[BAA Comets] NEW - Interactive comet finder charts

[willian souza]

Hello Graham,

That is amazing, great tool!
It works even on my samsung galaxy S II running android 4.1.2.
Regards,
Willian Souza
Sao Paulo/Brazil

-----Original Message-----

From: Graham Relf
Sent: 24 May 2013 18:12:33 GMT
To: BAA Comets discussion list
Cc: Sheridan Williams
Subject: [BAA Comets] NEW - Interactive comet finder charts

In response to requirements elucidated at the Comet Section meeting on
18th May, the comet ( http://britastro.org/computing/charts_comet.html )
and asteroid ( http://britastro.org/computing/charts_asteroid.html )
finder charts on britastro.org/computing will have a new feature from
now on. A preliminary sample can be seen at
http://britastro.org/computing/ch/_63PTest.html (63P/Wild).

As you move the mouse over the chart certain data for the nearest star
are displayed below it:

Star id (Flamsteed/Bayer or H... Hipparcos or T... Tycho)
V magnitude (+ "variable" if the star is variable in the Hipparcos/Tycho
data)
B - V (colour index; just a few stars do not have the data for this)

The id is given so that further information can be found elsewhere if
desired.
V magnitude is given to enable visual comet magnitude estimation using
the defocussing technique (see J.Shanklin, BAA Observing Guide to
Comets, 2002).
B - V is given so that stars with a similar colour index to the Sun can
be used. Dust comets are reflecting sunlight so comparison magnitudes
need to be for similar stars. The Sun's B - V value is reckoned to be
0.66 (see
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992PASP..104.1035G&db_key=AST&data_type=HTML&format=&high=44b52c369023103
David F. Gray, The inferred colour index of the Sun, 1992).

The chart also displays green boxes around the most Sun-like stars:
those in the range 0.60 < B - V < 0.72.

The interaction is done using standard HTML/JavaScript techniques that
have been around for many years and so should work in all browsers. It
has been tested in FireFox 20 and Internet Explorer 10. The code is
generated automatically by our own chart generator using Hipparcos/Tycho
data. Once you have the chart in your browser no further internet
connection is need for the interaction.

If you print the chart you will not get the star data. The idea is that
you select the stars you want and make a separate note of their
characteristics, perhaps written on the print. However, if you save the
whole page from your browser you should be able to view it from disc
with the full interaction.

The interactivity is not yet in the red-on-black versions of the charts
but that will come soon.

Please tell us about any problems or modifications you think would be
useful. I have already had feedback that the star data do not follow the
mouse in early versions of FireFox. It would be useful to know about
other exceptions, though I am not sure at this stage what could be done.

I hope I have demonstrated with this that having our own chart generator
is an advantage because we can make it do what we really need. (And I
enjoy the challenges involved.)

Graham
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