Echelle Spectrograph for SOFIA Sensitivity W e plot the NEFD for S N10 in 900s of integration on a point source For comparison Vega is included on all three plots SOFIA is able to observe single targets for up to 4hrs continuously ID: 277682
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EXES: The Echelon-Cross-Echelle Spectrograph for SOFIA
SensitivityWe plot the NEFD for S/N=10 in 900s of integration on a point source. For comparison, Vega is included on all three plots. SOFIA is able to observe single targets for up to ~4hrs continuously.
Curtis DeWitt1,2, Matthew J. Richter1, Mark E. McKelvey2, Andreas Seifahrt3, Peter T. Zell2, Dana H. Lynch2, Michael E. Case21 UC Davis Department of Physics, 2 NASA Ames Research Center, 3 University of Chicago Department of Astronomy and Astrophysics
The Advantage of SOFIA
A comparison of atmospheric transmission at Mauna Kea (blue) and from SOFIA (red) for various molecular species.
EXES on the IRTF
EXES was used on the IRTF in January
2011 to
get early experience with scientific operations. While useful, a misalignment of the telescope and the pre-optics caused significant slit loss, limiting the targets which could be observed. Successful observations of Venus are being analyzed.
Science Goals-Chemistry and dynamics of molecules (H20, CH4, and others) around HII regions, YSOs, disks.-Atmospheres of mass-losing AGB stars-Abundances in comets, solar system planets and moons’ atmospheres
Status of EXESEXES is fully-assembled in the lab at NASA Ames, undergoing characterization of the Si:As detector and a new echelle grating. It will undergo its first test flights on SOFIA in late 2012, and will become available to the community in Cycle 2 (2013-2014).
What is EXES? EXES is a first generation spectrograph for SOFIA EXES operates between 4.5 and 28.3 μm. EXES has three spectral modes and a camera mode for slit positioning high (R~100,000) medium (R~15000) low (R~3000) EXES uses a 1024x1024 Si:As detector optimized for low background. EXES features an echelon, a coarsely-ruled, steeply-blazed Al reflection grating for high resolution.
Aluminum R10 echelon grating for EXES
(40
” x 4”)
EXES mounted on IRTF in Jan 2011.
References
Richter et al., "Status of the Echelon-cross-
Echelle
Spectrograph for SOFIA," Ground-based and Airborne Instrumentation for Astronomy III, Ian S. McLean, Suzanne K. Ramsay, & Hideki
Takami
, Editors, Proc. SPIE 7735, 77356Q (2010
)
Richter et al., "Development and future use of the echelon-cross-
echelle
spectrograph on SOFIA," Ground-based and Airborne Instrumentation for Astronomy, Ian S. McLean & Masanori
Iye
, Editors, Proc. SPIE 6269, 62691H (
2006)