Allan Adler wrote in message ...
It is certainly inspiring to learn that one can discover extrasolar
planets using a telescope with a roughly 4 inch aperture. I think I
understand why three different telescopes at three different sites were
needed to discover it, since they had to sift through so many candidates
and this helped with the process of weeding out false alarms. However,
now that it has been discovered and its discovery confirmed, what are
the difficulties one would face in using a beginner's telescope, say
one of the $200 computer controlled models from Mead, to look at the
star in question and confirm the observations oneself? That seems like
a more tractable project than discovering it or proving beyond a shadow
of a doubt that it is correct.

I looked at the article of Torres et al and didn't find as much detail
as I hoped for about the light gathering equipment and analytical techniques.
I think the basic reference for the equipment was Latham 1992. Is there
some kind of standard attachment one can add to the, say, Mead mentioned
above that is adequate to collect the light and send the information to one's
laptop for analysis?

It is nice to know it was done with a small telescope, but it would be nicer
to know that all the equipment one needs to duplicate the observation and
analysis could be equally humble.

Hi, Allan,

I'm not much more of an expert on this subject than you are, but what
the heck. Sci.astro desperately needs an increase in its signal:noise
ratio.

There are amateurs observing known extrasolar planetary occulations.
You can find out more about them and their work at the American
Association of Variable Star Observers (http://www.aavso.org). If you
want to look for a *known* exoplanet, you stand a decent chance of
finding it.

I have a friend who is a member of this organization. He owns a Meade
8" Schmidt-Cassegrain reflector, and a hand-made CCD camera which saw
its first light a few months ago. I work with microscopes more than
telescopes. Still, many of the issues surrounding getting a good
quantitative image are the same.

You won't see these exoplanet transits by eye. Only a few extrasolar
planets have been observed by occultation so far. When these planets
pass in front of their parent stars, the light loss is pretty small,
peaking at around 2%. So you need to make really accurate
measurements of the intensity. Twinkling and other atmospheric
variations are a problem. The pixels on a CCD are not perfectly
uniform, either. How sharp is your focus? Is the light of your star
falling exactly on one pixel, or on several? What if the voltage that
you supply to the CCD varies a bit from time to time? Then,
successive images of the star would not be directly comparable. Have
you saturated any pixels? Is your CCD response linear? Is your
analog to digital conversion 8-bit or 12-bit?

To compensate for all of these possible problems, you would probably
want to image a star field that includes at least a few reference
stars that you do not expect to vary. You would want to take many
images, at a few different exposure times. Then you would need to do
a fair amount of math to tease out the variations as a function of
time.

I suspect that the use of three observing sites in the TReS study
improved the observations in at least three ways. First, one site
would often be able to observe when another was clouded out. Second,
the Canary Islands site and the Western U.S. sites were several time
zones apart, allowing almost 24-hour observations. Third, there would
be times of overlap, when light curves from multiple observing sites
could be compared.

So, can you go hunting for NEW expolanets yourself? Maybe. But
having a friend on another continent or two would help. And the
software to analyze the images is critical.

(Proposal for an amateur exoplanet hunting network: observers in
California, Chile, Canary Islands or Spain, South Africa, Japan, and
Australia.)

--
Rainforest laid low.
"Wake up and smell the ozone,"
Says man with chainsaw.
John J. Ladasky Jr., Ph.D.