The Gamma-Ray Burst (BATSE trigger number 6764, peak intensity of 6385 cts/s)
was detected on 1998 May 19, 12:20:13 UT. With the BeppoSAX WFC the location
could be deduced to a 3 arcmin error circle centered at
R.A. = 350.561, Decl. = +77.255 degrees (2000.0).
A follow-up observation with the BeppoSAX NFI instruments is being planned,
and also a RXTE scanning observation has been tried (see below).
A ROSAT TOO observation is not possible due to Sun angle constraints.
- GCN notice #74 = BeppoSAX GRB MAIL N. 98/15
Luigi Piro on behalf of the BeppoSAX team report:
GB980519 (BATSE trigger n.6764) has been detected by the GRBM of BeppoSAX
and by the WFC at about 12:20:00 UT of May 19.
A preliminary position by the WFC is:
RA(2000)=350.54
Dec(2000)=77.293
with an error radius of 5'.
A BeppoSAX follow up with the NFI is being planned.
- GCN notice #75 = BeppoSAX GRB MAIL N. 98/16
Luigi Piro on behalf of the BeppoSAX team report:
GB980519 (BATSE trigger n.6764) was detected by the GRBM of BeppoSAX
and by the WFC at about 12:20:00 UT of May 19.
Refined position from the WFC are:
RA(2000)=350.561
Dec(2000)=+77.255
with an error radius of 3'.
This is 2' from the preliminary position.
- GCN-RXTE_PCA_ALERT (by T.Takeshima)
COMMENTS: RXTE/PCA once tried to follow-up this GRB with
COMMENTS: normal BATSE/Locburst follow-up procedure. But as
COMMENTS: it turned out that the planned scans of 4 deg x 8
COMMENTS: deg do not cover the BeppoSAX position, we
COMMENTS: cancelled the follow-up with updated schedule
COMMENTS: and employed the direct slew procedure. We sent
COMMENTS: direct slew command at 15:38:52(UT) which is less
COMMENTS: than an hour after BeppoSAX alert comes in.
COMMENTS: RXTE/PCA arrived at. the BeppoSAX position at
COMMENTS: around 15:51 and stayed and stayed there until
COMMENTS: 16:18:23. Good time interval was 15:51-15:53
COMMENTS: (only 2 min). We tried to upload scan commands
COMMENTS: via update plan but could not make it due to the
COMMENTS: limitied time. Since there is an originally
COMMENTS: scheduled slew at 16:26, RXTE/PCA follow-up ends
COMMENTS: at this time. Detailed analysis is going on.
- GCN notice #78
The Nordic Optical Telescope GRB team (A.O. Jaunsen, J. Hjorth, M.I. Andersen,
K. Kjernsmo, H. Pedersen, E. Palazzi) reports the detection at the 2.5-m NOT
of an unresolved (in seeing of 1.5"-2"), variable object located within the
BeppoSAX error box of GRB 980519 (GCN #75).
The coordinates (+- 0.5") are
RA(2000) = 23 22 21.46
Dec(2000) = +77 15 43.0
The object had an I magnitude of about 19.5 on May 19.87 UTC but is not
detected in the DSS while objects of similar magnitude are. The OT had
faded by about 0.6 mag in V and I on May 20.0 UTC.
These observations suggest that the OT is the optical counterpart of
GRB 980519.
Preliminary Cousins I photometry (+-0.1 mag, not corrected for extinction) of
4 nearby reference stars yields
RA(2000) Dec(2000) I
A 23 22 17.74 +77 15 51.2 19.04
B 23 22 27.29 +77 15 43.5 19.49
C 23 22 28.50 +77 15 25.4 18.52
D 23 22 47.14 +77 16 23.5 15.69
On this system the OT had I=20.08 on May 20.00 UTC
Finding charts, images and updates are posted at
http://www.uio.no/~ajaunsen/grb980519 (and reproduced below).
Part of the field (left) with the suggested optical counterpart of
the Gamma-ray burst. The candidate is encircled, and the reference
stars are marked. The right image is a copy of the DSS1.
The variation of the magnitude of the candidate in the V band as a function of
time.
- GCN notice #79
S. G. Djorgovski, R. R. Gal, S. R. Kulkarni, J. S. Bloom, and A. Kelly,
on behalf of the Caltech GRB Collaboration, report:
"We obtained multicolor (BVRri) CCD images of the field of GRB 980519
(see GCN Circ. 75), using Palomar Observatory 200-inch and 60-inch
telescopes, on UT May 20.
We confirm the optical transient (OT) discovered by Jaunsen et al.
(GCN Circ. 78). The object is continuing to fade. Using the magnitudes
of stars B and C of Jaunsen et al. (their star A gives discrepant results)
to tie in the instrumental magnitude systems, we derive for the OT:
I = 21.46 (+- 0.1) in this magnitude system, on UT May 20.436 (mean epoch).
Comparing with the value of I = 20.08 mag in the same system on UT May 20.00
from Jaunsen et al., we derive the power-law decline slope of -1.98 for the
I-band light curve. This is fully consistent with the relative V-band
light curve given at http://www.uio.no/~ajaunsen/grb980519.
These measurements are preliminary. A more detailed analysis of the data
is in progress.
- GCN notice #80
The MDM Observatory GRB team (J. Kemp, J. Halpern) reports followup
photometry of the variable optical candidate discovered by Jaunsen et al.
(GCN #78) in the BeppoSAX error box of GRB 980519. In a series of CCD
images taken with the MDM 1.3m telescope, centered around May 20.31 UT,
the candidate had I=20.1+/-0.3, R=20.9+/-0.2. These magnitudes were
measured differentially with respect to stars A, B, and C of Jaunsen et
al., which we recalibrated using Landolt standards. Preliminary
photometry of those reference stars is as follows:
RA(2000) Dec(2000) R I
A 23 22 17.74 +77 15 51.2 17.93 17.28
B 23 22 27.29 +77 15 43.5 (19.26) (18.56)
C 23 22 28.50 +77 15 25.4 18.15 17.43
Parentheses indicate values that are less certain. Note the large
discrepancy between our I-band measurements and those of Jaunsen et al.;
the latter may instead refer to the V band.
MDM images will be posted at
http://cba.phys.columbia.edu/jonathan/grb/.
- GCN notice #81
The position of this burst has been obtained by triangulation using
Ulysses and BATSE preliminary data. It is described by an annulus
centered at RA(2000)=329.485, Dec(2000)=-11.873, whose radius is
89.981 degrees, and whose total width is 4.9 arcminutes. This
annulus intersects the refined SAX WFC error circle (BeppoSAX GRB
Mail No. 98/16) and is consistent with the position of the optical transient
reported by J. Hjorth (GCN 78). A figure may be found at
http://ssl.berkeley.edu/ipn3/980519/980519.eps. Processing with the final
data is expected to improve this position.
- GCN notice #82
On behalf of the Apache Point Observatory GRB team, A. Diercks & C.
Stubbs observed with the APO 3.5m telescope the optical transient (OT)
discovered by Jaunsen et al. (GCN #78) in the BeppoSAX error box of GRB
980519. Conditions were mostly cloudy with roughly 1.8 arcsec seeing.
Photometry by E. Deutsch & A. Diercks on a 1 hr series of images
centered around May 20.44 UT yields the following magnitudes and
relative uncertainties for the OT and reference stars:
ID R mag RelErr
-- ----- -----
OT 21.20 0.03
A 17.93 0.01
B 19.31 0.01
C 18.06 0.01
Absolute calibration is based only on R magnitudes of reference stars
reported by Kemp & Halpern (GCN #80). No independent calibration was
possible due to heavy clouds. Our measurement is 0.3 mag fainter than
the earlier observations of Kemp & Halpern (GCN #80).
Images are posted at:
http://www.astro.washington.edu/deutsch/grb/grb980519/.
- GCN notice #83
The U. S. Naval Observatory GRB team (F. J. Vrba, B. Canzian, S. E. Levine,
H. H. Guetter, A. A. Henden, C. B. Luginbuhl, J. A. Munn), D. H. Hartmann
(Clemson Univ.), and M. C. Jennings (IGPP, UCR visitor) report follow up
optical photometry of the variable object found by Jaunsen et al. (GCN #78)
within the BeppoSAX error circle of GRB980519 (see GCN #75). Observations
were obtained with the USNO Flagstaff Station 40-inch telescope between
UT 1998 May 20.143 and 20.328 under the pole and again between UT 1998
May 20.426 and 20.464 when the field could be re-acquired at large hour angle.
Four sets of observations were obtained in the Cousins R filter, two in the
Cousins I filter,
and one in the Johnson/Cousins V filter. Each set of observations consisted of
three co-added and dithered images of 10 minutes each. The observations were
obtained through variable cirrus clouds and haze. Preliminary reductions of
the R-filter data by comparing with the magnitudes of stars A, B, and C as
given in GCN #80 yield:
UT Date R (mag)
1998 May 20.163 20.39 +/- 0.12
20.229 20.77 +/- 0.15
20.287 20.87 +/- 0.13
20.445 21.15 +/- 0.13
The uncertainties reflect both the internal photometry errors and the scatter
in the magnitude offsets to stars A, B, and C. These data are consistent
with the single R magnitudes from the MDM telescope (GCN #80) and the APO
3.5-m telescope (GCN #82). The lightcurve derived from these combined
datapoints can be found on our web site at:
http://psyche.usno.navy.mil/nofs/grb/grb980519.html.
During this time interval the data do not appear to be consistent with a simple
power law decrease in brightness.
In a more detailed analysis we plan to also reduce these data with respect to
two TYCHO stars within our CCD FOV and to analyze the V and I data to
investigate colors.
For further information contact F. J. Vrba at fjv@nofs.navy.mil or by telephone
at (520) 779-5132.
- GCN notice #84
On behalf of the Nordic Optical Telescope GRB team J. Hjorth, A. O. Jaunsen,
K. Kjernsmo, and H. Pedersen report updated as well as new photometry of the
optical transient (Jaunsen et al., GCN #78) believed to be related to
GRB 980519.
As indicated by Djorgovski et al. (GCN #79) and Kemp & Halpern (GCN #80) the
photometry reported in GCN #78 was incorrect. This was due to the strongly
variable, non-photometric conditions prevailing at the time of observations.
Adopting the Kemp & Halpern (GCN #80) zero point the updated photometry of the
OT yields I=18.48+-0.1 on May 19.88 UT and I=19.05+-0.03 on May 20.00 UT.
In the same photometric system we report the following measurements:
May 20.98 UT I=21.64+-0.2
May 21.17 UT I=21.64+-0.1
These measurements are uncertain as the OT is close to the detection limit
in our images.
Thus, the rapid decay has continued during May 20 UT. Our last measurements
provide marginal evidence that the decay has leveled off. If confirmed, this
may be due to non-trivial intrinsic variability of the source or to an extra
source of light along the line of sight to the OT, eg. the host galaxy.
The above findings are preliminary. A more detailed analysis of the data
is in progress.
- GCN notice #85
We obtained images of the localization of GRB 980519 (GCN circ 75) as
reported by BeppoSAX team, on May 19 and 20 using the 90cm Schmidt
telescope of the Observatoire de la Cote d'Azur.
The optical transient reported by Jaunsen et al. (GCN Circ. 78) is
clearly detected and fading on images taken at UT May 19.862556,
20.076519, 20.964261 on unfiltered exposures.
The corresponding magnitudes are
May 19.862556 19.06 +- 0.26
May 20.076519 19.81 +- 0.37
May 20.964261 22.06 +- 0.76
The power-law slope decline is roughly 2.0, which, given the
uncertainties is consistent with the value reported by Djorgovski et al.
(GCN circ. 79)
The images, the light curve and a small GIF animation is given at
http://wwwrc.obs-azur.fr/schmidt/980519.html.
- GCN notice #86
V. Connaughton (National Research Council and NASA Marshall Space Flight
Center) reports on behalf of the BATSE GRB team:
GRB980519 (GCN 74) was detected by BATSE on May 19.51403 as trigger
6764. The event lasted about 60 seconds and was seen as a series of
spikes riding on a single pulse for the first 20 seconds, followed by a
gradual decay. A peak flux of 6.94 +/- 0.25 photons cm^-2 s^-1 between
50 and 300 keV, integrated over 64 ms, places it in the brightest 12%
of BATSE bursts. The fluence above 25 keV is
2.54 +/- 0.41 x 10^-5 erg cm^-2. The location is consistent with the
BeppoSAX-WFC position in GCN 74 & 75. A light curve of the event can
currently be obtained by e-mail from me at vc@msfc.nasa.gov, or will be
available next week at http://www.batse.msfc.nasa.gov/~kippen/batserbr/
when the BATSE Web server is back in operation.
- BeppoSAX GRB MAIL N. 98/18
A previously unknown X-ray source has been found by MECS during the
follow up observation starting about 10 hrs after the GRB.
Position is:
R.A.(2000)= 23h22m22s
Dec.(2000)= 77d16m06s
with an error radius of 50"
The source shows a decay behaviour during the one day observation.
Its position is consistent with the optical transient (GCN. 78).
L.A. Antonelli & L.Nicastro
on behalf of BeppoSAX Mission Scientist
- GCN notice #87
J. S. Bloom, S. G. Djorgovski, R. R. Gal, S. R. Kulkarni, and
A. Kelly, on behalf of the Caltech GRB Collaboration, report:
"We obtained CCD images of the field of GRB 980519 using COSMIC on the
Palomar Observatory 200-inch on UT May 20. In particular, we imaged the
GRB field for 500 s (Cousins R) and 600 s (Gunn i). We photometrically
calibrated our Gunn i-band and Cousins R-band images against standard
Landolt 1992 (AJ 104, 340) stars (in SA 113). We accounted for atmosphere
extinction and included a color correction term in the fit to account for
the fact that Landolt reports magnitudes in a different R and I band
system. Derived magnitudes of the following 10 secondary stars are thus in
the Londolt RI system (we kept the naming the convention of Jansen et al.
GCN 78):
Object RA DEC I_landolt err R_landolt err
A 23:22:20.0 +77:15:52 17.34 +/- 0.05 17.94 +/- 0.05
B 29.6 44 18.64 +/- 0.05 19.41 +/- 0.05
C 28.7 26 17.57 +/- 0.05 18.10 +/- 0.05
E 20.6 24 18.85 +/- 0.05 20.19 +/- 0.06
F 31.8 45 18.48 +/- 0.05 19.91 +/- 0.06
G 33.2 +77:14:59 17.25 +/- 0.05 19.02 +/- 0.05
H 20.7 14:55 18.13 +/- 0.05 19.44 +/- 0.05
I 09.2 +77:15:51 19.27 +/- 0.06 19.80 +/- 0.06
J 07.6 +77:16:01 19.05 +/- 0.06 20.08 +/- 0.06
L 35.0 16:15 18.57 +/- 0.05 19.21 +/- 0.05
Uncertainty in optimum aperture size for each star is the dominate source
of statistical error. There is an overall zero-point systematic error (not
included above) in each band which amounts to 0.150 mag (I) and 0.151 (R).
The approximate RA and DEC are measured in J2000 from the Digital Sky
Survey (DSS).
We note our derivation for A,B, and C magnitudes are highly discrepant
from that of Jansen et al. GCN #78, but agree quite well with that of Kemp
and Halpern (GCN #80) and Diercks et al. (GCN #82). At the time of
observations we find the OT has magnitudes of May 20.43 UT, I_landolt =
20.86 +/- 0.11; May 20.48 UT, R_landolt = 21.57 +/- 0.09.
A finding chart with the secondary stars noted may be found at
http://astro.caltech.edu/~jsb/grb980519.ps.
- GCN notice #88
R. R. Gal, J. S. Bloom, C. Steidel, K. L. Adelberger, S. G. Djorgovski,
and S. R. Kulkarni, on behalf of the Caltech GRB Collaboration, report:
"We have obtained additional photometric CCD images of the field of
GRB 980519. C. Steidel and K. Adelberberger have obtained 11 minutes of
R-band data using the W.M. Keck Observatory 10-m, and R. Gal has obtained
800 sec. of i band data and 750 sec. of R band data with the Palomar
Observatory 5-m on UT May 21. We measured magnitudes for the OT using the
Landolt magnitude system derived by Bloom et al.(GCN #87) for the nearby
stars. The OT is no longer visible in our i-band data, with an upper limit of
I > 21.6 +/- 0.7, at UT May 21.43. The OT is still seen in the R band with
R = 23.48 +/- 0.2 at UT May 21.469 (Palomar) and R = 23.10 +/- 0.13 at
UT May 21.6 (Keck). The fainter Palomar magnitude at the earlier epoch is
likely due to poor seeing conditions (>2") which place the object close
to our detection limit.
C. Steidel and K. Adelberger also report that in seeing conditions
of 0.75" at Keck the OT is not distinguishable from a point source.
We note that these observations place an upper limit on the magnitude of the
OT host galaxy of not brighter than R ~ 24 mag.
Our R-band magnitudes are consistent with the source still fading with a slope
of approximately 2.0, while the I-band data do not provide additional
constraints on the slope.
- GCN notice #89
D. A. Frail, G. B. Taylor (NRAO), S. R. Kulkarni (Caltech), and
the BeppoSAX GRB team report:
Beginning on May 19.8, May 20.6 and May 22.3 UT we observed the field
containing the fading X-ray source 1SAX J2322.3+7716 (Nicastro et
al. IAUC 6912) with the VLA at 8.3 GHz. The May 22.3 UT observations
detected a 102+/-19 microJy radio source coincident with the optical
transient first seen by Jaunsen et al. (GCN 78). The radio source VLA
J2322+7715 is at ra = 23h22m21.49s dec = +77d15'43.2" (equinox J2000)
with a conservative error of 0.1 arcsec in each coordinate.
Re-examining this location for the data taken on May 19.8 UT and May
20.6 UT we measure a flux density of 38+/-28 and 68+/-27 microJy,
respectively. We propose that VLA J2322+7715 is the radio afterglow
from GRB 980519. Additional radio observations are in progress to look
for significant variability.
- GCN notice #90
F. J. Castander, R. Evans, D. E. Reichart, D. Q. Lamb
and W. Wild, University of Chicago, report:
"We made I-band observations of the BeppoSAX WFC error
circle for GRB980519 (GCN #75) on May 21.34 - 21.36 UT and
May 22.27 - 22.38 UT, using the 41-inch telescope at Yerkes
Observatory. On May 21.35, we detected the optical transient
reported by Jaunsen et al. (GCN #78) at about I = 21.9 mag,
near the limiting magnitude of the image. On May 22.33, we did
not detect the optical transient down to an image limiting
magnituide of I = 21.0 mag. These magnitudes are tied to
the Bloom et al. (GCN #87) calibration standards.
- GCN notice #91
On behalf of the Manastash Ridge Observatory GRB team, A. Diercks &
J. Morgan observed with the MRO 0.76m telescope the optical transient
(OT) discovered by Jaunsen et al. (GCN #78) in the BeppoSAX error box
of GRB 980519. Conditions were cloudy with roughly 3 arcsec seeing.
Photometry by E. Deutsch & A. Diercks on a 12,000s series of images
centered around May 20.4 UT yields the following magnitudes and
uncertainties for the OT and reference objects:
ID R mag RelErr
-- ----- -----
OT 21.07 0.25
A 17.93 0.05
B 19.36 0.08
C 18.06 0.05
Absolute calibration is based only on R magnitudes of reference stars
reported by Bloom et al. (GCN #87). No independent calibration was
possible due to thick clouds. Our measurement is consistent with the
nearly simultaneous R magnitudes reported in GCN #80 and GCN #82.
- GCN notice #92
R. R. Gal, J. S. Bloom, S. G. Djorgovski, and S. R. Kulkarni on behalf
of the Caltech GRB Collaboration, report:
"In addition to the I and R photometry reported by Bloom et al. (GCN
#87), we have photometered the B and V Palomar 200inch images of the
field of GRB 980519. Derived magnitudes of the following 7 secondary
stars are in the Landolt BV system (see GCN #87 for details):
Star B err(B) V err(V)
A 19.51 0.13 18.31 0.12
B 21.74 0.34 20.05 0.09
C 19.27 0.11 18.35 0.08
E 22.88 0.11 21.07 0.24
F 22.61 0.17 20.83 0.13
G 21.51 0.19 19.74 0.10
H 21.94 0.29 20.26 0.13
The derived magnitudes of the OT are:
May 20.4485 UT, B = 22.53 +/- .14
May 20.466 UT, V = 21.74 +/- .16
May 21.448 UT, B > 22.9 (3-sigma upper limit)
May 21.476 UT, V > 22.0 (3-sigma upper limit)
The non-detection on May 21 is consistent with the power-law decline
slope of beta = -1.98 reported in Djorgovski et al. (GCN #79).
Moreover, broadband colors circa May 20.4 (BV reported herein; RI
reported in Bloom #87) suggest a spectral index of alpha = -1.26 +/-
0.3. This is also consistent with the simple blastwave model
(eg. Wijers, Rees and Meszaros MNRAS 288, L51.) prediction that alpha
= (2/3) beta. The V-band point is somewhat higher (~3 sigma) than the
extrapolated spectrum, suggesting the spectrum of the transient may
not have been a pure power-law. Lastly, given the general consistency
of spectral slope with flux time decay, we note the absence of strong
extinction in the OT (in contrast to GRB 980329).
- GCN notice #96
The U. S. Naval Observatory GRB team (A. A. Henden, F. J. Vrba,
C. B. Luginbuhl, B. Canzian, S. E. Levine, H. H. Guetter, J. A. Munn)
report follow up optical photometry of the secondary standards
(see Jaunsen, et. al. GCN 78 and Bloom, et. al. GCN 87) in the field
of GRB980519. The observations were made on two photometric nights
during the past week with the USNO 1.0m telescope. Johnson BV and
Cousins RI filters were used, with an average of 32 Landolt standards
of wide color range and extinction observed on each night. The
transformations are accurate to 0.01-0.02mag per single observation.
DAOPHOT psf fitting was used in the GRB field, with magnitude
corrections to adjust the photometry to a standard aperture diameter.
Given below is the photometry, with errors based on the variance
between the two nights. More detail, including coordinates and
comparisons between other published values for these stars, can
be found on our Web site at:
http://psyche.usno.navy.mil/nofs/grb/grb980519.html
For further information contact A. A. Henden at aah@nofs.navy.mil or by
telephone at (520) 779-5132.
ID B Berr V Verr R Rerr I Ierr
--------------------------------------------------------------
A 19.661 0.114 18.558 0.018 17.914 0.005 17.338 0.027
B 20.218 0.061 19.318 0.027 18.477 0.001
C 19.313 0.060 18.549 0.027 18.029 0.004 17.525 0.004
D 16.433 0.003 15.614 0.005 15.139 0.000 14.686 0.004
E 21.230 0.146 19.998 0.030 18.767 0.022
F 21.174 0.226 19.900 0.109 18.578 0.289
G 19.915 0.006 18.867 0.004 17.999 0.054
H 20.574 0.062 19.432 0.044 17.990 0.050
I 20.054 0.021 19.645 0.042 19.138 0.007
J 20.907 0.036 20.001 0.011 19.148 0.011
- GCN notice #124
Elia Leibowitz and Peter Ibbetson, Wise Observatory, Tel Aviv University,
Israel report:
Using the Wise Observatory 1-m telescope and the observatory Tectronix CCD
camera, we obtained on May 20 a 1800 sec exposure of GRB980519, through a B
filter. The time of mid-exposure is 01:22:11 UT. The image of the optical
counterpart is at the limit of detectability. Applying the DAOPHOT
photometry package we measured the instrumental magnitude of the counterpart
and of nearby stars. Based on the B calibration of stars C and D of Henden
et al. (GCN Circ. #96), we estimate the B magnitude of the optical counterpart
as 20.95+/-0.25 mag.
- GCN notice #148
V. Sokolov, S. Zharikov (SAO-RAS), E. Palazzi (ITeSRE-CNR),
L. Nicastro (IFCAI-CNR) and the SAX-GRB team report:
"On 1998 July 23.85 UT and 24.96 UT we obtained a deep Rc band image of
the field of the GRB 980519 optical transient (Jaunsen et al. GCN #78)
with the 6-m BTA telescope of SAO-RAS. The total observing time was 9600 s
with 600 s per exposure. Conditions were photometric with an average seeing
of 1.20 arcsec. A faint extended source is clearly detected at the position
of the OT. Due to the faintness of the object, we are not able to check
if between the two nights there was any luminosity variation.
The object magnitude was the same within the errors,
and the photometry of the GRB 980519 OT in 2.5 arcsec diameter aperture
was made by two observational nights and gave Rc = 26.05 +/- 0.22.
For photometric calibration we used the secondary standards from
Henden et al. (GCN #96).
From the time of optical observations of GRB980519 OT with Keck and Palomar
(GCN #88) in the R band
the assumed power-law decline slope of -1.98 (GCN #79) would make the OT
undetectable at the epoch of our observations.
So, we conclude that the OT has stopped its power law decay a long time ago,
and the observable now extended object is the host galaxy of GRB 980519 and
it could be the faintest among those known up today.
Images of the field will be posted at
http://www.sao.ru/~zhar/home/GRB/980519.html (see below).
- GCN notice #149
J. S. Bloom, S. R. Kulkarni, S. G. Djorgovski, R. R. Gal, A. Eichelberger,
D. A. Frail report on behalf of the Caltech/NRAO GRB collaboration:
"Data were obtained on the Keck II telescope on July 18, 1998 UT by
Kulkarni and P. Groot (U. of Amsterdam) using the LRIS instrument. We
confirm the existence of a faint object with R_c= 26.1 +/- 0.3 (July
18.516) at the position of the optical transient of GRB 980519 (GCN #78)
and noted recently by Sokolov et al. (GCN 148). The exposure time was 1500
s. Despite excellent seeing conditions (0.6 arcsec, full width at half
maximum) we see little evidence for extension of the source, the presumed
host of the GRB. In addition, we note the non-detection (Gunn-i > 24.5)
of the host on July 29.396 1998 (2400 sec exp; 1.5 arcsec seeing) with
COSMIC on the 200-inch Telescope at Palomar.
The Keck image of the host of GRB 980519 and secondary standard stars (GCN
#87) may be obtained at
http://astro.caltech.edu/~jsb/host_grb980519.ps. (see below)"
- Optical light curve from Halpern etal (astro-ph/9903418):
- X-ray afterglow decay light curve (from Vreeswijk etal,
astroph/9904169)
- Optical lightcurve and more (from Jaunsen etal, ApJ 546 (2001))
True-color images centered on the fading optical counterpart of
GRB 980519 at epoch 1998 May 20.05, 20.136, and 20.21 UT. North is up,
and east is to the left. The field measures 1 x 1 arcmin.
Upper panel shows the multicolor light curves of GRB 980519 with the
expected rebrightening due to an SN explosion based on the SN 1998bw
light curves (Galama et al. 1998). The host detections by Sokolov et al.
(1998) and Bloom et al. (1998b) are marked by boxes. The lower panel
shows the combined data points after the offsets relative to the RC-band
data have been applied and the host contribution subtracted. The
interpolated (solid lines) and extrapolated (dotted lines) power laws are
also plotted. The inset shows the data from the first night only.
In the left panel we show the broadband spectrum before (filled) and after
(open) correction for Galactic extinction. The right panel shows the
corrected and extrapolated optical spectral slope and the X-ray
measurement by Nicastro et al. (1999) with the estimated X-ray slope
corresponding to X = 1.8 (dashed line) and its 1 uncertainty values
tied by the X-ray measurement (dotted line).
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