摘要:

We characterize the error distribution of BATSE GRB locations by modeling the distribution of separations between BATSE locations and IPN annuli. We determine error model parameters by maximizing likelihood and rank the models by their Bayesian odds ratios. The best models have several systematic error terms. The simplest good model has a 1.9 degree systematic error with probability 73&percent; and 5.4 degrees with probability 27&percent;. A more complex model adds a dependence on the datatype used to derive the location. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55302

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The well-known positions of the Bursting Pulsar (GROJ1744-28) and the soft gamma repeater SGR1806-20 represent “space truth” data (the equivalent of “ground truth” data in remote sensing) which can be used to verify the accuracy of the IPN location technique. About 500 bursts from GROJ1744-28, and several dozen bursts from SGR1806-20, have been observed jointly by BATSE and Ulysses. Using these data, we have been able to verify the timing accuracy of the Ulysses data in numerous spacecraft and experiment operating modes, the cross-correlation technique used to compare the light curves of gamma-ray bursts from different spacecraft, and the method used to derive burst positions by triangulation. We show that the uncertainties in the triangulation technique are dominated by count rate statistics, and that no systematic errors exist whose magnitude is comparable to the statistical errors. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55303

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present the preliminary spatial analysis of 278 bursts that have been localized by BATSE and the two-spacecraftCompton/UlyssesInterplanetary Network. The large number and superior accuracy of the combined BATSE/Ulysseslocations provides improved sensitivity to small-angle source properties. We find that the locations are consistent with large- and small-scale isotropy, with no significant small-angle clustering. We constrain the fraction of sources in clusters and discuss the implications for burst repetition. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55305

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The recently developed BATSE Rapid Burst Response (RBR) system provides gamma-ray burst locations accurate to ∼2°–3° for several bursts per month within ∼15–35 minutes of onset. Combined with wide-field or scanning instruments, this system offers the chance of detecting prompt x-ray/optical/radio afterglow emission from many bursts. We discuss the operation, performance and status of the BATSE RBR system as well as results from coordinated multi-wavelength follow-up observations. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55306

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

BeppoSAX has been added to the 3rd Interplanetary Network of gamma-ray burst detectors. Of the ≈8 events observed to date by Ulysses and the BeppoSAX Gamma-Ray Burst Monitor (GRBM), four have been localized by triangulation, resulting in annuli whose 3 &sgr; widths are as small as63″.These data give error boxes whose sizes can be as much as an order of magnitude smaller than those obtained with the SAX Wide Field Camera (WFC). They can be used to confirm the association between fading X-ray and optical sources and gamma-ray bursts. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55307

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Given the broad range of error box sizes available from the GRB Coordinates Network (GCN) and the range of time delays involved, there is now the opportunity for many more instruments, than could use the old BACODINE system, to make follow-up observations to detect the GRB counterpart. We present a set of scenarios (some taken from existing GCN site operations and some from anticipated operations) to guide the potential new observer in matching his/her instrument’s capabilities with the GCN burst location information and in setting up the follow-up observing procedures. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55308

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

One of the enhancements of the newly created GRB Coordinates Network (GCN) is a web page that contains all the RA, Dec, Date, Time, and Intensity information distributed by the GCN, plus some additional information not amenable to the other GCN distribution methods. The web page is a table with all the BATSE-Original, -Final, -MAXBC, and -LOCBURST, RXTE-PCA, RXTE-ASM, COMPTEL and IPN information, plus light-curves. The page is automatically updated by the GCN programs in real-time (within a minute after the information is distributed by GCN). This table provides the follow-up observer with a central location where he/she can see the pertinent information summarized so that he/she can make optimal decisions on whether to observe a given GRB, and, if so, then determine the details of the observation. The web page format and contents are described and suggested uses are given. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55309

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present a status report on the broad range of follow-up observations made by the various GRB Coordinates Network (GCN) operations. Because of the wide variety and complexity of the observations, only summaries for each site and each waveband will be reported: numbers of observations and range for the time delays to be on-target, error box coverage percentages, and flux measurements or upper limits. Emphasis will be given to follow-up observations within the last year. A few of the more significant sites and observations will be high-lighted and a listing of the new instruments soon to come on-line will be given. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55310

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Angular sky exposure is presented for a number of published BATSE gamma-ray burst catalogs. A new algorithm was required due to telemetry gaps resulting from onboard tape recorder failures; the new algorithm improves the 1B Catalog exposure calculation. The most influential effects limiting BATSE’s exposure are (1) deadtime due to triggering, (2) sky blockage by the Earth, and (3) trigger disabling when the spacecraft is in the SAA and over other specific Earth locations. Exposure has improved during the Compton Gamma-Ray Observatory (CGRO) mission as a result of decreased Solar flares and magnetospheric particle events. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55311

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The Two-Point Angular Correlation Function (TPACF) is a standard analysis tool used to study angular anisotropies. Since BATSE’s sky exposure (the angular sampling of gamma-ray bursts) is anisotropic, the TPACF should at some point identify anisotropies in BATSE burst catalogs due to sky exposure. The effects of BATSE sky exposure are thus explored here for the BATSE 3B and 4B catalogs. Sky-exposure effects are found to be small. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55312

出版商:AIP    

年代:1998

数据来源: AIP