  We present a comprehensive re-analysis of stellar photometric variability in
the field of the open cluster M37 following the application of a new photometry
and de-trending method to MMT/Megacam image archive. This new analysis allows a
rare opportunity to explore photometric variability over a broad range of
time-scales, from minutes to a month. The intent of this work is to examine the
entire sample of over 30,000 objects for periodic, aperiodic, and sporadic
behaviors in their light curves. We show a modified version of the fast
$\chi^{2}$ periodogram algorithm (F$\chi^{2}$) and change-point analysis (CPA)
as tools for detecting and assessing the significance of periodic and
non-periodic variations. The benefits of our new photometry and analysis
methods are evident. A total of 2306 stars exhibit convincing variations that
are induced by flares, pulsations, eclipses, starspots, and unknown causes in
some cases. This represents a 60% increase in the number of variables known in
this field. Moreover, 30 of the previously identified variables are found to be
false positives resulting from time-dependent systematic effects. New catalog
includes 61 eclipsing binary systems, 92 multiperiodic variable stars, 132
aperiodic variables, and 436 flare stars, as well as several hundreds of
rotating variables. Based on extended and improved catalog of variables, we
investigate the basic properties (e.g., period, amplitude, type) of all
variables. The catalog can be accessed through the web interface
(http://stardb.yonsei.ac.kr/).
