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May 19, 1999: Moviegoers attending the weekend premier
of The Phantom Menace are in for an extra treat when the Moon
eclipses the bright star Regulus Friday night. It's a rare naked
eye occultation, the likes of which won't be seen again in most
parts of North America until 2005.
Right: Tired of standing in long
ticket lines with nothing to do? Don't forget to look up at the
sky this Friday night. The Moon and Regulus will put on a sky
show this weekend to entertain waiting moviegoers before the
main event begins.
"Both Regulus and the Moon are bright, so it should be possible
to view the event in spite of light pollution in urban areas,"
says Dr. Tony Phillips, a NASA astronomer. "Many people
will be outdoors anyway, either on their way to a movie theatre
or waiting in line. It's an opportunity not to be missed."
Finding Regulus is easy. Go outside after sunset and look toward
the southwest. The Moon and Regulus will be shining brightly
about 50 degrees above the horizon. Regulus is a 1st magnitude
blue-white star located about 85 light-years away. It's thought
to be about three times as massive as our sun. Regulus is a popular
setting for science fiction stories. For example, the fictional
planet Regulus III appeared in the Deep Space Nine episode
"Fascination", and events on Regulus V were an important
part of the Star Trek episode "Amok Time."
The occultation will be visible in northern Mexico, and
throughout the United States and Canada. When to watch depends
on exactly where you live. The farther west you are, the earlier
the occultation will take place. Regulus will vanish behind the
Moon's limb before sunset in the far Northwest, in twilight for
most of the West and the north-central states and a little after
midnight in the East, when the Moon is setting over the western
horizon.
Occultation times for many US and Canadian cities are tabulated
below. If your home town is not listed, simply use the times
for the nearest city as a guide. A more complete
listing is provided at the International
Timing Association web site and there are also an excellent
set of timing
maps available from Sky
& Telescope.
Regulus Occultation Times
May 21 - 22, 1999
Location Disappearance Reappearance Zone
Atlanta GA 12:25 am 1:25 am EDT
Boston MA 12:15 am 1:10 am EDT
Brownsville TX 11:41 pm 12:25 am CDT
Chicago IL 11:09 pm 12:12 am CDT
Dallas TX 11:23 pm 12:21 am CDT
Denver CO 10:01 pm 11:07 pm MDT
Detroit MI 12:11 am 1:12 am EDT
HamiltonBermuda 1:30 am ------ ADT
Houston TX 11:31 pm 12:25 am CDT
Kansas City MO 11:10 pm 12:15 am CDT
Los Angeles CA 9:11 pm 9:49 pm PDT
Memphis TN 11:20 pm 12:22 am CDT
Miami FL 12:42 am 1:33 am EDT
Minneapolis MN 11:00 pm 12:05 am CDT
Montreal PQ 12:10 am 1:05 am EDT
New Orleans LA 11:32 pm 12:27 am CDT
New York NY 12:17 am 1:14 am EDT
Norfolk VA 12:22 am 1:20 am EDT
OklahomaCity OK 11:16 pm 12:18 am CDT
Philadelphia PA 12:18 am 1:15 am EDT
Phoenix AZ 9:14 pm 10:03 pm MST
SaltLakeCity UT 9:52 pm 10:58 pm MDT
SanFrancisco CA 8:54 pm 9:41 pm PDT
St John's NF 1:39 am ------ NDT
St Louis MO 11:14 pm 12:17 am CDT
Tampa FL 12:37 am 1:31 am EDT
Toronto ON 12:10 am 1:09 am EDT
Washington DC 12:19 am 1:17 am EDT
Winnipeg MB 10:48 pm 11:54 pm CDT
Times listed
as "am" refer to Friday, May 21, and "pm"
times occur on Saturday, May 22. |
No matter where you live, Regulus will vanish behind
the Moon's dark edge and reappear from behind the sunlit side.
To see the reappearance you may need a telescope or a good set
of binoculars since the star will be buried in the glare of the
Moon's sunlit limb. You can use the diagram below to estimate
where along the limb to see Regulus emerge.
Above: The path that Regulus will
take behind the Moon as seen from various cities, adapted from
Sky
& Telescope.
Astronomers hope that the occultation, occuring as it does at
a convenient time of night over the United States and Canada,
will be observed by thousands of sky watchers. If enough people
record the event on video, scientists could use the tapes to
construct a very precise map of the moon's limb. Accurate profiles
of the lunar terrain are important because they help scientists
interpret solar eclipses and address issues like the constancy
of the sun's diameter and its long-term energy output.
Want to help? You don't have to be an astronomer to participate.
All that's required are a good home camcorder (with 12x or higher
zoom), a shortwave receiver, and a view of the moon.
 Experts suggest that you begin your recording
at least 15 minutes before the occultation. For a bright star
like Regulus no telescope should be necessary. Simply zoom in
on the Moon's limb and center the field of view at the point
where you expect Regulus to vanish (see the diagram, above).
The recording should continue for several minutes after the star
disappears. A tripod will provide the best image stability, but
hand-held recordings can also provide good data.
To make your observations useful to scientists, you will need
to record an accurate time signal on the audio track of the video
recorder. The easiest way to do this is to tune a shortwave reciever
to WWV,
which transmits time signals at 2.5, 5, 10, 15, and 20 MHz, and
position the receiver within listening distance of your camcorder's
microphone. To hear what a WWV signal sounds like, you can phone
(303) 499-7111. Another good source of time information is the
Canadian radio station CHU which broadcasts at 3.330 MHz and
7.335 MHz.
It is also important to specify your latitude and longitude as
accurately as possible. The best way to locate your observing
site is with the aid of a GPS
receiver. Unfortunately, these are still expensive and not
widely available. Another approach is to carefully measure topographic
survey maps. In the USA, suitable maps can be ordered directly
from the US Geological Survey by calling 1-800-USAMAPS. Even
if you don't have a GPS receiver or can't obtain a map, the International
Occultation Timing Association can often figure your location
provided that you carefully measure the distance of your observing
site from local landmarks such as buildings or street intersections.
When occultation is over please mail a copy of your tape to Dr.
Tony Phillips, 162 Alpine Drive, Bishop CA, 93514. Don't forget
to include a brief letter describing your observing site, its
location, and the equipment you used to film the occultation.
Portions of your tape will be digitized for possible use in future
NASA Space Science News headlines (with full credit to the photographers).
Then the tape will be forwarded to IOTA for further scientific
analysis.
Left: On September 18, 1997, many
stargazers in the U. S. were able to watch a lovely early morning
lunar occultation as a bright Moon passed in front of Saturn.
This animated
gif image was captured at the Whipple Observatory atop Arizona's
Mount Hopkins.
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