Sub-group on the Densification of the Optical Frame Newsletter 6 June 21, 2000 Dear Colleagues, This is the sixth newsletter of the Sub-group on the Densification of the Optical Reference Frame. As all of you are aware, the General Assembly will be held in Manchester this August. I will be present and hope to see many of you there. Dafydd Wyn Evans (dwe@ast.cam.ac.uk) has reserved a room so those interested in densification issues can meet in an informal setting. The location and time are Room Roscoe, August 14 from 16:00 to 17:30. Since the General Assembly is only a few weeks away, an update on various projects is in order. The "Projects" page under the WG website has been recently revised. Here are a few items I would like to highlight. 1) IAU Colloquium 180, titled "Towards Models and Constants for Sub-Microarcsecond Astrometry" was held in Washington, DC March 27 through 31. Several resolutions were drafted; they can be found at the colloquium website at 'http://aa.usno.navy.mil/colloq180/'. The proceedings have just gone to press and will be mailed directly to all registered participants, who should receive them in July. In addition, some will be available at the IAU General Assembly. 2) The Tycho-2 Catalogue was released in February. See the Projects page for additional information. All of you should have received a CD in the mail. If not, contact me. 3) An update on the Carlsberg Meridian Circle (CAMC) observing program is now available on the Projects page. 4) The UCAC1 catalogue was released in March. See the Projects page for additional information. 5) An abstract on using the Pulkovo photographic data set to densify the optical reference frame has been added to the Projects page. 6) The 2MASS project's second incremental release was made in March. Again, see the Projects page of the WG website. As always, I am open to suggestions about the website, including posting news on other projects which may be important to the group. I hope to see each of you in England. Sincerely, Sean Urban U.S. Naval Observatory June 23, 2000 http://ad.usno.navy.mil/ad/dens_wg/dens.html