[Aavso-photometry] Chart Generator for EPS AUR

[Jeff Hopkins]

Hi Bob.

Check http://www.hposoft.com/EAur09/Starinfo.html

Currently my PMT Photon Counting BV values for epsilon Aurigae are B= 
3.6041 SD = 0.0016 and V= 3.0499 SD = 0.0021
No check star is needed.

For procedure:
I suggest taking 3-lambda ten second reading in B then V followed by 
one sky reading in each filter. If the sky reading are high relative 
to the star + sky, take three sky readings in each filter for the 
sky. Repeat for epsilon, lambda, epsilon, lambda, epsilon and lambda. 
Reduce the data and take the difference then normalize to lambda's 
published values. You should then have three magnitudes for B and 
three for V. Average each filter's magnitude and take a standard 
deviation. Those data are then what should be used. Do this as 
quickly as you can and the data should be good. When reducing the 
data you should take into account extinction. You can use lambda to 
calculate the extinction. If you observe close to the meridian the 
difference in extinction between lambda and epsilon will be minimal. 
The further from the meridian the more important the extinction 
correction is.

Let me know if you have any questions.

Glad to have you involved. You should visit the web site and check 
how to become a campaign member and send me the data and I will add 
you.

Good luck.

Jeff

At 19:54 -0700 01/26/2008, Bob Crumrine wrote:
Jeff and others,

I'd like to begin doing single channel photometry of Eps Aur while 
it's still high in the sky, using my SSP3 and 8" LX-200.  What are 
good Comp and Check stars and what are the accepted V and B-V for 
them?

Thanks,
Bob Crumrine (CRR)
near Rochester, NY

Jeff Hopkins wrote:

Hi Steve,

Epsilon Aurigae is a 3rd magnitude (V) star and pretty easy to find,
right next to Capella and at the vertex of the triangle known as the
kids. Lambda Aurigae is the normal comparison star. While there are
other stars closer, they are too faint for CCD work in that if you
stay linear with epsilon the comparison stars will be in the noise.
For CCD photometry there are two major problems, the brightness and
wide separation of program and comparison stars.

Bob Buchheim wrote an article for the SAS Vol. 5 Number 3 Newsletter
titled "Getting Ready for Epsilon Aurigae." He indicated the problem
with CCD photometry and the brightness of epsilon Aurigae. He
suggested stopping down the telescope, but that does not solve the
separation (around 5 degrees) of the program and comparison star.

At HPO we have investigate using a 50mm F/2.0 camera lens on a DSI
Pro. Preliminary results are very encouraging. Both epsilon and
lambda Aurigae fit in the image and by defocusing the image a bit
under sampling is solved. Several nights have produce BVRI data where
3 sets were 0.01 magnitude or between data spread. I'm in the process
of writing up the procedure. While this is CCD filter photometry, it
is very different from CCD photometry of fainter stars.

Of course the star system works best with single channel photometry.
For more information check
<http://www.hposoft.com/Campaign09.html>http://www.hposoft.com/Campaign09.html

Jeff

At 18:26 -0700 01/21/2008, Steven Orlando wrote:


Hello All!

On the homepage, there was a call for data for EPS AUR. However,
when I go to  plot a chart I get no photometric start for my FOV.

Anyone have a link to a star chart for this star?

Steve
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-- 
Jeff Hopkins
HPO SOFT
Counting Photons
http://www.hposoft.com/Astro/astro.html
Hopkins Phoenix Observatory
7812 West Clayton Drive
Phoenix, Arizona 85033-2439 U.S.A.
(623)849-5889
(623) 247-1190 (Fax)
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