T. L. Roellig

University of Minnesota Duluth, Duluth, Minnesota, United States

Are you T. L. Roellig?

Claim your profile

Publications (153)370.46 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the world’s largest airborne observatory, featuring a 2.5 meter effective aperture telescope housed in the aft section of a Boeing 747SP aircraft. SOFIA’s current instrument suite includes: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), a 5-40 μm dual band imager/grism spectrometer developed at Cornell University; HIPO (High-speed Imaging Photometer for Occultations), a 0.3-1.1μm imager built by Lowell Observatory; GREAT (German Receiver for Astronomy at Terahertz Frequencies), a multichannel heterodyne spectrometer from 60-240 μm, developed by a consortium led by the Max Planck Institute for Radio Astronomy; FLITECAM (First Light Infrared Test Experiment CAMera), a 1-5 μm wide-field imager/grism spectrometer developed at UCLA; FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), a 42-200 μm IFU grating spectrograph completed by University Stuttgart; and EXES (Echelon-Cross-Echelle Spectrograph), a 5-28 μm highresolution spectrometer designed at the University of Texas and being completed by UC Davis and NASA Ames Research Center. HAWC+ (High-resolution Airborne Wideband Camera) is a 50-240 μm imager that was originally developed at the University of Chicago as a first-generation instrument (HAWC), and is being upgraded at JPL to add polarimetry and new detectors developed at Goddard Space Flight Center (GSFC). SOFIA will continually update its instrument suite with new instrumentation, technology demonstration experiments and upgrades to the existing instrument suite. This paper details the current instrument capabilities and status, as well as the plans for future instrumentation.
    SPIE Astronomical Telescopes + Instrumentation; 07/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities are viewed as a first comprehensive assessment of the Observatory's performance and are used to guide future development activities, as well as to identify additional Observatory upgrades. Pointing stability was evaluated, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an active mass damper system installed on the telescope. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have also been performed. Additional tests targeted basic Observatory capabilities and requirements, including pointing accuracy, chopper evaluation and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA Observatory performance and characterization.
    The Astrophysical Journal Supplement Series 05/2014; 212(2). DOI:10.1088/0067-0049/212/2/24 · 14.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory, carrying a 2.5 m telescope onboard a heavily modified Boeing 747SP aircraft. SOFIA is optimized for operation at infrared wavelengths, much of which is obscured for ground-based observatories by atmospheric water vapor. The SOFIA science instrument complement consists of seven instruments: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), GREAT (German Receiver for Astronomy at Terahertz Frequencies), HIPO (High-speed Imaging Photometer for Occultations), FLITECAM (First Light Infrared Test Experiment CAMera), FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), EXES (Echelon-Cross-Echelle Spectrograph), and HAWC (High-resolution Airborne Wideband Camera). FORCAST is a 5-40 μm imager with grism spectroscopy, developed at Cornell University. GREAT is a heterodyne spectrometer providing high-resolution spectroscopy in several bands from 60-240 μm, developed at the Max Planck Institute for Radio Astronomy. HIPO is a 0.3-1.1 μm imager, developed at Lowell Observatory. FLITECAM is a 1-5 μm wide-field imager with grism spectroscopy, developed at UCLA. FIFI-LS is a 42-210 μm integral field imaging grating spectrometer, developed at the University of Stuttgart. EXES is a 5-28 μm high-resolution spectrograph, developed at UC Davis and NASA ARC. HAWC is a 50-240 μm imager, developed at the University of Chicago, and undergoing an upgrade at JPL to add polarimetry capability and substantially larger GSFC detectors. We describe the capabilities, performance, and status of each instrument, highlighting science results obtained using FORCAST, GREAT, and HIPO during SOFIA Early Science observations conducted in 2011.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2013; DOI:10.1117/12.2022791 · 0.20 Impact Factor
  • E. E. Becklin, R. D. Gehrz, T. L. Roellig
    [Show abstract] [Hide abstract]
    ABSTRACT: The joint U.S. and German Stratospheric Observatory for Infrared Astronomy (SOFIA), a program to develop and operate a 2.5-meter infrared airborne telescope in a Boeing 747SP, has obtained first science with the FORCAST camera in the 5 to 40 micron spectral region and the GREAT heterodyne spectrometer in the 130 to 240 micron spectral region. We briefly review the characteristics and status of the observatory. Spectacular science results on regions of star formation will be discussed. The FORCAST images show several discoveries and the potential for determining how massive stars form in our Galaxy. The GREAT heterodyne spectrometer has made mapping observations of the [C II] line at 158 microns, high J CO lines, and other molecular lines including SH. The HIPO high speed photometer and the high speed camera FDC were used to observe the 2011 June 23 UT stellar occultation by Pluto.
    Proceedings of SPIE - The International Society for Optical Engineering 10/2012; DOI:10.1117/12.931308 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for Observatory performance evaluation. These in-flight opportunities have been viewed as a first comprehensive assessment of the Observatory's performance and will be used to address the development activity that is planned for 2012, as well as to identify additional Observatory upgrades. A series of 8 SOFIA Characterization And Integration flights have been conducted from June to December 2011. The HIPO science instrument in conjunction with the DSI Super Fast Diagnostic Camera (SFDC) have been used to evaluate pointing stability, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an Active Mass Damper system installed on Telescope Assembly. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have been performed using the HIPO+FLITECAM Science Instrument conguration (FLIPO). A number of additional tests and measurements have targeted basic Observatory capabilities and requirements including, but not limited to, pointing accuracy, chopper evaluation and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA Observatory performance and characterization.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.925736 · 0.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent infrared (IR) observations of freshly-formed dust in supernova remnants (SNRs) have yielded significantly lower dust masses than predicted by theoretical models and measured from high redshift observations. The Crab Nebula's pulsar wind is thought to be sweeping up freshly-formed supernova (SN) dust along with the ejected gas. The evidence for this dust was found in the form of an IR excess in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially resolved emission spectra of dust in the Crab Nebula acquired with the Infrared Spectrograph aboard the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from from S, Si, Ne, Ar, O, Fe, and Ni. We derived a synchrotron spectral map from the 3.6 and 4.5 microns images, and subtracted this contribution from our data to produce a map of the residual continuum emission from dust. The dust emission appears to be concentrated along the ejecta filaments and is well described by an amorphous carbon or silicate grain compositions. We find a dust temperature of 55+/- 4 K for silicates and 60 +/- 7 K for carbon grains. The total estimated dust mass is 0.0012-0.012 solar masses, well below the theoretical dust yield predicted for a core-collapse supernova. Our grain heating model implies that the dust grain radii are relatively small, unlike what is expected for dust grains formed in a Type IIP SN.
    The Astrophysical Journal 05/2012; 753(1). DOI:10.1088/0004-637X/753/1/72 · 6.28 Impact Factor
  • Thomas L. Roellig, L. Yuen, D. Sisson, R. Hang
    [Show abstract] [Hide abstract]
    ABSTRACT: NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) airborne observatory flies in a modified B747-SP aircraft in the lower stratosphere above more than 99.9% of the Earth’s water vapor. As low as this residual water vapor is, it will still affect SOFIA’s infrared and sub-millimeter astronomical observations. As a result, a heterodyne instrument has been developed to observe the strength and shape of the 183GHz rotational line of water, allowing measurements of the integrated water vapor overburden in flight. In order to be useful in correcting the astronomical signals, the required measured precipitable water vapor accuracy must be 2 microns or better, 3 sigma, and measured at least once a minute. The Water Vapor Monitor has flown 22 times during the SOFIA Early Science shared-risk period. The instrument water vapor overburden data obtained were then compared with concurrent data from GOES-V satellites to perform a preliminary calibration of the measurements. This presentation will cover the results of these flights. The final flight calibration necessary to reach the required accuracy will await subsequent flights following the SOFIA observatory upgrade that is taking place during the spring and summer of 2012.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory For Infrared Astronomy (SOFIA) is an airborne observatory consisting of a specially modified Boeing 747SP with a 2.7 m telescope, flying at altitudes as high as 13.7 km (45,000 ft). Designed to observe at wavelengths from 0.3 μm to 1.6 mm, SOFIA operates above 99.8% of the water vapor that obscures much of the infrared and submillimeter. SOFIA has seven science instruments under development, including an occultation photometer, near-, mid-, and far-infrared cameras, infrared spectrometers, and heterodyne receivers. SOFIA, a joint project between NASA and the German Aerospace Center Deutsches Zentrum für Luft und-Raumfahrt, began initial science flights in 2010 December, and has conducted 30 science flights in the subsequent year. During this early science period three instruments have flown: the mid-infrared camera FORCAST, the heterodyne spectrometer GREAT, and the occultation photometer HIPO. This Letter provides an overview of the observatory and its early performance.
    The Astrophysical Journal Letters 03/2012; 749(2):L17. DOI:10.1088/2041-8205/749/2/L17 · 5.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents spectra in the 2 to 20 μm range of quiescent cloud material located in the IC 5146 cloud complex. The spectra were obtained with NASA's Infrared Telescope Facility SpeX instrument and the Spitzer Space Telescope's Infrared Spectrometer. We use these spectra to investigate dust and ice absorption features in pristine regions of the cloud that are unaltered by embedded stars. We find that the H2O-ice threshold extinction is 4.03 ± 0.05 mag. Once foreground extinction is taken into account, however, the threshold drops to 3.2 mag, equivalent to that found for the Taurus dark cloud, generally assumed to be the touchstone quiescent cloud against which all other dense cloud and embedded young stellar object observations are compared. Substructure in the trough of the silicate band for two sources is attributed to CH3OH and NH3 in the ices, present at the ~2% and ~5% levels, respectively, relative to H2O-ice. The correlation of the silicate feature with the E(J – K) color excess is found to follow a much shallower slope relative to lines of sight that probe diffuse clouds, supporting the previous results by Chiar et al.
    The Astrophysical Journal 03/2011; 731(1):9. DOI:10.1088/0004-637X/731/1/9 · 6.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint U.S./German project, is a 2.5-meter infrared airborne telescope carried by a Boeing 747-SP that flies in the stratosphere at altitudes as high as 45,000 feet (13.72 km). This facility is capable of observing from 0.3 {\mu}m to 1.6 mm with an average transmission greater than 80 percent. SOFIA will be staged out of the NASA Dryden Flight Research Center aircraft operations facility at Palmdale, CA. The SOFIA Science Mission Operations (SMO) will be located at NASA Ames Research Center, Moffett Field, CA. First science flights began in 2010 and a full operations schedule of up to one hundred 8 to 10 hour flights per year will be reached by 2014. The observatory is expected to operate until the mid 2030's. SOFIAs initial complement of seven focal plane instruments includes broadband imagers, moderate-resolution spectrographs that will resolve broad features due to dust and large molecules, and high-resolution spectrometers capable of studying the kinematics of atomic and molecular gas at sub-km/s resolution. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community and for future instrumentation development. The operational characteristics of the SOFIA first-generation instruments are summarized. The status of the flight test program is discussed and we show First Light images obtained at wavelengths from 5.4 to 37 \"im with the FORCAST imaging camera. Additional information about SOFIA is available at http://www.sofia.usra.edu and http://www.sofia.usra.edu/Science/docs/SofiaScienceVision051809-1.pdf
    Advances in Space Research 02/2011; 48(6). DOI:10.1016/j.asr.2011.05.023 · 1.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Spectroscopic observations of 189 targets were obtained using eleven different optical/near-infrared instruments at eight different observatories. Details of this follow-up are given in Table 2. (12 data files).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have conducted a 4030 deg2 near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to Digitized Sky Survey images, we find that 107 of our proper motion candidates lack counterparts at B, R, and I bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the "blue L" and "red L" dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST.
    The Astrophysical Journal Supplement Series 08/2010; 190(1):100. DOI:10.1088/0067-0049/190/1/100 · 14.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have conducted a 4030-square-deg near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to DSS images, we find that 107 of our proper motion candidates lack counterparts at B-, R-, and I-bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five "red L" dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight "blue L" dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the "blue L" and "red L" dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST. Comment: To appear in the September 2010 issue of The Astrophysical Journal, Supplement Series
  • Source
    R. D. Gehrz, T. L. Roellig, M. W. Werner
    [Show abstract] [Hide abstract]
    ABSTRACT: A key to the success of the Spitzer Space Telescope (formerly SIRTF) Mission was a unique management structure that promoted open communication and collaboration among scientific, engineering, and contractor personnel at all levels of the project. This helped us to recruit and maintain the very best people to work on Spitzer. We describe the management concept that led to the success of the mission. Specific examples of how the project benefited from the communication and reporting structure, and lessons learned about technology are described.
    Proceedings of SPIE - The International Society for Optical Engineering 08/2010; DOI:10.1117/12.864363 · 0.20 Impact Factor
  • Thomas L. Roellig, Lunming Yuen, David Sisson, Allan Meyer
    [Show abstract] [Hide abstract]
    ABSTRACT: The SOFIA airborne observatory flies in the lower stratosphere above more than 99.9% of the Earth's water vapor. As low as this residual water vapor is, it will still affect SOFIA's infrared and sub-millimeter astronomical observations. As a result, a heterodyne instrument operating at 183 GHz will be used to measure the integrated water vapor overburden in flight. The accuracy of the measured precipitable water vapor must be 2 microns or better, 3 sigma, and measured at least once a minute. This presentation will cover the design and the measured laboratory performance of this instrument, and will discuss other options for determining the water vapor overburden during the SOFIA Early Science shared-risk period.
    Proceedings of SPIE - The International Society for Optical Engineering 07/2010; DOI:10.1117/12.856506 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint U.S./German Project to develop and operate a 2.5-meter infrared airborne telescope in a Boeing 747-SP that flies in the stratosphere at altitudes as high as 45,000 and is capable of observations from 0.3 microns to 1.6 mm with an average transmission greater than 80 percent. SOFIA will be staged out of the NASA Dryden Flight Research Center aircraft operations facility at Palmdale, CA and the SOFIA Science Mission Operations Center (SSMOC) will be located at NASA Ames Research Center, Moffett Field, CA. First science flights will begin in 2010, and the number of flights will ramp up annually with a flight rate of over 100 8 to 10 hour flights per year expected by 2014. The observatory is expected to operate until the mid 2030's. SOFIA will initially fly with eight focal plane instruments that include broadband imagers, moderate resolution spectrographs that will resolve broad features due to dust and large molecules, and high resolution spectrometers capable of studying the kinematics of molecular and atomic gas lines at km/s resolution. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community and future instrumentation developments. The operational characteristics of the SOFIA first-generation instruments are summarized and we give several specific examples of the types of scientific studies to which these instruments are expected to make fundamental scientific contributions.
  • Source
    R. D. Gehrz, E. E. Becklin, T. L. Roellig
    [Show abstract] [Hide abstract]
    ABSTRACT: The U.S./German Stratospheric Observatory for Infrared Astronomy (SOFIA, Figure 1) is a 2.5-meter infrared airborne telescope in a Boeing 747-SP flying in the stratosphere at altitudes as high as 45,000 feet where the atmospheric transmission averages ≥ 80% throughout the 0.3 - 1600 μm spectral region. SOFIA's first-generation instruments include broadband imagers, moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km s−1 resolution. These and future instruments will enable SOFIA to make unique contributions to studies of the physics and chemistry of stellar evolution for many decades. Science flights will begin in 2010. A full operations schedule of at least 100 flights per year will begin in 2014 and will continue for 20 years. The SOFIA Guest Investigator (GI) program, open to investigators worldwide, will constitute the major portion of the SOFIA observing program.
    Proceedings of the International Astronomical Union 10/2009; 5:529 - 530. DOI:10.1017/S1743921310010537
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a joint US/German Project to develop and operate a gyrostabilized 2.5-m telescope in a Boeing 747-SP. This observatory will allow astronomical observations from 0.3 μm to sub-millimeter wavelengths at stratospheric altitudes as high as 45,000 ft where the atmosphere is not only cloud-free, but largely transparent at infrared wavelengths. The dynamics and chemistry of interstellar matter, and the details of embedded star formation will be key science goals. In addition, SOFIA’s unique portability will enable large-telescope observations at sites required to observe transient phenomena and location specific events. SOFIA will offer the convenient accessibility of a ground-based telescope for servicing, maintenance, and regular technology upgrades, yet will also have many of the performance advantages of a space-based telescope. Initially, SOFIA will fly with nine first-generation focal plane instruments that include broad-band imagers, moderate resolution spectrographs that will resolve broad features from dust and large molecules, and high resolution spectrometers capable of studying the chemistry and detailed kinematics of molecular and atomic gas. First science flights will begin in 2010, leading to a full operations schedule of about 120 8–10 h flights per year by 2014. The next call for instrument development that can respond to scientifically exciting new technologies will be issued in 2010. We describe the SOFIA facility and outline the opportunities for observations by the general scientific community with cutting edge focal plane technology. We summarize the operational characteristics of the first-generation instruments and give specific examples of the types of fundamental scientific studies these instruments are expected to make.
    Advances in Space Research 08/2009; 44(4-44):413-432. DOI:10.1016/j.asr.2009.04.011 · 1.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The mid-infrared spectrum of the rather circular planetary nebula NGC 2792 taken with the Spitzer Space Telescope is presented. This spectrum is combined with the ultraviolet IUE spectrum and with the spectrum in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebula is then calculated in two ways. First by directly calculating and adding individual ion abundances, and secondly by building a model nebula that attempts to reproduce the observed spectrum. Because it is now possible to include the nebular temperature gradient, the chemical composition is more accurate than has been given earlier in the literature. Discussion of both the central star and the evolution of the star-nebula is then given.
    Astronomy and Astrophysics 07/2009; DOI:10.1051/0004-6361/200912076 · 4.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An updated Science Vision for the SOFIA project is presented, including an overview of the characteristics and capabilities of the observatory and first generation instruments. A primary focus is placed on four science themes: 'The Formation of Stars and Planets', 'The Interstellar Medium of the Milky Way', 'Galaxies and the Galactic Center' and 'Planetary Science'. Comment: 128 pages pdf format Version 2 corrects: Attribution for Figure 5-1 Definition of "SIS" Affiliation of one of the contributors to the Science Vision

Publication Stats

3k Citations
370.46 Total Impact Points

Institutions

  • 2004–2012
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
  • 2008
    • NASA
      Вашингтон, West Virginia, United States
  • 2006
    • Joint Astronomy Centre
      Hilo, Hawaii, United States
  • 2005
    • Harvard-Smithsonian Center for Astrophysics
      • Smithsonian Astrophysical Observatory
      Cambridge, Massachusetts, United States
  • 1996
    • The University of Tokyo
      • Department of Astronomy
      Tokyo, Tokyo-to, Japan
    • Nagoya University
      • Division of Cell Science
      Nagoya, Aichi, Japan
  • 1985
    • University of California, Los Angeles
      Los Ángeles, California, United States
  • 1981
    • Cornell University
      • Center for Radiophysics and Space Research (CRSR)
      Ithaca, New York, United States