Useful Research?

[Martin Nicholson <Martin@crozet.demon.co.uk>]

Making maximum use of TASS data

Perhaps I should start by saying that nothing I have written here should
be seen as being in any way critical of individuals. Indeed some the
points might be obvious to TASS readers - nevertheless I hope I have
raised issues worth debating.

Let me start with a real attention grabber! Is looking for new variable
stars a useful project?

I have seen highly respected amateur astronomers suggest "useful
projects" for fellow enthusiasts to undertake that were anything but
useful! For example the globular cluster M3 has been the subject of
extensive professional research and numerous refereed articles on the
large number of variable stars that can be observed. The periods and
amplitudes of these variables are easily obtained from the World Wide
Web but amateurs with small telescopes are still being urged to collect
duplicate data. Fun it might be, useful research it is certainly not.

It seems to me that there are four main stages in useful astronomical
research. 

In brief they are:
1) Deciding on the project
2) Collecting the data
3) Processing the data
4) Publishing the data in a manner acceptable to the wider astronomical
community

I have used the phrase "useful astronomical research" quite deliberately
since much time and effort is wasted by amateur astronomers on projects
that are rendered pointless when the participants ignore one or more of
the basic principles of science. "One variable at a time" is a well
established doctrine that astronomers should ignore at their peril. 

Let me turn to the specifics of variable star research. It seems to me
that taking images of the same part of the sky at intervals is a
perfectly acceptable way of searching for stars that appear to vary in
brightness. The key though is the phrase "that appear to vary in
brightness". Any experienced user of a CCD will tell you that all sorts
of factors can influence the readings obtained - the degree of moonlight
and the presence or absence of thin high cloud are just two factors that
spring to mind.  I have also carried out work on asteroid light-curves
that show variations of as much as 0.1 magnitudes in readings taken 5
minutes apart on nights where the above mentioned variables can be
ignored. I respectfully suggest that unless we can standardise the
results taken on different nights much of the value of the data
collected disappears.

Calibrating every value on every image against the results obtained for
ten or a dozen known non-variable stars that appear on the same exposure
might be helpful.

I read recently that the vast majority of scientific data is never
looked at by those responsible for collecting it. Whatever processing
methodology TASS decides to adopt it needs to involve as many people as
possible. Too few "data crunchers" can mean that data is coming in
faster than it can be processed. The backlog then never gets cleared.

I identified 900 variables in earlier TASS data that needed to be
examined more carefully. The data has been in the public domain since
December 1999 but virtually no progress has been made. By the time my
web site had been created most of the active participants had moved on
to collecting yet more data. Take a quick look at

http://www.further-education.com/tass/variablefront.htm

I suppose what I am saying is that collecting data without the
supporting infrastructure to process it is not a sensible policy.

Moving on - suppose we are satisfied that a star is variable. Without
accurate information on the position, the period and the amplitude of
the variation then this information is hardly worthy of note.
Information on a minimum of two complete cycles should be regarded as
the qualification for publication. This might take the best part of two
years of data collection for long period variables.

Once the information is of the required quality and quantity where
should it be published so that other astronomers can find it? It seems
to me that although most enthusiasts have heard of the GCVS there is
still some uncertainty as to exactly how to get information included in
the catalogue. There are lots of variable results floating around on any
number of web sites that have clearly never been submitted to any third
party.

Martin Nicholson, Daventry, UK

International Astronomical Union's Minor Planet Centre - Observatory Code 456
http://www.gcse-ict.info/astronomy/front.htm