First-light
observations by the GREAT H-channel on SOFIA: map of planetary nebula
NGC 7027 in the neutral oxygen emission line at 63 microns. The
effective angular resolution is indicated by the gray circle at lower
left. © GREAT Consortium
With successful commissioning of its high-frequency channel, the GREAT
(German Receiver for Astronomy at Terahertz Frequencies) far-infrared
spectrometer onboard SOFIA is ready to explore new realms.
The new so-called H-channel was first tested during SOFIA flights on
May 14, 16, and 17, and confirmed to be working perfectly. It is based
upon an extremely sensitive superconductive detector and a novel
"quantum cascade" terahertz laser. With that receiver added, the GREAT
instrument is now capable of high-resolution spectroscopy of
astrophysically important lines of atomic neutral oxygen [OI] at a
wavelength of 63 μm (frequency of 4.74 TeraHertz).
First-light spectra were obtained towards planetary nebula NGC 7027
(Figure 1). That nebula is an expanding bubble of gas expelled by a
dying star with approximately twice the mass of our Sun, 3,000
light-years away in the constellation of Cygnus. The nebula has been
extensively studied at other wavelengths, but only GREAT can resolve the
velocities of the expanding envelope in the [OI] line. The spectrum
(Figure 2) represents only 2 minutes of integration, illustrating the
superb sensitivity of the GREAT instrument carried into the stratosphere
by SOFIA.
The GREAT far-infrared spectrometer (gold vertical structure in the
foreground) is mounted to SOFIA's telescope during the observatory's
first southern hemisphere deployment. © GREAT Consortium/R. Güsten
GREAT is a Principal Investigator-class instrument for SOFIA,
developed and maintained by the Max Planck Institute for Radio Astronomy
(PI: Rolf Guesten) and KOSMA at the University of Cologne (Co-I:
Juergen Stutzki), in collaboration with the DLR Institute of Planetary
Research (Co-I: Heinz-Wilhelm Huebers) and the Max Planck Institute for
Solar System Research (Co-I: Paul Hartogh).
SOFIA is a joint project of NASA and the German Aerospace
Center (DLR). The aircraft is based at NASA Armstrong Flight Research
Center that manages the program. NASA Ames Research Center at Moffett
Field, Calif., manages the SOFIA science and mission operations in
cooperation with the Universities Space Research Association (USRA)
headquartered in Columbia, Md., and the German SOFIA Institute (DSI) at
the University of Stuttgart.
CONTACT
Dr. Norbert Junkes
Presse- und Öffentlichkeitsarbeit
Phone:+49 228 525-399
Email: njunkes@mpifr-bonn.mpg.de
Dr. Dana Backman
SOFIA Outreach / SOFIA Science Center,
Phone:+1 650 604-2128
Email: dbackman@sofia.usra.edu
NASA Ames Research Center, Moffett Field, CA, USA 
