by Anthony Ayiomamitis
Venus is only second to the Moon when it comes to the brightest object visible in the evening sky and, in fact, is also visible during the day naked-eye when sufficiently away from the sun. For this particular occultation involving the Moon and Venus, the latter was characterized with an apparent diameter of 12.08 arc-seconds, a magnitude of -4.0 and a phase of 85.3% whereas the waxing 2.5-day old crescent Moon was at magnitude -6.8 and with a phase of only 6.6%. A Baader UV-IR/Cut filter was used to limit the FOV to the visible spectrum.
The human eye has a tendency to focus at a distance of 400 feet when focusing for "infinity". As a result, many celestial objects which are visible during the day can become a challenge due to the eye's default focusing for infinity. When the moon is near a celestial object of interest, however, the eye will easily focus properly for "infinity" when looking at the moon and which in turn will permit for the easy identification of the (neighbouring) celestial object of interest such as Venus below in broad daylight.
Technical Details:
Date: May 16, 2010 @ 11:48:30 UT+3 and 11:49:30 UT+3
Location: Athens, Greece (38.2997° N, 23.7430° E)
Equipment: AP 160 f/7.5 StarFire EDF, AP 1200GTO GEM, Canon EOS 5D Mk I, Baader UV/IR-Cut Filter
Exposures: 2 x 1/5000 sec, ISO 800, RAW Image Format, 4368 x 2912 Image Size, Manual Mode
Further details are available here and here.