Tech Note 102 (unfinished): The Mark IV "patch" dataset

[Michael Richmond <richmond@stupendous.cis.rit.edu>]

  I've been slowly, slowly working my way through a systematic
analysis of _some_ of the Mark IV data.  I have settled on one
particular way to select items from the database for further
analysis and (soon?) distribution and (less soon?) publication.

  You can read the unfinished first draft of a description of
this subset, and some of its properties, in Tech Note 102:

     http://stupendous.rit.edu/tass/technotes/tn0102.html

There are plenty of graphs and histograms, but no pretty pictures.

  The job is not yet finished: I need to take the information
I have now and figure out its properties when compared to
EXTERNAL catalogs, both astrometric and photometric.
The big task will be to

      A. search for systematic differences between Mark IV
                magnitudes and magntiudes on the standard
                V-band and I-band scale

      B. correct such differences, as far as possible
        
      C. document carefully the properties of the resulting corrected
                magnitudes

  There may be additional tasks to do before releasing the
data as well, such as:

      D. making spot-checks of objects with interesting
                properties to see how fruitful they may be

      E. searching for a few already-known-to-be-interesting
                objects (such as a few variable stars of
                different types, or stars with high proper motion)
                to see if this dataset reflects their
                properties accurately

      F. figuring out "weak points" in the dataset --
                such as stars with close companions --
                and adding flags to the dataset to alert
                users to the problem

  I'm putting this Tech Note on the web site now so that you
readers can check it over, ask for clarifications, suggest major
or minor changes, and so forth.  If there are additional quantities
that I should be computing, let me know -- it takes about
eight hours to recompute all the quantities, so it's easy
to do overnight.

  Oh, a special plea for help to Michael Sallmen: could you
tell me, in moderately gory detail, just how a new measurement
is added to the Mark IV database?  I want to know how 
measurements are assigned to existing star IDs, or generate
new star IDs.

  I will work on the photometric calibration next ....

                                          Michael