Venus, 1.2% crescent, two days before minimum elongation

I observed Venus’ very narrow crescent at only two days before the inferior conjunction, ie minimum elongation, at less than 9 degrees from the Sun, with only 1.2% illumination. Since this is a personal record, besides the transit observed in 2012, let me just paste here some trivia from Stellarium. Due to the Sun being very close, this post is something with the label: kids, don’t try this at home.

Venus on 2017-03-23 at 11:30 UTC:
distance: 42 million km (during the 2012 transit, it was 43 away)
apparent diameter: 59.3″ (1/30 of the Sun’s / Moon’s diameter)
illumination: 1.2% (this year’s minimum will be 1%, in two days)
position: 10°10′, 9 min
elongation: 8°58’52″(this year’s minimum, ie the inferior conjunction is just under 8°17′, on 2017-03-25 at around 16:30 UTC)

The equipment was a Scopium webcam at the SW MC 102/1300 scope on an HEQ5 mount, with or without a 2x barlow.

Finding Venus
Maybe it’s my bad, but I found no obvious daytime alignment method (like use the Sun, the Moon beeing too far away) in the controller. Being a temporary backyard setup, with no alignment at all (I have a general idea where north is), I started at the Sun with an ND 3.8 Baader solar filter, in order to adjust both the focus and get an idea about the coordinates the mount thinks it is pointing to. Then, having the Sun’s and Venus’ position from Stellarium, I guided the scope to the assumed coordinates. Given the glare of the Sun, visual observations were off the table, even with the improvised shade. So all that remained was canvasing the area with the filter now off, through the keyhole-like narrow field of the webcam. (Yes, I could have used the aligned finder scope’s wide field with the camera, but then again: the Sun). After a while (Hofstadter’s law applied), I succeeded :)

Some pictures below, they show details like how the color of the sky is off due to the white balance being off while recording with the color webcam.

(tovább…)

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