[Aavso-photometry] Possible new variable? (corrected)

[Jeff Hopkins]

Hi Dave,

Interesting.

I just came in from doing some UBV work. A fantastic night here in 
the middle of Phoenix, Arizona.

I see your Star P follows the new variable. That would be suspect.

A suggestion for your plots. Uses a finer magnitude scale and plot 
LHP058 star separately and combine both plots into one jpg or gif. As 
it is it is hard to see variations of 0.01 magnitude.

While I am not involved with this project nor have other than a 
passing interest in the data, I am interested in your technique. For 
the data to be useful to me I would want to know the data spread of 
the program star(s). The other data is fine for you to check things, 
but the proof of the pudding is what the spread (SD) of the program 
star data is. If it were me I would take three images at the required 
exposure and get 3 data points, average and calculate a SD. This 
would produce a SD for each program star data point, which as far as 
I am concerned is much more meaningful. As I believe I mention 
before, my work is primarily single channel UBV photon counting and 
JH solid date work with a SSP-4. I also have been doing some BVRI CCD 
work and am still refining my technique, hence the interest in your 
work.

Good luck with your project.

Jeff

At 17:57 -0700 12/13/2007, Dave Lane wrote:
>Jeff Hopkins wrote:
>>  And what does that tell you about the error for the program star 
>>measurements?
>
>Hi Jeff,
>
>It actually tells us a lot, particularly when a few check stars are 
>measured, since they was exposed at the same time as the program and 
>reference star through the same airmass with the CCD at the same 
>temperature and with the same read-noise. Arguably if one of the 
>stars was sitting on top of a particularly noisy pixel or a cosmic 
>ray hit.
>
>My processing pipeline that processes the data automatically also 
>produces several diagnostic measurements for each star measured. 
>These include airmass, FWHM, background level, S/N ratio, maximum 
>pixel, integrated intensity, and of course differential magnitude. 
>One can easily scan down a list of measurements and pick out the 
>ones that had issues with guiding, clouds, focus, transparency, etc. 
>They could be treated separately (or just tossed out).
>
>--- Dave
>
>ps. last night's data shows the new variable continuing to vary, now 
>at the 0.05 magnitude range 
>(http://www.davelane.ca/aro/images/20071212-lph058v.gif)

-- 
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