GRB 990316

P. Ibbetson, E.O. Ofek and E.M. Leibowitz report:
 On March 16 1999, some 7.5 hours after the outburst of GRB990316 (Trigger Num.
 7475), using the 1 m telescope of the Wise Observatory, we have taken 5 CCD
 frames of 900 seconds exposure and FOV of 11x11 arcmin^{2} each, through an R
 filter. Together they cover a square box of nearly 0.3x0.3 deg^{2} around
 RA=10:06:16  Dec=-05:13:31 (J2000), at the mean UT 17:34. We have not
 identified any new object relative to the corresponding DSS images, up to a
 limiting magnitude of 19.5. Within a box of 11x11 arcmin^{2} around the
 central point the limiting magnitude is 19.9.

H.S. Park, L. Ott, R. Porrata (LLNL), G. Williams, D. Hartmann 
(Clemson Univ.) report on behalf of the LOTIS collaboration:
 
LOTIS obtained realtime images of GRB990316 (BATSE Trigger 7475).
LOTIS  started recording the first image 13.6 sec after the burst
(on the rising edge of the GRB light curve). The first image was taken
with a 30 s integration time, thus this image completely overlapped the
remainder of the GRB gamma-ray emission which lasted a total of ~40 sec.
The first image from one of our 4 cameras (each with 8.8 x 8.8 deg
field of view) covers > 98% of the BATSE 3 sigma (0.3 deg statistical +
1.6 deg systematic) error circle. The GRB location is further
constrained by an annulus derived from IPN data (GCN/IPN notice) 
that passes through the BATSE error circle in the image. 
 
We searched for optical transients in this image by 1) comparing
background images taken at later times and 2)comparing the stellar
objects in the image with objects in the Guide Star Catalog and Digital
Sky Survey images. We found one transient object at RA=147.54, 
DEC=-4.95 (J2000) near the edge of the IPN annulus with V~12.5 
brightness. This object was seen only in the first image. No object
is seen in the DSS image at this location. The second image was 
started after the gamma ray emission was over (at 55 sec after the 
start of the burst). We cannot rule out the possibility that this OT 
is a local effect rather than associated with the gamma ray burst. 
However, we encourage follow up observations at this location for 
possible afterglow observations.
 
Further analysis is in progress and associated data will be placed
on our web page.

Howard E. Bond (Space Telescope Science Institute), Kevin M. McLin (CASA,
University of Colorado), and James Rhoads (Kitt Peak National Observatory)
report on behalf of the KPNO GRB followup team:

We have observed the location of the LOTIS candidate optical transient
reported by Park et al (GCN 277
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 ).  Bond has obtained a 300 second V band
image using the KPNO 4 meter Mayall telescope; the observation is
centered at 1999 March 18, 06:45 UT.

McLin observed the same field for a total of 1800 seconds in R band using
the KPNO 0.9 meter telescope; the observations were centered at 06:30 UT.

Conditions were clear with 1.6 to 1.7 arcsecond seeing.

Comparing our images to the digitized POSS-II red plates, we find no
compelling evidence for any new source above the POSS plate limit.
This implies an approximate limit of R>21 for any fading source
consistent with the location of the LOTIS candidate.
(We have assumed that the positional uncertainty is less than 1 arcminute
for the LOTIS source, based on the 15 arcsecond LOTIS pixel size.  Our
actual fields of view were 36' for the 4m and 23' for the 0.9m data, so
could be used to search for transients over a larger area.)

Our R and V band images are both deeper than the POSS plates, and further
CCD photometry is encouraged to see whether any fainter sources are varying.
The R band image and a subsection of the V band image are available
on the Web from http://www.noao.edu/noao/grb/990316.html .  Please note
that these images are not fully reduced; they will be replaced with
fully reduced images when available.

I.-A. Yadigaroglu, C. Liu & J. P. Halpern (Columbia U.), H. E. Bond (STScI)
report on behalf of the MDM Observatory GRB follow-up team:
 
"We imaged in the V band the location of the LOTIS optical candidate (GCN
277
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 ) for GRB 990316 on Mar 19.22 using the MDM Observatory 2.4m telescope. 
A total of 40 minutes exposure was obtained in seeing of 1.0 arcsec. The
image was compared to an image of the same region obtained the previous
night at the KPNO 4m telescope (GCN 278
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 ). No fading objects are found in
a conservative 2 arcmin radius around the LOTIS position. A calibration
using a Landolt standard gives plate limits of 23.9 and 23.0 for the Mar
19.22 and 18.28 images respectively. For reference, the magnitudes of two
nearby stars are V = 20.25 at (J2000) RA 9:50:14.6, Dec -4:56:32.3, and
V = 20.14 at RA 9:50:14.9, Dec -4:56:56.3. An asteroid with V = 22.6 is
detected on Mar 18.28 an arcminute away from the LOTIS position."

This message may be cited.

T.J. Galama (U. of Amsterdam), E. Pian, E. Palazzi, F. Frontera,
N. Masetti (ITESRE, CNR, Bologna), K.C. Sahu (STScI), P.M. Vreeswijk,
E. Rol (U. of Amsterdam), J. van Paradijs (U. of Amsterdam and U. of
Alabama in Huntsville), C. Kouveliotou (USRA/MSFC), O. Hainaut, and
V. Doublier (ESO/Chile) report:

"We have observed the location of the LOTIS candidate optical
transient reported by Park et al (GCN 277
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 ) with the European Southern
Observatory (ESO) New Technology Telescope (NTT) on March 18.18 and
March 19.17 in V and R for 900 sec each. We do not find objects
variable by more than 0.25 magnitudes down to V = 24.1, R = 24.3 in a
2 x 2 arcmin region around the LOTIS position. The magnitudes are
measured relative to a star at RA 09:50:13.26, DEC -04:57:45.6 (V =
19.25; R = 19.03; we estimate an absolute calibration uncertainty of
0.15 magnitude). "

This message is citeable.

T.J. Galama, P.M. Vreeswijk, E. Rol (U. of Amsterdam), J. van Paradijs
(U. of Amsterdam and U. of Alabama in Huntsville), C. Kouveliotou
(USRA/MSFC), R.G. Strom (NFRA and U. of Amsterdam) and A.G. de Bruyn
(NFRA and U. of Groningen) report:

"We have observed the location of the LOTIS candidate optical
transient reported by Park et al (GCN 277
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 ) with the Westerbork
Synthesis Radio Telescope (WSRT) at 4.88 GHz on March 20.90 (for 11
hours). We do not find any radio source brighter than 130 microJy (3
sigma) in a 2 x 2 arcmin region around the LOTIS position."

This message is citeable.

A. O. Jaunsen (University of Oslo),
M. I. Andersen (Nordic Optical Telescope, La Palma),
J. Hjorth, and H. Pedersen (University of Copenhagen) report:

We obtained R band images of the area around the possible LOTIS optical
counterpart to GRB 990316 (GCN #277
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 ) with the Nordic Optical Telescope 
on March 18.865 (1800 sec, FWHM = 1.40") and March 19.118 (1200 sec, 
FWHM = 1.45").  We find no evidence for variable objects in the 6' x 6' 
field centred on the LOTIS position.  A plot of the difference in inferred 
magnitude versus magnitude for objects detected in the field is posted on
the web page given below.  Comparison between a combined image of our NOT 
data and the KPNO R-band image (Bond et al., GCN #278
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 ) also give no 
significantly variable object.

All images obtained of the LOTIS position may be combined to reach fainter 
detection levels.  For this purpose we make our fully reduced and WCS (USNO 
A2.0) calibrated NOT images available at
http://www.astro.uio.no/~ajaunsen/grb990316/ .