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Venus Image 2023/06/21(UT)
Ioannis A. Bouhras,Luigi Morrone,Antonio Cidadao
I.Bouhras,L.Morrone,A.Cidadao
[Ioannis A. Bouhras : Peristeri,Athens,Greece]
Under good seeing condition and average transparency
[Luigi Morrone : City Agerola Italy]
As described, 14" LX200 working at f/5, PO Neptune C-II camera without window, IDAS VW-1 (1000nm/20nm) filter, and EO 950nm/25nm as a nightside control (should only represent glare from dayside; did not perform subtractions yet).
Data was obtained during 30min (single SER), at 16:27 UT, near the meridian, with positive detection but with no features visible. Imaging resumed from 18:37UT, uninterruptedly until 21:29 UT, mostly as 15min SERs, followed by the control image, at 21:45 UT. Each one of these SERs is shown individually, and also following averaging of four consecutive 15min SERs. Imaging data was 100ms, gain 100 offset 10 until19:55 UT, and 200ms, gain 100, offset 10 until the end of the session (maintained for the 950nm filter). Sunset was around 20:00 UT.
Surface detail compatible with Alta Regio (arrows) was visible on single 15min SERs from about sunset onwards, and much better seen on 1h averaged data (4x 15min).
There was a broad and dark area to the south of Alta Regio (arrowheads) that is not convincingly coincident with Imdr Regio. As my filter (1000/20nm) is not completely aligned to the max thermal emission window (1010nm-1020nm), I wonder if could not correspond to a local, thicker, atmospheric cloud that was decreasing surface thermal signal. It was readily visible in multiple 15min data. I do keep planet position changing during capture, thus it is quite unlikely that it corresponds to sensor dust or defects (and sensor is clean). Anyone saw this feature?
Finally, the 950nm/25nm filter identified the "glare zone" near the limb where, although the NS is visible, existing features can be artifactually masked.
≪アントニオ シダダオ ポルトガル≫
[Antonio Cidadao Oeiras - Portugal]
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