[Aavso-photometry] Chart Generator for EPS AUR

[Jeff Hopkins]

Hi Steve,

I hope to have time to finish the camera lens procedure sometime this 
week. I will post a URL when it's on my server.

Arne indicated  a way you can do it with a telescope, but that method 
requires stopping it down and essentially doing single channel 
photometry using a CCD. Check the SAS newsletter Vol. 5 Number 3  at
http://www.socastrosci.org/ for information on how Bob Buchheim 
suggests doing this. It would be interesting to see how that works 
out compared to the the wide field method.

The wide FOV method  am developing seems to work well. The critical 
area is the defocusing. The images look horrible. but produce good 
photometric data. The better focused ones produced poor data.

I should have the procedure finished later this week.

BTW, for those interested Matthew Templeton wrote an excellent 
article called "Variable Star of the Season, January 2008 Epsilon 
Aurigae." See http://www.aavso.org/vstar/vsots/

Jeff

At 19:38 -0700 01/21/2008, Steven Orlando wrote:
>Jeff and Mike,
>
>I know it is a bright star, but how can you get an accurate mag if you don't
>have comp stars.
>
>Of course, you can use a 35mm camera lens to widen the field. I don't have a
>50 mm camera lens. I can use an 80 mm camera lens.
>
>What I understand is that as long as you get epsilon and lambda Aur in the
>same field, you can do photometry.
>
>Please post the link to the procedure you write up. I am interested in
>taking a look at it.
>
>Steve
>----- Original Message -----
>From: "Jeff Hopkins" <phxjeff at hposoft.com>
>To: "Steven Orlando" <sorlando at sorlando.com>;
><aavso-photometry at mira.aavso.org>; <aavso-discussion at mira.aavso.org>
>Sent: Monday, January 21, 2008 8:38 PM
>Subject: Re: [Aavso-photometry] Chart Generator for EPS AUR
>
>>  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
>>
>>  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
>>>_______________________________________________
>>>
>>>Aavso-photometry mailing list
>>>Aavso-photometry at mira.aavso.org
>>>http://www.aavso.org/mailman/listinfo/aavso-photometry
>>
>>  --
>>  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)
>>  www.hposoft.com
>
>_______________________________________________
>
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>Aavso-photometry at mira.aavso.org
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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)
www.hposoft.com