Gamma Ray Burst optical follow-up program
    C. Veillet (CFHT)  - M. Boer  (CESR)


GCN circulars archive
GRBs localized with WFC (BeppoSAX) or BATSE/RXTE or ASM (RXTE)
Information About Recent Specially-Selected GRBs

Christian Veillet's Homepage


GRB990123 GRB000301C GRB000604 GRB000926

GRB010222  observations

 
Composite view of the vicinity of the OT

March 2    (posted on March 2)
 
 

(click on the image to zoom)


This is a combination of two 10 mn images 
using MOS in imaging mode 
(EEV detector 0.28"/pixel - seeing ~0.8")
The OT is in the center of the image

 

GCN #1003

GRB010222 - Optical observation and decay

The optical counterpart of GRB010222 has been observed using the
CFHT Multi Object Spectrograph in imaging mode at the Cassegrain
focus of the 3.6-m CFH Telescope on the night of March 1 to 2.

Two 10 mn images were obtained with a seeing of about 0.8".

Photometric reduction made as outlined on GCN #1000 leads to:

Mar. 2.641   R = 23.10 +/- 0.10

The index of the power law decay fitting the R light curve data
since 0.6 days after the burst (including the revised and new
measurements by Holland et al. in GCN #1002) is 1.25 +/- 0.03,
the same as our previous determination (Veillet, GCN #1000) and
not significantly different from the GCN #1002 value.

While a few objects are now seen in a radius of 4", the OT is
still a point like object.

More information (with the new images of the OT) can be found at
http://www.cfht.hawaii.edu/~veillet/grb.html

M. Pakull, L. Mirioni, and J. McDonald are acknowledged for their
help  in this observation.

This message may be cited.
 
 


March 1    (posted on March 1)
 

(click on the image to zoom and get a larger field)


This is a combination of two 10 mn images 
using MOS in imaging mode 
(EEV detector 0.28"/pixel - seeing ~0.8")
The OT is in the center of the image...


1 is the star like object used for overall consistency check 
of the field with Henden's list (GCN #987).
2 is the object used for faint object photometry quality.

GCN #1000

GRB010222 - Optical observation and decay

The optical counterpart of GRB010222 has been observed using the
CFHT Multi Object Spectrograph in imaging mode at the Cassegrain
focus of the 3.6-m CFH Telescope on the night of Feb. 28 to March 1.

Two 10 mn images were obtained in much better conditions than
the night before (GCN #998) with a seeing of about 0.8".  There are
only a few point like sources in the vicinity of the OT. A star like
object ~11" S of the OT has been carefully measured with respect
to the two stars used in GCN #998 and has a very consistent R
magnitude on the MOS exposures (R = 20.13 +/- 0.02). A fainter
object 8" from the OT is used for internal consistency checks at
R = 22.35.

Precise reduction of the images from Feb. 28 and March 1 gives the
following results:

Feb. 28.653 UTC   R = 22.73 +/- 0.10
Mar. 01.628 UTC   R = 22.96 +/- 0.10

The index of the power law decay given in GCN #998 is not
significantly modified and found as 1.25 +/- 0.06.

There is not structure found on the OT, which is still seen as a
point source on the March 1 combined image.

More information (with the new images of the OT) can be found at
http://www.cfht.hawaii.edu/~veillet/grb.html

M. Pakull, L. Mirioni, and J. McDonald are acknowledged for their
help  in this observation.

This message may be cited.



February 28   (posted on February 28)
 

(click on the image for a larger field)


One image has  been taken at the end of the night
(10 mn in R) using MOS in imaging mode 
(EEV detector 0.28"/pixel - seeing ~1.5")
The OT is in the center of the image...

GCN #998

GRB010222 - Optical observation and decay

The optical counterpart of GRB010222 has been observed using the
CFHT Multi Object Spectrograph in imaging mode at the Cassegrain
focus of the 3.6-m CFH Telescope on the night of Feb. 27 to 28.

One image was obtained in relatively poor conditions (seeing ~ 1.5").
A preliminary reduction using stars (223.008250,43.006507) and
(223.098277,42.994077) from Henden's list (GCN #987) gives:

Feb. 28.653 UTC   R = 22.60 +/- 0.15

The relative photometry of the two stars used is consistent
with our image within 0.02 magnitudes. Using all the measurements
of the R magnitude of the OT published in the GCN's (corrected if
needed to put them back in the photometric system of Henden's list),
the R magnitude is following a nice power law decay with an index of
1.20 +/- 0.07 since 0.6 days after the burst.

An image of the OT and a graph of the decay are available at
http://www.cfht.hawaii.edu/~veillet/grb.html

S. Lilly and J. McDonald are acknowledged for their help in
this observation.

This message may be cited.