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Special Notice #177: Observing Campaign on the Secondary Eclipse of zeta Aurigae

AAVSO Special Notice #177

Observing Campaign on the Secondary Eclipse of zeta Aurigae
November 12, 2009

As part of the AAVSO's Citizen Sky Project experienced observers are encouraged to contribute high precision observations of zeta Aurigae during the remainder of the month of November.  The nature of this system makes the secondary eclipse very difficult to observe with a minimal change in brightness.  Characterization of the secondary eclipse will be a challenging endeavor to observers.

Zeta Aurigae is a bright (V ~ 3.75 out of eclipse), northern eclipsing variable with a known period of 2.66 years.  The system contains a hot, luminous B7V star and a more luminous K5II star.  During primary eclipse (which occurred in March 2009), the blue B7V star is obscured by the larger orange K5II star.  The secondary eclipse is more difficult to detect, because the B7V star obscures a small portion of the K5II star's light.  The approximate date of the eclipse is November 17, 2009, with an anticipated duration of about 40 days.  The K5II star is known to exhibit variations of 0.05 magnitude, therefore high precision photometry is necessary for this short campaign.

For more information,including comp star coordinates and magnitudes, please visit:

This AAVSO Special Notice was prepared by B. Kloppenborg and A. Henden.

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