The Lunar X

Date & Time: Oct 22 2012, 21:00 JST(+0900), 4shots composed with 1/20sec. exposed
Optical: BORG 60ED with Televue PowerMate5X (f=1750mm, F29.2)
with BaaderPlanetarium Moon&Skyglow filter
Auto-guided with Kenko SKYMEMO portable Equatorial
Digital Camera: Canon EOS 600D (Remodeled)
Location: Hitachi city, Ibaraki pref.

Camera Settings: Recording format...JPEG-FINE (5184 x 3456)
Sensitivity...ISO1600, White Balance...Manual

This picture has captured the first quarter of Moon. Perhaps you can realize that there is alphabetic letter of "X" at around a bit southern terminator. This optical illusion is called "Lunar X", we can see it clearly for only several hours in the first quarter of Moon.
The Lunar X has been known widely since a Canadian amateur observer introduced in 2004. The pattern is made from an outer ring surrounded by three craters of Purbach, La Caille, and Blanchinus. I have displayed time change of Lunar X for about 2.5 hours in right column, you can see that the X-shape appeared from shadow gradually.
Although it's difficult to see the Lunar X with naked eyes, you can detect clearly only with compact telescopes.

Around Central series of craters

Around Bullialdus

Copyright(c) 2012 by Naoyuki Kurita, All rights reserved.
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