3102 Krok, provisional designation 1981 QA, is a rare-type asteroid and slow rotator, classified as a near-Earth object of the Amor group, that measures approximately 1.5 kilometers in diameter.
It was discovered on 21 August 1981, by Slovak astronomer Ladislav Brožek at Kleť Observatory in the Czech Republic.
In the SMASS taxonomy it is classified as a common S-type asteroid, and the "ExploreNEOs" Warm Spitzer program assigns a transitional Sqw-type.
Lightcurve analysis gave an exceptionally long rotation period of 147.8 hours with a brightness amplitude of 1.0 magnitude, which indicates that the body has a non-spheroidal shape (U=3).
[5] Between 2000 and 2005, several photometric observations made by Czech astronomer Petr Pravec gave a similar period between 149.4 and 151.8 and an amplitude of 0.7 to 1.3 (U=3/3-).