Wednesday, June 27, 2007

Daylight Astronomy: A dog owner's observations

Over the course of years that I have been observing at the Great Lawn I have met a lot of people, perhaps in the thousands, sharing the eyepiece to bring the heavens a little closer to them. I look forward to seeing the familiar people and dog owners each session. It is a important part of the observing experience and emphasizes that the community of New York.

This past Saturday I had gone out early at the Top of the Lawn to observe Moon and Venus during daylight hours. Later at civil twilight Saturn sprung up nearby Venus and Jupiter glowed brightly in the east above the trees. The crowds seemed to enjoy the challenge of spotting Venus naked eye during the day. Most continued challenging themselves when Saturn breeched that threshold of contrast and was visible in civil twilight. By this time, I trained the scope on each planet and offered a look to everyone who wished to observe.

Stan, dog owner of Gee, passed through and documented the event by taking some photographs of this Saturday session. Visit his website to read about his observing report of the session "Only in New York".

Stan mentions the term "chimping" which I learned from a davep post.

Thursday, June 21, 2007

rainbow over citi

skyline looking east after the rain.
what's a rainbow?

summer solstice

medicinal properties of the sun

Tuesday, June 19, 2007

Venus Occultation, June 2007

Session name: 20070618.1205

I missed the Venus occultation earlier in the day. Actually the probability was very low to see the ingress event because it occurred shortly after Moonrise at 8:54AM EDT. Work prevented observing the egress event which was at a better altitude to swing the likelihood to more favorable odds. Recently, the horizons have been hazy looking so I don't know if anyone observed it. I am waiting for Charlie's report.

Instead, I slipped out of the office a little past noon. It was well past the Venus occultation but wanted to see how easy the ceescent & Venus were to see naked eye. The sky was littered with moving cumulus clouds and swashed with a coat of haze. I consulted PftP and located the overturned crescent with little difficulty. Its contrast with background sky was low. Venus was not as easy which needed bins first. After that I knew where to look and get my focus adjusted. As long as the clouds permitted, Venus persisted naked eye the entire session.

Curious, I asked a couple of guys if they could see the crescent. I pointed out where to look and after a few moments, one said he could see the upside moon. Asking if he could see Venus at one o'clock to the moon and about 3 ~ 4 moon diameters, he said he couldn't. I handed him the bins and then he caught the whole scene. He remarked how bright Venus was but still couldn't see naked eye.

My observation revealed that Venus is substantially brighter as a "point of light" (at 7x magnification) and is whiter than Moon. Side by side, along with the clouds, it is evident that the Moon is not so white.

Saturday, June 16, 2007

June's 21 hour crescent crescent Moon

Session name: 20070615.1810

Appearance of crescent at time of sighting.
(screenshot of detail below)

I arrived early at TotL East to establish azimuth references on the trees along my western horizon with the setting Sun. The tree line rises from 7° ~ 9° in the area I was working with. This helps to determine where to look and I use the same technique with stars when marking a morning horizon for old crescents. During this time until sunset, I observed Sun with my solar paddle and located Venus in the bins and then naked eye. Kentaurian was one of the many persons that stopped by to enjoy the daytime astronomy. He would be key in observing the crescent at the prescribed time.

I had the wrong mental note of Moon's elevation at the predicted sighting by thinking it was to be 10° (an approximate value at sunset). At 20:44 EDT Moon was 7°27' so following Ken's recommendation we moved further east and on the Great Lawn to get a lower horizon. I had no azimuth references at the new location but Ken suggested landmarks including the Beresford Tower. At 20:50 EDT using Fujinon 7x50 binoculars, the thin crescent was easy to see, unintimidated by the haze and avoiding clouds at Alt/Az of 6°39'/300°19'.. Moments later the tripod-mounted Taks were leveled on the crescent, illuminated along an arc from 3:00 ~ 7:30.

At 20:53, I could discern the moon's limb, a "line" from 3:00 ~ 6:00, naked eye without optical aid. Ken confirmed minutes later with his own naked eye sighting. Naked eye was extremely difficult but visible for next 9 minutes.

Prior to spotting it we were talking about using Mercury as a convenient reference point. It sounded like a great idea and having evaluated the sky and recent experience Ken thought Mercury should be visible. We never saw it. Once our attention was on the crescent, I forgot to look out for Mercury which was 1° higher in elevation and a binocular field (7 1/2°) south along our horizon.

The crescent moon set between a dip in the trees at 21:02 EDT. The water tower and protuberances along the trees' profile provided landmark's to aid in seeing the moon set naked eye. At the time of disappearance, the moon was 4°37' in altitude. For 12 - 13 minutes, we watched the crescent slip across the sky as we skipped along our landscape trying to find an everlasting horizon.

Screenshots providing the details

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images: Screenshots of Planetarium for the Palm, assembled with gimp

Sunday, June 10, 2007

June crescent moon alert

previous post - forecasting crescents in 2007

The time of the month for crescent moons is approaching. This month offers the second best bracket interval of the year for our location. If the weather permits then this interval could be as close as 39 hours between the two observations. Absolutely a personal best if it occurs. A confluence of events has to occur to have the right conditions and for this one the significant variable will be the weather. I look forward to the challenge of the rising 28 1/2 day crescent because in absolute terms of time relative to the Sun, it will be the ~17h45m from New Moon.

The crescent conditions are provided below. They rise to each side of the Sun which happens to be near M1 between the horns of Taurus. On the day of the old crescent, Moon will rise with Pleiades which is ~7° further south along the horizon.

Old crescent moon
14 Jun :: predicted sighting 04:40 ~04:45 EDT
Age :: 28d13h (-17.7h prior to New Moon)
1.0% illuminated
11° 39' W elongation
Moderate; altitude at predicted time 1° 41'

Young crescent moon

15 Jun :: predicted sighting 20:50 ~ 20:55 EDT
Age :: 21h24m
1.2% illuminated
12° 50' E elongation
Easy; altitude at predicted time 6° 30'

Bracket the crescents
Interval - 39h


Black-crowned Night-herons

Black-crowned Night-heron at the Pond

Recently, Cat Rock has hosted my sunset observing sessions and walking around the Pond is one route I take. I frequently see two Black-crowned Night-herons. It's become a game to find them against a backdrop of trees and shrubs. the stocky bird stands hunched on partially submersed tree limbs or nearby the lip of a drainage pipe (as shogun in this picture). The Black-crowned Night-heron reminds me of a penguin probably because of size. Don't get me wrong you wouldn't mistake one as a penguin but it is my first impression. The two plumes that sprout from their crown will attract your attention, they are so distinctive to this bird. One heron is 1/2 times larger than the other. I make two assumptions: (a) other pair is a male and female; (b)the larger one is the male. I am confident enough to distinguish the two when they're apart, the female heron's legs are more vibrant yellow and I judge her size relative to nearby objects.

Red-tailed Hawk

Red-tailed Hawk on the London

I understand that the two Red-tailed Hawks, Charlotte and Junior, have taken a new home on 56th & 7th Ave. this is the couple that nested a home precariously on an ornamental ledge on the east side of the trump Pare building.

The other day something caught my eye looking out the living room window. Turns out it as one of the hawks. The hawk approached from the northeast and perched at four different spots in a span of 15 minutes. the last flight from the building, the hawk returned to the northeast. later that evening I walked to the supermarket to see the hawk flying circular patterns above 56th and Broadway. In this great density of steel and mortar, it is amazing that fauna would even consider this a suitable habitat.

Closeup of the Red-tailed Hawk perched on the London.

Friday, June 08, 2007

20070607 - Sun spots & sunsets

Session name:20070607

Sunset looking west on W57th St.

This is a sunset one week past Manhattanhenge. The Sun continues a northerly march along our horizon until June 21st. On this day, Summer Solstice occurs at 2:06pm EDT, where Earth reaches its maximum distance from the Sun in our annual orbit. This point on the orbit is known as aphelion. Slowly the Sun begins a retreat southward on our horizon. And around July 11th, Manhattanhenge occurs for the second time.

I completed a short observing session with the Tak bins at Cat Rock. Here I observed Sunspots 960, 959, and 958 in the bins. They were too small for me to see without magnification looking through a solar filter. To complete the session I observed Venus both naked eye and in the bins. At 22x magnification, Venus in last quarter is obvious. Astromick's image shows this nicely.

I packed up, walked around the Pond, stopped to observe the Black-crowned Night-Herons, and exited the park.

One couldn't ignore the Sun, but many did. Just like the night sky, just a few look up. A huge red-orange lozenge suspended over the street for all to see. This was boldness!! The Sun was still bright enough to cause some discomfort when looking more than a brief moment. I held the solar paddle up to the sun though it appeared weakly. The atmosphere abated the luminosity and brilliance. Reds and orange dominated this scene, a classic sunset.