Re: Fwd: [Aavso-photometry] pipeline

[Fraser Farrell <fraser@trilobytes.com.au>]

On Fri, 2 Jan 2004, Thomas Droege wrote:
>The solution is to take as much data as possible with as much information
>as possible as to how the data was taken.  Then as time goes on and the
>data is studied, then it might be possible to sort out the things that are
>important for taking good data.  Then it will be possible to select the
>good data.
>
>At the moment, I have very little indication as to what will make good
>data.  I am particularly suspicious of the I data since I think things are
>going on in the sky that causes big problems with the I data.



Tom,

Scientific history is full of bad data that turn out to be useful
after all. Possibly in another context. So keep on taking those images
and archiving them.

The example most readily to mind is observations of ancient eclipses;
where a typical report reads something like "During the 9th year of
the reign of King Aarrgh, the sun turned black and stars were seen
over the city in the daytime". By modern data-collecting standards
this observation is "bad" (no timing of totality, no images, etc) but
nonetheless it can be used to investigate topics such as:

 - the Earth's rotation rate, and associated geophysical phenomena

 - secular accelerations in the Earth-Moon system

 - and of course the actual dates of King Aarrgh's birth/reign/death,
and associated events.

I doubt that the ancient scribes and historians would have considered
the data-collecting standards needed for the first two topics. But
note that they didn't need atomic clocks and lunar laser reflectors
to produce a useful data point anyway!



As for your I data, I wonder if aircraft contrails, not necessarily
visible to the eye, are affecting it? I recently read a climate report
describing a small but consistent drop in air temperatures, over the
continental US, during the last quarter of 2001. The authors
attributed the cooling to the grounding of commercial aviation at the
time, and the consequent -absence- of the usual aircraft contrails
that reflected outgoing heat back to the ground. I note that from your
location you're probably looking through some rather busy flight
corridors?

The (naive) test for this hypothesis is to compare your I data from
the 2001 "no flying" period with your recent I data of the same
starfields.



cheers,


Fraser Farrell

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