A widely publicized occultation of the bright star Regulus by asteroid Erigone on March 20th went unseen because bad weather blanketed the entire path — from upstate New York to Bermuda.It had all the makings of a Big Event. For several seconds early on March 20th, the bright star Regulus was going to literally disappear from view — briefly covered by the faint asteroid 163 Erigone. Lying along the path was a densely populated urban corridor that even included New York City.
Never before had the occultation of so bright a star been predicted for North America, and literally millions of people had the potential to see it. "Regulus shines right through moonlight and light pollution that's in the sky — even the light pollution over a city like New York," wrote my S&T colleague Alan MacRobert in his preview of the event.
But sometimes the weather gods just don't see eye-to-eye with skywatchers. About 5 days beforehand, devoted observer and veteran meteorologist Joe Rao saw ominous signs in the forecast. "For the last few days," he told observers via email, "the models have been indicating that an approaching cold front from the west would bring cloudy and showery conditions to eastern New York State for March 20 at 2 a.m. EDT."
Rao thought the front might push through in time for clearing to work in behind it — but no such luck. As time for the historic occultation neared, most of the predicted path was hopelessly socked in. S&T assistant editor Camille Carlisle had ventured into upstate New York for the event. "We were totally clouded out for the occultation," she says. "It looked like someone had thrown a fuzzy wool blanket over the sky." Those in the Big Apple fared no better. "Alas, it was cloudy with fog and drizzle here in New York City," reported Tony Hoffman, "with not even a glimpse of the Moon, let alone any stars, tonight.""I made the decision not to go to New York at all, due to the 100% socked in forecast for the entire Northeast," grumbles Indiana-based observer Dan McGlaun. "A huge weather disaster for a once-in-a-lifetime event, in my opinion."
The most intrepid occultation-chasers had tried to dodge the stormy Northeast by flying to Bermuda, parts of which lay in the path. But the weather there wasn't much better. "We had mostly clear skies during the 5 hours preceding the event, allowing time to set up and pre-point all of my systems at the various locations spread across Bermuda," recalls David Dunham, who heads the International Occultation Timing Association.
Then the conditions deteriorated at the spot where he settled in to observe the event. "Shortly after acquiring Regulus, clouds moved in, but the bright star only faded a little in those clouds and never disappeared." In other words, no occultation occurred at that location, which was 2 km inside the path's predicted northeast limit. "When I returned to Pompano Beach," he continues, "Tim Haymes said that the clouds were quite thick there so that Regulus was not visible with his equipment around the time of the occultation." Another of Dunham's remote camera setups recorded the star fading substantially amid the clouds — but never disappearing. "So, based on that," he concludes, "it looks like there was no occultation to be seen anywhere from Bermuda." (His full report is here.)
In fact, Dunham hasn't heard of anyone having seen the occultation from anywhere along the path. "Although there were a few breaks here and there," he says, "apparently none came at the right time in the right direction for anyone in or near the path in North America."
This was a big one to miss, but there's always "next time." IOTA members are already setting their collective sights on the next occultation, which is likewise unusual. On April 16th, Venus occults 3.7-magnitude Lambda Aquarii. It'll be interesting to see what happens as the star disappears and reappears through the planet's thick atmosphere. But there won't be a huge metropolis along the path this time: It mostly traces across the South Pacific, with limited visibility from New Zealand, eastern Australia, Fiji, Papua New Guinea, and some bits of the Caroline Islands and Micronesia.You can also look forward to an occultation of Saturn by the nearly full Moon one day later, April 17th. As the map here shows, it should be observable from the lower half of South America.
Make those plane reservations soon!