Observations in Sodankylä

Last night it was clear sky here in Sodankylä, and I tried to make some observations. There was nevertheless some haze in the sky, and there was a corona visible around Moon. And then I also noticed, that some street lights that had been broken in the yard of my apartment were fixed – a fact that caused a slight increase in the amount of light pollution. Anyway, I could make couple of observations, I observed R Tri and Z Uma. R Tri has now passed it’s maximum, and it’s brightness was about 5.5 magnitudes, the maximum brightness of this star is approximately 5.3-5.4. Z Uma has been getting even brighter.

And then I noticed one thing about my observations of Z Uma, I have been constantly underestimating the brightness of this star (when comparing with the average observations of this star in the database of AAVSO during my latest observing attempts). This time I estimated that the brightness of the star was about 7.5, which is about 0,5 magnitudes lesser than the average of the estimations, at least when estimating the average visually. I wonder, why this might be happening. One reason could be the comparison star interval – in the comparison chart of AAVSO (reversed B for visual observations), there are not any stars with magnitude ~6, and it might be affecting my estimate. I compared the variable with the star of magnitude 7.9 and 5.8. This interval is fairly large, and I think it might be useful to have a star that has a magnitude between these stars. There are some stars with magnitude with ~6, but they are quite far away from the variable itself.

The asteroid 2005YU55 could have been visible, but I wasn’t able to print out any maps, and also the object was at low altitude in the horizon of Sodankylä, and also in early evening (when it could have been visible) there was haze in the sky which made observing difficult. And also the Moon was interfering severely. Because of these reasons, I didn’t do any observing attempt of this object.

Observing session: #20/11-12
Date: 8/9.11.2011
Time: 20.45-22.15
Place: Sodankylä, Finland
Instruments used: L102/1000mm
Objects observed: R Tri, Z Uma
Conditions: NELM: 5.3, SQM: 18.76, -1 – -2 °C, clear sky, some haze in the sky, calm, no aurorae, 96% Moon in south at altitude of 30°


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