Re: Data Processing (1) - further thoughts

[Tom Droege <droege@wwa.com>]

Martin and other data fans,

At 09:15 AM 12/29/99 +0000, you wrote:
>In message <199912281901.OAA00720@a188-l009.rit.edu>, Stupendous Man
><richmond@a188-l009.rit.edu> writes
>>
>>  Martin Nicholson writes:
>This means that if I confined my study to those stars >3 times the
>median value I would only find 16% of the known variables.

Yep, this is the sad fact of data analysis.   Pushing the 3 sigma lower
just gives a lot of false hits.  Even 3 sigma will give quite a few.  This
would be OK if we had a follow up group to take better measurements and
confirm the true variables from the noise.  This explains why I encourage
everyone to take on this work.  

This also explains my present gloom.  The camera is just noisier than I
think it should be.  We have to work hard to get the noise down so the
standard deviation goes down.  Then we can find more stuff.  Other ways to
reduce the noise are to move to a high mountain where the conditions are
perfect and to work out a perfiect calibration proceedure.  

Still, tass has been designed to get some good data while working under
lousy conditions.  We do this by taking a lot of bad data in bad locations
and processing it into good data.  It is sort of like seti in this respect.  

OK, I will be the first to admit that lots of bad measurements do not equal
a few good measurements.  But to get good measurements, we have to move to
a mountain top somewhere.   Most of us cannot do that and keep our jobs (or
in my case, my wife's job).  Furthermore, some of us are addicted to the
things that a big city can bring.  So tass is designed to still work when
run by amateurs working under terrible conditions.  

As you can see, we can still find some good stuff.  The Mark IVs should
measure about 40,000,000 stars.  Of these about 1,000,000 would be variable
if we could measure them with enough accuracy (OK, Arne, possibly it is
only 400,000 - it depends on the accuracy of the measurement, does it
not?).  If we get 5% of these, then we will find 50,000 new variables.  By
memory, this about doubles the current known variables.  

So there is a lot we can do, even with bad measurements and bad conditions.
 My goal is to do what is possible letting amateurs run from their homes.

Tom Droege