHOTOELECTRIC PHOTOMETRISTS October 4, 1991

MULTIWAVELENGTH MONITORING OF 2349+28 II PEGASI

Astronomers at NASA will be monitoring s:pectroscopically the RS CVn star II 
Pegasi between October 11 and 14 at Kitt Peak National Observatory, and they 
have requested the assistance of our photometrists for correlating the 
spectroscopic data with the photoelectric. Please monitor this star photoelectrically, 
in multiwavelength regions, using UBVRI filters (all if possible, otherwise whichever 
filter(s) you have) throughout this month and in particular between October 11 and 
14.

II Peg is a bright RS CVn system, which displays activity in all regions of the 
electromagnetic spectrum. It is one of the most active of the RS CVn stars, 
with a period of 6.7 days and displaying a migrating optical light curve with 
large and variable amplitude attributed to star spots. Optical spectroscopic 
observations have indicated that major flares occur in this star once every 
five hours. Flare activity has also been detected in the ultraviolet, x-ray, 
and U-band data. The extent of flare activity may have an impact on the
validity of the existing models of these stars.

Photoelectric photometry throughout the night (ranging from one to five times a 
night) and extended throughout the month will provide information on the optical 
behavior, and also on the presence of flare activity and the phase dependence 
(if any) of the flares.

The astronomers' intensive wide-wavelength spectroscopic observations should 
enable them to determine the time profile of the flares in several spectral 
lines and any dependence the flares may have on rotational phase.

Accompanying is a photoelectric photometry chart for this star identifying the 
variable and the comparison and check stars. Please use this chart in making 
your observations, and send observations to Howard Landis, the Chairman of the 
AAVSO Photoelectric Photometry Committee, for reduction and transmission of the 
data to the astronomers.

Your contribution to this very interesting research will be important in its success. 
Many thanks for your efforts and good observing!

Janet A. Mattei
Director

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