Comet 8P/Tuttle Second try with no success

Session name: 20080103.1950

Equipped with tripod and 22x60 binoculars I was unable to detect Comet 8P/Tuttle. The illustration shows a 20° field of view of the area where the comet is located. Ephemeris I used is MPC 60098. (Checking the link, I see it is updated.)

Sky conditions were clear with a light air, temp was sub-freezing. The sky was bright above the Hampshire House and neighboring Essex House, providing a binocular limiting magnitude around 9.1. Naked eye used eta Psc and gamma Ari to zero in on the spot. However, 7x50s and 22x60s yielded no success. Gamma Ari, Mesarthim, a double star with 7.8" separation of the nearly equal magnitudes, was cleanly resolved in the 22x60s.

Venus from Drip Rock

Session name: 20071021.1145

A warm Saturday afternoon at Drip Rock. Skies were clear and a light air, temp around 70° F. As has become custom, I was welcomed to the rock by a homeless women whom I have seen on recent sessions. Yards away down the slope of the rock before me were two young girls, one of them unclothed to her underwear to catch the rays of Sol. Unfortunately, she attracted the queer, perverted type of human nature. I made it clear he was not welcome in these parts but he remained. I thought this guy's a pro, definitely not a first-timer. I mentioned to one of the girls about the freak but she looked back and then shrugged him off.

The sky blue background were very clear that once I got my bearings where to look Venus glistened like a shard of glass wanting to be discovered.

When I arrived Venus was already began her descent being at altitude/azimuth ~ 235°/43°. Venus at magnitude -4.4 is in Leo one can expect to see the planet high in the sky as the early Spring ecliptic is still north of the celestial Equator. The sun is 46° east in Virgo.

Seeing was moderate but the light air was enough to shake the scope and the image when observing at 117x. It made it difficult to snap pictures using a 2x barlow with the Plossl 20mm eyepiece. With a size of 26.3" I could see the phase to be just shy of first quarter, slight horns still visible at the waxing tips. Along the sunrise terminator shows a softness in contrast to the crisp hard edge of the limb. In this phase it easy to draw a circle with the mind's eye completing the arc of the bright limb. Planetarium for the Palm reports the venetian phase at 93°44'. Next Saturday, Venus will be at first quarter and almost 2" smaller, and becoming smaller and smaller as she waxes to Full Venus.


Medium camera shot demonstrating how easy Venus is to see. Foreground objects can be of help to orient oneself in the sky, however, it is important to relax the eyes and let them focus to infinity and not the leaves.


A snapshot of Venus with a 35mm equivalent focal length of 3452mm = ( Focal length in 35mm * magnification) = (42.1mm * 82x).

Geology of Drip Rock

A few months ago I read a delightful online book and then followed two of the tours verbatim providing a leisurely program of Central Park geology. To make the tour's more convenient, I downloaded & viewed the webpages to my Newton MessagesPad 2100 with Steve Weyer's Newtscape browser and bookmaker/reader. With a small fanny pack Nikon CoolPix 995 and Newton were both tucked away securely as I romped and roamed over the glaciated roches moutonées.

As a result of this I am more acutely aware of the many outcroppings that abound in Central Park. It's like when never noticing the families and children on the Upper West Side until my wife and I started our family. From where did all the strollers come?

Take for instance this photo. Here one can see an erratic, a boulder picked up from the north somewhere and carried down and deposited in Central Park by the Wisconsin ice sheet. Well that's the definition of an erratic but I would be careful to apply it to these found throughout the park. Granted they are large and probably just as heavy but with the blasting out of rocks for nearby roads and walks, I suspect some probability that the landscapers thought it a nice touch.

Drip Rock is a common Manhattan Schist outcropping like the many seen all about the park. It's a pedestal that stands above the moving crowds and horse carriages. Stationary atop of the rock with telescope pointing to celestial south-southeast, the world turns, and daytime astronomical events reveal celestial glories above a horizon of skyscrapers. Now that I've imbibed on some geological awareness, a huge granite dike presents itself at my feet. For the uninformed it could go unnoticed as concrete filling.

This granite dike is an intrusive igneous rock consisting of the minerals feldspar, quartz, and mica. It has a speckled appearance to it. There are two types of granite, granite and granite pegmatite (pegmatite for convenience), and they are distinguished by the size of their grain. The granite grain is smaller and finer, having resulted from rapid cooling. Geologists have determined that the igneous material was injected in to the crevices of a host rock which lost most of its heat.

At the end of the granite dike there are veins of raised, threadlike lines continuing away from the dike, likewise cutting across the grain of the rock. Two can be seen running parallel to the fracture in the rock. Hanley and Graff point out that "

these are veins of quartz thought to have originated when scalding, silica-rich fluids were forced by subterranean pressure into hairline fissures in the rock.

These fissures can be observed throuhout the park on many outcrops, larger and small.
Pegmatite, on the other hand, has larger grains, which the heated host rock provided time for the grains to grow larger. The larger, coarser grains of pegmatite are just as easy to recognize as a foreign object in the schist as the finer granite and can have a pinkish or whitish color.

Manhattan schist exhibits a foliation include that is typical of metamorphic rock. Simply the rock displays a direction or grain. The igneous intrusions can cut across the grain, known as dikes, or run parallel, called sills. Most that I have noticed are dikes like the one illustrated previously.

This large band on the southside of the outcrop to be a granite sill as it is folded into the direction of the rock's grain.


Books of Interest

Hanley, Thomas and M. M. Graff. Rock Trails in Central Park. Greensward Foundation, Inc. 1976.

Raymo, Chet & Maureen Raymo. Written in Stone. Black Dome Press Corp., Hensonville, N.Y. 1989.

Schuberth, Christopher J. The Geology of New York City and environs. Natural History Press, Garden City, N.Y. 1968.


My favorite Central Park map.
- Note to find Drip Rock follow E 62nd St., marked near the lower left corner, across the Park passing Center Drive. Drip Rock is labeled. Across the street to the south is Cop Cot, another area that I use for daytime observation. Nearby my daughter and I catch-n-release fireflies, giving this location a household name Firefly Garden.

nature's work

a tree grew within a tree grows. Drip Rock is to the right in the picture. an erratic in the background.

20070120 - Daytime Crescent paired with Venus

Session name: 20070120.1310

I stole away at lunch yesterday with Tak backpack to look for the young crescent moon. At this time she's already 1 day 14 hours past New Moon. Initially I thought this was to be a cinch. Since I am surrounded by buildings that rise, in some cases, to 60° ~ 70° in elevation, I went first to Cop Cot and then settled at Drip Rock. Since I couldn't see it naked eye I thought that the buildings were obstructing the view.

The Sun's apparent path across the northerner's winter sky is low, and so the ecliptic too is low. Shadows mute most of the cross streets and avenues can suffer the same. The Sun just can't peek high enough to shine his glory down.

I measured off from Sun with outstretched hand and then scan the sky with the handheld bins. In the handheld bins spotted the young crescent pretty quickly and was surprised by the low contrast. I would have thought the 3.3% illuminated crescent to be brighter and greater contrast with the sky. It was darker than passing clouds and in a queer sort of way provided contrast that kept it visible with thin filaments of clouds passing over.

In the field of view, Venus sat up around two o'clock and the Moon was around eight o'clock and LARGE. In spite of its size, its brightness did not contrast sharply with the pale bluish white background sky. On top of the clouds were passing through at as regular clip, sometimes thick enough to snuff out Venus.

As I observed, I couldn't help but think of those record holders who observe crescents as young as 15 hours - even younger! I'm under the impression that these sightings didn't have the advantage of having a bright planet nearby as a convenient landmark. One has to have this kind of experience where one can scan a field of view and allow the eye to find and focus across the field of view, just as repeated tennis lessons develop muscle memory. I looked away on occasion just so I would have to recover it - a kind of volley.

Two passersby took turns at the eyepieces of the Tak bins. I described what they would be looking for and each said after some time of closing one eye, moving their head about, squinting with both eyes that they saw the Moon. I had a feeling it was Venus because that is much brighter, and once resolved easiest to see in the field of view. I suggested that they look for a large, low contrast crescent on the other side. Soon enough they got it. They hadn't a previous mental experience to identify the crescent moon. They were both both shocked by its faintness and large size. Each had found it with a Eureka! feeling.