Some Mark IV results from last summer's AAS poster

[Stupendous Man <richmond@a188-l009.rit.edu>]

  Recent discussions have reminded me that I put together
a poster for last summer's meeting of the American Astronomical
Society, but never shared it with the TASS E-mail list.
The poster described the results of analysis of Disk Set 18,
taken with Tom's Mark IV in Batavia.  I concentrated on three
good nights in the data set.

  You can find Postscript graphs of several quantities on-line
in a temporary place:

           http://a188-l009.rit.edu/richmond/temp/

The files are

       astrom_res_i.ps         errors in positions of stars measured from
                                     Mark IV images
                                     (note that about half have errors
                                      smaller than 0.5 arcsec)

       astrom_res_i_grid.ps    errors in measured positions, as a function
                                     of location in an image.  You will
                                     see that positions are worst at the
                                     edges of the frame.  These are residuals
                                     from a cubic fit.

       phot_magsig_i_I.ps      photometric errors in repeated measurements
                                     of the same star (in I)

       phot_magsig_i_V.ps      ditto for V

       phot_res_ghi_I.ps       errors in photometry, as a function of location
                                     in an image (I-band).  Clearly a strong
                                     systematic trend

       phot_res_ghi_V.ps       ditto in V-band.  The systematic trend is
                                     much smaller for this filter

  Sorry that I don't have time for more explanation now; maybe next
week.  I ought to write it all up as a Tech Note :-(

                                           Michael Richmond