This paper describes a process of spacecraft flight software development that reuses requirements, designs, and implementations. Beginning in 1997, The Johns Hopkins University Applied Physics Laboratory (JHU/APL) developed the flight software for five different space missions: (1) Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED), (2) COmet Nucleus TOUR (CONTOUR), (3) MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER), (4) Solar TErrestrial RElations Observatory (STEREO), and (5) New Horizons, a mission to Pluto and beyond. JHU/APL met strict constraints of budget and schedule by reusing products from each mission for the following one in a successively more comprehensive fashion. Keys to the success of this reuse are consistent external interface protocols, rigorous requirements management, retention of the original development documentation, use of a consistent development process, and a group organization that fosters reuse. The reused packages include bootstrap, task scheduling, uplink, command handling, autonomy, and 1553 bus support.

During 16 weeks of continuous SETI observing at the Parkes Observatory in New South Wales, Australia, a set of time-averaged data with 643 Hz resolution were recorded and returned to the SETI Institute for post-processing. These data are the 14 second (10 frame) average powers in each of 15,552 "subband" channels covering 10 MHz of the spectrum in both right and left circular polarizations that were used by the signal detection hardware to baseline and threshold the 1 Hz high resolution SETI spectra. The observations covered frequencies from 1.2 to 3 GHz, tracking 209 stellar targets across the, sky. The data at each frequency were averaged over all directions and then interrogated to attempt to determine the prevalence of radio frequency interference (RFI). Estimates were made for the probability of encountering RFI at a particular frequency. Particular attention has been paid to those portions of the spectrum that are allocated as primary use status, or footnote protection for radioastronomy. This sixteen-week snapshot of the RFI situation at Parkes is by now out of date. Unfortunately, a year later, the situation has undoubtedly worsened. (C) 2000 Elsevier Science Ltd. All rights reserved.

AbstractWe report on a search for narrow band emissions from the vicinity of 36 solar type (F6 to K4) target stars and 13 other non-solar type stars within 11.5 parsecs at 5 possible interstellar beacon frequencies of π*fH, 2π*fH, e*fOH, e*(fOH+fH) and3He (4.462, 8.925, 4.532, 8.393 and 8.666 GHz respectively). The frequencies were selected by scaling important naturally occurring lines by fundamental constants. The stars were selected for a distance of less than 11.5 parsecs to give sufficient time for a nearby civilisation to have detected early Earth radio leakage signals and to have replied. The search was carried using the 64-m Parkes telescope with the Phoenix instrumentation and the 22-m Mopra telescope for candidate verification. The instrument combination allowed for a low interference, high resolution, high sensitivity search. We did not detect any signals from any of the target stars. If a civilisation at a distance of 10 pc had beamed 10 kW signals at us using a 100-m dish, we would have detected the transmission at the 10 sigma level. Thus we can exclude signals above this level.

The phase and amplitude weights of each element in an adaptive, digitally beamformed array antenna can be calculated by a systolic parallel processor. The authors propose that the entire weight calculation (both QR decomposition, previously discussed by W.M. Gentleman and H.T. Kung (1981), and the back-substitutions, which are presented for the first time) be performed in a triangular array of processors. This has the highly desirable property of graceful degradation: the loss of one or more component processors does not cause the computed weights to degrade catastrophically. The loss of a processor in the systolic array merely reduces the number of available degrees of freedom. Moreover, the processing array does not need to be globally reconfigured; the functions of all the remaining processors are unaffected and their interconnections are undisturbed. The authors describe the processing flow in the systolic array, show how its degradation is inherently graceful, and present a realistic example of graceful degradation.

view Abstract Citations (46) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Molecular Gas within 2 degrees of the Galactic Center. I. Survey of 13CO Emission Heiligman, Gary M. Abstract The emission from the Galactic center at 2.72 mm from (C-13)O has been surveyed, and the results are reported. Data from 488 spectra taken in the region of l between -2.0 deg and +2.0 deg and b between -0.467 deg and +0.467 deg, and with a spectral resolution of 2.7 km/s over the V(LSR) range of -300 km/s to +300 km/s, are presented in eight l-v diagrams and in 123 maps in the plane of the sky. An averaged l-v diagram shows that virtually all of the (C-13)O emission falls within a roughly symmetrical parallelogram in l-v space; the center of symmetry is near l = +0.25 deg, V(LSR) = +30 km/s. A map of the integrated (C-13)O is presented which is very similar to maps of the far-IR continuum in which Sgr A, B2, C, and D are prominent. Maps of the emission at absolute value of V(LSR) above 100 km/s show that most of the high-velocity gas is tilted out of the Galactic plane by 7 deg; the nuclear disk appears to be inclined to the line of sight by about 85 deg. Publication: The Astrophysical Journal Pub Date: March 1987 DOI: 10.1086/165102 Bibcode: 1987ApJ...314..747H Keywords: Carbon Monoxide; Galactic Nuclei; Interstellar Gas; Milky Way Galaxy; Molecular Clouds; Astronomical Coordinates; Astronomical Maps; Galactic Structure; Temperature Distribution; Astrophysics; GALAXIES: THE GALAXY; INTERSTELLAR: MOLECULES; GALAXIES: NUCLEI full text sources ADS | data products SIMBAD (4)

view Abstract Citations (31) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Aperture-Synthesis Observations of Carbon Monoxide in the EGG Nebula Heiligman, G. M. ; Berge, G. L. ; Claussen, M. J. ; Leighton, R. B. ; Lo, K. Y. ; Masson, C. R. ; Moffet, A. T. ; Phillips, T. G. ; Sargent, A. I. ; Scott, S. L. ; Scoville, N. Z. ; Wannier, P. G. ; Woody, D. P. Abstract The authors have mapped the λ = 2.6 mm emission from CO in the bipolar nebula CRL 2688 (the Egg Nebula) with 7arcsec resolution using the Owens Valley millimeter-wave interferometer. The detected CO emission is confined to a bright core 10arcsec×15arcsec in size; it is centered on and has the same position angle as the optical reflection nebula. There is a velocity gradient of 3 km s-1arcsec-1 along the major axis of the core source. The bright core source has a high excitation temperature of ≡70K. The similarity between the CO and optical images strongly suggests that the bright CO core is spatially coincident with the visible reflecting dust. Publication: The Astrophysical Journal Pub Date: September 1986 DOI: 10.1086/164501 Bibcode: 1986ApJ...308..306H Keywords: Carbon Monoxide; Planetary Nebulae; Synthetic Apertures; Image Processing; Interstellar Matter; Molecular Spectra; Radio Interferometers; Astrophysics; INTERSTELLAR: MOLECULES; NEBULAE: INDIVIDUAL ALPHANUMERIC: CRL 2688 full text sources ADS | data products SIMBAD (1)

Annals of the New York Academy of SciencesVolume 470, Issue 1 p. 379-379 Microwave Measurement of the Galactic Helium-3 Abundance G. M. HEILIGMAN, G. M. HEILIGMAN NASINRC Resident Research Associate, Jet Propulsion Laboratory, California Institute of Technology Pasadena, California 91 109Search for more papers by this authorD. G. YORK, D. G. YORK University of Chicago Chicago, Illinois 60637Search for more papers by this author G. M. HEILIGMAN, G. M. HEILIGMAN NASINRC Resident Research Associate, Jet Propulsion Laboratory, California Institute of Technology Pasadena, California 91 109Search for more papers by this authorD. G. YORK, D. G. YORK University of Chicago Chicago, Illinois 60637Search for more papers by this author First published: May 1986 https://doi.org/10.1111/j.1749-6632.1986.tb48004.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume470, Issue1Twelfth Texas Symposium On Relaivistic AstrophysicsMay 1986Pages 379-379 RelatedInformation

view Abstract Citations (28) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Clump 1: an Unusual Molecular Cloud Complex near the Galactic Center Bania, T. M. ; Stark, A. A. ; Heiligman, G. M. Abstract The properties of the (C-12)O and (C-13)O emission from Clump I, a complex of molecular clouds which shows the largest noncircular velocities of any molecular material known in the Milky Way, are studied. Observations of the J = 1-0 rotational transitions of the above molecules are reported, and the large-scale distribution and kinematics of the molecular gas in the direction of Clump I are discussed. The small-scale structure is described based on one arcmin resolution of (C-13)O data. Physical properties of the molecular material are derived, and the dynamics of the Clump I clouds are discussed in the context of their stability against Galactic tidal forces. It is concluded that all the clouds in the complex are gravitationally bound, although their outer envelopes may be tidally disrupted by the Galactic potential. The relative motion of the clouds is qualitatively similar to giant molecular cloud complexes in spiral arms of the outer Galactic disk, but the velocities are higher. Publication: The Astrophysical Journal Pub Date: August 1986 DOI: 10.1086/164422 Bibcode: 1986ApJ...307..350B Keywords: Galactic Nuclei; Galactic Structure; Interstellar Gas; Milky Way Galaxy; Molecular Clouds; Astronomical Maps; Carbon Monoxide; Hydrogen; Molecular Rotation; Molecular Spectra; Astrophysics; GALAXIES: MILKY WAY; GALAXIES: NUCLEI; GALAXIES: STRUCTURE; INTERSTELLAR: MOLECULES full text sources ADS | data products SIMBAD (5)

NGC7027 is a very young planetary nebula in which the ionization of the red giant wind is only partially complete. Previous measurements of the CO (1–0) emission at 115 GHz from NGC7027 (Mufson, Lyon, Marioni, 1975) did not have enough angular resolution to reveal the structure of the neutral cloud. We have recently mapped the CO (1–0) emission from NGC7027 (Masson et al., Ap. J., in preparation), using the Owens Valley Millimeter-wave Interferometer with a resolution of 7″ × 11″.

view Abstract Citations (63) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-resolution CO observations of NGC 7027. Masson, C. R. ; Cheung, K. W. ; Berge, G. L. ; Claussen, M. J. ; Heiligman, G. M. ; Leighton, R. B. ; Lo, K. Y. ; Moffet, A. T. ; Phillips, T. G. ; Sargent, A. I. ; Scott, S. L. ; Woody, D. P. Abstract High-resolution maps have been made of 2.6 mm CO(1-0) emission from the planetary nebula NGC 7027 using the Owens Valley millimeter-wave interferometer. The observations demonstrate the anisotropic structure of the neutral cloud. The influence of this cloud on the structure of the H II region is discussed. Anomalous, high-velocity CO emission wings are also detected, and the relation between these and the interface between the ionized and neutral zones is analyzed. Publication: The Astrophysical Journal Pub Date: May 1985 DOI: 10.1086/163176 Bibcode: 1985ApJ...292..464M Keywords: Carbon Monoxide; Molecular Clouds; Neutral Gases; Planetary Nebulae; Radio Sources (Astronomy); Astronomical Maps; Emission Spectra; H Ii Regions; Ionized Gases; Mass Distribution; Millimeter Waves; Radial Velocity; Stellar Envelopes; Astrophysics full text sources ADS | data products SIMBAD (1)

view Abstract Citations (121) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Aperture synthesis observations of CO emission from the nucleus of IC342. Lo, K. Y. ; Berge, G. L. ; Claussen, M. J. ; Heiligman, G. M. ; Leighton, R. B. ; Masson, C. R. ; Moffet, A. T. ; Phillips, T. G. ; Sargent, A. I. ; Scott, S. L. ; Wannier, P. G. ; Woody, D. P. Abstract The first aperture synthesis maps of 2.6 mm wavelength CO (J = 1-0) emission from an external galaxy, IC 342. The 7-arcsec resolution maps of the nuclear region were made with the Owens Valley Millimeter-Wave Interferometer. They reveal that the CO source is distributed in a bar, 300 pc x more than about 1500 pc, with a velocity gradient across the width of the bar. The observations suggest that the molecular gas in the nucleus is moving in response to an oval gravitational potential. The implications of an oval potential on enhanced star formation and other activities are discussed. Publication: The Astrophysical Journal Pub Date: July 1984 DOI: 10.1086/184305 Bibcode: 1984ApJ...282L..59L Keywords: Carbon Monoxide; Galactic Nuclei; Galactic Structure; Interstellar Gas; Astronomical Maps; Brightness Temperature; Millimeter Waves; Stellar Evolution; Astrophysics full text sources ADS | data products NED (4) SIMBAD (3)

view Abstract Citations (37) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Aperture synthesis observations of CO emission from the W3 molecular cloud core. Claussen, M. J. ; Berge, G. L. ; Heiligman, G. M. ; Leighton, R. B. ; Lo, K. Y. ; Masson, C. R. ; Moffet, A. T. ; Phillips, T. G. ; Sargent, A. I. ; Scott, S. L. ; Wannier, P. G. ; Woody, D. P. Abstract The first aperture synthesis maps of (C-12)(O) (J = 1-0) emission from a galactic star-forming region are presented. The line and continuum emission from a 1 arcmin field centered on W3 IRS5 have been mapped with the Owens Valley millimeter-wave interferometer. Although no radio continuum emission from IRS5 was detected to a five sigma limit of 130 mJy, compact sources of high velocity red- and blue-shifted CO emission with T(B) of about 20 K were found associated with IRS5. The estimated mass in each wing is one solar mass, with density of about 100,000/cu cm. The outflow is similar to other known sources with high-velocity emission and has a short dynamic lifetime such as found in Orion. It is suggested that the two infrared sources which comprise IRS5 are in differing stages of evolution. Publication: The Astrophysical Journal Pub Date: October 1984 DOI: 10.1086/184370 Bibcode: 1984ApJ...285L..79C Keywords: Emission Spectra; Infrared Stars; Interferometry; Molecular Clouds; Radio Sources (Astronomy); Stellar Evolution; Astronomical Maps; Carbon Monoxide; Millimeter Waves; Radial Velocity; Synthetic Apertures; Astrophysics full text sources ADS | data products SIMBAD (1)

We report here the progress of a survey of galactic nuclei for water-vapour maser emission at 22.235 GHz. We observed 29 late-type galaxies in November 1982, January 1983, and September 1983 using the 40-m radio telescope of the Owens Valley Radio Observatory (OVRO) equipped with a travelling-wave maser receiver1. We have detected maser emission from four nuclei: NGC4258 (M106), NGC1068 (M77), NGC3034 (M82), and NGC6946. The masers in NGC4258 and NGC1068 are extremely luminous; NGC1068 has the most luminous water-vapour maser yet reported—350 L⊙ assuming isotropic emission. We suggest that the extremely bright nuclear masers indicate an ongoing burst of star formation, and therefore provide a useful probe of the physical conditions of the starburst phenomenon.