GRB Fireball Persists

It's still there. The optical counterpart [ http://antwrp.gsfc.nasa.gov/apod/ap970625.html ] to the instantly famous gamma-ray burst [ http://antwrp.gsfc.nasa.gov/apod/ap961123.html ] (GRB) that occurred last February 28th [ http://antwrp.gsfc.nasa.gov/apod/ap970319.html ] has faded - but not completely. The astronomical community [ http://www.aas.org ] had waited patiently for months for the Earth [ http://antwrp.gsfc.nasa.gov/apod/ap960819.html ] to proceed far enough along in its orbit [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ] so that the Sun [ http://www.seds.org/nineplanets/nineplanets/sol.html ]'s glare no longer ruined inspection of the location of this historic flash. The above picture [ http://oposite.stsci.edu/pubinfo/PR/97/30.html ] of GRB 970228 [ http://antwrp.gsfc.nasa.gov/apod/ap970407.html ], taken September 5th and released just yesterday [ http://oposite.stsci.edu/pubinfo/PR/97/30/PR.html ], shows an extended structure in the center that hasn't changed. However, the arrow indicates a point on the upper right [ http://antwrp.gsfc.nasa.gov/apod/ap970422.html ] that is now five times dimmer than in preceding months. This fading point [ http://antwrp.gsfc.nasa.gov/apod/ap970422.html ] fits a model where the GRB [ http://antwrp.gsfc.nasa.gov/apod/ap970917.html http://www.batse.msfc.nasa.gov/astronomy/grb/ ] originated in a fireball [ http://antwrp.gsfc.nasa.gov/apod/ap970917.html http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997ApJ%2E%2E%2E485L%2E%2E%2E5W&db_key=AST&nosetcookie=1 ] across the universe. The constant brightness of the extended feature indicates that it is not reflected emission from the GRB [ http://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/grbhist.html ] and might be the host galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap970625.html ]. Even so, the great GRB mystery [ http://antwrp.gsfc.nasa.gov/diamond_jubilee/debate_1995.html ] is not yet over: for one thing, how come other GRBs don't appear to occur in galactic hosts [ http://xxx.lanl.gov/abs/astro-ph/9709067 ]?

A. Fruchter, E. Pian (STScI [ http://www.stsci.edu/ ]), et al., STIS [ http://hires.gsfc.nasa.gov/ ], HST [ http://www.stsci.edu/hst/ ], NASA [ http://www.nasa.gov ]

Goddard Space Flight Center (GSFC)

Earth

http://antwrp.gsfc.nasa.gov/apod/ap970917.html

SPD-APOD-ap970917