SOLAR ECLIPSE IN NEW YORK, 2017 AUGUST 21
---------------------------------------
John Pazmino
NYSkies Astronomy Inc
www.nyskies.org
nyskies@nyskies.org
2017 July 28
Introduction
----------
A total solar eclipse sweeps west-east across the entire
continental United States on Monday 21 August 2017. Astronomers from
every where in the country, and from overseas, are heading into the
central path to observe the totality. Yet there are many astronomers
who, for various reasons, will watch the eclipse from the NYSkies
region as a deep partial.
I leave out the explanation of eclipse mechanics and cycles.
Please see my article at
www.nyskies.org/articles/pazmino/ecl-fact.htm
General description
-----------------
This eclipse starts in the northern Pacific Ocean at 16:49 UT,
where the Moon's shadow first touches the Earth. There totality takes
place at local sunrise. At 17:16 UT it hits land in Oregon, to begin
its flight across the United States. Totality at this point is 1m 55s.
The shadow flies thru Oregon, Idaho,, Wyoming, Nebraska, Kansas,
Missouri, Illinois, Kentucky.
At 18:26 UT the eclipse hits maximum duration near Hopkinsville,
kentucky. Totality is 2m 40s and path width is about 145 kilometers.
The shadow continues thru Kentucky, Tennessee, Georgia, South
Carolina. At Charleston, South Carolina, the Moon's shadow leaves land
at 18:43 UT. Totality is then 2m 34s. The shadow lifts off of the
Earth in the eastern Atlantic Ocean at 20:02 UT, where totality occurs
at local sunset.
Timetable of events
-----------------
The schedule here is for a midpoint on Manhattan and is valid
thruout the NYSkies region. The eclipse occurs a minute or so earlier
in north New Jersey; later, Long Island. The coverage is a percent or
so less in Metro North. It's a little more in central New Jersey.
Mind the altitude of the Sun, which may challenge some camera
tripods. One trick is to mount the camera backwards. When the tripod
is tilted down, the camera points up.
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PARTIAL SOLAR ECLIPSE, NEW YORK, 2017 AUGUST 21
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Duration 2h 38m, Obscuration 71%, Magnitude 0.768
------------------------------------------------
EDST | event | alt-az | remarks
------+---------------+--------+--------
06:11 | sunrise | 00 071 | start of daylight
12:58 | Sun transit | 61 180 | apparent noon
13:23 | 1st contact | 60 192 | Moon enters on right
14:45 | mid eclipse | 53 227 | 71% covered on bottom
16:01 | 4th contact | 41 247 | Moon leaves on left
19:44 | sunset | 00 289 | end of daylight
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Public eclipse viewing
--------------------
Because the totality path is so close to NYSkies, there is an
ongoing mass migration of astronomers into that path. Some are taking
commercial eclipse tours while others are hopping a train, bus, plane
to a town in the path and then scooting back home after the eclipse.
This exodus already in late July is depleting crews of astronomy
centers for major solar eclipse sessions. Crew is also thinned out for
public viewing of the Perseid meteor shower, on August 11-12.
As at late July there were NO announced eclipse, or meteor,
sessions for the public. Sessions COULD be set up with smaller staff
to hand, at the last minute, well after the issue of NYC Events for
August 2017. There are several lectures about the eclipse in July and
August, usually as a topic for a club's normal monthly meeting.
NYSkies had its preparation session at its July 21st Seminar.
Please use the contacts in that, or the July, issue to inquire
about latest news of public eclipse observing.
Viewing location
--------------
There is NO special or favored site in NYSkies for watching this
eclipse. The aspect and hour of the eclipse is substantially the same
every where in NYSkies.
You may observe from home on the roof, yard, stoop. You may avail
of any public park, field, waterfront.
In NYSkies all suitable locations are accessible by short drives
by car or short rides by transit. The latter is specially welcome
because you do not need large, heavy, bulky gear for this eclipse.
Observing kits can be packed into a shoulder bag or wheeled luggage.
The one sanity check for a prospective site is the diurnal arc of
the Sun. The eclipse begins in high south-southwest and ends in mid
southwest. ideally the Sun should be in sight for the whole eclipse,
about 2-1/2 hours.
Other considerations are conveniences like refreshments and
restrooms, refuge from sudden rain, air-condition, and general peace
and quiet.
Weather
-----
August in New York can be torrid and humid, with hazy skies and
daytime showers. Temperatures can stand in the 30Cs with humidity near
100%. Forecasts are loose, with repeated instances of wrong -- for the
worse and the better -- predictions.
It is not necessary to be under the Sun for the entire eclipse.
That will generate intense discomfort from the heat and moisture.
Staying in shelter or shade and stepping out every five or ten minutes
is a sensible procedure for thoro coverage of this eclipse.
Wear a hat to keep sun off of your head and face. Wear loose airy
clothes. Have at ready a rain-shedder cloth to protect your eclipse
setup in case of showers.
If feasible have cool water or fruit juice and unsalted finger
snacks. Have a lawn chair with pillows
Eclpse safety
-----------
I emphasize features of this eclipse pertinent to New York City
and surrounds, where the Moon glides over the south side of the Sun in
mid afternoon of August 21st. For starts, the Sun's face is always
exposed, with all of his dangers to unprotected eyes. Direct viewing
of the eclipse requires proper solar filters.
Please obtain these filters, even if only the cardboard spectacles
from only astronomy sources and not undocumented vendors. There sprang
up from the immense demand for filters a manufacture of filters that
casually look dark enough but have no validation for eye protection.
Maintain custody, care, control of your eclipse rig at all times.
Do not allow untutored people to handle it and never leave it
unattended. When not in active use, drape a cloth over it to deter
curious hands. The cloth also lets the rig cool off from a spell of
solar viewing.
Be vigilant with children who may try to stare at the Sun without
eye protection. Eclipse glasses may fall off or be casually removed.
Consider setting up a projection for the eclipse to satisfy a
party or public. The image from a small scope is sent into a shaded
area where a screen is mounted. This may be a simple white sheet of
cardboard.
Ambient changes
-------------
In spite of the large part of the Sun's disc covered by the Moon,
there is no casual noticeable darkening of the sky. A photometer, such
as the light meter of a camera, will register a two or three f-stop
dimming. A camera manually set to the normal daylight setting will
produce darker images near mid eclipse.
For broken clouds or thin overcast, the changes in sky brightness
from these clouds will completely overwhelm any effect of the Moon.
Near mid eclipse shadows of short straight objects are curved.
Finger shadows look like claws. Pinhole images thru trees, grills,
knot-holes, small punctures, are faithful replicas of the solar disc
with the Moon over it. There could be a drop in air temperature,
comparable to that from a thin cloud passing over the Sun. A series of
thermometer readings taken every ten minutes, and trended on a graph
against hour, may reveal the effect of the eclipse apart from that of
cloud or haze.
There are no sky color shift from the eclipse. The quality of
daylight remains th same thruout the eclipse. Colorations are caused
by local weather conditions.
Planets in the sky
----------------
The brightest of the classical planets are in the sky with the Sun
during the eclipse. Normally they are invisible in daylight. Venus is
about 34 degrees west of the Sun along the ecliptic; Jupiter, 51
degrees east.
With sharp vision and knowing just where to look many people can
spot Venus by day. A very few can also find Jupiter. If near mid
eclipse the sky is truly clear, a deep blue with temperatures in the
10Cs and wind sweeping thru the air, you may try to find Venus and
Jupiter with binoculars. Altho you will not notice a significant sky
darkening from the eclipse, the sky is about 1/4 of its full daytime
brightness, giving the planets a darker background.
First carefully focus the binoculars on distant landscape, order
at least 1/2 kilometer away. Then look over the landscape where the
planets are, as worked out with you planetarium software and
familiarity with the observing site. The alt-az of both planets at
14:45 EDST is:
------------------
planet | elon | alt-az
--------+------+-------
Venus | 34 W | 35 268
Jupiter | 51 E | 39 153
-----------------------
The planets travel along their own diurnal arcs,
Spot these positions over your landscape in the dys before the
eclipse while mapping your site. Both planets follow their own diurnal
paths thru the sky, which you must trace out with the software for
other times during the eclipse.
Sit in a comfortable chair. Don't try this experiment standing up.
You'll quickly tire and lose aim. Let the eyes relax. Check the focus
on remote landscape.
Venus should show up as a white pinpoint; Jupiter, a yellowish
one. After the eclipse Jupiter will be in high south. If you can,
inspect it with a telescope. You'll be surprised how textured and
colorful it is!
For hazy or thinly clouded sky, the planets are oblitterated from
view. Mars and Mercury are also in the sky nearer to the Sun but they
are not reasonably visible in daylight.
Photography
---------
Cameras and other imaging devices must be protected by front-end
solar filters. Let the camera find the exposure in 'auto' mode. Any
deficiency of image quality can be fixed in an image editor software.
A montage sequence of the eclipse is easiest made by pasting
separate images into a new blank image in the editor. Only the higher
end cameras allow double-exposure, the feature used in film
photography for an eclipse sequence.
One concern in the last ten years is the wholesale migration of
photography from chemical film to electronics. Many devices are
sensitive to near and mid infrared as well as to optical wavelengths.
It is possible, but I don't know for sure, that filters for newer
imagining devices COULD transmit these infrared band. If so, these
filters CAN NOT be used for viewing by eye.They are ONLY for the
picture-taking instrument
Grand Central Terminal
--------------------
The eclipse occurs on Manhattan during the hours the Sun shines in
line with park Avenue in early-mid afternoon. The Sun passes thru
grilled borders of windows in the Terminal and throws sun splashes on
the floor of the Main Concourse. Normally these are round and attract
almost no notice from the hundreds of thousands of daily visitors in
the depot.
During the eclipse these splashes, genuine pinhole images of the
solar disc, replicate the Moon's passage across the solar disc. The
long throw from the high windows to the floor is tens of meters,
making the Sun's image some 20 cm in diameter.
Make a smooth white stiff card, like from a gift box, about 184
meter square. Bring it to the Terminal at 13:00 EDST. Arriving early
lets you find a convenient sharp splash. Hold the card face-on to the
sun's rays.
Make sure you pick a splash from the south windows, facing 42nd
Street, and NOT reflections off of the Met Life building on the north.
Splashes from the latter are distorted.
Clouds that may come over the Sun show up well, as will any large
sunspots. With your back to the Sun the Moon enters the solar disc
from the right. It then passes over the upper part of the Sun and
leaves at the left.
You may have to skip to an other splash if the first one is
blocked off by a structure in the Concourse. By around 15:30 EDST the
Sun moves behind buildings on the west side of Park Av, ending its
creation of splashes.
NOTATE MAGIS BENE!! There is NO official program for eclipse
watching inside the Terminal!. You merely stand away from people flow
and rake occasional looks at the image on your card. Other people will
ask what you are doing, leading to a knock-off dialog of the eclipse.
Just avoid blocking or impeding traffic flow as people surge hither
thither around the Concourse.
other solar eclipses
------------------
The next solar eclipse for NYSkies is on 2021 June 10. This
eclipse requires a clear northeast horizon because the Sun rises
almost exactly at mid eclipse! The Moon covers most of the left side
of the solar disc. Then after as the Sun arcs higher the Moon slides
off at the bottom.
The eclipse is annular in its central path in Canada and
Greenland. The Moon is too small to fully cover the Sun.
The table below from NASA's eclipse web lists recent and near
future solar eclipses visible from New York.
All of the eclipses are partials because their central paths miss
New York or there is no central path.
In this table all hours are EST, ignoring the summer shift to
EDST. 'S' against an hour is the time of local sunset. The eclipse
continues after sunset. A 'R' means the time is for sunrise. The
eclipse begins before sunrise.
------------------------------------------------------------
local date type begin max end alt-az magn obsc
------------ ---- ---- ----- ----- ------ ------ -----
2001 Dec 14 Annr 16:13 16:26S 16:26S 00 239 0.123 0.050
2013 Nov 03 Hybr 06:32R 06:32R 07:11 00 110 0.557 0.455
2014 Oct 23 Part 16:49 17:01S 17:01S 00 255 0.140 0.060
2017 Aug 21 Totl 12:23 13:45 15:01 53 226 0.770 0.716
2021 Jun 10 Annr 04:28R 04:33 05:31 01 059 0.797 0.725
2023 Oct 14 Annr 11:09 12:22 13:36 40 193 0.349 0.230
2024 Apr 08 Totl 13:10 14:25 15:36 43 235 0.911 0.900
2025 Mar 29 Part 05:47R 05:47R 06:05 00 85 0.326 0.214
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Conclusion
--------
This August 21 eclipse is a wonderful event, even if you are in
town, away from the totality path. It demonstrates celestial mechanics
and causes some interesting effects around you. it prepares ou for the
partial phases of a future total eclipse you may travel to.
As long as the Sun is visible, not completely hidden by solid
clouds, you should make all effort to watch the eclipse. Even passing
clouds do not hurt the view because there is no critical instant that
must be witnessed or else.
When your fellow astronomers return from the totality zone, thru
will appreciate your experience with this eclipse, as told at the
'eclipse roundup' club meeting.