k.s.min, on 20 Feb 2019 - 10:40 AM, said:
l observed the Tycho crater on this night with my 320mm refractor.
With careful attention l found a ghost companion crater of the Tycho ...from where [A] ray stretched toward the South pole .
Unlike the other prominent Tycho's magnificent long rays(1000~3000km length) ,,[A] was not focused at the Tycho's center......so, l guess it was burst out from other crater.
l could see the subtle rim of this crater which diameter is about 80% of Tycho...l measured in the eyepieces.
The ghost crater is need to see a bit powerful instrument as its very low contrast at this lunation....also its bottom mantle was seemed buried by 160km diameter dark gray outer mantle of Tycho.
As the brightness with weathering of the [A] ray is almost same as the other Tycho's rays, the formation time gap must not be much different.
l guess at first the ghost crater was made, then some 10~100 thousend years later the Tycho was made.
Tycho is a relatively young crater, with an estimated age of 108 million years based on analysis of samples of the crater ray recovered during the Apollo 16 mission.
Sketch and Lunar Observation dialogue here: https://www.cloudyni...host-companion/
Somebody could propose different opinions.