* Astronomy

Blobrana · L

RE: GRB 080319B

Blobrana · L

Title: Constraints on the optical precursor to the naked-eye burst GRB080319B from Pi of the Sky observations
Authors: Lech Wiktor Piotrowski

I present the results of the search for an optical precursor to the naked-eye burst - GRB080319B, which reached 5.87m optical peak luminosity in the "Pi of the Sky" data. A burst of such a high brightness could have been preceded by an optical precursor luminous enough to be in detection range of our experiment. The "Pi of the Sky" cameras observed the coordinates of the GRB for about 20 minutes prior to the explosion, thus provided crucial data for the precursor search. No signal within 3 sigma limit was found. A limit of 12m (V-band equivalent) was set based on the data combined from two cameras, the most robust limit to my knowledge for this precursor.

Read more (51kb, PDF)

Blobrana · L

Title: A long and homogeneous optical monitoring of the 'naked-eye' burst GRB 080319B with the Palomar-60 telescope
Authors: P. Veres, J. Kelemen, B. Cenko, Z. Bagoly, I. Horvath

GRB 080319B is one of the brightest and most extensively sampled bursts. It has good coverage at many wavelengths. Here we present the optical observations of the Palomar 60 inch telescope, which spans a long time interval after the burst. We augment the optical dataset with freely available Swift BAT and XRT observations reduced by us. We also compare our conclusions with the published parameters from the rich literature about this burst.

Read more (62kb, PDF)

Blobrana · L

GRB 080319B was a remarkable gamma-ray burst (GRB) detected by the Swift satellite at 06:12 UTC on March 19, 2008. The burst set a new record for the farthest object that could be seen with the naked eye, it had a peak apparent magnitude of 5.8 and remained theoretically visible to human eyes for approximately 30 seconds. The magnitude was brighter than 9.0 for some 60 seconds.
Source

Blobrana · L

Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth.
GRB 080319B was so intense that, despite happening halfway across the Universe, it could have been seen briefly with the unaided eye (ESO 08/08). In a paper to appear in the 11 September issue of Nature, Judith Racusin of Penn State University, Pennsylvania (USA), and a team of 92 co-authors report observations across the electromagnetic spectrum that began 30 minutes before the explosion and followed it for months afterwards.

Read more

Blobrana · L

Data from satellites and observatories around the globe show a jet from a powerful stellar explosion witnessed March 19 was aimed almost directly at Earth.
NASA's Swift satellite detected the explosion - formally named GRB 080319B - at 2:13 a.m. EDT that morning and pinpointed its position in the constellation Bootes. The event, called a gamma-ray burst, became bright enough for human eyes to see. Observations of the event are giving astronomers the most detailed portrait of a burst ever recorded.

Read more

Blobrana · L

NASA will hold a media teleconference Wednesday, Sept. 10, at 1 p.m. EDT, to discuss new results regarding the gamma-ray burst GRB 080319B, which was visible to the naked eye.

Read more

Blobrana · L

Title: Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion
Authors: J.S. Bloom (1,2), D. A. Perley (1), W. Li (1), N. R. Butler (1), A. A. Miller (1), D. Kocevski (1), D. A. Kann (3), R. J. Foley (1), H.-W. Chen (4), A. V. Filippenko (1), D. L. Starr (1,5), B. Macomber (1), J. X. Prochaska (6), R. Chornock (1), D. Poznanski (1), S. Klose (3), M. F. Skrutskie (7), S. Lopez (8), P. Hall (9), K. Glazebrook (10), C. H. Blake (11) ((1) UCB, (2) Sloan Fellow, (3) Tautenburg, (4) U of Chicago, (5) LCOGT, (6) UCO/Lick Observatory, (7) U. Virginia, (8) Universidad de Chile, (9) Toronto, (10) Swinburne University of Technology, (11) Harvard/CfA)
(Version v2)

The first gamma-ray burst confirmed to be bright enough to be seen with the naked eye, GRB 080319B at redshift z = 0.937, allowed for exquisite follow-up observations across the electromagnetic spectrum. We present our detailed optical and infrared observations of the afterglow, consisting of over 5000 images starting 51 s after the GRB trigger, in concert with our own analysis of the Swift UVOT, BAT, and XRT data. The event is extreme not only in observed properties but intrinsically: it was the most luminous event ever recorded at optical and infrared wavelengths and had an exceedingly high isotropic-equivalent energy release in gamma-rays. At early times, the afterglow evolution is broadly consistent with being reverse-shock dominated, but then is subsumed by a forward shock at around 1000 s. The overall spectral energy distribution, spanning from ultraviolet through near-infrared wavelengths, shows no evidence for a significant amount of dust extinction in the host frame. The afterglow evolution, however, is highly chromatic: starting at about 1000 s the index shifts blueward before shifting back to the red at late times. In our deepest late-time observations, we find tentative evidence for an optical jet break and a highly luminous supernova. Finally, we examine the detectability of such events with current and future facilities and find that such an event could be detected in gamma-rays by BAT out to z = 10.7 (8 sigma), while the nominal EXIST sensitivity would allow detection to z = 32. At K band, this source would have been easily detected with meter-class telescopes to z = 17.

Read more (957kb, PDF)

Blobrana · L

Title: GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe
Authors: J. L. Racusin, S.V. Karpov, M. Sokolowski, J. Granot, X. F. Wu, V. Pal'shin, S. Covino, A.J. van der Horst, S. R. Oates, P. Schady, R. J. Smith, J. Cummings, R.L.C. Starling, L. W. Piotrowski, B. Zhang, P.A. Evans, S. T. Holland, K. Malek, M. T. Page, L. Vetere, R. Margutti, C. Guidorzi, A. Kamble, P.A. Curran, A. Beardmore, C. Kouveliotou, L. Mankiewicz, A. Melandri, P.T. O'Brien, K.L. Page, T. Piran, N. R. Tanvir, G. Wrochna, R.L. Aptekar, C. Bartolini, S. Barthelmy, G. M. Beskin, S. Bondar, S. Campana, A. Cucchiara, M. Cwiok, P. D'Avanzo, V. D'Elia, M. Della Valle, W. Dominik, A. Falcone, F. Fiore, D. B. Fox, D. D. Frederiks, A. S. Fruchter, D. Fugazza, M. Garrett, N. Gehrels, S. Golenetskii, A. Gomboc, G. Greco, A. Guarnieri, S. Immler, G. Kasprowicz, A. J. Levan, et al. (24 additional authors not shown)

Long duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of a massive star. Over the last forty years, our understanding of the GRB phenomenon has progressed dramatically; nevertheless, fortuitous circumstances occasionally arise that provide access to a regime not yet probed. GRB 080319B presented such an opportunity, with extraordinarily bright prompt optical emission that peaked at a visual magnitude of 5.3, making it briefly visible with the naked eye. It was captured in exquisite detail by wide-field telescopes, imaging the burst location from before the time of the explosion. The combination of these unique optical data with simultaneous gamma-ray observations provides powerful diagnostics of the detailed physics of this explosion within seconds of its formation. Here we show that the prompt optical and gamma-ray emissions from this event likely arise from different spectral components within the same physical region located at a large distance from the source, implying an extremely relativistic outflow. The chromatic behaviour of the broadband afterglow is consistent with viewing the GRB down the very narrow inner core of a two-component jet that is expanding into a wind-like environment consistent with the massive star origin of long GRBs. These circumstances can explain the extreme properties of this GRB.

Read more (2111kb, PDF)

Blobrana · L

Title: Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion
Authors: J.S. Bloom (1,2), D. A. Perley (1), W. Li (1), N. R. Butler (1), A. A. Miller (1), D. Kocevski (1), D. A. Kann (3), R. J. Foley (1), H.-W. Chen (4), A. V. Filippenko (1), D. L. Starr (1,5), B. Macomber (1), J. X. Prochaska (6), R. Chornock (1), D. Poznanski (1), S. Klose (3) (1. UCB, 2. Sloan, 3. Tautenburg, 4. U of Chicago, 5. LCOGT, 6. UCO/Lick Observatory)

The first gamma-ray burst (GRB) confirmed to be bright enough to be seen with the naked eye, GRB 080319B, allowed for exquisite follow-up across the electromagnetic spectrum. We present our detailed optical and infrared observations of the afterglow, consisting of over 5000 images starting 122 s after the GRB trigger, in concert with our own analysis of the Swift UVOT, BAT, and XRT data. The event is extreme not only in observed properties but intrinsically: it was the most luminous ever recorded at optical wavelengths and had an exceedingly high isotropic-equivalent energy release in gamma-rays. At early times, the afterglow evolution is broadly consistent with being reverse-shock dominated, then is subsumed by a forward shock at around 1000 s. Analysis of the forward shock suggests that the remarkable energetics of this burst may be owed largely to extreme collimation. The spectral energy distribution, spanning from ultraviolet through near-infrared, shows no evidence for a significant amount of dust extinction in the host frame. We do find significant colour evolution in the optical afterglow: starting at about 1000 s the index shifts blueward before apparently shifting back to the red at late times. Finally, we examine the detectability of such events with current and future facilities and find that such an event could be detected in gamma-rays by BAT out to z = 4.9 (8 sigma), while the nominal EXIST sensitivity would allow detection to z = 12.2. At K-band this source would have been easily detected with meter-class telescopes to z = 17.

Read more (249kb, PDF)