========================================================================
  Microlensing optical depth and event rate toward the Galactic bulge
                from eight years of OGLE-IV observations

  P. Mroz, A. Udalski, M. K. Szymanski, I. Soszynski, L. Wyrzykowski,
   P. Pietrukowicz, S. Kozlowski, R. Poleski, J. Skowron, K. Ulaczyk,
                       K. Rybicki, and P. Iwanek

========================================================================

pmroz@astrouw.edu.pl

The directory structure is as follows:

README            - this file

table3.dat        - electronic version of Table 3 (best-fitting 
                    parameters of the analyzed microlensing events)
                    
table5.dat        - electronic version of Table 5 (surface density
                    of stars in OGLE-IV subfields)
                    
table6.dat        - electronic version of Table 6 (basic information
                    about analyzed fields)

table7.dat        - electronic version of Table 7 (microlensing optical
                    depths and event rates in OGLE-IV fields, averaged
                    over sources brighter than I_s = 21)

phot/             - calibrated I-band photometry of individual events
phot.tar.gz       - gzipped phot/ directory

eff/              - event detection efficiencies in individual fields
eff.tar.gz        - gzipped eff/ directory

get_OGLE_field.py - useful Python scripts that return the Equatorial and 
                    Galactic coordinates of vertices of OGLE-IV fields
                    and plot OGLE fields/subfields

Format of the photometry files:
------------------------------------------------------------------------
 Bytes  Format Units   Description
------------------------------------------------------------------------
  1- 13 F13.5  HJD     Heliocentric Julian Date
 15- 20 F6.3   mag     I magnitude
 22- 26 F5.3   mag     Magnitude error
------------------------------------------------------------------------

The I-band photometry is calibrated to the standard system. 
The uncertainties were corrected using Skowron et al. (2016)'s 
prescriptions.

Format of the detection efficiency files:
------------------------------------------------------------------------
 Bytes  Format Units   Description
------------------------------------------------------------------------
  1-  5 F5.3   ---     Minimal log(t_E)
  7- 11 F5.3   ---     Maximal log(t_E)
 13- 20 F8.6   ---     Detection efficiency
------------------------------------------------------------------------

Updates:

2019-09-19  Event rates per unit area were added to Table 7 to match
            the accepted version of the paper.