GRB 980703: A Reassuring Redshift
Explanation:
In the old days, just over a year ago,
astronomers had little idea of the true distance to
gamma-ray bursts.
Did these
enigmatic explosions occur in our
outer Galaxy, or in the
outer Universe?
Last May, a first telling distance measure was made -
GRB 970508 showed an
absorption line with a
redshift of about
0.8 - indicating that this
gamma-ray burst (GRB) was an enormous distance away.
Skeptics, however, are not always convinced by an
unrepeated measurement. Since then, though,
other tantalizing coincidences have occurred:
GRB 971214 occurred unusually
near a galaxy with the enormous redshift of 3.4, and
GRB 980425 occurred
unusually near a peculiar low-redshift
supernova.
Skeptics were intrigued. Now, the potentially definitive
implications of the
above-pictured optical transient
might impress even the cautious.
GRB 980703's optical transient shows a
well-measured redshift from both an
absorption line
and an
emission line: 0.97. The above negative highlights the
uncommon transient source with the label "OT", while letters
designate common
comparison stars.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
