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Alert Notice PEP #0: Multiwavelength monitoring of 2349+28 II Pegasi

October 4, 1991

Note: This Notice was originally titled:
SPECIAL AAVSO ALERT NOTICE TO PHOTOELECTRIC PHOTOMETRISTS MULTIWAVELENGTH MONITORING OF 2349+28 II PEGASI

It has been given the somewhat odd name "Alert Notice PEP #0" in 2014 so it will fit in with the other special PEP Alert Notices created by Aaron Price in 2001-2004. Eventually all of these special PEP Alert Notices will be renamed to something more consistent with Alert and Special Notice procotols. EOW 10/27/2014

Astronomers at NASA will be monitoring spectroscopically 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

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