We present the R_c band light curve of the optical transient (OT) associated
with GRB970228, based on re-evaluation of existing photometry. Data obtained
until April 1997 suggested a slowing down of the decay of the optical
brightness. However, the HST observations in September 1997 show that the light
curve of the point source is well represented by a single power law, with a
``dip'', about a week after the burst occured. The exponent of the power law
decay is $\alpha$ = --1.10 $\pm$ 0.04. As the point source weakened it also
became redder.Comment: 5 pages, latex, to appear in Gamma-Ray Bursts, 4-th Huntsville
  Symposium, eds Meegan, Preece, Koshu

C. A. Meegan

C. Kouveliotou

C. Robinson

D Eichler

F. D. Macchetto

G. J. Fishman

HL Johnson

J Van Paradijs

J. Bloom

J. Heise

J. in't Zand

J. Telting

J. van Paradijs

JA Holtzman

K Sahu

K. C. Sahu

L. Petro

M. Livio

M. Pettini

MS Bessel

MS Bessell

N. Tanvir

P Mészáros

P. J. Groot

PS Thé

R. G. M. Rutten

R. G. Strom

T Piran

T. Galama

English

arXiv

The origin of gamma-ray bursts has been one of the great unsolved mysteries in high-energy astrophysics for almost 30 years. The recent discovery of fading sources at X-ray and optical wavelengths coincident with the location of the gamma-ray burst GRB970228 therefore provides an unprecedented opportunity to probe the nature of these high-energy events. The optical counterpart appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that place gamma-ray bursts at cosmological distances, although a range of mechanisms for producing the bursts is still allowed. A crucial piece of information for distinguishing between such models is how the brightness of the optical counterpart evolves with time. Here we re-evaluate the existing photometry of the optical counterpart of GRB970228 to construct an optical light curve for the transient event. We find that between 21 hours and six days after the burst, the R-band brightness decreased by a factor of approximately 40, with any subsequent decrease in brightness occurring at a much slower rate. As the point source faded, it also became redder. The initial behaviour of the source appears to be consistent with the 'fireball' model, but the subsequent decrease in the rate of fading may prove harder to explain

Heise, J.

Fishman, G. J.

Strom, R. G.

Telting, J.

Galama, T.

vanParadijs, J.

Petro, L.

Robinson, C. R.

Meegan, C. A.

Bloom, J.

Kouveliotou, C.

Macchetto, F. D.

Tanvir, N.

Int Zand, J.

Pettini, M.

Rutten, R. G. M.

Livio, M.

Groot, P. J.

Sahu, K. C.

NASA Technical Reports Server

NASA-TM-112 889
The decay of optical emission
from the  /-ray burst
GRB970228
T. Galama*, P. J. Groot% J. van Paradijs*%
C. Kouveliotou$§, C. R. Roblnson$§, G. J. Fishman§,
C. A. Meegan§, K. C. Sahull, M. Livioll, L. Petroll,
F. D. Macchettoll, J. Heise% J. in't Zand% R. G. Strom_#,
J. Teltingr>, R. G. M. Rutten#, M. Pettini**, N. Tanvirtt
& J. Bloomtt
" Astronomical Institute 'Ftnton Pannekoek", University qfAmsterdam, d- Centre
]br High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam,
The Netherhlnds
t Physics l)epartment, Universit), o(,,Uabama in Huntsville, thlntsvilh',
Ahtbanul 35899, USA
$ Universities Space Research Association
§ NASA Marshall Space Hight Center, E&84, Huntsville, Alabanla 35812,
USA
I]Space Telescope Science Institute, 3700 San Martin l)rive, Bahimore,
Maryland 21218, USA
9jSRON Laboratory fi_r Space Research, Sorbonnelaan 2, 3584 CA Utrecht,
I71eNetherlands
# Netherhlnds Foundation ]br Research in Astronomy, Postbus 2, 7990 AA
Dwingeloo, The Nethedands
_szIsaac Newton (;roup, Apartado de Correos 321, 38780 Santa Cruz de La Pahna,
Tener([e',Canary Islands
** Royal Greenwich Observatory Madingle), Road, Canlbrid_e CB3 0EZ, UK
t? hlstitute of Astronom); Madmgley Road, Cambridge CB3 0HA, UK
The origin of _,-ray bursts has been one of the great unsolved
mysteries in high-energy astrophysics for almost 30 years. The
recent discovery of fading sources at X-ray _ and optical 2'3 wave-
lengths coincident with the location of the _,-ray burst
GRB970228 therefore provides an unprecedented opportunity
to probe the nature of these high-energy events. The optical
counterpart appears to be a transient point source embedded in
a region of extended nebulosity _-6, the latter having been tenta-
tively identified as a high-redshift galaxy 3. This would seem to
favour models that place 3,-ray bursts at cosmological distances,
although a range of mechanisms for producing the bursts is still
allowed. A crucial piece of information for distinguishing between
such models is how the brightness of the optical counterpart
evolves with time. Here we re-evaluate the existing photometry of
the optical counterpart of GRB970228 to construct an optical light
curve for the transient event. We find that between 21 hours and
six days after the burst, the R-band brightness decreased by a
factor of _40, with any subsequent decrease in brightness occur-
ring at a much slower rate. As the point source faded, it also
became redder. The initial behaviour of the source appears to be
consistent with the 'fireball' model 7, but the subsequent decrease
in the rate of fading may prove harder to explain.
The 3_-ray burst of 28 February 1997, detected 8 with the Gamma-
Ray Burst Monitor on board the BeppoSAX satellite, and located
with an _3' radius position with the Wide Field Camera on the
same satellite, was the first for which a fading X-ray' and optical
counterpart 2'_'were discovered.
The optical counterpart was discovered 2_ from a comparison of
V- and 1-band images taken with the William Herschel Telescope
(WHT) on February 28.99 ul; and the Isaac Newton Telescope (INT;
V band) and the WHT (l band) on March 8.Sur. After the
counterpart had weakened by several magnitudes, it was found to
coincide with an extended object _''a. In subsequent observations
with the Hubble Space Telescope (HST) on 26 March and 7 April
1997, Sahu et al) _'found that the optical counterpart consists of a
letters to nature
point source and an extended (_ l") object, offset from the point
source by _0.5". The extension is in the same direction as that seen
in the earlier ground-based observations.
In view of the importance of the optical light curve in constrain-
ing possible models of y-ray bursts, we have re-assessed the
photometric information presented by Van Paradijs et al), together
with more recent information in light of the HST findings, and
derived an optical light curve of the point source component of the
GRB counterpart.
In Table 1 we have collected the available optical photometry on
GRB970228. These results have been obtained in several passbands,
primaril_ V, R and I (effective wavelengths _5,500 A, _6,500 A and
_8,000A, respectively, corresponding closely to the Cousins VRI
system). As the R band occupies a central position relative to most
of the passbands used in the available observations, we have reduced
all photometry to the R band. In the required interpolations we have
assumed that the spectra of the point source and the extended
emission are similar to main-sequence stars (that is, not dominated
by emission lines). We have used the relation between the colour
indices V - R and V - I given by Th4 et al. H for late-type stars; for
bluer stars we have inferred this relation from the tables given by
lohnson _2for main-sequence stars and the colour transformations
to the Cousins VRI system given by BesselP '. For given magnitudes
V and I the uncertainty in the interpolated magnitude R is
determined by the uncertainty in the ratio c_ = (V- R)/I V- I),
because R = V - c_(V - I). Over the range in (V - l) covered by
the point source, this ratio c_ varies between 0.45 (at V - I = 0.7)
and 0.55 (at V - I = 2.0). We have made alternative estimates of_
from numerical integrations of pnwer-law flux distributions
(F(M _- X_, with fl ranging between - 4 and +2), and of Planck
functions (with temperatures between 3,000 and 10,000K), each
muhiplied by V, R and I response functions 14. We find that these
'theoretical' oe values cluster near 0.4, that is, only slightly smaller
than the values observed for stars. We conclude that if the flux
distribution of the optical counterpart is smooth, the uncertainty in
the interpolation of R from Vand I is unlikely to exceed 0.1 mag.
From the Vand I magnitudes obtained from the two HST images
(Table 1; to arrive at these values we applied a colour-dependent
correction term _) we infer that between the two HSTobservations
the point source became marginally fainter; the extended source did
not show a significant brightness change.
In the 28 February observation with the WHT the optical
transient is much brighter than any stead}, counterpart, and the
Table 1 Summary of optical observations
Date Time Telescope Magnitude Remarks
('JT)
Feb 28 184 BUT R - 211 _ 0.2 OT
Feb 28 194 RAO R - 205 +05 OT
Feb. 28 238 WHT V-213 t 01 OT
Feb. 28 238 WHT t = 20.6 ' 01 OT
Mar. 03 24 APO B 233 + 0.5 OT
Mar. 04 207 NOT V > 242 OT + ext.source
Mar. 06 7.7 Keck R - 24.0 OT + ext.source
Mar 08 207 INT V > 236 OT + ext source
Mar 08 212 WriT i > 222 OT + ext.source
Mar 09 215 INT R - 24.0+ 0.2 OT +ext. source
Mar 09 20.5 INT B - 25.4+ 0.4 OT +ext. source
Mar 13 0.0 N17 R - 24.3+ 0.2 OT + ext.source
Mar 26 9.2 HST V = 261 + 0.1 OT
Mar 26 112 HST 1-242 +01 OT
Mar 26 9.2 HST V - 249 + 03 Ext source
Mar. 26 11.2 HST I - 24.5 + 03 Ext source
Apr. 7 5.2 HST V = 264 * 0.1 OT
Apr. 7 72 HST I - 26.4 - 01 OT
Apr. 7 52 HST V = 252 _ 0.35 Exl source
Apr. 7 Z2 HST 1 - 243 - 0.35 Ext source
Abbreviations: OT, optical transient; ext source, extended sourcel BUT, Bologna University
Telescope; RAO, Rome Astrophysical Observatory: WHT, William Herschel Telescope; APO,
Apache Point Observatory; NOT. Nordic Optical Telescope; INT, Isaac Newlon TF,leacope;
HS_ Hubble Space Telescope
NATURE VOL 387129 MAY 1997 479
https://ntrs.nasa.gov/search.jsp?R=19970028955 2020-06-16T01:16:15+00:00Z
letters to nature
latter's contribution can therefore be entirely neglected. From a re-
analysis of the images we confirm the (_,.; I) magnitudes for the
transient as given before e'_ (Table l), but those for the substantially
weaker nearby star are somewhat different: (V, I)= (23.0, 21.2).
The latter values are in good agreement with those obtained with the
HST: (V, I) = (23.0, 21.4).
Guarneri et aL l_ found no variable objects in B- and R-band
images taken with the Bologna University Telescope on February
28.76, and on March 1.81, 3.76, 4.82 and 5.86UT. However, a
subsequent analysis of these images confirms that the optical
transient is present on February 28.76 UT at the position given
by Groot et al. _ with R = 21.1 _+ 0.2 (A. Guarnieri, personal
communication).
Pedichini et aL _7confirmed the detection of the optical transient
on a Schmidt CCD image taken at the Rome Astrophysical Obser-
vatory on February 28.81 VT;it was then 1.6 _+ 0.5 mag brighter than
the nearby late-type star (for which R = 22.1); The broad-band
filter used in this observation had a peak at 7,000 A, similar to that of
the R band, but because its width is almost twice that of the latter the
inferred R = 20.5 _+ 0.5 may suffer from a colour effect. But because
on February 28.99u'r (at about the same brightness level)
V I = 0.7, this colour effect is likely to be small compared to
the quoted error of 0.5 mag.
In an observation with the Apache Point Observatory on March
3.1 tJ1; Margon et al. '_ detected the optical transient at
B = 23.3 _+ 0.5. We have inferred an estimated R-band magnitude,
by interpolating between the colour index B - R = 1.4, observed on
Table 2 TheR-band light curve of GRB970228
Date (ur) Telescope R (OT+ ext.source) R (OT)
Feb 28.76 BUT 21.1 +_0.2 21.1 ± 0.2
Feb 28.81 RAO 20.5 + 0.5 20.5 ± 0.5
Feb. 28.99 WHT 20.9 * 0.14 20.9 +_0.14
Mar 03.10 APO 222 + 0.7 22.3' ii'_
Mar 04.86 NOT >23.3 >236
Mar, 06.32 Keck 24,0 * 0.2 24.8',i,
Mar 08.88 INT + WHT >22.6 >22.8
Mar 09.90 INT 24,0 _+0.2 24.8 _fi,
Mar. t3.00 NTT 24,3 + 0.2 25.6:'i_
Mar. 26.42 HST 24.1 ÷ 0.2 25.17 ± 0.13
Apr. 07.23 HST 242 + 0.15 25.50 ÷ 0.13
Abbrevialions as Table 1,
2O
22
_= 24
"O
¢-
&
................
+
X_ X
-0.5 0 0.5 1 1.5 2
log(t)
Figure 1 R-band light curve of the point source component in the optical
counterpart of GRB970228The R-banddata are from Table 2, andt represents the
time interval since the -c-rayburst occurred For reference, an exponential decay
with _-= 1.4days plus a constant is shown as a solid curve.
9 March (see Table 1), and a value for this colour index on 28
February, B - R = 1.1, inferred from the observed V - I, assuming
again that the (B - R, V - I) relation follows that of main-sequence
stars. This estimate of R involves an extrapolation rather than an
interpolation (as with V and I observations); this entails an addi-
tional uncertainty, which we conservatively estimate at 0.5 mag. The
corresponding R-band magnitude on March 3.1trT then is
22.2 + 0.7.
In the 4 March observation with the Nordic Optical Telescope,
and the 8 March observations with the WHT and the INT, the
counterpart was not detected (see Table 1 for the upper limits).
In the 9 March observation with the INT and the 13 March
observations with the ESO New Technology Telescope (NTT), the
source is detected. In the NTT image the source appears extended;
this was found _°independently from images obtained with the Keck
Telescope. The direction of this offset is consistent with being caused
by the faint extended emission detected with the HST observations.
We have transformed the collection of V, R and I magnitudes to
one common R-band magnitude, in the following way. For near-
simultaneous Vand/observations we have used the ( V - I, V - R)
relation (see above) to get R= V-(V-R). In case no such
simultaneous observations are available, we have interpolated
linearly in the relation between (V, V- I) obtained from the 28
February and the HSTobservations. We have collected these results
in Table 2.
We note that the R-band magnitude for the combined point
source plus extended component obtained from the HST images
(Table 2) differs substantially from the value, R = 24.9 + 0.3, given
by Metzger et al. _ on 5 and 6 April 1997. Moreover, their conclusion
that the component causing the earlier (ground-based) images to
appear extended has faded below detection level seems difficult to
reconcile with the HST observation that both in the V and l bands
the extended component is at least as bright as the point source.
We have subtracted the contribution of the extended component
from the ground-based results. From the corrected HST magnitudes
(see above) we infer that the R-band magnitude of the extended
component (averaged over the two HST observations) is
R = 24.7 _+0.3. These corrected R-band magnitudes for the point
source are also given in Table 2.
The R-band light curve obtained from our analysis of the
available photometry is shown in Fig. 1, in which we have plotted
R versus log t, where t is the time since the y-ray burst occurred.
A single power-law decay of the flux (that is, F_(t) zc t ") during
the entire 38-day period does not represent the data well. The upper
limit on R obtained on 4 March and the R magnitude measured on 6
March are incompatible with such decay, which in Fig. 1 would be
represented by a straight line.
The initial decline, between 28 February and 6 March was much
faster than that after 6 March. Before 6 March the average decay rate
was 0.7+°_2_mag d _, during the month following 6 March it was
_002 I
0.02 (_.o4magd . Expressed in terms of a power-law exponent or,
2 1+°'_the average decay before 6 March corresponds to o_ = . _,
whereas after 6 March we find _¢ < 0.35. Expressed in terms of an
exponential decay time r of the R-band flux, we find before 6 March
r _ 1.4 d, and afterwards r > 25 d.
As the point-source component of the optical transient became
fainter, it also became redder, from V - I = 0.7 at V = 21.3 (28
February) to V- I = 1.9 at V= 26.1 (26 March), and V- I = 1.8
at V = 26.4 (7 April).
The exponent of the power law describing the decay of the X-ray
afterglow of GRB970228, as obtained from the results given by
Costa et al. _ and Yoshida et al. 2", is (xx = 1.4 _+ 0.2. A comparison of
this value with the initial power-law slope of the optical brightness
decay indicates that during the first week after the ",/-ray burst the
optical transient decayed more rapidly than the X-ray transient.
From recent comparisons _''-_of the optical and X-ray observations
of GRB970228 with predictions of the 'fireball' model (see, for
480 NATURE VOI_ 387129 MAY 1997
example, Meszaros 7) it has been concluded that this model is
consistent with the initial decay of the ",/-ray burst afterglow. We
note however, that the decay does not continue beyond 6 March.
This slow-down of the brightness decrease after 6 March may be the
result of changes in one or more factors determining the optical
emission, such as changes in source geometry, or optical depth
effects. It may signal the changeover to a different dominant energy
source. If y-ray bursts are the result of mergers of neutron star
binaries (see, for example, Piran 22 and references therein), decay of
radioactive nuclei produced by de-neutronization of neutron-star
matter 23 may play a role. []
Received 17 April; accepted 6 May 1997
1, Costa, b. et al. L4U (Tire No 6576 (1997).
2. (]root, P. J, et al. IAU Circ, No. 6584 ( 1997L
3. Van Paradi s, . et al. Transient optical emissmn from the error box of the 5' ray burst of 28 February
1997. Nature386, 686 689 I 997)
4. Sahu, K., hivio, M, Petro, L, & Maccheuo, F. D. IAU (ire Nil 6606 (1997).
5. Sahu, K et al. IAU Circ. No, 6619 (19971.
6, Sahu, K et aL The optical counterpart Io 3' ray burst (;RB90228 observed using the [tubble Space
"]_lescope. Nature 387, 476 478 (1997).
7. Mesz,iros P. in Proc. 17th 7_xa_ Svnlpos on Reiativisti_ Astrophysics; Ann. NY Acad Sci 759, 440-445
(1995)
8. Costa, E, etaL IAUCirc No, 6572 (1997L
9. Gmot, P. I. et al. L4U Circ No. 6588 {1997).
10. Metzger, M. R. et al. IAU Circ, No. 6588 (1997)
I I. Th,_, P. S, Steenman, H. & Alcaino, G, Relations bet_veen spectral types, absolute magnitudes, and colour
indices of red dwarfs in the Cousins pholometric system. Astron. Astrophys. 132, 385 388 (1984).
12, lohnsnn, It. L. Astronomical measuremenls in the infrared. Annu, Rev, Astron..4strophys, 4, 191-206
( 1966L
I?,_ Bessell, M S. UBVRI photometry. I1 The Cousins VRI system, its temperalure and absolute flux
calibration, and relevance for two-dimensional photometry, th_bl. Astron. Soc Paci[[ 91,589-607 (1979).
14. Bessel, M. S, UBVRI Photometry with a Ga-As pfiotomuttiplier. Publ. ,4stron, Soc. Paof 88, 557-560
(1976).
15. Holtzman, L A. et al. The pholomemc perlbrmance and calibratifm of WFPC2. Pubt Astron. Soc.
Pat[l" 107, 1065 1093 (1995),
16, Guarnieri, A i't al. IAU Cirl, No. 6582 ( 19971
17. Pedichini, F. et at, /AU C'irc No. 6635 (1997)
18. Margon, B,, l)eutsch, E W, lamb, D. Q. & Castander, E J, IAU Circ. No. 6618 11997)
19. Metzger, M. R. t,t al. IAI ,'('ire No. 6631 (1997).
2(I. Yoshida, A. ct al. IAU ('ire No 6593 ( 1997L
2 I. Wilers, R. A. ,M. L, Rees, M. I. & Meszaros. IZ Shocked by GRB970228: the afterglow of a cosmological
fireball. Mon Not, R Astron. Sot. (submitted).
22. Piran, T. in t ?ompacI Stars m Binarws (cds van Paradijs, 1., van den Heuvel, E. P 1. & Kuulkers, E) 489-
502 (Proc IAU Syrup, 165. Kluwer, Dordrecht, 1996L
23. Eichler, D., Livio, M. Piran, T. & Schramm, D. Nucleosynthesis, neutrino bursts and gamma rays
from coalescing neutron s_ars. Nature 340, 126 128 (1986)
Acknowledgements. We _hank A. Guarnieri and I- Stella fi)r information about he r pbolometrv. The
WHT is operatedon behalf of the UK PPa.R( ant he I)utch NFRA at lhc Spanish observatory Roquede
Los Muchachos on La Palma, Spain T, Galama was supported by NFRA; C. Konveliolou and I. van
Paradijs were supporled b_ NASA.
C.rrespondence should be addressed to C,K,
letters to nature
NATURE IVOL 387129 MAY 1997 481



The Decay of Optical Emission from the gamma-Ray Burst GRB970228

Van Paradijs, J.

Robinson, C.

In't Zand, J.

VU Research Portal

The decay of optical emission from the γ-ray burst GRB970228

Galama, T.J.

Groot, P.J.

van Paradijs, J.A.

Robinson, C.R.

Fishman, G.J.

Meegan, C.A.

Sahu, K.C.

Macchetto, F.

in 't Zand, J.J.M.

Strom, R.G.

Telting, J.H.

Rutten, R.G.M.

Tanvir, N.R.

Bloom, J.S.

UvA-DARE

The deacy of the optical emission from the gamma-ray burst GRB970228

International Migration, Integration and Social Cohesion online publications

UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)UvA-DARE (Digital Academic Repository)The deacy of the optical emission from the gamma-ray burst GRB970228Galama, T.J.; Groot, P.J.; van Paradijs, J.A.; Kouveliotou, C.; Robinson, C.R.; Fishman, G.J.;Meegan, C.A.; Sahu, K.C.; Livio, M.; Petro, L.; Macchetto, F.; Heise, J.; in 't Zand, J.J.M.;Strom, R.G.; Telting, J.H.; Rutten, R.G.M.; Pettini, M.; Tanvir, N.R.; Bloom, J.S.DOI10.1038/387479a0Publication date1997Published inNatureLink to publicationCitation for published version (APA):Galama, T. J., Groot, P. J., van Paradijs, J. A., Kouveliotou, C., Robinson, C. R., Fishman, G.J., Meegan, C. A., Sahu, K. C., Livio, M., Petro, L., Macchetto, F., Heise, J., in 't Zand, J. J.M., Strom, R. G., Telting, J. H., Rutten, R. G. M., Pettini, M., Tanvir, N. R., & Bloom, J. S.(1997). The deacy of the optical emission from the gamma-ray burst GRB970228. Nature,387, 479-481. https://doi.org/10.1038/387479a0General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an opencontent license (like Creative Commons).Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, pleaselet the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the materialinaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letterto: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. Youwill be contacted as soon as possible.Download date:26 Oct 2023

NARCIS 

Crossref

UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl)UvA-DARE (Digital Academic Repository)The deacy of the optical emission from the gamma-ray burst GRB970228Galama, T.J.; Groot, P.J.; van Paradijs, J.A.; Kouveliotou, C.; Robinson, C.R.; Fishman, G.J.;Meegan, C.A.; Sahu, K.C.; Livio, M.; Petro, L.; Macchetto, F.; Heise, J.; in 't Zand, J.J.M.;Strom, R.G.; Telting, J.H.; Rutten, R.G.M.; Pettini, M.; Tanvir, N.R.; Bloom, J.S.DOI10.1038/387479a0Publication date1997Published inNatureLink to publicationCitation for published version (APA):Galama, T. J., Groot, P. J., van Paradijs, J. A., Kouveliotou, C., Robinson, C. R., Fishman, G.J., Meegan, C. A., Sahu, K. C., Livio, M., Petro, L., Macchetto, F., Heise, J., in 't Zand, J. J.M., Strom, R. G., Telting, J. H., Rutten, R. G. M., Pettini, M., Tanvir, N. R., & Bloom, J. S.(1997). The deacy of the optical emission from the gamma-ray burst GRB970228. Nature,387, 479-481. https://doi.org/10.1038/387479a0General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s)and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an opencontent license (like Creative Commons).Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, pleaselet the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the materialinaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letterto: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. Youwill be contacted as soon as possible.Download date:25 Jul 2022

The decay of optical emission from the Gamma-Ray Burst GRB 970228

The decay of optical emission from the Gamma-Ray Burst GRB 970228

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server

VU Research Portal

UvA-DARE

International Migration, Integration and Social Cohesion online publications

NARCIS

NARCIS

Crossref

International Migration, Integration and Social Cohesion online publications