-
V. D. Pal'shin,
K. Hurley,
D. S. Svinkin,
R. L. Aptekar,
S. V. Golenetskii,
D. D. Frederiks,
E. P. Mazets,
P. P. Oleynik,
M. V. Ulanov,
T. Cline, [......],
M. Rapisarda,
P. Soffitta,
G. Di Cocco,
F. Fuschino,
M. Galli,
C. Labanti,
M. Marisaldi,
J. -L. Atteia,
R. Vanderspek,
G. Ricker
[show abstract]
[hide abstract]
ABSTRACT: Between the launch of the GGS Wind spacecraft in 1994 November and the end of
2010, the Konus-Wind experiment detected 314 short-duration gamma-ray bursts
(including 24 bursts which can be classified as short bursts with extended
emission). During this period, the IPN consisted of up to eleven spacecraft,
and using triangulation, the localizations of 276 bursts were obtained. We
present the IPN localization data on these events.
01/2013;
-
I. Mitrofanov,
M. Litvak,
A. Sanin,
A. Malakhov,
D. Golovin,
W. Boynton,
G. Droege,
G. Chin,
L. Evans,
K. Harshman, [......],
G. Milikh,
M. Mokrousov,
R. Starr,
R. Sagdeev,
V. Shevchenko,
V. Shvetsov,
V. Tret'yakov, J. Trombka,
A. Varenikov,
A. Vostrukhin
[show abstract]
[hide abstract]
ABSTRACT: [1] Results are presented for the LEND instrument onboard LRO for the detection of local spots of suppression and excess of epithermal neutron emission at the lunar poles. Twelve local Neutron Suppression Regions (NSRs) and Neutron Excess Regions (NERs) are detected. It is shown using the data from the LOLA and Diviner instruments that six NSRs have the empirical property “less local irradiation and lower temperature – fewer local neutrons.” These NSRs may be identified with spots of water-ice rich permafrost on the Moon. It is shown that detected NSRs are include in both permanently shadowed and illuminated areas, and they are not coincident with Permanently Shadowed Regions (PSRs) at the bottom of polar craters, as has been commonly expected before LEND presented neutron data with high spatial resolution.
Journal of Geophysical Research 07/2012; 117(e12):1991-2012. · 3.02 Impact Factor
-
I. G. Mitrofanov,
A. Bartels,
Y. I. Bobrovnitsky,
W. Boynton,
G. Chin,
H. Enos,
L. Evans,
S. Floyd,
J. Garvin,
D. V. Golovin, [......],
V. N. Shvetsov,
R. Starr,
G. N. Timoshenko,
T. M. Tomilina,
V. I. Tretyakov, J. Trombka,
V. S. Troshin,
V. N. Uvarov,
A. B. Varennikov,
A. A. Vostrukhin
[show abstract]
[hide abstract]
ABSTRACT: The design of the Lunar Exploration Neutron Detector (LEND) experiment is presented, which was optimized to address several
of the primary measurement requirements of NASA’s Lunar Reconnaissance Orbiter (LRO): high spatial resolution hydrogen mapping
of the Moon’s upper-most surface, identification of putative deposits of appreciable near-surface water ice in the Moon’s
polar cold traps, and characterization of the human-relevant space radiation environment in lunar orbit. A comprehensive program
of LEND instrument physical calibrations is discussed and the baseline scenario of LEND observations from the primary LRO
lunar orbit is presented. LEND data products will be useful for determining the next stages of the emerging global lunar exploration
program, and they will facilitate the study of the physics of hydrogen implantation and diffusion in the regolith, test the
presence of water ice deposits in lunar cold polar traps, and investigate the role of neutrons within the radiation environment
of the shallow lunar surface.
Moon-Neutrons emission-Surface composition-Radiationbackground
Space Science Reviews 04/2012; 150(1):183-207. · 3.61 Impact Factor
-
K. Hurley,
J.-L. Atteia,
C. Barraud,
A. Pélangeon,
M. Boër,
R. Vanderspek,
G. Ricker,
E. Mazets,
S. Golenetskii,
D. D. Frederiks, [......],
K. Makishima,
C. Guidorzi,
F. Frontera,
C. E. Montanari,
F. Rossi, J. Trombka,
T. McClanahan,
R. Starr,
J. Goldsten,
and R. Gold
[show abstract]
[hide abstract]
ABSTRACT: Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High Energy Transient Experiment 2 spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 157 bursts were obtained. We present the IPN localization data on these events.
The Astrophysical Journal Supplement Series 12/2011; 197(2):34. · 13.46 Impact Factor
-
K. Hurley,
M. S. Briggs,
R. M. Kippen,
C. Kouveliotou,
G. Fishman,
C. Meegan,
T. Cline, J. Trombka,
T. McClanahan,
W. Boynton,
R. Starr,
R. McNutt,
and M. Boër
[show abstract]
[hide abstract]
ABSTRACT: We present Interplanetary Network localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 11 arcsec and 21°, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48,000 arcmin2, resulting in an average reduction of the BATSE error circle area of a factor of 87.
The Astrophysical Journal Supplement Series 08/2011; 196(1):1. · 13.46 Impact Factor
-
K. Hurley,
C. Guidorzi,
F. Frontera,
E. Montanari,
F. Rossi,
M. Feroci,
E. Mazets,
S. Golenetskii,
D. D. Frederiks,
V. D. Pal'shin, [......],
M. L. Litvak,
A. B. Sanin,
W. Boynton,
C. Fellows,
K. Harshman,
J. Goldsten,
R. Gold,
D. M. Smith,
C. Wigger,
and W. Hajdas
[show abstract]
[hide abstract]
ABSTRACT: Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 786 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.
The Astrophysical Journal Supplement Series 11/2010; 191(1):179. · 13.46 Impact Factor
-
I G Mitrofanov,
A B Sanin,
W V Boynton,
G Chin,
J B Garvin,
D Golovin,
L G Evans,
K Harshman,
A S Kozyrev,
M L Litvak, [......],
V Shevchenko,
V Shvetsov,
D E Smith,
R Starr,
V I Tretyakov, J Trombka,
D Usikov,
A Varenikov,
A Vostrukhin,
M T Zuber
[show abstract]
[hide abstract]
ABSTRACT: Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of the lunar poles. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to detect hydrogen-bearing volatiles directly. Neutron flux measurements of the Moon's south polar region from the Lunar Exploration Neutron Detector (LEND) on the Lunar Reconnaissance Orbiter (LRO) spacecraft were used to select the optimal impact site for LCROSS. LEND data show several regions where the epithermal neutron flux from the surface is suppressed, which is indicative of enhanced hydrogen content. These regions are not spatially coincident with permanently shadowed regions of the Moon. The LCROSS impact site inside the Cabeus crater demonstrates the highest hydrogen concentration in the lunar south polar region, corresponding to an estimated content of 0.5 to 4.0% water ice by weight, depending on the thickness of any overlying dry regolith layer. The distribution of hydrogen across the region is consistent with buried water ice from cometary impacts, hydrogen implantation from the solar wind, and/or other as yet unknown sources.
Science 10/2010; 330(6003):483-6. · 31.20 Impact Factor
-
K. Hurley,
J. -L. Atteia,
C. Barraud,
A. Pelangeon,
M. Boer,
R. Vanderspek,
G. Ricker,
E. Mazets,
S. Golenetskii,
D. D. Frederiks, [......],
T Murakami,
K. Makishima,
C. Guidorzi,
F. Frontera,
C. E. Montanari,
F. Rossi, J. Trombka,
T. McClanahan,
R. Starr J. Goldsten,
R. Gold
[show abstract]
[hide abstract]
ABSTRACT: Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the FREGATE experiment aboard the HETE-II spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 157 bursts were obtained. We present the IPN localization data on these events. Comment: 37 pages, 3 figures. To be submitted to ApJSS. Table 5 was truncated in the original version, and has been replaced. Revised 9/2010 to correct errors in some ecliptic latitudes in table 5. Also, 3 bursts were added to the catalog
07/2009;
-
S. Klose,
B. Stecklum,
N. Masetti,
E. Pian,
E. Palazzi,
A. A. Henden,
D. H. Hartmann,
O. Fischer,
J. Gorosabel,
C. Sánchez-Fernández, [......],
R. Gold,
E. Mazets,
S. Golenetskii,
K. Noeske,
P. Papaderos,
P. M. Vreeswijk,
N. Tanvir,
A. Oscoz,
J. A. Muñoz,
and J. M. Castro Ceron
[show abstract]
[hide abstract]
ABSTRACT: We report near-infrared and optical follow-up observations of the afterglow of the GRB 000418 starting 2.5 days after the occurrence of the burst and extending over nearly 7 weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy, we find its magnitude to be R = 23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K ≈ 4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long) bursts are associated with events in star-forming regions.
The Astrophysical Journal 12/2008; 545(1):271. · 6.02 Impact Factor
-
K. Hurley,
B. Stern,
J. Kommers,
T. Cline,
E. Mazets,
S. Golenetskii, J. Trombka,
T. McClanahan,
J. Goldsten,
M. Feroci,
F. Frontera,
C. Guidorzi,
E. Montanari,
W. Lewin,
C. Meegan,
G. Fishman,
C. Kouveliotou,
S. Sinha,
and S. Seetha
[show abstract]
[hide abstract]
ABSTRACT: We present Interplanetary Network (IPN) detection and localization information for 211 gamma-ray bursts (GRBs) observed as untriggered events by the Burst and Transient Source Experiment (BATSE) and published in catalogs by Kommers et al. and Stern et al. IPN confirmations have been obtained by analyzing the data from 11 experiments. For any given burst observed by BATSE and one other distant spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 14'' and 56, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in a reduction of the area of up to a factor of ~650. When three widely separated spacecraft observed a burst, the result is an error box whose area is as much as 30,000 times smaller than that of the BATSE error circle. Because the IPN instruments are considerably less sensitive than BATSE, they generally did not detect the weakest untriggered bursts but did detect the more intense ones, which failed to trigger BATSE when the trigger was disabled. In a few cases, we have been able to identify the probable origin of bursts as soft gamma repeaters. The vast majority of the IPN-detected events, however, are GRBs, and the confirmation of them validates many of the procedures utilized to detect BATSE untriggered bursts.
The Astrophysical Journal Supplement Series 12/2008; 156(2):217. · 13.46 Impact Factor
-
K. Hurley,
E. Berger,
A. Castro-Tirado,
J. M. Castro Cerón,
T. Cline,
M. Feroci,
D. A. Frail,
F. Frontera,
N. Masetti,
C. Guidorzi, [......],
S. Golenetskii,
D. Frederiks,
G. Morrison,
A. Oksanen,
M. Moilanen,
H.-S. Park,
P. A. Price,
J. Prochaska, J. Trombka,
and G. Williams
[show abstract]
[hide abstract]
ABSTRACT: We present interplanetary network localization, spectral, and time history information for four short-duration, hard spectrum gamma-ray bursts, GRB 000607, GRB 001025B, GRB 001204, and GRB 010119. All of these events were followed up with sensitive radio and optical observations (the first and only such bursts to be followed up in the radio to date), but no detections were made, demonstrating that the short bursts do not have anomalously intense afterglows. We discuss the upper limits and show that the lack of observable counterparts is consistent with both the hypothesis that the afterglow behavior of the short bursts is like that of the long-duration bursts, many of which similarly have no detectable afterglows, as well as the hypothesis that the short bursts have no detectable afterglows at all. Small number statistics do not allow a clear choice between these alternatives, but given the present detection rates of various missions, we show that progress can be expected in the near future.
The Astrophysical Journal 12/2008; 567(1):447. · 6.02 Impact Factor
-
K. Hurley,
T. Cline,
E. Mazets,
R. Aptekar,
S. Golenetskii,
D. Frederiks,
D. Frail,
S. Kulkarni, J. Trombka,
T. McClanahan,
R. Starr,
and J. Goldsten
[show abstract]
[hide abstract]
ABSTRACT: The extremely energetic (~10-4 ergs cm-2) gamma-ray burst (GRB) of 1999 December 8 was triangulated to an ~14 arcmin2 error box ~1.8 days after its arrival at Earth with the third interplanetary network (IPN), which consists of the Ulysses, Near-Earth Asteroid Rendezvous, and Wind spacecraft. Radio observations with the Very Large Array ~2.7 days after the burst revealed a bright fading counterpart whose position is consistent with that of an optical transient source with a redshift of 0.707. We present the time history, peak flux, fluence, and refined 1.3 arcmin2 error box of this event and discuss its energetics. This is the first time that a counterpart has been found for a GRB localized only by the IPN.
The Astrophysical Journal 12/2008; 534(1):L23. · 6.02 Impact Factor
-
K. Pedersen,
K. Hurley,
J. Hjorth,
D. A. Smith,
M. I. Andersen,
L. Christensen,
T. Cline,
J. P. U. Fynbo,
J. Goldsten,
S. Golenetskii, [......],
P. Jakobsson,
B. L. Jensen,
B. Milvang-Jensen,
T. McClanahan,
P. Møller,
V. Palshin,
N. Schartel, J. Trombka,
M. Ulanov,
and D. Watson
[show abstract]
[hide abstract]
ABSTRACT: We identify the fading X-ray afterglow of GRB 001025A from XMM-Newton observations obtained 1.9-2.3 days, 2 yr, and 2.5 yr after the burst. The nondetection of an optical counterpart to an upper limit of R = 25.5, 1.20 days after the burst, makes GRB 001025A a "dark" burst. Based on the X-ray afterglow spectral properties of GRB 001025A, we argue that some bursts appear optically dark because their afterglow is faint and their cooling frequency is close to the X-ray band. This interpretation is applicable to several of the few other dark bursts where the X-ray spectral index has been measured. The X-ray afterglow flux of GRB 001025A is an order of magnitude lower than for typical long-duration gamma-ray bursts. The spectrum of the X-ray afterglow can be fitted with an absorbed synchrotron emission model, an absorbed thermal plasma model, or a combination thereof. For the latter, an extrapolation to optical wavelengths can be reconciled with the R-band upper limit on the afterglow, without invoking any optical circumburst absorption, provided the cooling frequency is close to the X-ray band. Alternatively, if the X-ray afterglow is due to synchrotron emission only, 7 mag of extinction in the observed R-band is required to meet the R-band upper limit, making GRB 001025A much more obscured than bursts with detected optical afterglows. Based on the column density of X-ray-absorbing circumburst matter, an SMC gas-to-dust ratio is insufficient to produce this amount of extinction. The X-ray tail of the prompt emission enters a steep temporal decay excluding that the tail of the prompt emission is the onset of the afterglow. To within the astrometric uncertainty, this afterglow was coincident with an extended object, seen in a deep VLT R-band image, which we identify as the likely host galaxy of GRB 001025A.
The Astrophysical Journal 12/2008; 636(1):381. · 6.02 Impact Factor
-
I G Mitrofanov,
A B Sanin,
D V Golovin,
M L Litvak,
A A Konovalov,
A S Kozyrev,
A V Malakhov,
M I Mokrousov,
V I Tretyakov,
V S Troshin, [......],
G Chin,
S Floyd,
J Garvin,
J Keller,
T McClanahan, J Trombka,
W Boynton,
K Harshman,
R Starr,
L Evans
[show abstract]
[hide abstract]
ABSTRACT: The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed.
Astrobiology 09/2008; 8(4):793-804. · 2.15 Impact Factor
-
K. Hurley,
M. S. Briggs,
R. M. Kippen,
C. Kouveliotou,
C. Meegan,
G. Fishman,
T. Cline, J. Trombka,
T. McClanahan,
W. Boynton,
R. Starr,
R. McNutt,
M. Boer
[show abstract]
[hide abstract]
ABSTRACT: We present Interplanetary Network (IPN) localization information for 343
gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE)
between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray
Observatory (CGRO) mission, obtained by analyzing the arrival times of these
bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO
spacecraft. For any given burst observed by CGRO and one other spacecraft,
arrival time analysis (or "triangulation") results in an annulus of possible
arrival directions whose half-width varies between 11 arcseconds and 21
degrees, depending on the intensity, time history, and arrival direction of the
burst,as well as the distance between the spacecraft. This annulus generally
intersects the BATSE error circle, resulting in an average reduction of the
area of a factor of 20. When all three spacecraft observe a burst, the result
is an error box whose area varies between 1 and 48000 square arcminutes,
resulting in an average reduction of the BATSE error circle area of a factor of
87.
05/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: Interplanetary spacecraft have been used with orbiting satellites for over 25 years to precisely localize gamma ray transients
by the measurement of their timedelay geometry. The first interplanetary network (IPN) made both discoveries and controversies,
and the latest is making possible a significant number of GRB counterpart observations. The IPN technique was pursued with
dedicated payloads, with piggy-back experiments, and by the creative modifications of other experiments. The achievement of
the NEAR in-flight software revision added a distant vertex to the array of Ulysses and the near-Earth group of GGS-Wind Konus,
Beppo-Sax and Rossi-XTE. This 3-way long-baseline network culminated IPN history by, in the year 2000 alone, enabling over
one-third of the afterglow searches and 5 redshift measurements. Future IPN possibilities are also outlined.
02/2006: pages 375-377;
-
K. Pedersen,
K. Hurley,
J. Hjorth,
D A Smith,
M. I. Andersen,
L. Christensen,
T. Cline,
J. P. U. Fynbo,
J. Goldsten,
S. Golenetskii, [......],
P. Jakobsson,
B. L. Jensen,
B. Milvang-Jensen,
T. McClanahan,
P. Moller,
V. Palshin,
N. Schartel, J. Trombka,
M. Ulanov,
D. Watson
[show abstract]
[hide abstract]
ABSTRACT: We identify the fading X-ray afterglow of GRB 001025A from XMM-Newton observations obtained 1.9-2.3 days, 2 years, and 2.5 years after the burst. The non-detection of an optical counterpart to an upper limit of R=25.5, 1.20 days after the burst, makes GRB 001025A a ``dark'' burst. Based on the X-ray afterglow spectral properties of GRB 001025A, we argue that some bursts appear optically dark because their afterglow is faint and their cooling frequency is close to the X-ray band. This interpretation is applicable to several of the few other dark bursts where the X-ray spectral index has been measured. The X-ray afterglow flux of GRB 001025A is an order of magnitude lower than for typical long-duration gamma-ray bursts. The spectrum of the X-ray afterglow can be fitted with an absorbed synchrotron emission model, an absorbed thermal plasma model, or a combination thereof. For the latter, an extrapolation to optical wavelengths can be reconciled with the R-band upper limit on the afterglow, without invoking any optical circumburst absorption, provided the cooling frequency is close to the X-ray band. Alternatively, if the X-ray afterglow is due to synchrotron emission only, seven magnitudes of extinction in the observed R-band is required to meet the R-band upper limit, making GRB 001025A much more obscured than bursts with detected optical afterglows. Based on the column density of X-ray absorbing circumburst matter, an SMC gas-to-dust ratio is insufficient to produce this amount of extinction. The X-ray tail of the prompt emission enters a steep temporal decay excluding that the tail of the prompt emission is the onset of the afterglow (abridged).
10/2005;
-
K. Hurley,
B. Stern,
J. Kommers,
T. Cline,
E. Mazets,
S. Golenetskii, J. Trombka,
T. McClanahan,
J. Goldsten,
M. Feroci,
F. Frontera,
C. Guidorzi,
E. Montanari,
W. Lewin,
C. Meegan,
G. Fishman,
C. Kouveliotou,
S. Sinha,
S. Seetha
[show abstract]
[hide abstract]
ABSTRACT: We present Interplanetary Network (IPN) detection and localization
information for 211 gamma-ray bursts (GRBs) observed as untriggered
events by the Burst and Transient Source Experiment (BATSE) and
published in catalogs by Kommers et al. (Cat. ) and Stern et al. (Cat.
). IPN confirmations have been obtained by analyzing the data from 11
experiments. For any given burst observed by BATSE and one other distant
spacecraft, arrival time analysis (or "triangulation") results in an
annulus of possible arrival directions whose half-width varies between
14' and 5.6{deg}, depending on the intensity, time history, and arrival
direction of the burst, as well as the distance between the spacecraft.
This annulus generally intersects the BATSE error circle, resulting in a
reduction of the area of up to a factor of ~650. When three widely
separated spacecraft observed a burst, the result is an error box whose
area is as much as 30,000 times smaller than that of the BATSE error
circle. Because the IPN instruments are considerably less sensitive than
BATSE, they generally did not detect the weakest untriggered bursts but
did detect the more intense ones, which failed to trigger BATSE when the
trigger was disabled. In a few cases, we have been able to identify the
probable origin of bursts as soft gamma repeaters. The vast majority of
the IPN-detected events, however, are GRBs, and the confirmation of them
validates many of the procedures utilized to detect BATSE untriggered
bursts.
(4 data files).
VizieR Online Data Catalog. 07/2005; 215:60217.
-
P. A. Price,
E. Berger,
S. R. Kulkarni,
S. G. Djorgovski,
D. W. Fox,
A. Mahabal,
K. Hurley,
J. S. Bloom,
D. A. Frail,
T. J. Galama, [......],
G. Morrison,
D. E. Reichart,
S. A. Yost,
R. Sari,
T. S. Axelrod,
T. Cline,
S. Golenetskii,
E. Mazets,
B. P. Schmidt, J. Trombka
[show abstract]
[hide abstract]
ABSTRACT: Of all the well localized gamma-ray bursts, GRB 000911 has the longest duration (T_90 ~ 500 s), and ranks in the top 1% of BATSE bursts for fluence. Here, we report the discovery of the afterglow of this unique burst. In order to simultaneously fit our radio and optical observations, we are required to invoke a model involving an hard electron distribution, p ~ 1.5 and a jet-break time less than 1.5 day. A spectrum of the host galaxy taken 111 days after the burst reveals a single emission line, interpreted as [OII] at a redshift z = 1.0585, and a continuum break which we interpret as the Balmer limit at this redshift. Despite the long T_90, the afterglow of GRB 000911 is not unusual in any other way when compared to the set of afterglows studied to date. We conclude that the duration of the GRB plays little part in determining the physics of the afterglow. Comment: 14 pages, 7 figures. Submitted to ApJ
10/2001;
-
A. Smette,
A. S. Fruchter,
T. R. Gull,
K. C. Sahu,
L. Petro,
H. Ferguson,
J. Rhoads,
D. L. Lindler,
R. Gibbons,
D. W. Hogg, [......],
R. Wijers,
J. P. U. Fynbo,
J. Gorosabel,
J. Hjorth,
B. L. Jensen,
A Levine,
D A Smith,
T. Cline,
K. Hurley, J. Trombka
[show abstract]
[hide abstract]
ABSTRACT: We present HST/STIS observations of the optical counterpart (OT) of the gamma-ray burster GRB 000301C obtained on 2000 March 6, five days after the burst. CCD clear aperture imaging reveals a R ~ 21.50+/-0.15 source with no apparent host galaxy. An 8000 s, 1150 < lambda/A < 3300 NUV-MAMA prism spectrum shows a relatively flat continuum (in f_lambda) between 2800 and 3300 A, with a mean flux 8.7 (+0.8,-1.6)+/- 2.6 10^(-18) ergs/s/cm^2/A, and a sharp break centered at 2797+/-25 A. We interpret it as HI Lyman break at z = 2.067+/-0.025 indicating the presence of a cloud with a HI column density log(HI) > 18 on the line-of-sight to the OT. This value is conservatively a lower limit to the GRB redshift. However, the facts that large N(HI) system are usually considered as progenitors of present day galaxies and that other OTs are found associated with star forming galaxies strongly suggest that it is the GRB redshift. In any case, this represents the largest direct redshift determination of a gamma-ray burster to date. Our data are compatible with an OT spectrum represented by a power-law with an intrinsic index \alpha = 1.2((f_nu \propto nu^-alpha) and no extinction in the host galaxy or with alpha = 0.5 and extinction by a SMC-like dust in the OT rest-frame with A_V = 0.15. The large N(HI) and the lack of detected host is similar to the situation for damped Ly-alpha absorbers at z > 2.
08/2000;
