[Aavso-photometry] UBV Photon Counting

[Jeff Hopkins]

Hello Arne,

I'm curious what CCD detector you use for the U band work. I looked 
over the specifications and spectral response of several CCDs and 
they all seem pretty dead in the U band.

Jeff

At 10:54 -0700 1/19/05, Arne Henden wrote:
>Bessell has a U-band prescription that uses a Schott IR blocker,
>reasonably effective for CCDs.  We use such a filter here
>as CuSO4 is very difficult to work with (tends to break).
>   I do a fair amount of U-band work, especially time series
>on bright variables, but also calibration work for things
>like GRBs.  You can do reasonably well with a CCD, with the
>usual constraints of whether your telescope works well at
>U and how well you can calibrate out the atmosphere.
>Arne
>
>Richard Miles wrote:
>>  Jeff,
>>  Your UBV observations of BET PER and write up on your webpage at:
>>  http://www.hposoft.com/Astro/PEP/algol.html
>>  is most impressive and very enjoyable to read.  Well done.
>>  Like you I started EPS AUR observtions in 1982 but unlike you I 
>>did not think to keep measuring its out-of-eclipse characteristics 
>>ahead of the next (2009) eclipse - nice paper on this.
>>  I should be getting a filter wheel for my main scope later this 
>>year so I shall have to make sure I get a U filter.  However I am 
>>very doubtful of its efficacity because unlike the 1P21 phototube, 
>>the red leak will really wreck the true U signal when measured by a 
>>CCD.  If I remember, the advice was to include a copper sulphate 
>>window to block the IR side - now there's a challenge!
>>  I wonder if anyone else on this list is doing U photometry 
>>(successfully) with a CCD camera?
>>  Richard
>>
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>>

-- 
Jeff Hopkins
HPO SOFT
http://www.hposoft.com/Astro/astro.html

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