Sunday, May 02, 2010

20100430 - Planets Continue To Please

Session name: 20100430.1900
Location: TotL
Objects observed
Satellites: International Space Station, Iridium 42 Flare, 2 unknown satellites
Solar system: Moon in Sco, Venus in Tau, Mars in Cnc, and Saturn in Vir
Constellations: Gem, Leo, Virgo, Lib, Sco, UMi, UMa, Boo, Com, CrB,
Deep sky: M3, M44, M65*, M66*, NGC 2903*, Melotte 111* ("*" indicates attempted not seen)

[public observing Saturn]
This session began with setting up the scope prior to sunset at the top of the lawn. Screams and cheers for the softball teams filled the air and a few kids played soccer in the midst of reclining people on blankets. Warm temps and clear skies brought people out in numbers.

Within minutes of opening the Teleport, it drew many questions from those nearby and stopped curious persons walking past. Ken strolled up while I setup and Tom C would arrive early, too, and each helped answer questions from the passersby. It wasn't that much longer that we had Venus in the scope and Tom prepared everyone for an 8:02PM passing of the International Space Station. Shortly after sunset in the twilight sky we all observed the ISS, about -2 magnitude, lumbering across a clear sky from southwest to northeast. It was visible for at least 30 - 40 seconds, maybe longer. With Venus setting into the trees to our west, the scope was turned to Saturn, high in our eastern sky. A line formed to see Saturn with two attendant moons trailing close by just off the rings. To finish off the Solar System tour, we pointed out Mars high above our heads. In the scope, many could easily see the reddish-orangy hue and that it was a disk.

Through the eyepiece, Mars appears much smaller than Venus and Saturn. To begin with, it is physically small and our distance from Mars increases as earth travels faster in its orbit around the Sun, its size shrinks and brightness dims in the coming months.

Transparency was only fair even though there was no visible cloud cover. The handle stars of the Little Dipper were very difficult and cores of brighter galaxies were lost on a background sky that didn't offer enough contrast. Open cluster M44 and globular cluster M3 were the only deep sky objects shared with the public.

Saturn captured the most scope time satisfying the many who stopped. In addition to the planets, we observed the brighter constellations without telescope or binoculars. Using the Big Dipper, we starhopped following the familiar jingle, "Arc to Arcturus and spike to Spica". We traced out constellations like Bootes, Leo, and the upper half of Gemini. We noted where invisible Cancer and faint Virgo occupy areas of the sky.

The traffic flow was busiest early in the session and I stopped counting after the first dozen or so people. A steady flow of people continued to stop by the crowd density was much thinner later into the night.

[image of Moon shot with point-n-shoot]
Concluding the session, with the telescope packed, we observed the rising Moon just east of Antares, Scorpio's alpha star. We enjoyed observing with naked eye and monopod-mounted 7x50 binoculars. The honey-colored Moon provided an opportunity to test our visual acuity with hard to see lunar features. W.H Pickering, an American astronomer in early twentieth century, designed a list of 12 lunar features for naked eye observers ordered by increasing difficulty. Though Charlie and I were not following this list, I'd say confidently we reached #9, Sinus Medii. I can't say I saw #11, a dark feature on the Appennine Bench but we could discern the curving line of the Appennine Mountain range.

Observing details
M3. A bright globular cluster in CVn, easily seen in 7x50 handheld bins as a fuzzy object in the base of a long, narrow isoceles triangle; at 75x, distinctly a globular cluster with a bright central nucleus and smooth brighness contour extending out from core, some granularity and mostly unresolved; at 181x, cluster resolves stars along the edge and hovering above the cluster. Used Arcturus for starhopping.

M44, Beehive Cluster, Praesepe. A bright, large, loose open cluster in Cnc., shaped like a Xmas tree or wedge with multiple groupings of nearly equally bright stars, a faint glow of unresolved stars filled in a small area in the NE end of cluster; used Mars for starhopping.

NGC 2903, M65, M66. Attempted but not observed, three galaxies in Leo that have been observed in the past from this location with this scope; found starfields relatively easy but couldn't say with confidence that the galaxies were detected; starhopped from epsilon Leo for NGC 2903, from Chort (theta Leo) for M65/66.

Saturn with four moons. Mostly viewed at 181x; Titan and Rhea on the trailing side, Tethys and Dione, may have glimpsed Enceladus near the ring, on leading side; shadow apparent as narrow black line adjacent to the upper side (field of view) of the ring; shallow ring inclination apparent; graduated darkening/shading from ring to pole on upper hemisphere,most pronounced on the pole; a subtle, broad stripe across the lower hemisphere but not edge to edge.

Mars. Observed at 181x; a small round disk, no phase discerned, fiery, reddish-orange color; could see a croissant-shaped dark patch on face of disk, extending from top right of center across the left and down.

Session Details
Optics: Teleport 10" reflector; magnifications used 32x, 75x, 98x, 181x; Fujinon 7x50
Observing party: Charlie, Ken, Tom, Peter
Visitors: 3 dozen++
Weather: Clear skies, no clouds,16 ½ day Moon in Sco, calm air to light breeze
Seeing: II - III (Antonaldi); atmospheric steadiness good with regular noticeable air turbulence at high magnification
Transparency: Fair; 3-4 stars of Little Dipper
Manhattan Skyline: Broad, diffused light cone spanning from Citigroup Bldg to Times Square; Citigroup Bldg and adjacent bldg hidden from our view, GE Bldg, Times Sqaure worst offenders
NELM: 4.2

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