The bright gamma-ray burst of February 22, 2001

Follows a quick reference guide for BeppoSAX measurements on GRB010222. The full details are accessible through a preprint of a paper accepted by ApJ on June 6, 2001. The X-ray afterglow data are available for public use at this anonymous ftp site.

On February 22, 2001, at 7:23 Universal Time, BeppoSAX instruments detected for the 45th time a gamma-ray burst: GRB010222. This burst is one of the brightest discovered thus far with BeppoSAX, and also one of the longest with a duration of about 5 minutes. The fluences and fluxes are ranked as follows within the set of BeppoSAX bursts:

Rankings in gamma-rays: #3 in peak flux after GRB000210 and GRB9901238.6X10-6 erg s-1cm-2
#2 in fluence after GRB9901239.3X10-5 erg cm-2
Rankings in X-rays: #2 in peak flux after GRB9907122.1X10-7 erg s-1cm-2
#1 in fluence1.0X10-5 erg cm-2

Signal strength of GRB010222 as a function of time during the first minutes in BeppoSAX's Gamma-Ray Burst Monitor

The Wide Field Cameras on BeppoSAX were used to quickly determine a 2.5 arcminute position of GRB010222. This position was distributed in the scientific community 3.2 hours after the burst. Within an hour, the optical afterglow was indentified in the WFC error box by Henden and collaborators at the US Naval Observatory, and within 8 hours the distance to this object was published by Garnavich et al. of Harvard-Smithsonian Center for Astrophysics and collaborators, as 3.5 billion light years.

This image is a composite made by Barbara Mochejska of CCD images collected at the F. L. Whipple Observatory 1.2-meter telescope by J. McDowell and R. Kilgard. The size is 5 arcmin by 5 arcmin.

Because of its brightness, a major effort was initiated by scientists to study this gamma-ray burst in great detail at radio, optical and X-ray wavelengths, using state-of-the-art telescopes such as the narrow-field instruments on BeppoSAX, the Very Large Array of radio telescopes in New Mexico, the Hubble Space Telescope and the Chandra X-ray Observatory. Follows an image of the X-ray afterglow as observed with BeppoSAX.

Two sequential frames taken with the Medium-Energy Concentrator Spectrometer on BeppoSAX that show a bright and fading X-ray afterglow. The cross marks the position of the optical counterpart (at 8 arcsec from the X-ray centroid).

Follows the afterglow light curve, in the optical R-band (top right) and in 2-10 keV X-rays (from WFC and NFI data). In the bottom right-hand corner is a data point from Chandra X-ray Observatory observations (Harrison et al. 2001). There is an achromatic break at an early 0.5 days after the GRB event. This may be interpreted as due to a quick break in a dense circumburst medium. The earliest NFI data point is at 8 hours after the GRB at 1.2X10-11 erg s-1 cm-2 which is the brightest of all GRB afterglows except one (GRB991216).

Optical and X-ray light curves of the afterglow.

Papers on GRB010222 submitted to refereed journals:

For a compilation of over 40 GCN and IAU circulars, see Jochen Greiner's page on GRB010222.

Links to other web pages on GRB 010222:

Jean in 't Zand, SRON, November 15, 2001