17./18.8.2012 – observing in best conditions so far this season

Date: 17./18.8.2012
Time: 01:50-03:00
Observing site: Visitor Centre, Seitseminen National Park, Finland
Instrument: L102/1000mm (4” refractor)

NELM: 5,8
SQM: 20,87
Darkness of the background sky: 2
Seeing: 2
Transparency: 2
Weather: Clear sky, calm, no Moon, humid air, 11°C

Objects observed: SS Cyg (visual), T Ari (visual)

During this night, sky got clear quite late, but when it got clear, the conditions were really good, best so far this season! The sky was darker than earlier this season, SQM reading was about 20,87!During this session I observed SS Cyg again, which is still in it’s bright state. Besides SS Cyg, I observed T Ari as a new star for me. This star is also underobserved, and needs more attention!

I estimated it’s brightness to be 9,0, but I noticed quite large discrepancy between my and observations made by other AAVSO observers. There are only handful of recent observations of this star in the AAVSO database, which of course makes it more difficult to assess the behaviour of this star exactly. I planned to observe this star again next night if the sky is clear to make sure, that I wasn’t making any too big error with the brightness estimation. One possible source of error could be the fact that the condensation of moisture was very intense last night and all the optical surfaces could have been covered with dew..

Variable star observations:

Date Time Star Mag. Comp.
17./18.8.2012 02.10 SS Cyg 8.6 8.6
17./18.8.2012 02.45 T Ari 9.0 9.0/9.5

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