共 94 条
[1]
Relativistic outflows from remnants of compact object mergers and their viability for short gamma-ray bursts
[J].
Aloy, MA
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Janka, HT
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Müller, E
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ASTRONOMY & ASTROPHYSICS,
2005, 436 (01)
:273-311

Aloy, MA
论文数: 0 引用数: 0
h-index: 0
机构:
Max Planck Inst Astrophys, D-85741 Garching, Germany Max Planck Inst Astrophys, D-85741 Garching, Germany

Janka, HT
论文数: 0 引用数: 0
h-index: 0
机构:
Max Planck Inst Astrophys, D-85741 Garching, Germany Max Planck Inst Astrophys, D-85741 Garching, Germany

Müller, E
论文数: 0 引用数: 0
h-index: 0
机构:
Max Planck Inst Astrophys, D-85741 Garching, Germany Max Planck Inst Astrophys, D-85741 Garching, Germany
[2]
The Ep,i-Eiso correlation in gamma-ray bursts:: updated observational status, re-analysis and main implications
[J].
Amati, Lorenzo
.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,
2006, 372 (01)
:233-245

Amati, Lorenzo
论文数: 0 引用数: 0
h-index: 0
机构:
INAF IASF Bologna, Bologna, Italy INAF IASF Bologna, Bologna, Italy
[3]
[Anonymous], ARXIV150905543
[4]
[Anonymous], 2012, Gamma-Ray Bursts, Cambridge Astrophysics Series 51, DOI DOI 10.1017/CBO9780511980336.010
[5]
Neutrino pair annihilation near accreting, stellar-mass black holes
[J].
Birkl, R.
;
Aloy, M. A.
;
Janka, H. -Th.
;
Mueller, E.
.
ASTRONOMY & ASTROPHYSICS,
2007, 463 (01)
:51-67

Birkl, R.
论文数: 0 引用数: 0
h-index: 0
机构: Max Planck Inst Astrophys, D-85741 Garching, Germany

Aloy, M. A.
论文数: 0 引用数: 0
h-index: 0
机构: Max Planck Inst Astrophys, D-85741 Garching, Germany

Janka, H. -Th.
论文数: 0 引用数: 0
h-index: 0
机构: Max Planck Inst Astrophys, D-85741 Garching, Germany

Mueller, E.
论文数: 0 引用数: 0
h-index: 0
机构: Max Planck Inst Astrophys, D-85741 Garching, Germany
[6]
ELECTROMAGNETIC EXTRACTION OF ENERGY FROM KERR BLACK-HOLES
[J].
BLANDFORD, RD
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ZNAJEK, RL
.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,
1977, 179 (02)
:433-456

BLANDFORD, RD
论文数: 0 引用数: 0
h-index: 0
机构:
INST ASTRON OBSERV,CAMBRIDGE CB3 0HA,ENGLAND INST ASTRON OBSERV,CAMBRIDGE CB3 0HA,ENGLAND

ZNAJEK, RL
论文数: 0 引用数: 0
h-index: 0
机构:
INST ASTRON OBSERV,CAMBRIDGE CB3 0HA,ENGLAND INST ASTRON OBSERV,CAMBRIDGE CB3 0HA,ENGLAND
[7]
Gamma-ray burst energetics and the gamma-ray burst Hubble diagram: Promises and limitations
[J].
Bloom, JS
;
Frail, DA
;
Kulkarni, SR
.
ASTROPHYSICAL JOURNAL,
2003, 594 (02)
:674-683

Bloom, JS
论文数: 0 引用数: 0
h-index: 0
机构: Harvard Soc Fellows, Cambridge, MA 02138 USA

Frail, DA
论文数: 0 引用数: 0
h-index: 0
机构: Harvard Soc Fellows, Cambridge, MA 02138 USA

Kulkarni, SR
论文数: 0 引用数: 0
h-index: 0
机构: Harvard Soc Fellows, Cambridge, MA 02138 USA
[8]
Bright X-ray flares in gamma-ray burst afterglows
[J].
Burrows, DN
;
Romano, P
;
Falcone, A
;
Kobayashi, S
;
Zhang, B
;
Moretti, A
;
O'Brien, PT
;
Goad, MR
;
Campana, S
;
Page, KL
;
Angelini, L
;
Barthelmy, S
;
Beardmore, AP
;
Capalbi, M
;
Chincarini, G
;
Cummings, J
;
Cusumano, G
;
Fox, D
;
Giommi, P
;
Hill, JE
;
Kennea, JA
;
Krimm, H
;
Mangano, V
;
Marshall, F
;
Mészáros, P
;
Morris, DC
;
Nousek, JA
;
Osborne, JP
;
Pagani, C
;
Perri, M
;
Tagliaferri, G
;
Wells, AA
;
Woosley, S
;
Gehrels, N
.
SCIENCE,
2005, 309 (5742)
:1833-1835

Burrows, DN
论文数: 0 引用数: 0
h-index: 0
机构:
Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Romano, P
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Falcone, A
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Kobayashi, S
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Zhang, B
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Moretti, A
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

O'Brien, PT
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Goad, MR
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Campana, S
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Page, KL
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Angelini, L
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Barthelmy, S
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Beardmore, AP
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Capalbi, M
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Chincarini, G
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Cummings, J
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Cusumano, G
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Fox, D
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Giommi, P
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Hill, JE
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Kennea, JA
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Krimm, H
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Mangano, V
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Marshall, F
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Mészáros, P
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Morris, DC
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Nousek, JA
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Osborne, JP
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Pagani, C
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Perri, M
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Tagliaferri, G
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Wells, AA
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Woosley, S
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA

Gehrels, N
论文数: 0 引用数: 0
h-index: 0
机构: Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA
[9]
AFTERGLOW OBSERVATIONS OF FERMI LARGE AREA TELESCOPE GAMMA-RAY BURSTS AND THE EMERGING CLASS OF HYPER-ENERGETIC EVENTS
[J].
Cenko, S. B.
;
Frail, D. A.
;
Harrison, F. A.
;
Haislip, J. B.
;
Reichart, D. E.
;
Butler, N. R.
;
Cobb, B. E.
;
Cucchiara, A.
;
Berger, E.
;
Bloom, J. S.
;
Chandra, P.
;
Fox, D. B.
;
Perley, D. A.
;
Prochaska, J. X.
;
Filippenko, A. V.
;
Glazebrook, K.
;
Ivarsen, K. M.
;
Kasliwal, M. M.
;
Kulkarni, S. R.
;
LaCluyze, A. P.
;
Lopez, S.
;
Morgan, A. N.
;
Pettini, M.
;
Rana, V. R.
.
ASTROPHYSICAL JOURNAL,
2011, 732 (01)

Cenko, S. B.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Frail, D. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Natl Radio Astron Observ, Socorro, NM 87801 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Harrison, F. A.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Haislip, J. B.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Reichart, D. E.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Butler, N. R.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Cobb, B. E.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Cucchiara, A.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Berger, E.
论文数: 0 引用数: 0
h-index: 0
机构:
Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Bloom, J. S.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Chandra, P.
论文数: 0 引用数: 0
h-index: 0
机构:
Royal Mil Coll Canada, Dept Phys, Kingston, ON, Canada Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Fox, D. B.
论文数: 0 引用数: 0
h-index: 0
机构:
Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Perley, D. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Prochaska, J. X.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Santa Cruz, Dept Astron & Astrophys, UCO Lick Observ, Santa Cruz, CA 95064 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Filippenko, A. V.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

论文数: 引用数:
h-index:
机构:

Ivarsen, K. M.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Kasliwal, M. M.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Kulkarni, S. R.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

LaCluyze, A. P.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

论文数: 引用数:
h-index:
机构:

Morgan, A. N.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

论文数: 引用数:
h-index:
机构:

Rana, V. R.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[10]
THE COLLIMATION AND ENERGETICS OF THE BRIGHTEST SWIFT GAMMA-RAY BURSTS
[J].
Cenko, S. B.
;
Frail, D. A.
;
Harrison, F. A.
;
Kulkarni, S. R.
;
Nakar, E.
;
Chandra, P. C.
;
Butler, N. R.
;
Fox, D. B.
;
Gal-Yam, A.
;
Kasliwal, M. M.
;
Kelemen, J.
;
Moon, D. -S
;
Ofek, E. O.
;
Price, P. A.
;
Rau, A.
;
Soderberg, A. M.
;
Teplitz, H. I.
;
Werner, M. W.
;
Bock, D. C. -J.
;
Bloom, J. S.
;
Starr, D. A.
;
Filippenko, A. V.
;
Chevalier, R. A.
;
Gehrels, N.
;
Nousek, J. N.
;
Piran, T.
.
ASTROPHYSICAL JOURNAL,
2010, 711 (02)
:641-654

Cenko, S. B.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Frail, D. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Natl Radio Astron Observ, Socorro, NM 87801 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Harrison, F. A.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Kulkarni, S. R.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Nakar, E.
论文数: 0 引用数: 0
h-index: 0
机构:
Tel Aviv Univ, Raymond & Beverly Sackler Sch Phys & Astron, IL-69978 Tel Aviv, Israel Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Chandra, P. C.
论文数: 0 引用数: 0
h-index: 0
机构:
Royal Mil Coll Canada, Dept Phys, Kingston, ON, Canada Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Butler, N. R.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Fox, D. B.
论文数: 0 引用数: 0
h-index: 0
机构:
Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

论文数: 引用数:
h-index:
机构:

Kasliwal, M. M.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Kelemen, J.
论文数: 0 引用数: 0
h-index: 0
机构:
Konkoly Observ Budapest, H-1525 Budapest, Hungary Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Moon, D. -S
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Toronto, Dept Astron & Astrophys, Toronto, ON M5S 3H4, Canada Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Ofek, E. O.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Price, P. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Rau, A.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Dept Astron, Pasadena, CA 91125 USA
Max Planck Inst Extraterr Phys, D-85748 Garching, Germany Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Soderberg, A. M.
论文数: 0 引用数: 0
h-index: 0
机构:
Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Teplitz, H. I.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Spitzer Sci Ctr, Pasadena, CA 91125 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Werner, M. W.
论文数: 0 引用数: 0
h-index: 0
机构:
CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Bock, D. C. -J.
论文数: 0 引用数: 0
h-index: 0
机构:
Combined Array Res Millimeter Wave Astron, Big Pine, CA 93513 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Bloom, J. S.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Starr, D. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
Las Cumbres Observ Global Telescope Network Inc, Santa Barbara, CA 93117 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Filippenko, A. V.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Chevalier, R. A.
论文数: 0 引用数: 0
h-index: 0
机构:
Univ Virginia, Dept Astron, Charlottesville, VA 22904 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Gehrels, N.
论文数: 0 引用数: 0
h-index: 0
机构:
NASA, Goddard Space Flight Ctr, Astrophys Sci Div, Greenbelt, MD 20770 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Nousek, J. N.
论文数: 0 引用数: 0
h-index: 0
机构:
Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

Piran, T.
论文数: 0 引用数: 0
h-index: 0
机构:
Hebrew Univ Jerusalem, Racah Inst Phys, IL-91904 Jerusalem, Israel Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA