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[vsolj-alert 249] (fwd) Re: GRB 990123


理研 吉田

Date: Sun, 24 Jan 1999 15:49:47 +0900
From: Atsumasa Yoshida <ayoshida@crown.riken.go.jp>
Message-ID: <vsolj-alert249@hoge.baba.hajime.jp>
To: tvsolj-alert@ooruri.kusastro.kyoto-u.ac.jp
Subject: GRB990123 optical observation

GRB(GRB time 1/23 9:47:14 UT)から30秒後に9等になったという報告が
ROTSE-I teamから出ています。

理研 吉田

From: GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>
To: ayoshida@postman.riken.go.jp
Subject: GRB990123, early optical counterpart detection
Date: Sat, 23 Jan 1999 18:17:04 -0500 (EST)

NUMBER:  205
SUBJECT: GRB990123, early optical counterpart detection
DATE:    99/01/23 23:15:16 GMT
FROM:    Carl Akerlof at U.Michigan  <akerlof@mich1.physics.lsa.umich.edu>

C. W. Akerlof and T. A. McKay (Univ. of Michigan) report on behalf of the ROTSE
collaboration (Michigan/LANL/LLNL):

We observed the error box of GRB 990123 provided by the BACODINE Burst Position
Notice dated 23-Jan-99 09:46:59 using the ROTSE-I telephoto camera array
located at Los Alamos, New Mexico. The first exposure began at 9:47:18.30,
22.18 seconds after the nominal burst trigger time. A rapidly fading object was
discovered at the coordinates, RA = 231.3754, DEC = 44.7666 (J2000) which is
within 1/3 of a pixel of the optical counterpart reported by Odewahn et al.
(GCN #201). The light curve for this object is relatively complex: the
luminosity increases by 3 magnitudes between the first and second exposures.
Estimated magnitudes for the first six exposures are given below:

        UTC     exposure     m_v

    9:47:18.3    5 secs.    11.82
    9:47:43.5    5 secs.     8.95
    9:47:08.8    5 secs.    10.08
    9:51:37.5   75 secs.    13.22
    9:54:22.8   75 secs.    14.00
    9:57:08.1   75 secs.    14.53

Note that the ROTSE-I detector system uses an unfiltered broadband CCD so that
magnitude estimates are based on comparisons to catalog values for nearby
stars. Sky patrol images of the same coordinates taken 133 minutes earlier
showed no evidence of the transient to a limit of at least two magnitudes
deeper. A more extensive analysis of this data will be available in the near

The discovery images will be posted on the ROTSE Web page at:

This message is quotable in publications.

From: GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>
To: ayoshida@postman.riken.go.jp
Subject: GRB990123 Optical Observation
Date: Sat, 23 Jan 1999 17:46:17 -0500 (EST)

NUMBER:  204
SUBJECT: GRB990123 Optical Observation
DATE:    99/01/23 22:44:31 GMT
FROM:    Jin Zhu at Beijing Obs  <grb@bac.pku.edu.cn>

GRB 990123 Optical Observation

J. Zhu, H. T. Zhang, on behave of the Beijing Astronomical Observatory GRB 
team, report:

"R-band image of the BeppoSAX WFC error circle of GRB 990123 (Piro, GCN #199)
were obtained on 1999 Jan 23.756 UT, 8.5 hours after the GRB, with the BAO 
0.6/0.9m Schmidt telescope in Xinglong. The weather was bad, so only one
20-min. exposure image taken under thin cloud was usable (FWHM=6").

Central part of the image is posted at

A faint object could be seen closed to the optical candidate position 
suggested by S. C. Odewahn et al. (GCN, #201). Its position from our 
measurement is RA=15:25:30.28, Dec=+44:45:59.0 (1 sigma = 0.5"), with 
magnitude of 19.2 (+/- 0.5 ?) if using the following 4 stars' magnitude 
information from the USNO-A V1.0 catalogue (David Monet, et. al.):

No. RA_mea (2000.0) Dec_mea  RA_cat (2000.0) Dec_cat mag.
--- -----------------------  ----------------------- ----
1   15:25:27.03 +44:46:23.3  15:25:27.04 +44:46:23.2 14.4
2   15:25:36.47 +44:44:37.6  15:25:36.45 +44:44:37.6 15.3
3   15:25:32.57 +44:44:29.9  15:25:32.66 +44:44:29.9 18.5
4   15:25:27.42 +44:44:42.5  15:25:27.48 +44:44:43.6 19.7

The object in our image seems slightly extended and slightly southwest
comparing with the discovery image of Odewahn et al., but it seems
to be impossible to confirm from only one image in not good quality.
However, it could be concluded that if such an object (in our image)
would not be real, the optical transient in Odewahn et al.'s images must 
be faded largely between the 4.6 hours interval.

This report may be cited."



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