WORKING GROUP ON
ASTROMETRY BY SMALL GROUND-BASED TELESCOPES
Purpose of this working group
This Working Group on Astrometry by Small Ground Based Telescopes is a Working Group of the
IAU Division A on Fundamental Astronomy.
It has been initiated during the XXVIth General Assembly of the IAU in Prague, in August 2006 by the
Division 1 (Fundamental Astronomy) of the IAU.
It has been extended by the division 1 or division A during the following general assemblies.
The goal of this WG is to update and maintain information on astrometric programmes
and activities carried out by small telescopes (up to 2m diameter), to diffuse news through these
pages and by e-mails, to facilitate the collaborations and to help for the coordination
of the activities, when possible, in astrometry from ground-based telescopes.
These telescopes are generally easier to access than the larger ones and allow
us to carry out observational programs on medium and long term. Thanks to these
properties they are precious tools to contribute to the advance of our knowledge
of the celestial bodies: many Solar System objects and some astrophysical objects.
More generally, the small telescopes due to their number and their geographical
spread, are very efficient for observation in network. This is a strength which
is successfully applied for coordinated programs.
The intent of the Working Group is to help coordinate the
existing programmes, to exchange information at an international level
and to encourage participation in different projects in astrometry at
large. Astrometric measurements of positions for dynamics, fundamental
astronomy or astrophysics, but also photometric observations of events
for determination of size and shape, determination of the parameters of
rotation can pay benefit from these instruments. This is possible for
example thanks to observations of mutual events of the natural
satellites, stellar occultations, mutual events of binary asteroids, etc.
Several such campaigns are encouraged.
Furthermore the role of the WG is also to teach the astrometry theory and
practice to the next generation, this is why the organization of training stays
The Working Group operates mainly by e-mail. Follow this link for a list of the current
Members of the Working Group.
To the members: please send any updated email addresses or changes of Institutes to the IAU Secretariat at: iauinfos(at)iap.fr
- Gaia Follow-up: The space mission Gaia will is triggering daily alerts for ground-based observations.
A dedicated network for astrometric observations on alert and follow-up of the Solar System objects, Gaia-FUN-SSO,
has been set up for this goal and started to operate in 2011. The Gaia alert system is daily operating since October 2016.
Observers will ensure fast observations of newly detected by the probe.
They can register and access the alerts
at this address .
Furthermore before this mission and its avalanche of high accurate
data, several observations can be made with small telescopes such as
the determination of some asteroidal masses and the improvement of
orbital models of neglected natural satellites.
More information on the Gaia accompanying observations from the ground is available on this page.
- Other follow-up: The work of the actual surveys and the advent of new large and fast surveys
(e.g. Pan-Starrs, LSST,...) which store huge amounts of data, reinforce the
need to have follow-up observations in particular for the study of the Near-Earth
objects and the improvement of their orbits. Astrometry by small telescopes
is very useful for this goal. For example:
Minor Planet Center posts a list of the NEOs
which require to be observed. See also the MPC NEA Confirmation page.
- the ESA Near Earth Coordination Center web site gives
also a list;
- the NEODys2 web gives another list.
- the NASA/JPL publishes a list of potentially hazardous asteroids that could be useful to observe.
- several NEOs follow-up programs are accessible through addresses published in
this JPL page
- Mutual event campaigns: photometry for astrometric purposes In 2021 we entered in a new mutual event season of the Galilean satellites
of Jupiter. Small telescopes can lead to astrometry of very high precision. Further details are available on the
- Various astrometric activities: Numerous astrometric activities are performed with small telescopes. Here, we post a link to a
list of the activities
and, when possible, to some web pages from the teams themselves. A special mention will be made for activities which
require a coordination of astrometric activities and which could use
these pages in order to get in touch other teams.
In this section, we post a list of relevant documents and references related
to astrometry by small ground-based telescopes. Don't hesitate to send such
new references to the chairperson of this WG.
The following links are related to the topics of the WG:
Updated: 7 February 2023