New Problem Sets

[Tom Droege <tdroege2@earthlink.net>]

This EROS paper suggests some new problem sets.

3) Apply the EROS technique to the pipeline output to look for variable stars.

4) Apply Welch-Stetson to the pipeline output to look for variable stars.

5) Apply some other technique to look for variable stars.

6)  I hope to talk with David Charbeneau in a few days.  Possibly I can get 
information on how they reduce their data from him.  Someone may want to 
try to convert it for use with tass data.

For 3) and 4) I can provide a big list of stars to work with.  I have 
written a program which operates on a sorted list of .cal files (the 
Michael Richmond pipeline output) and produces a list of stars in the same 
format where all the observations of a star are grouped together.  This 
list has one line for each observation.  I also can make a summary list 
with one line per star which can be used to select stars from the bigger 
list.  At the moment, such list will have large systematic errors related 
to problem 2) below.  However, I can pick a list that is "pretty good' and 
which will allow software development.  When photom gets better I will be 
able to send out improved lists.  Mike Sallman and Richard von Blucher may 
want to rethink the data sets that they ask for as I have not yet sent out 
data.

I am working on a less than sophisticated scheme for #5.  Mostly it is an 
excuse to work on Linux skills.  At the moment, the output is not very flat 
for successive observations of the same non varying star.  What is needed 
is Michael's photom-0.x.  Photom-0.2 presently blows up for some data 
sets.  Michael may have found the problem, but there may be other problems 
yet to be found.  So until we get better photom output I plan to work on 
the existing output to see what I can do to make it a little better.  It is 
not so bad now if one picks a good night.

Michael has also made progress on problem 1) below.   So perhaps 1) and 2) 
belong to Michael, though Michael has said that anyone is free to work on 
these or any other problems.

Linux is spoiling me.  After several attempts to get the EROS paper using 
my Windows machine and watching it crash the system when I tried to print, 
I went to Linux and it worked the first time.

The first two problems are copied below:

1)  The star matching program fails.  This almost always happens for the I 
image so it is not due to a bad position in the fits header.  Sometimes 
more frames will pass and generate .ast files if one fusses with the RA and 
Decl. position.  But it does not help very much.  A data set will be made 
available with good and bad runs from the set below.  Ask for Data Set 21 
if you want to work on this problem.  I am betting that this has something 
to do with the V focus being sharper than the I focus.

2)  Michael's photom-0.2 sometimes blows up.  When it does so, It produces 
*very large* offsets in the mag values.  +/- 10 mags or so.  Photom-0.2 is 
supposed to remove small differences over the 2.3 hour run due to changing 
sky conditions and the like.  It does some good, but sometimes introduces 
very large errors.  I suspect that it is also introducing smaller errors 
for other frames.  Note here the V correction blows up more often.  Again a 
sharpness problem?  As for Data Set 22 if you want to work on this problem.

Tom Droege

At 10:41 AM 4/16/02 -0400, you wrote:

>   The EROS group, who monitor selected fields in the galactic plane,
>have published a paper describing their discovery of hundreds of
>variable stars in two particular fields.  You can find it on the
>astro-ph preprint server:
>
>         http://xxx.lanl.gov/abs/astro-ph/0204246