LOTIS Search for Early-Time Optical Afterglows: GRB 971227

Williams, G. G.; Park, H. S.; Ables, E.; Band, D. L.; Barthelmy, S. D.; Bionta, R.; Butterworth, P. S.; Cline, T.; Ferguson, Donald H.; Fishman, G. J.; Gehrels, N.; Hartmann, D. H.; Hurley, K.; Kouveliotou, C.; Meegan, C. A.; Ott, L.; Parker, E. F.; Porrata, R.

doi:10.1086/312092

Cited by 16 publications

(5 citation statements)

References 29 publications

(32 reference statements)

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“…The following table lists the 13 events for which LOTIS achieved the best overall coverage. These results have been published [ $ I , [9], [lo]. Table 1 shows our best events during this period.…”

Section: Lotis Results and Interpretationmentioning

confidence: 53%

Prompt GRB optical follow-up experiments

Park¹,

Williams²,

Ables³

et al. 2001

AIP Conference Proceedings

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Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations of coordinates provided by Beppo/SAX and IPN GRB. These follow-up observations have shown that GRBs are at cosmological distances and interact with surrounding material as described by the fireball model. However, prompt optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. Unlike later time afterglows, prompt optical measurements would provide information on the GRB progenitor. LO-TIS is the very first automated and dedicated telescope system that actively utilizes the GRB Coordinates Network (GCN) and it attempts to measure simultaneous optical light curve associated with GRBs. A€ter 3 years of running, LOTIS has responded to 75 GRB triggers. The lack of any optical signal in any of the LOTIS images places numerical limits on the surrounding matter density, and other physical parameters in the environment of the G B progenitor. This paper presents LOTIS results and describes other prompt GRB follow-up experiments including the Super-LOTIS at Kitt Peak in Arizona.

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Section: Lotis Results and Interpretationmentioning

confidence: 53%

Prompt GRB optical follow-up experiments

Park¹,

Williams²,

Ables³

et al. 2001

AIP Conference Proceedings

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“…Results from GROCSE and LOTIS are presented in Park et al [1], Park et al [2], and Williams et al [3] and therefore will not be discussed further here. The Super-LOTIS telescope has observed more than 50 GRB error boxes since routine operations began in April 2000.…”

Section: Resultsmentioning

confidence: 99%

The Search for Optical and Near-Infrared Counterparts of GRBs with the Super-LOTIS Telescope

Williams¹,

Park²,

Barthelmy

et al. 2004

AIP Conference Proceedings

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“…Varying the burst duration, the peak energy of the GRB spectrum, or its slope has little effect on the resulting afterglow light curve. Rykoff et al 2002) and by R (t > 1200 s) > 14 and R (t < 3000 s) > 15 obtained by LOTIS for GRBs 971227 and 010921, respectively (Williams et al 1999;Park et al 2002).…”

Section: E a R Ly A F T E R G L Ow E M I S S I O Nmentioning

confidence: 93%

Creation of electron-positron wind in gamma-ray bursts and its effect on the early afterglow emission

Kumar

Panaitescu

2004

Monthly Notices of the Royal Astronomical Society

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We calculate the creation of electron–positron pairs in gamma‐ray bursts (GRBs) resulting from the collision between scattered and outward‐moving gamma‐ray photons. The number of pairs exceeds the number of ambient‐medium electrons encountered by the GRB ejecta up to ∼1016 cm from the centre of explosion. The shock resulting from the interaction of the ejecta with the pair wind may increase the afterglow synchrotron emission peak flux, in the optical band, during the first few minutes by a factor of less than about 5. The peak intensity of the optical afterglow increases with the density of the surrounding medium. Therefore, observations of the optical flux at early times constrain the density of the circumburst medium. If the electron and magnetic field energies behind the forward shock sweeping up the pair wind and the circumburst medium are as inferred from fits to the broad‐band afterglow emission at 0.5–100 d, then the current upper limits on the optical counterpart emission, set by the ROTSE and LOTIS experiments, indicate that the circumburst medium within 0.01 pc is less dense than 100 cm−3 or, if a wind, corresponds to a progenitor mass‐loss to wind‐speed ratio below 10−6 M⊙ yr−1/(103 km s−1).

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LOTIS Search for Early-Time Optical Afterglows: GRB 971227

Cited by 16 publications

References 29 publications

Prompt GRB optical follow-up experiments

Prompt GRB optical follow-up experiments

The Search for Optical and Near-Infrared Counterparts of GRBs with the Super-LOTIS Telescope

Creation of electron-positron wind in gamma-ray bursts and its effect on the early afterglow emission

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