Paul A. Heckert

UBVRI field comparison stars for selected active quasars and BL Lacertae objects

UBV (Johnson) and RI (Cousins) magnitudes of field comparison stars for several active quasars and BL Lacertae objects are presented. The comparison stars can be used for photoelectric and CCD monitoring of the variability in brightness and optical-continuum spectral index of these BL Lacs and QSOs. 21 references.

A Decade of Starspot Activity on the Eclipsing Short-Period RS Canum Venaticorum Star WY Cancri: 1988-1997

We present optical photometry of the short-period eclipsing RS CVn system WY Cancri for the years 1988–1997. For each light curve, we model the distortion waves in order to study the behavior of starspots in this system. After removing the spot effects from the light curves, we model the cleaned data to obtain system parameters. We also note changes in the luminosity of the primary star that are not explained by the spot variation.

Spectroscopic and Photometric Observations of the Short-Period RS CVn-Type Star UV Piscium

High-resolution spectroscopic observations around the Hα line and BVRI photometry from 1993 to 2003 of the eclipsing short-period RS CVn star BH Vir are presented. The simultaneous solution of our radial velocity curves and light curves yielded the following values for global parameters of the components: M1 = 1.173 ± 0.006 M� ; M2 = 1.046 ± 0.005 M� ; R1 = 1.22 ± 0.05 R� ; R2 = 1.11 ± 0.04 R� ;i = 87.5 ◦ ± 0.8 ◦ . The measured rotational broadening of the spectral lines corresponds to equatorial velocities V1 = 79.8 km s −1 and V2 = 68.4 km s −1 . Our data reveal considerable Hα emission excess of the two stellar components. We modelled the photometric data to find the size and location of the starspots for each year. The established decreasing trend of the spot latitudes may indicate a latitudinal cycle of at least a decade.

Long-term luminosity variations and period changes in CG Cygni

We report new photometry of CG Cyg from 1998-2002. We also analyze published photometry collected since 1965. An O-C analysis reveals evidence of a third body in the system having a 51 year orbital period. After removing the effects of the third body, we note a remaining 22.5 year cyclic variation in the O-C curve that is similar to the period of the luminosity variations. Modeling the spot activity for 28 V band light curves obtained between 1965 and 2002 confirms the presence of two active longitude belts (ALBs) at approximately 90 ◦ and 270 ◦ . Most of the spots occur at mid latitudes with a few at low latitudes. We note no spots at latitudes greater than 60 ◦ .

Do the Secular Variations in WY Cancri Mark the Spot Cycles

I present optical photometry of the short-period eclipsing RS Canum Venaticorum binary WY Cancri taken after the most recent secular luminosity increase, in 1997. Data taken between the previous two secular luminosity increases, in 1988 and 1997, show a tendency for spots to migrate toward increasing longitude within an active longitude belt. These new data show a trend for spots to migrate in the opposite direction, toward decreasing longitude. Based on these trends, I suggest that WY Cnc shows cyclic behavior and that the previously observed secular luminosity increases in WY Cnc mark the start of new magnetic activity cycles in which the direction of longitudinal spot migration reverses. Continued observations will of course be necessary to confirm this hypothesis.

Optical to mid-infrared polarimetry of OH 0739-14

Optical and mid-IR polarimetry and optical photometry are presented for OH 0739 - 14 (= OH 231.8 + 4.2), and previous NIR polarimetry is confirmed. The wavelength dependence of the polarization is modeled. A model using 50-nm silicate grains fits the data at optical and NIR wavelengths but does not do well at the 10-micron silicate feature. The model with 100-nm ice grains fits the data well except at the L band, which is near the 3.08-micron ice absorption feature. The source is most likely to contain a mixture of these two grain species. 34 references.

Three X-ray flares near primary eclipse of the RS CVn binary XY UMa

We report on an archival X-ray observation of the eclipsing RS CVn binary XY UMa (

Long Term SPOT Activity on Eclipsing RS CVn Stars: RS CVn, SS Boo, and MM HER

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Spectroscopic and photometric observations of the short-period RS CVn-type star BH Virginis

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Infrared photometry of Beta Lyrae - 1977-1982

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