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AAVSO Special Notice #192: Update on the epsilon Aurigae eclipse AAVSO HOME > publications > special notice

AAVSO Special Notice #192

Update on the epsilon Aurigae eclipse
February 3, 2010

Epsilon Aurigae continues to progress through its first eclipse
since 1982-84. Visual and photometric observation means place it at
around magnitude 3.7-3.8. Totality was likely reached sometime in
January, but it will take some time to analyze the data to establish
a specific date. Totality is expected to last about 15 months, but
the system is not expected to remain quiet during this time. Small
amplitude modulations are being detected which are likely not
associated with the eclipse itself. However, their exact source is
still debated. The amplitude of these modulations are at the limit
of the average observer's ability to detect visually. Therefore this
may make a nice, challenging system to test your eyes. Right now,
epsilon Aurigae is well placed for observing high in the sky right
after dusk.

In addition to these modulations, a mid-eclipse brightening of a few
tenths of a magnitude have been reported in past eclipses. If
confirmed, it would contribute significantly to our understanding of
the structure of the eclipsing disk of material. The problem is this
will happen next summer when epsilon Aurigae is near solar
conjunction. So observations very early in the morning later this
season will be very important. It may be a good idea to begin
practicing twilight observations right now.

A naked-eye, visual chart for observing epsilon Aurigae can be
downloaded at:

http://www.aavso.org/observing/charts/epsaur-chart.png

Observers interested in DSLR or photoelectric photometers may want 
to use this project as an entry point. A team of observers is
working on a series of tutorials on the Citizen Sky web site. More
information is available at the following URL:

http://www.citizensky.org/teams/dslr-documentation-and-reduction

General information regarding the epsilon Aurigae campaign and a 
series of online discussion forums can be found at the Citizen Sky
web site:

http://www.citizensky.org

A nice illustration of the system has been prepared by Citizen Sky 
participant Nico Camargo:

http://www.citizensky.org/sites/default/files/epsaurside-nico-med.png

This AAVSO Special Notice was prepared by Aaron Price.
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