GRB 010126

K. Hurley, on behalf of the Ulysses GRB team, and D. Smith, on
behalf of the RXTE ASM GRB team, report:

This burst, which was incorrectly reported as occurring on the 25th in
today's GCN notice, was observed, with rather poor statistics, by
Ulysses.  It had a duration of ~10 s, a 25-100 keV fluence of ~2 x
10^-6 erg/cm^2, and a peak flux over 0.25 s of ~7 x 10^-7 erg/cm^2 s.
These numbers should be regarded as very approximate due to the
weakness of the burst. We have done a very rough, preliminary
triangulation using the RXTE ASM 5 - 12 keV data and the Ulysses 25 -
150 keV data.  Although the time histories are somewhat different in
these two energy ranges, the result indicates that the GRB came from
the northern part of the RXTE ASM error box, above declination ~ 49 o 20 '.  
If this event was observed by Konus-WIND or NEAR, a smaller
error box can probably be derived.





[GCN OPS NOTE:  Please note that the calendar dates for the recent
GCN/RXTE_ASM_GRB_POSITION Notice contained an error.  The date was listed as
GRB_DATE:                 11935 TJD;    25 DOY;   01/01/25
but the correct dates are
GRB_DATE:                 11935 TJD;    26 DOY;   01/01/26
This error occurred in the GCN processing of the ASM message -- it was not part
of the original ASM submission.  The burst occurred today, and not yesterday
as might be inferred by casual inspection of the DOY or YY/MM/DD fields.
GCN apologizes for this error.]

K. Hurley, on behalf of the Ulysses GRB team, T. Cline, E. Mazets, 
and S. Golenetskii, on behalf of the Konus-WIND GRB team, and D.
Smith, on behalf of the RXTE ASM GRB team, report:

Ulysses and Konus observed this burst at ~33048 s.  Triangulation
gives a Ulysses/KONUS/RXTE error box whose area is ~50 sq. arcmin.
and whose coordinates are:

    RA(2000)                              DEC(2000)
 ERROR BOX CENTER:  11 h 57 m 08.61 s     49 o 44 '  36.00 " 
 ERROR BOX CORNER 1: 11 h 56 m 19.62 s     49 o 34 '  54.86 " 
 ERROR BOX CORNER 2: 11 h 56 m 52.98 s     49 o 38 '  27.86 " 
 ERROR BOX CORNER 3: 11 h 57 m 48.00 s     49 o 51 '  48.00 " 
 ERROR BOX CORNER 4: 11 h 57 m 34.00 s     49 o 53 '  13.00 " 

If NEAR observed this burst, it may be possible to refine
this error box further.  

The RXTE data may be found at http://xte.mit.edu/grb010126/

P.A. Price (Caltech), A. Gal-Yam (Wise Obs.) and J.S. Bloom (Caltech) report
on behalf of a larger collaboration:

"We have observed the IPN error box of GRB010126 (Hurley et al. GCN #922
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with the Wise 40-inch telescope in R-band starting at approx Jan 27.04 UT.
Our 8x600s images cover the entire error box with two overlapping pointings.
The effective integration time varies over the area of the error box.  From
visual inspection of the combined image, we do not find any objects which
are not present on the Digital Sky Survey 2 red plate."

[GCN OPS NOTE (27jan01): A typo on the observation time was corrected
from 21.04 UT to 27.04 UT.]

GRB010126

C. Bartolini, A. Guarnieri and A. Piccioni, Departement of Astronomy,
Bologna University, and S. Bernabei, L. Fabbroni and R. Gualandi,
Bologna Observatory, communicate:
"We observed the error box of GRB010126 on January 27, 2001, in poor
weather conditions (seeing 2".5) with the 1.5 m Loiano telescope. 
Two CCD frames, 13'X13', centered on the error box center reported by
K. Hurley on GCN922
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 , were obtained in R band with start times UT 01:05:00
(30 min) and UT 01:39:00 (20 min), respectively.
A preliminary inspection of the two frames shows a possible variable
object (r.a. 11 57 07.3, de. 49 44 26.5) not present in the DSSII-red,
barely over the plate detection limit.  This object, by comparison
between the two frames, seems to be fading.  Deeper analysis is in
progress."

[GCN OPS NOTE(28 Jan 01): This Circular was sent at 01/01/27  04:29:01 GMT,
but was not distributed because the submitor was not in the vetted list
at that time.]

H. Pedersen, J. Hjorth, B. L. Jensen (U. of Copenhagen), 
M. I. Andersen (University of Oulu), J. P. U. Fynbo (ESO, Garching), 
J. Gorosabel (DSRI, Copenhagen), A. A. Kaas (Nordic Optical Telescope),
L. Takalo, and R. Rekola (Tuorla Observatory), report on behalf of a 
wider collaboration:

GRB010126 Optical Observations
------------------------------

"Using the 2.56-m Nordic Optical Telescope (+ALFOSC), La Palma, we have 
obtained a total of eight images which cover the error box (Hurley, GCN 922
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 ) 
by means of four consecutive pointings: 

UT                    Filter    Exp.time         Seeing
===========================================================
2001 January 27.21    R         (4 x ) 180 s     0.85" FWHM 
2001 January 28.13    R         (4 x ) 180 s     0.90" FWHM 

Intercomparison of the images has revealed no candidate counterpart 
to magnitude ~22.5 .

The object reported by Bartolini et al. (GCN 924
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 ) is detected on two 
overlapping exposures, i.e. 360 s, at each epoch. Using the nearby USNO 
star U1350_08031605 as reference, we find R = 21.17 +/- 0.20 (epoch 1) and 
R = 21.29 +/- 0.20 (epoch 2), i.e. consistent with no variability."

N. Masetti, E. Palazzi (ITeSRE, CNR, Bologna), M. Pedani, A. Magazzu,
F. Ghinassi (TNG) and E. Pian (OATs, Trieste), on behalf of a larger
collaboration, report:


"We acquired optical R-band images of the central part of the 
GRB010126 Ulysses/Konus/RXTE error box (Hurley et al., GCN #922
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on 2001 Jan. 27.26 and 28.27 UT (i.e. 21 and 45 hours after the GRB) 
with TNG+Dolores. The total exposure time was 10 minutes for each epoch. 
Seeing was 1.3 and 1.7 arcsec on the two epochs, respectively. 
The images covered about 60% of the GRB error box.

Photometric calibration was performed using the USNO-A2.0 catalog star
U1350_08031829, with magnitude R = 17.9 and coordinates (J2000) 
RA = 11 57 10.29; Dec = +49 46 58.9.

The comparison between the two epochs does not reveal any object
with significant brightness variation down to a 3-sigma limiting
magnitude R ~ 23.5 .
The object reported by Bartolini et al. (GCN #924
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 ) is well detected on
both epochs and is constant within the measurement errors at magnitude
R = 21.29 +- 0.05 (excluding zero-point calibration uncertainties).
This is consistent with the findings by Pedersen et al. (GCN #925
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 ).".


This message can be cited.

R. J. Nemiroff, D. Perez-Ramirez, W. E. Pereira,
J. B. Rafert, C. Ftaclas, and J. Fernandez 
(Michigan Tech)
report on behalf of the CONCAM collaboration:

The CONtinuous CAMera (CONCAM) operating at
Kitt Peak National Observatory has recorded fisheye 
images that provide crude limits on the attributes of 
an OT through non-detection. 

A relevant CONCAM frame contains an integration from 
33022 s to 33202 s that brackets 33048 s, the time 
of the GRB trigger reported by Hurley et al. in GCN922
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 , 
and the duration of the GRB as reported by Hurley et al. 
in GCN 921
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 .  Raw FITS data are available at 
http://concam.net .  Processed GIF images of this 
frames, the previous frame, and the following frame, 
are available here: 
http://concam.net/kp010126/kp010126ut0902.gif
http://concam.net/kp010126/kp010126ut0910.gif
http://concam.net/kp010126/kp010126ut0914.gif

No obvious optical counterpart down to about visual 
magnitude 6.3 over the three-minute exposure is visible 
on the frames.  This is, to the best of our knowledge, 
the first time an optical electronic instrument was 
observing a GRB location during a GRB trigger.

The time recorded on the CONCAM frames are behind the 
actual UT time by about 26 seconds.  We have corrected 
for this in this report so that the uncertainty in the 
above reported times is only about 2 seconds.

K. Hurley, on behalf of the Ulysses GRB team, D. Smith, on behalf
of the RXTE-ASM GRB team, T. Cline, on behalf of the Konus-Wind
and NEAR GRB teams, and E. Mazets and S. Golenetskii, on behalf
of the Konus-Wind GRB team, report:

NEAR observed this event, previously reported in GCN 921
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  and 922
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 .
Triangulating this burst with Ulysses, Konus, and NEAR gives a
preliminary, 3 sigma error box whose area is ~240 sq. arcmin. 
and whose coordinates are:

    RA(2000)                 DEC(2000)
 11 h 58 m 45.64 s     50 o  2 '  41.37 "  (CENTER)
 12 h  0 m  2.95 s     49 o 59 '   3.02 "  (CORNER)
 12 h  1 m  3.73 s     50 o  5 '  46.18 "  (CORNER)
 11 h 56 m 25.01 s     49 o 59 '  30.17 "  (CORNER)
 11 h 57 m 27.75 s     50 o  6 '  17.68 "  (CORNER)

Although this error box is consistent with the previous triangulations,
it excludes the 90% confidence RXTE-ASM error box, and therefore the
IPN/RXTE error boxes which were based on it.  However, extending the
long dimension of the ASM error box from 1.5 degrees (90% confidence)
to 2.0 degrees (3 sigma) does produce an RXTE-ASM/IPN intersection.
The resulting error box has an area of ~20 sq. arcmin. whose
coordinates are:

    RA(2000)		      DEC(2000)
 11 h 58 m 21.49 s      50 o 02 ' 20.00 " (CENTER)
 11 h 57 m 59.42 s	49 o 59 ' 20.44 " (CORNER)
 11 h 58 m 18.57 s  	49 o 59 ' 18.09 " (CORNER)
 11 h 58 m 40.70 s	50 o 04 ' 38.00 " (CORNER)
 11 h 58 m 27.26 s	50 o 06 ' 04.00 " (CORNER)

A map has been posted at ssl.berkeley.edu/ipn3/010126
showing the new RXTE-ASM error box and its intersection
with the IPN annuli.  (Do not attempt to derive coordinates
from this map, which is a plane projection.)

We regret any confusion caused.

GRB010126

C. Bartolini, A. Guarnieri, A. Piccioni , Departement of Astronomy,
and S. Bernabei, Bologna Observatory communicate: 
"Photometry of the object pointed out by us in GCN 924
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 : 
start time Jan 27.0451;  R = 21.3 +- 0.2 ; exp. time 30 min 
start time Jan 27.0687;  R = 21.3 +- 0.4 ; exp. time 20 min 
Calibration star: USNO U350_08031605. 
The hypotized short term variability (GCN 924
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 ) is excluded. 
Although these values are well above the detection limit of DSSII-red, 
the object is not present on it. This behaviour is consistent with a 
long term, large amplitude variable or an  eclipsing binary.
Our two CCD images can be retrieved by secure shell ftp at the address:
GRB@ermione.bo.astro.it, username GRB, passwd 01_0126."