The nature of GRBs still remains puzzling, but now most of
physicists believe that the objects are at cosmological distances
and represent to the most energetic explosions in the universe
(10^51 ergs i.e. 10^44 watts).
The observed rate of GRBs is roughly one per day and they came from
unpredictable positions on the sky. Their sky distribution is
There was enormous progress in the GRBs observations in the last years. The
X-ray as well as optical and radio afterglows of GRB have been
detected and investigated. However, much more observations are
still needed to explain completely their nature. It seems to be
that the multispectral observations - including optical imaging and
photometry - is the right way how to approach the problem.
After the discovery of optical transients (afterglows) of two GRBs
in 1997, more such observations are still urgently needed.
At present, the data about detected GRB (position and time) are
distributed generally by the GCN Network (GRBs Coordinates
Network, formerly BACODINE)
operated at the NASA GSFC. They distribute data of
different accuracy and at different delays after the times of GRBs.
In general, there are four most important basic groups of GRB
A. HETE triggers
Prompt information about GRBs detected by the the US satellite Compton
HETE. Typical time delay
between just a few seconds to roughly hours, the typical
accuracy 10 arcmin to degree radius.
B. INTEGRAL triggers
Prompt information about GRBs detected by the INTEGRAL satellite.
Typical time delay seconds to hours with
accuracy of order of a few arcmins.
C. IPN triggers
Delayed information about GRBs detected by the IPN Network.
Typical time delay hours to days, typical accuracy of order of 10 arcmin.
2.1 Organization of optical observations
What is needed: optical camera and/or telescope with CCD camera
and/or film/photographic plate:
Field of View (FOV) of order of 0.2 to 2 deg
In all cases, the deepest possible limiting magnitude should be
Everybody having the WF camera (FOV more than 3 deg) with lim mag
12 or better, camera with FOV of order of 1 - 3 deg with lim mag 13
or better, and a telescope with FOV of order of 10 min and lim mag
of 14 or better can contribute valuable new data.
The most convenient way to receive the data is the email. However,
if you have no email access, we can organize an alternative way of
getting you informed (fax, phone).
2.2 The observational sequences
The first observation should be performed immediately after
obtaining the GRB information. It should be immediately followed by
the second observation to prove the reality of objects detected.
The absolute minimum of observations are these two innitial images
followed by the two comparsison images taken a few days (or later)
However, more dense observations are strongly encouraged. In general,
we expect that there may be two
- possibly different - types of optical emmisions, the first being
the direct optical counterpart to the GRB, and the second being the
delayed optical afterglow caused by the interaction of expanding
relativistic fireball shell with interstellar matter. Hence, dense
optical observations are required at least for the first hours
after the time of GRB.
In general, wide field observations are important at the immediate
times after the GRBs, before better positions will be known, while
deeper narrow field observations are important for all well
positioned GRBs for all the time range between the event and 7 days
Standard BVRI filters should be used especially with CCD imaging,
although unfiltered images may be also of some value. With regard
to the maximum efficiency of the CCD, the R filter has been
negotioned as the standard one.
The photographic images may be also filtered (B, V or R depending
on the emulsion type) or unfiltered.
2.3 Data processing
The obtained images should be carefully investigated for all types
of optical activity inside the GRB error boxes, i.e. both for new
and variable objects (stars). The best technique how to do it is to
blink the obtained images either by software (for CCD frames) or by
blink microscope (for photographs). The data should be processed
immediately to avoid any delays since, in the case of positive
finding, this information should be provided to larger telescopes
to perform deep investigations of these candidates.
However, if you have no possibility to evaluate the data and/or you
need an assistence and service, contact us and we will try to help.
3. AGN/blazar monitoring
Extended optical investigations of GRB positions have provided
information on large optical flares with underlying faint AGNs at
these positions. In all of these cases, the light amplitude of the
flares was 10 mag or even more. This is similar to what is observed
for the recently detected optical afterglows for GRBs. There have
been also found AGN candidates at the positions of some GRBs.
Further, many of the AGNs and blazars are optically violent,
showing many types of variability and also large amplitude flares
but their light curves are generally undersampled so far. Hence
a better monitoring is extremely necessary to better understand the
physical processes in these objects.
We have selected a list of AGNs/blazars for detailed optical
monitoring. Most of them are optically very violent and many of
them can be easily accessed even by small telescopes.
Two types of optical observations are necessary:
A. Simultaneous and quasisimultaneous observations for satellite
campaigns or during high activity state of the object.
In both of this cases, you will be informed. Then the more dense
sampling (photometry) is welcomed, at least one point per night, but
more is better. For CCD observers, R filter should be preferred.
B. Standard monitoring of selected objects
Standar monitoring to follow the optical evolution of the object.
One observation per week could be enough, but again, more dense
light curve will be better. For CCD observers, R filter should be
The list of objects both of categories of A and B follows as well
as finding charts and standard stars. A more detailed up-dated
information is available via our web site at
4. Data policy
It is our aim to do the final data evaluation and publication
jointly. Everybody contributing to the data will be added to the
list of co-authors of all of the publications and presentations.
5. Information for newcomers
All new collaborators are welcomed. Let us know all the information
we need: names, addresses and telephone numbers of contact persons,
the exact geographic position of the observatory, list of
telescopes to be used within the program including their apertures,
detector types, focal lengths, FOVs, limiting magnitudes, typical
We will then add your email address to the distribution list. If no
email is available, please suggest an alternative method of
We can provide some support for the observers using photography.
The Czech Photography Firma FOMA BOHEMIA s.r.o. has
developed a blue-sensitive emulsion (planfilm) FOMA-ASTRO and
a panchromatic emulsion (film) FOMA ASA 800.
Everybody interested in the use of these inexpensive emulsions
should contact us.
Further, support and/or assistence with data evaluation
(photographic and CCD) may be also provided.
1. List of objects for monitoring
1.1. AGNs - candidates for the identification with GRBs
a. The 18 mag QSO at the position GRB960720
b. The BL Lac Object in the WATCH GRB Position
c. The BL Lac Object in the WATCH GRB Position
1.2. AGNs/blazars with suspected periodic flares
b. OQ 530(1418+546)
1.3. Others optically violent AGNs/blazars
a. B2 1308+326
b. ON 231
c. OJ 287
d. Mark 421
e. Mark 501
1.4 Others objects of interest
a. Flaring star in the GRB box 17m Greiner and Motch, A&A 1995
b. OT Borovicka, A&A 1995 - variable star inside GRB box