October 21, 2018

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Partial Magic

Originally published August 7, 2009 LPOD-Aug7-09.jpg
image by Filipe Dias (Algarve, Portugal)

A few hours ago, half a lunation later and on the opposite side of the Earth from where the total solar eclipse had been seen, I witnessed one of those boring and shy penumbral lunar eclipses... But I wanted to turn this hard-to-notice event into something interesting. In search for what would be the difference from in and out of today's penumbral eclipse, I decided to do take this picture, which is a simple subtraction between eclipse and after-eclipse (images taken at 0:39 UT and 02:19 UT on 2009/08/06). The image was taken through an H-alpha filter to block some light, and the bright zone on top (south hemisphere of the Moon) is clearly seen, showing where Earth's penumbra swept by. Almost unexpectedly there is some texture in this image. The Moon's apparent libration causes surface features to change place, and prevents the moon from being a dull grey color. Also the limb of the Moon suffered from the effects of Libration, even if just 100 minutes apart. This was observed from the south of Portugal. Images were taken with a CN-212 in F/4 Newtonian configuration, and an Atik-16HR camera. Exposure was really short (0.02s) even taken through a narrow H-alpha filter (reason for this was that it helps make the seeing calmer, and also because I did not want to change the filter as this was done in between other stuff)

Filipe Dias

Related Links
Filipe's astro pix

NOTE: I was astonished today to receive two submissions showing - for the first time? - difference images from in and out of a penumbral eclipse. Tomorrow will be the other image. Chuck Wood

Yesterday's LPOD: Where is That Moon?

Tomorrow's LPOD: Partial Part 2


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