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Zeta Aurigae Primary Eclipse Observing Campaign
Now that the epsilon Auriage eclipse has passed, several people have been asking me and Dr. Bob "what's next?" For me I'll spend this academic year finishing up my dissertation, helping finish team publications, and looking for my first postdoc. Dr. Stencel, on the other hand, has an intrest in several other systems one of which is Zeta Auriage.
Back in 2009 Jeffrey Hopkins and CSky teamed up for a mini observing campaign of the secondary eclipse of Zeta Auriage, one of the other stars in the asterisim known as "the kids" in Auriage. Now three years later the primary eclipse of this star system has arrived and we are yet again in need of your assistance to catch the eclipse.
This system is composed of a K-type supergiant and a bright B-type star. During the primary eclipse, the B-star, which is brighter in visual wavelenghts, passes behind the K star. Based upon the 1985 eclipse, we anticipate to see a 0.2 mag drop in V-band and a 1.7 mag drop at U. Of special importance are the ingress and egress phases where the B-star's light passes through the K-star's atmosphere, effectivly serving as a sharp probe of the K-star's layered composition.
Anticipated dates of importance:
1st Contact: 2011 Oct 29
2nd Contact 2011 Nov 2
Mid-eclipse 2011 Nov 20
3rd Contact 2011 Dec 9
4th contact 2011 Dec 13
We encourage visual observers along with instrumental observers. During the ingress and egress phases, several observations per night are requested whereas at other times 2-3 observations per week should be adequate. Because of the fast (1.5 day!) ingress phase, please pay special attention to the exact time of your observations. Along with photometry, if you have the capability of getting spectral data, that will be of high importance. Jeff has posted some details about this event to his 2011 Zeta Aurigae Campaign Website. During the next week we'll put together an AAVSO special notice and I'll update this post with that information as well.
NOTE: during the eclipse there is a significant color change so the color coefficient for DSLR observers will need to use a different color coefficient for zet Aur. The DSLR team is working on a way to use the R and G pixels together to avoid the need for a (B-V) color correction. Please contact any member of the team for more information.
Note that because this is a very fast eclipse, you could probably use these efforts in a paper for the upcoming special addition of the Journal of the AAVSO! If you have any questions, please post them in the photometry forums.
Below is the standard observing information copied from the 2009 campaign announcement:
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Several reasons:
1. convenience - it's adjacent to epsilon Aurigae and easy to capture in a frame of images, and a short hop spectroscopically;
2. timing - while we hope you will continue monitoring epsilon Aur this autumn, zeta goes through a much more rapid eclipse, and more precise timing of phases would be helpful - see http://arxiv.org/pdf/0802.2238v1 - see Figure 3 page 24 .
3. challenge - the 'tiny' hot star is eclipsed by the huge red supergiant in this case, and the eclipse is very much toward the blue/ultraviolet end of the spectrum, which will be harder to capture with red sensitive CCD equipment in general. The eclipse depth in V is less than 0.2 mag, but much deeper in B and U bands;
4. astrophysics - even though a long period binary, the separation of the hot star from the cool star is small in cool star radii - meaning both are tidally affected and radiation influenced. Partial phases contain evidence for atmospheric structure, and periastron occurs very soon after eclipse - a dynamic system.
Please report your results to AAVSO and the campaign webpage if you participate! Thank you.
It is a very interesting post. I read it almost but still have to read some. I have book marked it so that i will read it after when ever i get time. .
Hi all,
I'm using the intermediate-reduction sheet of Eps Aur adapted to zeta Aur. I observed zeta out of eclipse obtaining a mean of 3.74 Vmag and after 29th of october a mean of 3.93 mag and I use defocusing with stars brighter than six V magnitude.
My hardware for bright stars is Olympus 330-e with live focus using 50mm and 200mm lens tracked by Purus Astromechanik clock.
I used the same reduction sheet adapted for ag peg and eta aql and I posted measurements as ctia both in AAVSO database and in citizensky 10-stars program.
I use AstroArt for photometric measurements and I've modified slightly the reduction sheet adding a column ADU before the Imag column. Imag takes the value from ADU column using the expression -2.5xlog(ADU).
I find the reduction sheet very useful and a fine instrument of reduction,
Tiziano Colombo
Pisa-ITALY
astrotizio
CTIA