  We present a study on the relationship between the ratio of the depth of a
crater to its diameter and the diameter for lunar craters both on the maria and
on the highlands. We consider craters younger than 1.1 billion years in age,
i.e. of Copernican period. The aim of this work is to improve our understanding
of such relationships based on our new estimates of the craters's depth and
diameter. Previous studies considered similar relationships for much older
craters (up to 3.2 billion years). We calculated the depths of craters with
diameters from 10 to 100 km based on the altitude profiles derived from data
obtained by the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar
Reconnaissance Orbiter (LRO). The ratio h/D of the depth h of a crater to its
diameter D can diverge by up to a factor of two for craters with almost the
same diameters. The linear and power approximations (regressions) of the
dependence of h/D on D were made for simple and complex Copernican craters
selected from the data from Mazrouei et al. (2019) and Losiak et al. (2015).
For the separation of highland craters into two groups based only on their
dependences of h/D on D, at D<18 km these are mostly simple craters, although
some complex craters can have diameters D>16 km. Depths of mare craters with
D<14 km are greater than 0.15D. Following Pike's (1981) classification, we
group mare craters of D<15 km as simple craters. Mare craters with 15<D<18 km
fit both approximation curves for simple and complex craters. Depths of mare
craters with D>18 km are in a better agreement with the approximation curve of
h/D vs. D for complex craters than for simple craters. At the same diameter,
mare craters are deeper than highland craters at a diameter smaller than 30-40
km. For greater diameters, highland craters are deeper.
