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Site: UsingConcamsForQuantifyingLightPollution

Friends A wild idea, dont know if it will work There is is a CONCAM ( Continuous Camera) operated by Indian Astrophysics Intitute,bangalore , at HANLE ,LEH. This camera takes an all sky pic every 120 secs. Could we not use these pics as a ref for the no of stars which should be seen .After all Hanle was chosen for its clear skies and perfect(?) seeing. I tried to count the stars in the Leo quadrangle in the Hanle pic at 1000 hrs tonight but gave up after about 25. May be a simlar camera set up in ,say IIT Delhi, which is said to have a very bad light pollution, could give a comparative image which may give a direct measure of the sky condition there. I know this defeats the plan to involve more and more obsrvers to count the stars and popularise skywatching, but this could be an alternate. May be a network of such cameras, if made availabhle at resonable price , could be set up to continuously monitor the sky condition. Just like the pollution monitors set up at main squares in Delhi.

Cheers Ulhas Deshpande Mon Apr 7, 2008 6:06 pm

Ulhas, it is an interesting idea - whatever possibilities of analysing data for this are evolved, could perhaps also be adapted for digital camera images.

The only problem with these would be the possible uniformity of settings if a comparison is to be carried out. How uniform are the results with webcams and digital cameras, given the settings to be the same?

Of course, this would have to be a different comparison from the limiting magnitude one, as the eyes have changed :-)

Rathnasree Nehru Planetarium, New Delhi Tue Apr 8, 2008 6:10 am

You do not need concam for reference since good catalogs and atlases are already available. The idea of having a network of cameras is indeed a good one. The concam at Hanle was provided by the Michigan Technical University through a similar project. It should be possible to make similar ones using peltier-cooled CCD cameras and a fish-eye lens.

Good cameras are also available commercially now at about US$ 800. See Such a camera is used at the MMT observatory; see Using the raw data in counts, we should be able to make sky brightness maps from these images. I can provide some raw images in FITS format if someone is interested in developing automated software.

Tushar Prabhu Indian Institute of Astrophysics Bangalore Wed Apr 9, 2008 7:33 am

Tushar I did not mean to use CONCAM picture as a star atlas.What I had suggested was that Hamle Concam pic could be a base ref to calibrate /compute the sky condition at at other places in India if such anetweork could be set up Cheers

Ulhas Thu Apr 10, 2008 9:45 am

Ulhas, I think that the reference made by Prof. Prabhu, to a star atlas, might have been to imply that a calibration for concams with different settings etc. would be possible by looking at the magnitudes of known stars in the concam image and comparing with sky background.

Did I understand it correctly, Prof. Prabhu?

Rathnasree Thu Apr 10, 2008 9:50 am

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