The Moon.

No, it seems spherical.

In the name BKP, the letter P stands for parabolic mirror, which is odd—I haven't seen this cluster with a parabolic mirror before, though I've heard of it. Actually, this is an important parameter because a spherical mirror suffers from spherical aberration.

Honestly, I think my telescope's primary mirror is probably parabolic, because I don't see any aberrations in my images. My telescope is specifically called the Sky-Watcher BKP 1149 EQ2. I only said it was spherical because I found a similar telescope online that was listed as having a spherical mirror. I bought mine in 2013 and, to be honest, I don't remember exactly how it was described back then, but that was its model name.

Same here, this cluster with a parabolic mirror is very rare, I've always only seen it as a background.