Chandra :: Chronicles :: Trick Or Treat?

An overview of the Chandra mission and goals, Chandra's namesake, top 10 facts.

Classroom activities, printable materials, interactive games & more.

Overview of X-ray Astronomy and X-ray sources: black holes to galaxy clusters.

All Chandra images released to the public listed by date & by category

Current Chandra press releases, status reports, interviews & biographies.

A collection of multimedia, illustrations & animations, a glossary, FAQ & more.

A collection of illustrations, animations and video.

Chandra discoveries in an audio/video format.

Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit chandra.si.edu for current information.

Trick Or Treat?
In Pursuit of a "Target of Opportunity"

November 2, 1999 ::

Supernova 1999em
X-ray: NASA/CXC/SAO; Optical: Palomar Obs. DSS

It all started on Friday, October 29, when Alex Filippenko of the University of California at Berkeley notified Bob Kirshner at Harvard-Smithsonian that his supernova search project had a good candidate in a relatively nearby spiral galaxy, NGC 1637. Nearby in this case means about 25 million light years from Earth. Wei Dong Li, who is visiting Filippenko's group from the Beijing Astronomical Observatory, called his colleagues in Beijing, who confirmed the supernova, which was given the official name, SN1999em. Kirshner's group at the Smithsonian's Whipple Observatory in Arizona took a spectrum of the object on Saturday. The spectrum showed that the object was a Type II Supernova, an explosion produced by the collapse of the core of a massive star.

Kirshner took time off for dinner on Saturday night, then got in touch via e-mail with Harvey Tananbaum, director of the Chandra X-ray Center a little before 11 p.m. "There's a bright supernova in NGC 1637," he said. After giving some of the details, Kirshner signed off, "Explosively yours, Bob."

The discovery presented a dilemma for the Chandra team. On the one hand, a supernova this close to Earth goes off only once every five or ten years, and it would be the first time ever that an X-ray telescope with Chandra's sensitivity had looked at a new supernova. It definitely qualified as a Target of Opportunity (TOO) for which the normal observing program could be interrupted so Chandra could look at some new occurrence in the sky. On the other hand, the TOO program was not scheduled to begin until the Chandra Center had had more experience learning about the quirks of the observatory and the software used to command it.

Tananbaum decided to go for it, pending a review by various experts on the risks and rewards of such an undertaking. Shortly after 9:00 a.m. on Sunday, Tananbaum sent an e-mail to key team members, asking for their input.

Pat Slane of the Chandra Science Mission Planning group.
Photo: CXC

Pat Slane of the Chandra Science Mission Planning group was the first to respond, and he passed the word along to Bill Forman, the head of Science Mission Planning. Soon, e-mails and phone calls were zipping back and forth as the pros and cons of the observation were discussed, and the scientists juggled their children's Halloween party schedules. Slane managed to attend his child's party and stay in touch. (He went as a vampire with a cell phone).

Roger Brissenden, manager of the Chandra Center, weighed in with practical considerations such as pointing problems and the details as to how to interrupt the "load"-- the program that is sent up to direct Chandra's operation for a week. Ken Gage or Kevin Marsh of the Flight Ops team would have to be brought in write the necessary software to do this.

Walter Lewin of MIT, who had won the rights to Chandra's first observation of a nearby supernova, urged Tananbaum to, "... go for this one! A unique chance that we have been hoping for!!!!"

Anil Dosaj of the Chandra Science Mission Planning group.
Photo: CXC

Paul Plucinsky of the Chandra Center's ACIS team passed along useful information on ACIS, the instrument that would be used for the observation.

Li supplied an accurate position of the supernova.

Forman emphasized the need to carefully review the procedures to maintain spacecraft safety. Anil Dosaj volunteered to come in and prepare the official Operation Request, or OR file for the observation.

Scientists working on plans to observe Supernova 1999em.
Photo: CXC

he notified Tananbaum that they could replace the load by 2 a.m. Monday morning.

For the next 5 hours the team worked furiously, with Lewin and his colleague Derek Fox consulting with Plucinsky and Royce Buehler of MIT's ACIS team to plan the details of the observation. When they were finished, Brissenden called the team together for a final review at 9 p.m. Present were Jeff Shirer (TRW's - now NGST's) Flight Operations Team), Rob Cameron (Aspect Camera), Buehler (ACIS), Jon Chappell and Gerry Austin (HRC), Dosaj, Slane, Forman, and Marsh.

"The review is complete and there are no issues," Brissenden reported to Tananbaum. "Overall a good effort from the team in my opinion."

All that remained was to wait for the time slot to uplink to Chandra-- most of Monday--and for Chandra to slew over to the source -- about half an hour. The observation was begun at 6:37 p.m. on Monday, and continued for several hours. The data will probably take a week or so to be analyzed.

The optical spectrum exhibits a very blue continuum with broad emission features from hydrogen atoms and sodium that are typical of a Type II supernova remnant.
(Credit: CfA)

"I was impressed by how rapid the Chandra response was, " said Kirshner, who has the rights to a Hubble Space Telescope observation of the new supernova which will occur on Friday. "It typically takes a week for Hubble...Walter should be delighted."

"Walter ISSSSSSS DELIGHTED!!!!!!" Lewin responded.

The theoretical predictions of the X-ray luminosity of a new supernova vary widely, from very low to intense. Whether Supernova 1999em is a trick or a treat for astronomers will soon be known.

SN1999em proved to be a treat. Find out more at http://chandra.harvard.edu/photo/1999/sn1999em/ (14 Dec 99)

Receive updates by email GO
Info & Privacy Policy.

Articles from:

['15 | '14 | '13 | '12 | '11 | '10 | '09 | '08 |
'07 | '06 | '05 | '04 | '03 | '02 | '01 | '00 |
'99]

March 19 Where Are They Now? Steve Hawley

July 22 Harvey's Voyage

Oct 31 TYREL JOHNSON & JATILA VAN DER VEEN

Sep 27 Mirror Man

Dec 14 Chandra in 2012: A Teenager in Space

Oct 24 Look Back Time -- Remembering Franco

Where is Chandra Now?

RSS Feed

Chandra Twitter Updates

Follow Chandra on Twitter

Contact us: cxcpub@cfa.harvard.edu
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Cambridge, MA 02138 USA
Phone: 617.496.7941 Fax: 617.495.7356

Chandra X-ray Center, Operated for NASA by
the Smithsonian Astrophysical Observatory
This site was developed with funding from NASA under contract NAS8-03060.

Trick Or Treat? In Pursuit of a "Target of Opportunity"

Trick Or Treat?
In Pursuit of a "Target of Opportunity"