April 16, 2012: Overall sky survey

Diagram of Cassiopeia

Cassiopeia (IAU/Sky & Telescope)

I spent around 15–20 minutes outside today, just studying the overall sky. I was just out in front of my house, which is convenient, but there is a lot of light pollution from street lights and house lights. The trees and other buildings also obstruct much of the sky. But since the view from outside my front door is going to be the most convenient place to stargaze, I want to be familiar with it. Fortunately, the sky was completely clear, and it wasn’t too cold (about 43°F/6°C, with no wind).

My best view is to the south, with good views to the east and west, but obstructions to the north. The nice thing about tonight’s viewing was that the visible constellations represented a part of the sky with which I’m relatively familiar. The first thing I noticed was Mars nice and high in Leo, Sirius visible just above the horizon, and Venus close to setting. Orion, my favorite constellation, was setting. I could see Betelgeuse (α Ori) and the belt (ζ Ori, ε Ori, and δ Ori).

I’ve been trying to start systematically becoming familiar with the constellations, going quadrant by quadrant. I’ve started with “NQ1”, the eighth of the sky between right ascension 0h and 6h and above 0° declination. Most of the stars in this quadrant aren’t really visible at this time of year, since the sun is currently in this quadrant. I did try to focus on Cassiopeia, but it was close to setting. I could clearly see the five bright stars of the “W” asterism: ε Cas, δ Cas, γ Cas, α Cas, and β Cas. I also tried to study Perseus, since it’s a constellation with which I am really not familiar. I could make out four stars that were more or less parallel to the horizon, at about an altitude of 20°; reviewing my charts now, I assume these are δ Per, α Per, γ Per, and η Per. I’ll hope to recognize Perseus better once it’s more visible.

Overall, I think η Per was the dimmest star I saw tonight — it has an apparent magnitude of 3.75, making it a fourth-magnitude star. It’s not bad given the amount of light pollution.

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