UsingConcamsForQuantifyingLightPollution

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

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
http://www.astrovid.com/prod_details.php?pid=6
Such a camera is used at the MMT observatory; see
http://skycam.mmto.arizona.edu/
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