Tag Archives: Occultation

Central New York: Take Note (And Help Out)! – The Occultation Of Regulus By Asteroid Erigone On March 20th

Furthermore! CNYO members will be performing a test run of the occultation event for those attending both our lecture at Liverpool Public Library this Thursday (March 6th) and our session of the International Sidewalk Astronomy Night this Saturday (March 8th, weather-pending).

The official IOTA Press Release can be read on the CNYO site HERE.

Greetings fellow astrophiles,

Our daytime skies are (often) filled by starlight from our blindingly bright Sun, while our nighttime skies are a very sparse but more complicated arrangement of the Moon, planets, artificial satellites, stars, and a precious few galaxies and nebulae that can be seen without anything more than the 1x7mm binoculars built into our heads.

Occasionally, events happen “up there” that remind us that we live in a busier part of the Milky Way than the quiet regularity of our own Solar System lets on. All were treated to a nova in the constellation Delphinus last August, where a star otherwise invisible to the naked eye grew bright enough to see without optics, only to fade again weeks after. Comet ISON, heralded as a possible “comet of the century” almost a year before anyone had actual data, at least qualified for “comet of the year” as a dim fuzzball visible away from city lights in November (before fizzling out more dramatically in NASA images). The real winner of 2013 was unquestionably the meteor over Chelyabinsk, a 20 meter/14,000 ton near-Earth asteroid that surprised everyone (most especially the people of Chelyabinsk) last February 15th. The world benefited from the general mistrust of the police in Russia by its citizenry, as thousands of dashboard cams otherwise used to record traffic stops instead provided thousands of high-def videos and images of atmospheric entry.

Technology has dramatically changed amateur astronomy in the past decade, with CCD cameras and commodity telescopes in the hands of trained amateurs providing images that would give many NASA images a good run for their money. Amateur astronomers are now at the vanguard of the space monitoring movement, discovering near-Earth objects, watching the evolution of impacts on Jupiter, identifying supernova in our own and nearby galaxies, even tracking satellites that governments don’t acknowledge existing.

With all that in mind, CNY is going to have front row seats this coming March 20th as the Main Belt asteroid (163) Erigone slides briefly between ourselves and Regulus, the brightest star in the constellation Leo the Lion. This event, called an occultation, will dim or completely block the light coming from Regulus for up to 14 seconds, simultaneously giving scientists a chance to learn more about Erigone.

If you’re an amateur astronomer, citizen scientist, or just someone willing to look to your South at 2 a.m. once this year, fellow observers in CNY extend an invitation to you to report your findings to an organization that will use everyone’s data to determine the shape of Erigone.

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The path of Erigone’s shadow on CNY. Highest confidence of observing the occultation is between the blue lines, some additional confidence of observing it between the blue and red lines.

The International Occultation Timing Association (IOTA) has been planning for the Regulus occultation for many months, from mapping out the best places to observe the occultation to corralling amateur astronomers to help in the data collection. On the morning of March 20th (in the 2:00 to 2:10 a.m. EDT range), observers along a very thin stretch of our planet will point their scopes, cameras, and eyes to the sky to see the star Regulus either dim or go out completely for several seconds, only to reappear unscathed. Those few seconds mean everything to members of the IOTA planning to calculate the shape and size of Erigone, and they will not complain if more observers provide more data.

And just how will this timing data be used to estimate the shape of the distant asteroid Erigone? Consider the old Indian story of the blind men and the elephant. The elephant, being much larger than the stationary men, is believed to be very different things depending on where the measurement is taking place. One old man thinks the trunk is a snake, while another thinks that the leg is a pillar, while yet a third thinks that the tail is a rope.

Instead of a large, stationary animal, Erigone will be a swiftly moving rock that will cast a Regulus-powered shadow on the Earth, and CNY in particular. If Erigone were that elephant, observers at the trunk edge of the shadow would see Regulus disappear for only a second, those at the tail edge for less than a second, those at the center line of the belly for 10 seconds, and those lined up with the legs for 15 or so seconds. Consider the series of images below, showing the elephant’s shadow overlaid on blue lines that represent an observer seeing light from Regulus (Figure 1), red lines marking when those observers didn’t see the light from Regulus (Figure 2, and note that observers on the trunk side would have seen Regulus blink twice!), and finally the estimated shape of the elephant (in green) as taken from everyone’s submitted data (Figure 3).

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Figure 1. The hypothetical elephant’s outline over the light (blue) of Regulus.

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Figure 2. The locations and timings of when the light from Regulus was NOT observed (red).

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Figure 3. The outline of the hypothetical elephant (green) as estimated from the occultation measurements (red). You see? It works!

Taking the disappearance times and the locations of the reports, IOTA members can put together a complete disappearance map of the asteroid like that shown below for asteroid (234) Barbara. In the case of Erigone, the shadow it casts will almost certainly be visible from Utica (east edge) to Auburn (west edge) and might be observable from Little Falls to Seneca Falls. This approach to determining the asteroid’s shape means that people who DON’T see Regulus disappear are just as important as people who DO see it disappear, as the “DON’T”ers help narrow the maximum estimated width of the asteroid. All measurements are important measurements!

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The shape of asteroid (234) Barbara from occultation data.

The Solar System is a kind of shooting gallery of small and not-so-small objects, a fact we can only rarely appreciate given the distances involved. As technology improves and more people keep eyes on the sky, we may find more direct evidence of just how busy things are just in our own Solar System. Meantime, CNY observers can appreciate that we’re finally the best place to be to both study and enjoy an astronomical rarity (weather-permitting, of course).

But wait! There’s more! Only in the past few weeks have IOTA members stepped up their game, proposing to expand the range of observers here on the ground to look for evidence of a moon (or more) around Erigone. The process is the same, measuring any dips in the brightness of Regulus as Erigone approaches to occult. The difference here is that the dimming by a body orbiting Erigone may dip the brightness only slightly before or after Erigone does depending on its size. If the object is too small to obstruct our view of Regulus completely, it will drop Regulus’ brightness by what might be a pebble’s worth placed on top of your smartphone screen compared to Erigone’s cement block’s worth. If the object is large enough, it may occult Regulus completely as well, making the data processing all the more complicated. As you might expect, measuring that small change in brightness is not a task for lousy equipment, but is within the realm of possibility of local observers with good quality CCD cameras on their scopes. If any caught moon is significant in size, it will be easy for all to see and time.

Provided the sky is clear, anyone in CNY should be able to see the occultation with or without binoculars. Those interested in reporting their timing and dimming data are encouraged to check out the occultations.org/Regulus2014 website for all there is to know about the event, then the www.occultwatcher.net/regulus-erigone/ website to see what data the IOTA is looking for. To be kept in the orbital loop about the occultation and any observing plans around CNY, you can contact members of CNY Observers (www.cnyo.org) or check in with any of the other local astronomy clubs in CNY, all of whom have members planning on observing (and, hopefully, recording) the occultation.

IOTA Official Press Release: Best And Brightest Asteroid Occultation Ever To Be Visible Across New York State

Greetings fellow astrophiles!

Below is the official press release by the International Occultation Timing Association (IOTA) on the upcoming occultation of Regulus by asteroid Erigone on March 20th. CNYO will have more to announce about our efforts to monitor this occultation in the next week or two. Meantime, this is your one-month warning!

Public invited to help measure size and shape of distant asteroid

FOR IMMEDIATE RELEASE
Media contact: Ted Blank, tedblank@gmail.com
Alternate contact: Steve Preston, stevepr@acm.org

Just after 2:05 a.m. EDT on March 20, 2014, anyone with clear skies along a 70-mile-wide belt running diagonally from Long Island and New York City up through New York State into Canada may be able to see the bright star Regulus simply disappear from the sky for up to 14 seconds as an invisible asteroid glides silently in front of it.

A chance alignment of orbits is predicted to cause Regulus to “wink out” as the mammoth asteroid Erigone passes directly between Earth and the star, temporarily blocking its light from reaching us (the asteroid itself remains in its normal orbit which never comes anywhere near Earth). Regulus (the star which will wink out) is in the constellation Leo the Lion and, as one of the brightest stars in the sky, is easy to find.

An event where an object in space blocks the light from a distant star is called an “occultation,” from the Latin word meaning “to conceal or hide.” The International Occultation Timing Association (IOTA), a group of volunteers, collects observations on about 200 asteroid occultations per year. However, this is the first time that such a dramatic and obvious occultation will be visible in such a heavily populated area without the need for any kind of optical aid like a telescope or binoculars.

What makes this asteroid event more notable is that the public is invited to assist scientists in recording the event to measure the size and shape of the asteroid. Just by using a video camcorder, a digital SLR camera with video capability, or just a smartphone or a stopwatch, anyone can contribute to the scientific study of the asteroid in question. “In addition to the opportunity to share in a moment of celestial drama, we hope to enlist thousands of ‘citizen-scientists’ to time this event, allowing us to document it more thoroughly than any other asteroid occultation in history” said Steve Preston, President of IOTA. “The more observers scattered across the path of the shadow who time the disappearance and reappearance of the star, the more accurately we can measure the asteroid’s size and shape.”

IOTA has created a “Frequently Asked Questions” page at www.occultations.org/Regulus2014. Here, detailed information may be found on the recommended techniques that the public may use to record and time the event, as well as how to submit their observations for analysis after the event.

Although the asteroid will remain a safe 100 million miles from Earth, as it passes in front of the star its 70-mile-wide shadow will sweep from southeast to northwest across Nassau and Suffolk counties, all five boroughs of New York City and the Hudson River Valley, with the center of the predicted shadow path following a line roughly connecting New York City, White Plains, Newburgh, Oneonta, Rome and Pulaski before crossing into Canada. See Illustration 1 for the current prediction of where the shadow will pass.

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Ill. 1. Estimated path of the shadow of the asteroid Erigone during the occultation of Regulus on March 20, 2014. The green line represents the predicted center line of the ~50 mile wide asteroid shadow. The blue lines represent the width of the asteroid, where edges of the shadow would fall if the actual center of the shadow followed the green line. The red lines represent the uncertainty in the path, meaning that the actual shadow will most likely pass somewhere between the red lines. There is a smaller chance that one edge could be slightly outside one or the other of the red lines.

At the time of the occultation, Regulus will be about 40 degrees high in the southwest, or about half-way up from the horizon to a point straight overhead. Illustration 2 below is a “sky-map” showing the star’s location in the sky along with some convenient reference points to help get oriented.

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Ill. 2. Finder chart for March 20, 2014, looking southwest. The red dot at the top represents the point directly overhead. Regulus will be approximately half-way up in the sky, at the bottom of the reversed “question mark” that makes up the “mane” of Leo the Lion. Saturn, the Moon, Mars and Jupiter are shown on this map in the positions they will occupy on this date, as are the twin stars of Gemini (Castor and Pollux) just above Jupiter.

To choose an observing location, members of the public can refer to Illustration 1 and select any place between the outer lines. Since the path the shadow will follow may change slightly, observers should check the online zoomable map at tinyurl.com/regulus2014map in the days before the event for any last-minute adjustments to the path prediction. Additionally, people situated as far as 10 path-widths on either side of the center line are encouraged to make an observation in case Erigone has a moon which might momentarily block the star’s light. Video recordings will be needed to confirm the fleeting disappearance that a tiny moon of Erigone might cause.

After the event, the public may report their timing observations at tinyurl.com/regulus2014report, including reports of a “miss,” or no occultation. “Both actual timings and ‘miss’ observations are extremely valuable,” said Preston. “Timings of the disappearance measure the asteroid’s diameter in the dimension along its orbital path, but ‘miss’ observations improve our understanding of how wide it is across its path. Furthermore, both types of reports improve our understanding of the asteroid’s orbit.”

Typically only a few observers see these types of events, allowing the diameter of the asteroid to be measured at just a few places. However, with a large number of observers, the opportunity exists to categorize the asteroid’s entire silhouette, as seen for asteroid (234) Barbara in Illustration 3 below.

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Ill. 3. Outline of asteroid (234) Barbara obtained by multiple observers timing an occultation in 2009. The observers were spread out across an area over 40 miles wide. The horizontal white gaps in the solid lines represent the period of time when the asteroid blocked the light from the star for that observer. The gaps between the lines themselves represent the distance between observers on the ground. Each observer saw the star pass behind a slightly different portion of the asteroid, allowing the asteroid’s diameter to be measured at multiple locations. Note the large crater at the south end of the asteroid. This level of resolution is far greater than anything possible with ground-based telescopes, but more observers would have allowed even finer details to be measured.

Members of the public with additional questions should refer to the FAQ page at www.occultations.org/Regulus2014, email regulus2014@occultations.org or see the article in the March, 2014 issue of Sky and Telescope Magazine.

About IOTA

The International Occultation Timing Association, with its worldwide sister organizations in Europe, the United Kingdom, Australia/New Zealand, Japan, S. Asia/India, Mexico, Latin America and South Africa, provides free occultation predictions and planning and analysis software, sponsors online Internet discussion groups and publishes the Journal of Occultation Astronomy. The main IOTA webpage is www.occultations.org. The Yahoo discussion group can be found at http://groups.yahoo.com/neo/groups/IOTAoccultations/info and is open to all with an interest in this topic.

A PDF copy of an article from the March, 2014 issue of Sky and Telescope Magazine on the occultation is linked HERE. Permission to include this article has been granted by Sky and Telescope.

CNYO Observers Log: Comet ISON At Highland Forest, 15 November 2013

Greetings fellow astrophiles,

One of the benefits of spending your time in the sciences is the development of a healthy skepticism for science news that makes it out to the major print and online news services. Be it new findings on vitamins or “breakthroughs” in fusion, there’s often an astronomical difference between what appears in initial reports and what actually settles as established fact in the laboratory or marketplace. As one of my favorite radio personalities puts it (about military conflicts, but the logic applies) “The first three reports are always wrong.”

Comet ISON started out early this year with such headlines as “Comet Of The Century?” (and that was NASA), “ISON May Appear Brighter Than Full Moon As It Passes Earth,” (from HuffPo, among many others), and other all-too-optimistic accolades undeserving of an object for which almost nothing was known at the time. But it sounded good in the small news snippets that passed around many astronomy email lists. This last month has finally seen some more serious scientific questions raised in the media concerning its composition, actual brightness, flaring, etc., as real data has made its way to us for analysis. The final result, so far, is far from advertised early on. But coal to the eyes of a non-observer can be gold to to the eyes of an observer, so many an amateur has found time to make it outside to take in at least one view of Comet ISON.

It is with the above in mind that I report on a facebook-announced CNYO observing session for Comet ISON held on Friday, November 15th at the most unreasonable hour of 3:30 a.m. The attendees, including Ryan Goodson, Hanh Le, and myself, braved the bitter cold for a 30 minute drive South to Highland Forest, an all-around excellent location for enjoying the Night Sky (and, I am pleased to report, a future location of regularly-scheduled CNYO events for 2014. Post to follow!).

And why the 15th? There are many factors that govern when an observer will drag their equipment outside.

* The easy one is the weather – cloudy nights, bitter cold, or hot, swampy nights (and their associated mosquito infestations) leave the intrepid amateur to hang out at home and in the discussion forums on cloudynights.com.

* The second one is the presence or absence of the Moon. As our closest natural satellite, the Moon is one of the most enjoyable (and brightest) objects to spend one’s time exploring (and, with a clear window, can be done just as enjoyably indoors). The downside is that the lit Moon washes out the dim details of many a fuzzy nebula, galaxy, or comet. If the Moon is out, many an amateur astronomer isn’t. In the case of the morning of the 15th, the Moon set just before 4 a.m. (at which point something as dim in surface brightness as a comet becomes a much more tempting target).

* The third is the timing of the object itself. While much of what’s observed in the Night Sky lasts for hours at a time every night, certain events occur over relatively narrow windows. The occultation or transit of Jupiter’s moons is one, satellite or ISS fly-bys is another. Comet ISON at its then-current window was yet another one, as it rose quite close to the beginning of sunrise (“the beginning” meaning the start of brightening skies that would wash its detail out) and wasn’t going to appear at any more convenient a time prior to its closest approach to the Sun.

* The fourth is the combination of all three. During the week of the 11th, the skies were predicted to clear only at the end of the week, Comet ISON was set to rise later every morning in the East, and the Moon was set to set later and later in the West. Combined with increased cloud cover on the 16th, the early morning of the 15th became THE WINDOW for Comet ISON.

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The West and constellations from Highland Forest at 4:00 a.m. Click for full size.

The group convoy’ed out to a frosty Highland Forest and set up the scopes just to the East of the main building. As anyone who’s stopped at the building before or after a hike will know, the view from this location is remarkable, with a low tree line and steep-ish hill bracketing views of the Fenner Wind Farm towards the South and just a hint of Syracuse civilization towards the North. The Winter Constellations of Canis Major, Taurus and Orion just beginning to peak out at “reasonable hours” now were in full view to the West at 4:00 a.m. Comet ISON, while approaching uncomfortably low on the horizon for a Dob, was visible as a fuzzy 4th magnitude ball with a slight tail (most definitely an obvious object in Ryan’s New Moon Telescope Dob and my 25×100 Zhumell binos). The wind was just fast and gusty enough to keep us from finding Comet Lovejoy, which was at about 9th magnitude in the same sky (it will be a target for future observing sessions).

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Ryan Goodson sneaking a low peak at Comet ISON. Click for full size.

As of this posting on 30 November, ISON has just barely survived its trip around the Sun (earliest reports saying it had disintegrated, slightly later saying it may have survived as a dark ball, now more recent reports saying something with a tail has survived) but we don’t yet know if it’s going to be observable on its “way out.” Stay tuned to future reports.