Will Mysterious Gamma Delphinid Meteor Shower Shoot Stars Before 2027?

Summary: Will the mysterious Gamma Delphinid meteor shower, which was observed as an outburst June 10, 1930, shoot stars before its next outburst in 2027?

Gamma Delphinid meteor captured by two different all sky cameras in southern New Mexico, June 11, 2013: NASA’s Marshall Space Flight Center, CC BY NC 2.0, via Flickr

Will the mysterious Gamma Delphinid meteor shower, which announced its existence Tuesday, June 10, 1930, as a brief, brilliant outburst, shoot stars before its next projected outburst in 2027?

American astronomer Charles Pollard Olivier (April 10, 1884-Aug. 14, 1975) announced observation of the hithertofore unknown meteor shower in an article entitled “Meteor Notes” in the August-September 1930 issue of Popular Astronomy. Olivier had founded the American Meteor Society (AMS) in 1911 to promote visual study of random meteors and of meteor showers.

Paul S. Watson, a member of the American Meteor Society, reported the meteoric event to Olivier. Watson, along with co-observers Joseph Field and Frank Oertle, witnessed the outburst between 9:15 and 9:45 p.m. Eastern Standard Time, Tuesday, June 10, 1930 (2:15 to 2:45 a.m. Coordinated Universal Time, Wednesday, June 11, 1930), in Baltimore, Maryland.

The ”most unusual display” comprised 51 yellowish-white shooting stars. Despite the presence of a full moon and the shower’s brief duration, the shooting stars shone brightly. The trio’s report placed 39 at magnitude 1 and 10 at magnitude 0.

Watson’s report to Olivier identified the radiant, or apparent point of origin, for the meteor shower as tracing back to within 3 degrees of Gamma Delphini (γ Del; Gamma Del; γ Del) in Delphinus the Dolphin constellation. In his announcement in “Meteor Notes,” Olivier gave a rough calculation of 12 degrees above the horizon for the altitude of Gamma Delphini, as viewed at Baltimore, Maryland, at the time of the outburst. With the width of one fist, held at arm’s length, measuring approximately 10 degrees, Gamma Delphini’s altitude of 12 degrees equals about one and one-eighth fist widths above the horizon.

Meteor shower namesakes reflect the bright star or constellation nearest to the radiant at the shower’s peak. With a radiant near Gamma Delphini, Delphinus the Dolphin constellation’s third brightest star, the June 10, 1930, outburst is known as the Gamma Delphinid meteor shower.

Olivier reported the lack of meteors that night from his location, distanced about 100 miles northeast of Baltimore. Olivier’s outdoor observation point was on the grounds of Flower Observatory, where he served as the observatory’s fourth director for almost 25 years.

Located in Upper Darby Township, Delaware County, in southeastern Pennsylvania, Flower Observatory yielded good meteor viewing conditions June 10, 1930. Olivier noted in his announcement: “That same night was one of the most transparent we have had at Flower Observatory.”

Olivier unsuccessfully scanned the skies for about half an hour, beginning at 9:45 p.m. EST (2:45 UTC). University of Pennsylvania Astronomy Professor Samuel G. Barton, who was stationed indoors that night at the observatory’s 18-inch refracting telescope, made several 10 to 15 watches outdoors, with one preceding Olivier’s 9:45 p.m. start time. He also saw no meteors.

Eight and one-third decades later, a return outburst of the Gamma Delphinid meteor shower was projected for Tuesday, June 11, 2013. The geographic region of visibility favored the Americas.

American Meteor Society member Robert Lunsford pointed observers at mid-northern latitudes to Gamma Delphini’s June rising in the east after dusk. Earliest visibility was timed to Delphinus the Dolphin constellation’s appearance above the horizon.

In a live web chat beginning Monday, June 10, at 11 p.m. EDT (3 a.m. UTC, Tuesday, June 11), William “Bill” Cooke, program manager of NASA’s Meteoroid Environments Office at the Marshall Space Flight Center, gave easy viewing guidance. “Lie flat on your back and look straight up, 3:30-5:30 Eastern Time,” Cooke explained.

The moon, thin-slivered in its waxing crescent phase, offered no competition. Also, the moon exited early from the night sky, with moonset Tuesday, June 11, at 10:28 p.m. Eastern Daylight Time (2:28 a.m. UTC, Wednesday, June 12).

Peter Jenniskens, a Dutch and American astronomer and research scientist at NASA Ames Research Center and SETI (Search for Extraterrestrial Intelligence) Institute, and Esko Lyytinen, a Finnish mathematician and researcher, calculated a peak time of 4:30 a.m. EDT (8:30 a.m. UTC) for the June 11 display. They based their calculations upon the premise of an unknown, long-period comet, with an orbital period of more than 200 years, as the Gamma Delphinids’ parent body. Another important premise was the accuracy of nearness to Gamma Delphini as the reported radiant.

Unfortunately, the 2013 display was not a re-enactment of the 1930 outburst. Alan Boyle, MSNBC’s science editor, wrote on his website, Cosmic Log, that Bill Cooke described the faint event as a “very minor shower -- but that's why we look, right?”

Yet, stationed at geographical coordinates 35.50 north longitude, 105.89 west latitude, near Eldorado, north central New Mexico, natural phenomena videographer Thomas Ashcraft posted on Vimeo his capture of a "possible Gamma Dolphinid fireball." The impressive fireball flared Tuesday, June 11, at 2:38 a.m. Mountain Daylight Time (4:38 a.m. EDT; 8:38:34 UTC), only two minutes before the projected peak time.

Jenniskens and Lyytinen also have projected a possible outburst for June 2027. Although the Gamma Delphinid meteor shower’s parent body is unknown, the team’s premise of a long period comet is based upon the descriptions from the 1930 display.

The Gamma Delphinid meteor shower’s near-radiant, Gamma Delphini, is actually a binary star system comprising a yellow-white dwarf orbited by an orange subgiant. The fifth magnitude dwarf and fourth magnitude subgiant join Delphinus the Dolphin constellation from a distance of 104 light years. The duo also participates in the Dolphin’s diamond-like asterism, Job’s Coffin.

The takeaway for the elusive, hoped-for outburst of the mysterious Gamma Delphinid meteor shower is that observation, by experts as well as citizen scientists, will reveal whether the Gamma Delphinids shoot stars, faintly or dramatically, before 2027.

Probable Gamma Delphinid Fireball June 11, 2013 from Thomas Ashcraft on Vimeo.

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credit:

Gamma Delphinid meteor captured by two different all sky cameras in southern New Mexico, June 11, 2013: NASA’s Marshall Space Flight Center, CC BY NC 2.0, via Flickr @ https://www.flickr.com/photos/nasamarshall/9013480432/

For further information:

Ashcraft, Thomas. "Probable Gamma Delphinid Fireball June 11, 2013." VIMEO. June 11, 2013.
Available via VIMEO @ https://vimeo.com/68139353

Astro Bob (Bob King). “Rare Delphinid Meteor Shower May Erupt Tomorrow Morning.” AreaVoices. June 10, 2013.
Available @ http://astrobob.areavoices.com/2013/06/10/rare-delphinid-meteor-shower-may-erupt-tomorrow-morning/

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