Sub-group on the Densification of the Optical Frame
                       Newsletter 1 
                      September 29, 2003


Post-IAU General Assembly XXV report

Dear Colleagues,
  This is to inform you on some of the items that took place at the IAU
General Assembly held in Sydney in July.

There were several talks that dealt with the issues that concern members
of this group.  Two sessions of particular interest were the re-organization
of Division 1 and Joint Discussion 16, titled "The International Celestial
Reference System: Maintenance and Future Realizations".
During the first, Francois Mignard presented the ICRS Working Group
organization, status, and some of the work that has taken place over the
last triennium.  He also stated that the WG was very large and that 
some of the duties should continue in some capacity but that he felt that
the WG itself should dissolve.  There were several comments from 
audience members, myself included.  I stated that I understand that 
the size of the WG was indeed large, as is its scope, but that work in
densification of the optical frame has taken place recently and much
more will become complete over the next three years, hence this 
sub-group needs to be viable.  I felt it premature to disband the WG at
this time.

This exchange set the tone for my talk at JD16.  I started by stating that
it was not the use of the 700 or so ICRF object that most astronomers
know the ICRS/ICRF, but it is through the optical densification of the
frame -- from Hipparcos, Tycho-2, etc. -- that they know and understand
the frame.  I went through a summary of some of the major programs on
densification of the optical frame and explained that many of them were
not complete, yet would be in the next three years.  I also explained
that without some level of coordination -- hopefully via the IAU --
astrometry may become very confusing to non-experts due to several
different catalogs becoming available that seemingly fill the same niche.
Therefore, I pleaded, our group needed to continue under the IAU in some
capacity.

At this point Toshio Fukushima (chairman of Division I) stated that maybe
Commission 8 should be the supporting commission for this group, 
presumably becoming a working group.  (For those of you who may 
have forgotten, the ICRS WG is directly under Division I, not under an
individual commission).  Imants Platais, chairman of Commission
8, stated that he would welcome the group.  I stated that the details could
be worked out later, but I strongly believe that the group should 
continue in some capacity.  At the end of JD 16, there were discussions
regarding Division I re-organization, including what to do with the
sub-groups of the ICRS WG.  What was finally decided was that
no re-organization would happen for at least 6 months for our
sub-group, so everything would remain the same during that time.

For your information, new rules for the IAU organization have been
adopted.  One of those rules is that division presidents can instate
working groups at any time.

This is where we currently stand.  I am asking the members of this 
group what their desires are.

1) Do you believe that this group should continue in some capacity?
2) If so, do you want to remain a member?
3) What is your opinion on moving directly under Commission 8?


  
                      Sincerely,



                      Sean E. Urban
                      U.S. Naval Observatory
                      (202) 762-1445
                      seu@usno.navy.mil


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