Search NASA⌕ Search

Engineering topics

Hirabayashi, H.

Publications and source records attributed to Hirabayashi, H..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

The Pearson-Readhead Survey from Space

We are using the VSOP mission to observe a complete sample of Pearson-Readhead survey sources at 4.8 GHz to determine core brightness temperatures and pc-scale jet properties.

Radio↗
NASA NTRS2000

Space VLBI observations of 3C 279 at 1.6 and 5 GHz

We present VLBI Space Observatory Programme (VSOP) observations of the gamma-ray blazar 3C 279 at 1.6 and 5 GHz made on 1998 January 9-10 with the HALCA satellite and ground arrays including the Very Long Baseline Array (VLBA).

Extragalactic radio-sources baseline interferometr↗
NASA NTRS2000

The Pearson-Readhead Survey from space

The VSOP Space VLBI mission uses the HALCA spacecraft, launched from Japan in February 1997, in conjunction with gound radio observatories around the world to create a high resolution radio-wavelength imaging facility

Radio↗
NASA NTRS1995

Status of high temperature superconductor development for accelerator magnets

High temperature superconductors are still under development for various applications. As far as conductors for magnets are concerned, the development has just been started. Small coils wound by silver sheathed Bi-2212 and Bi-2223 oxide conductors have been reported by a few authors. Essential properties of high T(sub c) superconductors like pinning force, coherent length, intergrain coupling, weak link, thermal property, AC loss and mechanical strength are still not sufficiently understandable. In this talk, a review is given with comparison between the present achievement and the final requirement for high T(sub c) superconductors, which could be particularly used in accelerator magnets. Discussions on how to develop high T(sub c) superconductors for accelerator magnets are included with key parameters of essential properties. A proposal of how to make a prototype accelerator magnet with high T(sub c) superconductors with prospect for future development is also given.

Hirabayashi, H.↗
NASA NTRS1995

ARISE - Advanced Radio Interferometry Between Space and Earth

A mission is described called ARISE, Advanced Radio Interferometry between Space and Earth. ARISE will will provide affordable very long baseline interferometry (VLBI) using second- generation VLBI and one or more inflatable space radio telescopes.

radio interferometry ARISE very long baseline inte↗
NASA NTRS1994

22 GHz VLBI Survey: Status Report and Preliminary Results

A ground-based VLBI survey to measure the visibilities and correlated flux densities in continuum at 22 GHz of more than 140 extragalactic radio sources has been conducted with baselines up to approximately 11 000 km. The project has been designed to help in preparation of target lists for VSOP and Radioastron Space VLBI missions as well as providing observational data for statistical study of structural properties at 22 GHz on sub-milliarcsecond scales for this large sample of extragalactic sources.

VLBI extragalactic radio sources survey↗
NASA NTRS1993

Pulsar astrometry by using VLBI (PSR0329 between Kashima 26mPhi and Usuda 64mPhi)

Communications Research Laboratory (CRL) carried out a VLBI (Very Long Baseline Interferometer) experiment of the Pulsar 0329 plus 54 on November in 1992 between Kashima 26mPhi and Usuda 64mPhi. We got a correlation for it by using K-3 VLBI correlator which was developed by CRL. Though we observed a slow pulsar this time, we are going to make millisecond pulsar experiments by making good use of this result and by using K-4 correlator which is under developing in CRL. Its result will give us precise positions and proper motions of pulsars which are useful for obtaining precise pulsar timing.

Hama, S.↗
NASA NTRS1993

Microarcsecond proper motions of extragalactic water vapor masers in M33

A second-epoch spectral line VLBI synthesis map of the H2O maser associated with the H II region IC 133 in the galaxy M33 is presented. Thirty-two spatially distinct maser features were identified, and a second center of maser activity within the IC 133 complex, IC 133 West, which is displaced about 0.3 arcsec from IC 133 Main, was discovered. A comparison of the two available maps of IC 133 is used to estimate the right ascension components of proper motion over a period of 479 d for five maser features to accuracies of between 7 and 16 micro-as. The dispersions in transverse and radial velocities for the maser features are consistent with the accepted distance to M33 of 720 kpc, where the data admit a fractional uncertainty in distance of 50 percent.

Greenhill, L. J.↗
NASA NTRS1990

15 GHz space VLBI observations using an antenna on a TDRSS satellite

A 4.9 m diameter antenna in earth orbit, part of the Tracking and Data Relay Satellite System, was previously used for space VLBI observations at 2.3 GHz. It has now been used successfully with two ground antennas for VLBI measurements at 15 GHz. Although the sensitivity (gain/system temperature) of the orbiting antenna was a factor of 6 poorer at 15 GHz than at 2.3 GHz, 11 out of 22 extragalactic sources were detected on space-ground baselines, up to a maximum baseline of 1.63 earth diameters. The results suggest that the distribution of source visibilities at 15 and 2.3 GHz are similar for these baseline lengths. Model-dependent brightness temperatures of 1-2.5 x 10 to the 12th K were derived for six sources. This suggests that sources with brightness temperatures in this range are as common at 15 GHz as at 2.3 GHz. The coherence on space-ground baselines (this includes effects due to the phase transfer from the ground to the satellite and the reconstruction of the spacecraft orbit) was 0.76 for 340 s integrations.

Linfield, R. P.↗
NASA NTRS1988

The Pearson-Readhead Survey from Space

The VSOP Space VLBI mission uses the HALCA spacecraft, launched from Japan in February 1997, in conjunction with ground radio observatories around the world to create a high resolution radio-wave length imaging facility. We are using this unique facility to observe a complete sample of Pearson-Readhead Survey sources at 4.8 GHz to determine core brightness temperatures and pc-scale jet properties. The Pearson-Readhead sample has been used for extensive ground-based VLBI survey studies. This sample is ideal for a VSOP survey because the sources are strong, the VSOP u-v coverages are especially good above +350 declination, and multi-epoch ground-based VLBI data and other existing supporting data on these sources exceeds that of any other possible sample. We have chosen to observe a complete subset of this sample that is most likely to show fringes on space-earth baselines. To date we have imaged a majority of the 31 sources in our sample. In addition, we are obtaining matched- resolution 15 GHz observations using the VLBA at epochs close in time to the space VLBI observations to investigate the spectral indices of the source components at high resolution. We gratefully acknowledge the VSOP Project, which is led by the Japanese Institute of Space and Astronautical Science in cooperation with many organizations and radio telescopes around the world. This research was performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.

Preston, R. A.↗