A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2018 Dec 31, 11:36 -0800
Brad, you wrote:
"In terms of your intended observation, I personally do not see anything astronomically special. It may be auspicious and tickle your fancy to perform it during the eclipse."
I agree. This is mostly a novelty. There's no real benefit to shooting a lunar during the eclipse. But it might be fun.
"Your observation will be a star-moon lunar, in which some of the moon's light is attenuated by the eclipse. There are other methods which attenuate light, like filters. Am I missing something?"
Right. On its way into the shadow, when the Moon is about two-thirds eclipsed, the trailing bright limb which could still be used for a lunar, will be moderately deep in the penumbra, but this is barely noticeable and would not provide much attenuation. The total apparent magnitude of the Moon will be much reduced by then, but the surface brightness at the trailing edge, which is in the penumbra, will only be moderately reduced. The least sextant shade should produce more attenuation.
You listed some exotic lunar variants to try for fun. One that I had hoped to get was a Moon-Venus lunar while Venus was in transit on the face of the Sun. But clouds got in the way in 2004... and in 2012 the Moon was nearly 160° away from the transiting planet. Oh well. Better luck next time... The next Venus transits are in 2117 and 2125. Those dates are also both near full moon (I had to check!). No Venus-Moon lunar luck then either.