Asteroid Named After Sky & Telescope Editor Sean Walker

The International Astronomical Union (IAU) has designated asteroid 1995 TD in honor of longtime Sky & Telescope editor Sean Walker, naming it 13623 Seanwalker.

In addition to noting Sean’s work at the magazine, the IAU also noted that Sean is an “accomplished American artist” – having seen his painting firsthand, I can definitely vouch for that. And for those of you familiar with the work he has done at Sky & Telescope over the past couple of decades, you’ll know he’s an incredibly accomplished astrophotographer.

Sean was born in Concord, Massachusetts, and graduated from the Massachusetts College of Art and Design in Boston. But astronomy has always been a part of his life — his mother had a telescope and showed views of the planets to a young Sean and his three brothers.

While Sean was in college, one of the ways he supplemented his income was by taking slides of fellow artists’ work for their portfolios. In so doing, he learned the ins-and-outs of photography. Another side gig was working in the Audio/Visual department at Harvard University’s Science Center, where among his duties Sean would shoot 35-mm slides of the pages of Sky & Telescope for the lectures by historian of astronomy Owen Gingerich. After completing the work for Gingerich, Sean would then devour the pages of the magazine. Both side gigs set the stage for his future career.

Sean fully embraced astronomy when he got his own telescope, a Mirador spotting scope, and had a lot of fun pushing it around the sky.  Then in July 1994, his friend Mark Ferranti, the bass player for the Boston-based band Bim Skala Bim, showed Sean Comet Shoemaker-Levy’s impacts on Jupiter in his 60-mm telescope. After seeing that view, Sean thought to himself, “I need a better telescope!”

Inspired by the second edition of Alan Dyer’s book, The Backyard Astronomer’s Guide, Sean began a deep dive into astrophotography. In 2000, he joined the staff of Sky & Telescope as Ad Production Coordinator. Based on his knowledge and interest in astrophotography, he was asked to join the editorial department in 2004 as assistant editor under the tutelage of Dennis di Cicco. Around 2010, former Editor in Chief Bob Naeye introduced specific titles for editors’ position, so for a while Sean wore the hat of Imaging Editor, and later on was promoted to Associate Editor.

Among his many editorial tasks, Sean not only commissions articles on astrophotography and equipment but also writes many himself. He also covers products and works with authors on test reports and telescope-making stories. He’s a regular attendee at the Stellafane Convention in Springfield, Vermont, and most Aprils find him treading the floors at the Northeast Astronomy Forum in Suffern, New York, this country’s biggest astronomy trade fair. Sean also acts as the S&T representative on astronomy tours — this summer will find him back in Botswana alongside Contributing Editor Steve O’Meara.

Sean has built his own observatory — twice. The current incarnation is in his backyard in Litchfield, New Hampshire, where he lives with his lovely wife, Jane. Dunkelheit Observatory, whose name was inspired by the German band Rammstein, houses a Celestron C14 on a pier, in addition to another dozen or so telescopes. He dabbles in every type of astroimaging from nightscapes, to solar, lunar, planetary, and deep-sky.

But that’s not all. Through Dennis di Cicco, Sean got to know another club member, David Mittelman, who was curious about astrophotography and image processing. Sean started teaching David all he knew, and Dennis would often join them in their monthly sessions. During these sessions the trio discussed various ideas and projects, and eventually one took hold.

In 2016, Dennis, Sean, and David embarked on a project that targeted the whole sky, and so, the MDW Sky Survey was born, with the initials based on their last names. (For a fuller look at this survey, see mdwskysurvey.org as well as the October 2019 issue of the magazine). Remotely operating two 5-inch Astro-Physics telescopes equipped with hydrogen-alpha filters in New Mexico, the team completed the Northern Hemisphere campaign of the survey down to declination –32° in 2022. (David Mittelman sadly passed away in May 2017.) The pair of telescopes was then shipped to Chile, and a third was added, and are on track to complete the rest of the sky all the way to the South Celestial Pole by the end of 2025.

 The MDW Sky Survey work has elicited the attention of several research groups, culminating in a partnership with the Astronomy department at Columbia University. Through these collaborations Sean has helped unveil unknown nebulae (see page 62 in the June 2024 issue), and contributed to other discoveries. The IAU designation highlights Sean’s work on the MDW work alongside his other accomplishments.

Given that Sean’s fascination with astronomy began to bloom in the mid-90s, it seems fitting that Dennis di Cicco discovered “Sean’s asteroid” from his backyard observatory in Sudbury, Massachusetts, on October 3, 1995. I’m sure you’ll all join me in saying “Congratulations, Sean!” It’s such a well-deserved honor!