Universe Today
Live in the New York City tri-state area, or anywhere near the path above? One of the most unusual big ticket astronomical events of 2014 occurs on in the morning hours of Thursday March 20th, when the asteriod 163 Erigone "blocks" or
occults the bright star Regulus
.
This is
brightest star to be occulted
by an asteroid for
2014
, and has a potential to be observed by millions.
Occultations of stars by asteroids are often elusive events, involving faint stars and often occurring over remote locales. Not so with this one. In fact, the occultation of Regulus on March 20
th
will result in an "asteroid shadow" passing over viewers across the populous areas of New York and adjoining states in the U.S. northeast before racing into Canada.
And unlike most asteroid occultations, you won't need any special equipment to detect this event. Shining at magnitude +1.3, Regulus is an easy and familiar naked eye object and is the
22nd brightest
star in the sky. And heck, it might be interesting just to catch a view of the constellation Leo minus its brightest star!
[caption id="attachment_110196" align="alignnone" width="580"]
Finding Regulus: Looking westward from the New York tri-state region at the time of the occultation. Credit:
Stellarium
.[/caption]
Asteroid
163 Erigone
shines at magnitude+12.4 during the event. At 72 kilometres in diameter and 1.183 A.U.s distant during the occultation,
163 Erigone
was discovered by French astronomer Henri Joseph Perrotin on April 26
th
, 1876.
There's a great potential to learn more not only about 163 Erigone during the event, but Regulus itself. Amateur observations will play a key role in this effort. The
International Occultation Timing Association
(IOTA) seeks observations from this and hundreds of events that occur each year. Not only can such a precise measurement help to pin down an asteroid's orbit, but precise timing of the occultation can also paint a "picture" of the profile of the asteroid itself.
[caption id="attachment_110195" align="alignnone" width="580"]
An example of an asteroid shape profile created by observers during the occultation of a star by asteroid 55 Pandora in 2007. Each cord represents an observer. Credit- The IOTA.[/caption]
Regulus also has a faint
white dwarf companion
, and it's just possible that it may be spied a fraction of a second before or after the event. Does 163 Erigone have a moon? Several asteroids are now known to possess moons of their own, and it's just possible that 163 Erigone could have a tiny unseen companion, the presence of which would be revealed by a small secondary event. Observers along and outside the track from Nova Scotia down to Kentucky are urged to be vigilant for just such a surprise occurrence:
[caption id="attachment_110194" align="alignnone" width="580"]
A widened map of the March 20th event, noting the span over which an unseen "moon" of 163 Erigone could be potentially observed.
- Credit
-
IOTA/Ted Blank/Google Earth.[/caption]
The maximum duration for the event along the centerline is 14.3 seconds, and the
rank
for the event stands at 99%, meaning the path is pretty certain.
The shadow touches down on Earth in the mid-Atlantic at 5:53 Universal Time (UT), and grazes the island of Bermuda before making landfall over Long Island New York, New Jersey, Connecticut and northeastern Pennsylvania just after 6:06 UT/2:06 AM EDT. From there, the shadow of the asteroid heads to the northwest and crosses Lake Ontario into Canada before passing between the cities of Ottawa and Toronto just before 6:08 UT. Finally, it crosses out over Hudson Bay and Nunavut before departing the surface of our fair planet at 6:22 UT.
The path is about 117 kilometres wide, and the "shadow" races across the surface of the Earth at about 2.8 kilometres per second from the southeast to the northwest.
[caption id="attachment_110197" align="alignnone" width="580"]
A technical map including the specifics for the March 20th occultation of Regulus. Click to enlarge. Credit: The IOTA.[/caption]
Timing an occultation can be accomplished via audio or video recording, though accurate time is crucial for a meaningful scientific observation. The IOTA has a complete explanation of tried and true methods to use for
capturing and reporting the event
.
We had a chance to catch up with veteran asteroid occultation observer Ted Blank concerning the event and the large unprecedented effort underway to capture it.
He notes that Regulus stands as the brightest star that has been observed to have been occulted by an asteroid thus far when 166 Rhodope passed briefly in front of it on October 19
th
, 2005.
"This is the best and brightest occultation ever predicted to occur over a populated area, and that covers the entire 40 years of predictive efforts," Mr. Blank told
Universe Today
concerning the upcoming March 20
th
event.
The general public can participate in the scientific effort for observations as well.
"We're trying to make a "picket fence" of thousands of observers to catch this asteroid, so the best thing to do is to go out and observe. If they live anywhere near or in the path, just step outside (or watch from a warm house through a window). Make sure they are looking at the right star," Mr. Blank told
Universe Today
. "If they can travel an hour or so to be somewhere in the predicted path, by all means do so – they'll be home and back in bed well before rush hour starts! Then report what they saw at the
public reporting page
. If no occultation was seen, report a miss. This is more important that people think, since "miss" observations define the edges of the asteroid."
There is also a handy "
Occultation 1.0
" timing app now available for IPhone users for use during the event.
Mr. Blank also plans to webcast the occultation live via UStream, and urges people to check the
Regulus2014 Facebook page
for updates on the broadcast status, as well as the final regional weather prospects leading up event next week. For dedicated occultation chasers, mobility and the ability to change observing locale at the last moment if necessary may prove key to nabbing this one. One of our preferred sites to check the cloud cover forecast prior to observing any event is the
Clear Sky Chart
.
This promises to be a historic astronomical event. Thanks to Ted Blank and Brad Timerson at the IOTA for putting the public outreach project together for this one, and be sure not to miss the occultation of Regulus on March 20
th
!
