Date: 10-Jan-2006 @ 12:50p EST
Magnitude/Size: —4.1 / 63"
Alt./Az. (Venus): 32.5° / 188.0°
Elongation: 7.0° East
Illumination/Phase: 0.7% / 170.4°
Alt./Az. (Sun): 26.4° / 192.0°
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Conditions for viewing Venus in full daylight, naked eye or with binoculars, were less than ideal. High haze and thin clouds were getting in the way.
At 12:35p I arrived at Bryant Park looking to spot Venus in binoculars and was making little headway. Glare from sunlight illuminating the surrounding haze was a problem.
After 10 minutes I moved to a spot where I could determine the azimuth of the Sun. Where the Sun was spotted Venus would arrive above the same point 14 minutes later and approximately 6 degrees higher. This would help pinpoint where Venus should be.
A location was picked so that the Sun, after a few minutes, would be safely tucked away behind a building reducing the glare near the planet's location. It took around 5 minutes to finally see Venus' thin crescent shining weakly through haze and thin clouds.
Looking at the image above produced at the USNO site I can see why a typically brilliant Venus seemed somewhat subdued. This and the haze combined to make this attempt more difficult than usual. This was no six second sighting!
Question: What is the surface brightness of a crescent this size compared to the surface brightness of a gibbous Venus near opposition where it was a relatively easy object (less that 4° from the Sun) in a pair of 10×70's?
Relocating Venus with the 8.5×42 binoculars after taking some notes wasn't easy even though I knew the exact position. A minute or two was spent glassing the area before recovering it again. The last time Venus was spotted was around 12:55p.
Viewing the planet naked eye was attempted but without success.
2 Comments:
Hi Ben,
Had a great time at lunch and waltzing to Bryant Park for an opportunity to observe crescent Venus - with your optics :~D
SBr = m_v + 2.5 log(2827ab)
where m_v is visual magnitude and a & b are the dimensions of the object.
Don't know what the weather is for tomorrow but would like to try again. I haven't checked to see if it is possible, would you know off hand?
Thanks for making my first obseving session for the new year.
--peter
Peter,
Lunch and the trip to Bryant Park work out nicely. Thanks for the invite!
I worked out the surface brightness for Venus at inferior conjunction and superior conjunction. The numbers work out to 7.9 mag/sq" and 9.4 mag/sq" respectively. I added 8.89 to covert from arcminutes to arcseconds.
Does this seem right?
Thanks again.
Ben
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