[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

A new game to play: scan candidates for high proper motion




  In the course of putting together the "patches" dataset, 
I realized that it might be used to look for stars with
high proper motion (that is, movement across the sky relative
to other stars).  There have been many other surveys designed
specifically to find stars with high proper motion, so I
don't really expect to find many (any?) new stars in this
category .... but you never know.  

  One area in which TASS may have some advantage is in the
case of _very_ large proper motion, of >= 2 arcsec per year.
In some cases, the TASS cameras make many measurements of
the same field within a single year, so that such stars
will show clear movement, yet still easily be recognized
as a single source.  Some other proper motion surveys have
used two plates taken a decade or so part, during which such
swiftly moving stars might move so far that they might
not be recognized as the same object.

  Anyway, here's what I did:

         - fit each star's position in RA versus time with
                a straight line; it yields proper motion in RA
                (arcsec per year), plus a two-sigma estimate of the
                uncertainty in the motion

         - ditto Dec: proper motion in Dec (arcsec per year),
                plus two-sigma uncertainty in motion

         - pick stars which satisfy
           
              a.  at least 10 measurements
              b.  motion in at least one direction exceeds 5*2-sigma

  There were 1027 such candidates.  I wrote a Perl script which
gathered a bunch of information on each candidate, made some
plots showing all positions of the candidate, and motion as a function
of time, cutouts at the candidate's position from

        POSS I        (roughly 1950s)
        POSS II       (roughly late 1980s)
        2MASS         (roughly 2000)

plus a search for information at the position in SIMBAD.  All
this information is gathered together on one web page per candidate.
One can scan the page in just a few seconds -- I recommend going
to the end, where the cutouts of the sky surveys make it VERY
easy to judge whether motion is real or not.

  An example of a candidate with spurious proper motion is 

    http://spiff.rit.edu/tass/proper_motion/cand_294362/measure_294362.html

  An example of a candidate with TRUE proper motion -- alas, already
known to science -- is

    http://spiff.rit.edu/tass/proper_motion/cand_296359/measure_296359.html

 

  Here's what I ask of interested readers: could you please help me
to scan through this set of over 1000 stars and find those with
REAL proper motion?  Here's what to do:

     - go to the index page
       
           http://spiff.rit.edu/tass/proper_motion/group_cand_index.html

       where I have broken the 1027 stars into groups of 50.
       Pick one group.

     - click on the link for that group to go to its first candidate.
       
     - scan the information, decide if the candidate is real or not.
       If it is really moving, note its number

     - use the links at top or bottom of the page to go to the
       next candidate in the group

     - when you have finished 50 objects (it may help you to write down
       the index of the first candidate in the NEXT group, in case
       you lose count of your fifty), send an E-mail to the TASS
       mailing list with a summary of your results

  It's too many for me to do all by myself.  Help!


                                            Michael