New Venus
Taken by Giorgio Rizzarelli on August 14, 2015 @
Trieste, Italy
Click photo for larger image
| |
Camera Used: Unavailable Unavailable
Exposure Time: Unavailable
Aperture: Unavailable
ISO: Unavailable
Date Taken: Unavailable
|
|
| More images
Details:
New Venus. I should say almost new: I shooted 1 day before, because conjunction day was overcast. But phase was anyway 0.9%, and the crescent pointing upward (N).
A though session for experts: with just 8° elongation from Sun and scattered clouds, I had to check continuously that backlit clouds didn't get in the way, which would have been as pointing the unfiltered scope to Sun.
There was anyway haze: fairly hot scope, also for the external illumination (though lot of aluminum foil), raising air turbulence. Though, we still had an unusual hot African summer anticyclone, which also lent low turbulence (seeing 4/5) even at midday. Also, I started filming just after clouds left Sun, so that air was a bit colder.
For a such thin crescent, turbulence was much critical. Very good reference frames had to be selected manually. Multiple movies were shot at different exposures to raise dynamic range, also because haze reduced contrast.
Mount alignment was also though. I aligned the polar axis at dawn using stars, but the "motor" alignment has to be refreshed every 2 hours. With both Moon and Venus in Sun conjunction, at day Sun was the only naked eye or finder object to point (filtered). I could then find bright stars but had clouds there. As result Venus drifted and had to be "guided" manually.
DATE&TIME: 2015-Aug-14 12:00UT, Trieste (Italy).
CONDITIONS: Seeing 3-4/5, transparency 3/5, sparse/scattered clouds (just cleared that zone), 35°C, haze, weak hot wind, Venus alt 50° (culmination).
VENUS PARAMETERS: Phase 0.9%, distance 0.29 AU, apparent diameter 58", Sun elongation 8°.
EQUIPMENT: Celestron CPC8 (D=20cm) on equatorial wedge, Barlow 2x apo Antares (F=4m, f/20), iNova PLB-C2 color camera.
ELABORATION: Registax (4 out of 9 movies of 2000 captured frames each), GIMP (curves, color balance)
Photographer's website:
No URL provided.
|
|
|
