December 18, 2006

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What a Difference Two Weeks Makes


image byElias Chasiotis, Markopoulo, Greece

These are two images of Pythagoras, captured on November 15 and December 3rd 2006. The appearance of the crater changed dramatically between these dates due to moon libration. On the photo of November 15th Pythagoras looks wider but also smaller, because on that date the Moon had an apparent diameter of 29.78 arcminutes (19 hours before apogee), whereas on December 3rd it had a diameter of 32.92 arcminutes (45 hours before perigee). In fact, on December 3rd the Moon appeared 10.5% larger. Note also the lower contrast of the November 15 image which is because the Moon was then a crescent (illumination 27.9%) and had a lower surface brightness than on December 3, when it appeared almost full (illumination 98.4%).

Elias Chasiotis

Technical Details:
C11 at F18 + EQ6 Pro mount + DMK21BF04 firewire camera + Baader IR pass filter (Dec.3, 2006) + Baader IR cut (Nov.15, 2006) + Registax 4

Related Links:
Rükl plate 2

Yesterday's LPOD: Moving West

Tomorrow's LPOD: A Gray Day


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