Zobrazeno 1 - 10
of 51
pro vyhledávání: '"B. J. Geldzahler"'
Autor:
Patrick Charlot, L. D. Zhang, David A. Boboltz, B. J. Geldzahler, G. E. Lanyi, Alan L. Fey, Edward B. Fomalont, O. J. Sovers, Christopher S. Jacobs, C. J. Naudet, Chopo Ma, David Gordon, Jonathan D. Romney
Publikováno v:
The Astrophysical Journal
The Astrophysical Journal, American Astronomical Society, 2010, 139 (5), pp.1713-1770. ⟨10.1088/0004-6256/139/5/1713⟩
The Astrophysical Journal, American Astronomical Society, 2010, 139 (5), pp.1713-1770. ⟨10.1088/0004-6256/139/5/1713⟩
We have measured the sub-milli-arcsecond structure of 274 extragalactic sources at 24 and 43 GHz in order to assess their astrometric suitability for use in a high frequency celestial reference frame (CRF). Ten sessions of observations with the Very
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::415fbe9801ab36ce872460043024d0d9
https://doi.org/10.1088/0004-6256/139/5/1713
https://doi.org/10.1088/0004-6256/139/5/1713
Publikováno v:
The Astrophysical Journal. 592:486-497
Rossi X-Ray Timing Explorer (RXTE) observations of Sco X-1 during 1997-1999 have been analyzed for spectral characteristics. All the X-ray branches of Sco X-1 were observed during these epochs. On the basis of our observations, we present a simple mo
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b092981365a99bef0880eb1f2bb82c8f
https://doi.org/10.1086/375577
https://doi.org/10.1086/375577
Publikováno v:
Quantum Information and Computation XII.
Establishing a quantum communication network would provide advantages in areas such as security and information processing. Such a network would require the implementation of quantum teleportation between remote parties. However, for photonic "qudits
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::70b2bda5039a697e63b16398d78b435c
https://doi.org/10.1117/12.2050978
https://doi.org/10.1117/12.2050978
Publikováno v:
The Astrophysical Journal. 553:L27-L30
The evolution of the radio emission from Sco X-1 is determined from a 56-hour continuous VLBI observation and from shorter observations over a four-year period. The radio source consists of a variable core near the binary, and two variable compact ra
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b4b5061f4eec4cebda9f8b66d22bfc53
https://doi.org/10.1086/320490
https://doi.org/10.1086/320490
Publikováno v:
The Astrophysical Journal. 512:L121-L124
The results of eight VLBA observations at 5 GHz, spanning 3 yr, have yielded a measured trigonometric parallax for Sco X-1 of 000036±000004; hence, its distance is 2.8±0.3 kpc. This is the most precise parallax measured to date. Although our measur
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a99fac5624c28592809de49629abc75c
https://doi.org/10.1086/311889
https://doi.org/10.1086/311889
Publikováno v:
The Astrophysical Journal. 484:L55-L58
From three VLBA observations at 5 GHz, taken over 13 months, we have measured the trigonometric parallax of Sco X-1 as 000023 ± 000028; hence, its distance is greater than 1300 pc. This supports the hypothesis that Sco X-1 radiates at or near the Ed
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1445c78b1dd4619ed557952fb0a97a54
https://doi.org/10.1086/310771
https://doi.org/10.1086/310771
Publikováno v:
The Astrophysical Journal. 481:489-499
We present the results of the flux density variability observations of Sco X-1 obtained during six VLA observing sessions between 1981 and 1990. The light curves indicate three timescales of flux density variation: slow, intermediate, and rapid. The
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::14e0b7235dcf0edf262136b7cc17e0ad
https://doi.org/10.1086/304029
https://doi.org/10.1086/304029
Autor:
B. J. Geldzahler
Publikováno v:
SPIE Proceedings.
With the successful completion of a field demonstration of uplink arraying at 8 GHz (X-band) using real-time atmospheric compensation enabled by phase transfer rather than time transfer techniques- completion in mid-Aug 2010, NASA is interested in de
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::99603ced71e34592b024d1332b9ad468
https://doi.org/10.1117/12.924829
https://doi.org/10.1117/12.924829
Autor:
B. J. Geldzahler
Publikováno v:
SPIE Proceedings.
For several years, NASA has been pursuing demonstrations and development of coherent uplink arraying techniques for the next generation space communications and planetary radar systems. In addition radio science experiments would benefit with a 1000
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::4d7156bcb2fbcc3395b557057deb0363
https://doi.org/10.1117/12.896229
https://doi.org/10.1117/12.896229
Autor:
A. L. Fey, B. J. Geldzahler, David Gordon, P. Charlot, C. Ma, O. J. Sovers, David A. Boboltz, Jonathan D. Romney, L. D. Zhang, C. J. Naudet, G. E. Lanyi, Christopher S. Jacobs, Ed Fomalont
Publikováno v:
The Astronomical Journal
The Astronomical Journal, American Astronomical Society, 2010, 139, pp.1695-1712. ⟨10.1088/0004-6256/139/5/1695⟩
The Astronomical Journal, American Astronomical Society, 2010, 139, pp.1695-1712. ⟨10.1088/0004-6256/139/5/1695⟩
International audience; We present astrometric results for compact extragalactic objects observed with the Very Long Baseline Array at radio frequencies of 24 and 43 GHz. Data were obtained from ten 24 hr observing sessions made over a five-year peri
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::68decfdefd838603be080e0ea08e16a6
https://hal.archives-ouvertes.fr/hal-00466226
https://hal.archives-ouvertes.fr/hal-00466226
