  We present here the discovery of a new class of super-slow rotating asteroids
(P>1000 hours) in data extracted from the Asteroid Terrestrial-impact Last
Alert System (ATLAS) and Zwicky Transient Facility (ZTF) all-sky surveys. Of
the 39 rotation periods we report here, 32 have periods longer than any
previously reported unambiguous rotation periods currently in the Asteroid
Light Curve Database. In our sample, 7 objects have a rotation period > 4000
hours and the longest period we report here is 4812 hours (~200 days). We do
not observe any correlation between taxonomy, albedo, or orbital properties
with super-slow rotating status. The most plausible mechanism for the creation
of these very slow rotators is if their rotations were slowed by YORP
spin-down. Super-slow rotating asteroids may be common, with at least 0.4% of
the main-belt asteroid population with a size range between 2 and 20 km in
diameter rotating with periods longer than 1000 hours.
