Sunday, February 04, 2007

20070203 - better skies for naked eye

Session name: 20060703.1920
Equipment: Teleport TP-10 & Fujinon 7 x 50 FMTR-SX

The cab transported the scope & I up to Mariner's Gate. This is the usual entrance for Top of the Lawn observing sessions and it has a small grade hill right at the start. In fact, to the south just on the other side of the playground is the highest point in Central Park, Summit Rock. The summit, at 141 ft./43.0m, is 1 ft/0.30m higher than Vista Rock which sits on the far side of Turtle Pond at the south end of the Great Lawn. (Climbing up Belvedere Castle, one reaches the highest point in the park.) Summit Rock's great elevation bleeds along this edge of the park, a small ascent I sort of dread.

Walking up the grade I look through the naked trees seeing the Winter Hexagon and Orion blatantly in the sky. It does look clear. Bundled in layers of clothing, my jacket is tucked in my backpack to avoid overheating. Catching my eye to the northeast is the rising Moon maybe 2½° ~ 3° in altitude. A striking buttery yellow, a honey moon hue - she is large! The branches and limbs can't conceal this girl -- she's much too large. I lost sight of her as the foreground buildings occult her view and I arrive at TotL.

I set up the scope and put the fan on to get it cooling off. I looked around feeling at home. Last month there weren't many nights I got out so I was looking forward to this one. While waiting for scope time, I spent time using a pair of my favorite instruments: mine eyes.

The February 2 essay of the book, 365 Starry Nights, Chet Raymo refers to a small illustration that shows a section of sky looking south. He asks, "Can you find Orion on the drawing above?" I think for most of us we'd find it with no problem. When one easily gets their bearings, not only is Orion apparent but one can see a trail of constellations: Lepus, Columba, Puppis, Canis Major, Monoceros, Canis Minor, and a dense river of dots showing the path of the Milky Way. Chet describes how both dogs have a pair of stars of unequal brightness and Canis Major's is more widely separated. The lines created by the pairs are almost perpendicular.

Canis Minor's pair are Procyon & Gomeisa. Canis Major has the brightest evening star Sirius coupled with Mirzam, Arabic for "announcer". Canis Major's stars are brighter than its counterpart in Canis Minor.

Look further south in Canis Major two stars that are part of the big dog's hind quarters, Wezen and Adhara. Adhara, the brighter one, is west of the fainter Wezen. Low in declination these stars don't rise that high in altitude. Jumping west, I look for Furud, zeta Canis Major, a magnitude 3 star. The low elevation and the approaching gegenschein radiating from the CitiGroup building both present challenges to Columba. It takes a clear, transparent sky to pick these stars up, ranging from magnitudes 2.65 to 4.37. Magnitude 4+ is difficult at low altitudes approaching and beyond celestial south. The gorgeous Manhattan skyline and a dark night sky collide.

The scope had cooled down and maybe a dozen people, a blend of friends and first timers, passed over the course of this session. Moon was shown only to a few as it was low, stressing the dobsonian to a seemingly horizontal recline. A survey of the different objects consisted of:
  • Solar System: Saturn
  • Open Cluster: M35
  • Planetary Nebula: NGC2932, Eskimo Nebula
  • Bright Nebula: M42 & M43
  • Multiple Star: Trapezium
I didn't look so hard as the seeing was poor. Saturn was still soft at 100x but large enough for the people to recognize and admire. Personally, I preferred the naked eye skywatching. I recall looking to the west seeing Aries hanging perpendicular in the sky, dancing past the Pleiades & Hyades, into the sky describes above. Higher up approaching zenith, Gemini attracts attention. I'm waiting patiently for the clear, transparent night when M35 appears to glint for my naked eye.

And it was cold! The MONY clock flashed 24°/-5°C but it felt much, much colder than that when the wind gusted. Throughout the night, Charlie & I listened to the nearby tree crying of the cold: wheeee, wheee, wheee. It wasn't difficult to decide to pack the scope around 11~ish when the clouds came in.

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