Special Notice #252: Upcoming Eclipse of Zeta Aurigae

September 8, 2011:

Jeff Hopkins (Hopkins Phoenix Observatory, Phoenix, AZ) communicates regarding the upcoming eclipse of the 4th-magnitude binary system zeta Aurigae. He writes:

"This fall offers a unique opportunity to observe an interesting eclipsing binary star system. Zeta Aurigae (HD 32068) will be eclipsing late October through mid-December 2011. The star system will be placed high in the sky late evening and early morning. Zeta Aurigae eclipses once every 2.7 years with the eclipse lasting around 43 days. Both photometric and spectroscopic observations are requested.

First Contact is estimated at 29 October with ingress about 3 - 4 days and totality about 35 days. The exact time of first contact needs to be determined more precisely and this is an excellent opportunity to provide data for that determination. The following are the predicted Contact Times and Magnitudes:

1st Contact 29 October 2011 JD 24555864
2nd Contact 02 November 2011 JD 24555868
Mid-Eclipse 20 November 2011 JD 2455886
3rd Contact 09 December 2011 JD 24555905
4th Contact 13 December 2011 JD 24555909

U Band Magnitude Change 1.576
B Band Magnitude Change 0.213
V Band Magnitude Change 0.079

Instrument photometry is requested in the UBV bands. Longer wavelengths (RIJH) will probably not show a significant or any change in magnitude.  

Lambda Aurigae is the recommended comparison star, but eta Aurigae can be used for CCD and DSLR photometry.

Lambda Aurigae:
HD 34411; R.A. 05h 19m 08.4s, Dec. +40d 05' 57" (2000.0)
Magnitudes: I = 3.88, R = 4.19, V = 4.71, B = 5.34, U= 5.46

10 Eta Aurigae:
HD 32630; R.A. 05h 6m 30.8s, Dec. +41d 14' 04" (2000.0)
Magnitudes (from 2009 CCD photometry at HPO, 31 observations):
V = 3.230 SD 0.018, B = 3.225 SD 0.021, U = 2.687 SD 0.030
No R, I, or JH data. Photometry in those bands is not recommended.    

This Campaign is not recommended for visual observers. It is suggested that observations start immediately and continue through December 2011. Plan 2 - 3 observations per week until mid-October. During the times around ingress and egress, nightly and even more than once a night observations are suggested. Observations, questions, and comments can be sent to me at phxjeff@hposoft.com.

More details can be found on the International Zeta Aurigae Campaign 2011 web site at

Thank you."

Coordinates: R.A. 05 02 28.6   Dec. +41 04 33 (2000.0)

Charts: A chart for zet Aur may be found on the campaign website above or may be made using the AAVSO Variable Star Plotter (VSP) at http://www.aavso.org/vsp

Observations of zet Aur (000-BCT-906) may also be submitted to the AAVSO International Database as ZET AUR.

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.


Information on submitting observations to the AAVSO may be found at: http://www.aavso.org/webobs


A Special Notice archive is available at the following URL: http://www.aavso.org/special-notice-archive/

Subscribing and Unsubscribing may be done at the following URL: http://www.aavso.org/observation-notification#specialnotices