Astronomy, wildflowers and photography

Lunar Crater J Herschel
  
  The sun was rising across the 165 km wide irregular floor of this walled plain
crater at the time of this observation. J Herschel is a pre-Nectarian crater and
in the observing light was showing off a low inner rim, secondary craters, and
rubbly, slightly convex floor. With the Imbrium basin formation taking place a
couple of hundred million years after J Herschel, it is easy to see why this
crater looks so old and battered. The well defined outer rim to the south (up in
the sketch) has its rampart buried under the lavas of Mare Frigoris. Also the mare
looks to be at a slightly higher elevation than the crater floor on the other side
of the wall. Along the south wall to the west crater Horrebow (26 km) can be seen
superimposed upon Horrebow A. Out into Mare Frigoris a couple of dozen kilometers
are craters La Condamine B and J Herschel F both slightly under 20 km in diameter.
Sketching:
For this sketch I used: White CCP sketching paper, 2 HB graphite pencil and a black
ink pen. Contrast and brightness were adjusted after scanning.
Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
Date: 5-28-2007 1:01-1:40 UT
Temperature: 16° C (60° F)
Partly cloudy with haze, calm
Seeing: Antoniadi III
Colongitude 45.1 °
Lunation 11 days
Illumination 85.8 %
  
  Frank McCabe