Tuesday, December 18, 2007

Mars observation

Session name: 20071217.1645

This session about a dozen passersby stopped for views of an 8-day First Quarter Moon in Pisces and the little Mars at the foot of the Twin Castor. A light breeze, sometimes gusting to a moderate wind, rustled and darted dry leaves along the sidewalk. In the northeast sky and zenith, naked eye limiting magnitude was around magnitude 5 using my personal candlesticks in Cassiopeia and Perseus. Ahhh... it was was cold.

Despite its size, surface features can be discerned. The thin, dark necklace of Mare Boreum delineated the northern polar cap from the greater fields of reddish tint. Syrtis Major obviously rose from the southern hemisphere jutting up past the equator into the reddish fields, appearing to point one's eye toward the north polar ice cap. Leading in the eyepiece drift, Mare Tyrrhenum was not as bold and great in size as Mare Erythraeum which was situated on the trailing side. Over the course of the session features on the trailing side turned on to the disk. Beneath Syrtis Major, Iapygia completed the dark band across the disk joining the maria and capped Hellas near the south pole.


The Hunter rises over New York City

Session name:20071217.1645

City street lamps and Kin prove no match for the brilliant stars of Orion, the Hunter. Ahead the seven sisters flee, while the Bull's eye turns on Orion. Coming the rear his dogs follow. By the time we left, the Large Dog was obediently sitting on our manhattan-eastern horizon.


Sunday, December 16, 2007

Trapezium & Mars form Central Park

Session name:20071208.1945

On this short session, Kin and I observed and shared the views of Mars to about a dozen pedestrians and dog owners. Most of the evening the sky background appeared bright to our south and up to zenith, a little haze seemed to fill the air diffusing the lights of CitiGroup building and Times Square. We commented that seeing was not so good and transparency was significantly better in the celestial northeast with a naked eye limiting magnitude around magnitude 5.0.

At magnification to 121x, I could resolve the E & F star of the Trapezium. (Stan was able to see them and I can't recall if Kin separate them.) Below are two diagrams I created for use on the Palm. One is based on information in Burnham's Handbook for the reflector where it is inverted and mirror reversed. The Garfinkle-based diagram has north at top and adds a few extra measurements to stars beyond the reach of this 4" in city skies.

What makes resolving the magnitude 11 E & F stars challenging is the brightness of the nearby A & C stars, respectively. My experience has been that the E star is easier to detect than the F star because of A's brightness.

Trapezium Chart - BurnhamTrapezium Chart - Burnham

Trapezium Chart - GarfinkleTrapezium Chart - Garfinkle

Mars sketchWe could see surface features in the northern hemisphere with a white polar cap and contrasting maria: Mare Boreum formed a collar around the bright cap with Mare Acidalium adding some area in the center. In the southern hemisphere a large, dark smudgy area contrasted with the brightening around the limb and across the equatorial zone. It was difficult discern shape and extent since contrast was low with the surrounding surface. I suspect a great part of the darker albedo was Mare Erythraeum.

Most of the pedestrians were able to see the darker collar and obviously contrasting northern polar cap. I don't think they had as easy a time with the southern hemisphere or equatorial zone.

We disagreed on what we sensed across the equatorial region. Kin saw a brigher area extending across the entire disk, describing it as a contrast with the maria to north and south. I said I saw a crisp white disc that stood out above that bright equatorial band. The white spot is Chryse Planitia. I made this remark after consulting Brian Tung's terrific Palm application, Mars Map.
I felt that I saw it but lost confidence and considered that averted imagination miught be at play. That is why the sketch shows dots along the central region and doesn't include a small pea shape just east of center (opposite direction of drift).

Burnham's Celestial Handbook: An Observer's Guide to the Universe
Robert Burnham, Jr.

Star-Hopping: Your Visa to Viewing the Universe
Robert Garfinkle

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Sitta carolinensis

White-breasted nuthatch, Sitta carolinensis, in her classical pose. A common bird in Central Park, although my first observation and identification. Observed this female nuthatch alone spiraling down the trunk of a large Pin Oak (Quercus palustris Munchh.), stopping occasionally to poke her bill in the bark's crevice. I heard "cheep, cheep" from her, however, bird guides consulted describe a sound of "yank, yank". Her song could have been is "whi, whi, whi" as described in Peterson's Field Guide. When she reached this level, she returned up the tree the same way she came down - spiraling the girth of the tree trunk. Minutes later she flew off to a tree where a Blue Jay (Cyanocitta cristata) was seen higher up in the limbs.

Field Guides

Being around flora and fauna, I consult a few field guides at home or on the shelf of nearby Library. Concerning bird identification, I prefer Kaufman's Guide as it especially friendly to the novice with its Pictorial Table of Contents. Most cases I can identify the bird within these pages, if not then I can narrow down to which group it belongs. Turn the referenced section, where the section intro provides a little more detail. After that I thumb to the referenced page. So far I am batting a thousands with this book.

To get further info, next up was Peterson's field guide to Birds. This book described the detail of distinguishing between male and female. In this case, our solo White-breasted nuthatch is female revealed by her gray crown; a male nuthatch wears a black cap.

One can't go wrong in choosing between these two field guides they are both equally accessible and provide enough detail to identify and appreciate the bird under observation. If there is an emphasis on easy bird identification, Kaufman's is my choice here. The more experienced birder may not consider this such a requirement.

Resources for Birds of Central Park
Annotated Checklist to birds of Central Park from the Central Park Conservancy.

Kaufman Field Guide to Birds of North America
- Purposes and Goals of the Kaufman Field Guide Series

A Field Guide to the Birds of Eastern and Central North America
- About Roger Tory Peterson

Other field guides with a local interest
New York City Trees: A Field Guide for the Metropolitan Area

Field Guide to the Natural World of New York City

A Natural History of New York City

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