[AZ-Observing] Re: Photometric Night Definition
- From: Jeff Hopkins <phxjeff@xxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Mon, 12 Feb 2007 12:43:50 -0700
While I have no doubt there is at least one official criteria for a
photometric night, to me it means being able to obtain good
photometry.
Take last night, it was nearly completely overcast at sunset. Shortly
thereafter there were breaks in the clouds. I doubt few would say it
was a photometric night, but indeed it was (between the clouds).
Many nights I do BTCP (between the clouds photometry) and get
excellent results. Last night of 3 sets of readings the V has a data
spread standard deviation of 0.0026, B 0.0031 and U of 0.0055
magnitudes. Last night was certainly a photometric night between the
clouds (PNBTC).
Jeff
At 10:47 -0700 02/12/2007, edwin hubble wrote:
>In response to Keith Schlottman's question, two days
>ago, I can contribute the following:
>
>As I understand it, the Sloan Digital Sky Survey
>standard for a photometric night is as follows:
>
>During the night, the repeated measurements of
>brightness of an object, very carefully calibrated
>with all sky photometric reference stars, should have
>a root mean square deviation from the mean of less
>than 0.02 magnitude.
>
>They use a dedicated 50 cm photometric calibration
>instrument to do this, next to the 2.5 meter survey
>telescope.
>
>Their photometric calibration stars have been observed
>by the Naval Observatory in Flagstaff.
>
>A specification much tighter than 0.02 would give too
>few nights to be practical.
>
> Victor Herrero
> hubble_edwin@xxxxxxxxx
> http://hubbleed.bravehost.com/
--
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.
www.hposoft.com
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