Newsletter IAU WG densification of optical reference frame
==========================================================

2007 May 04

Dear WG members and interested parties,

I did not receive many responds from my request for input to
this working group.  Adding in some items from my knowledge,
here is a list of projects/groups relevant to our WG:

  Automated Transit Circle, CMC, San Fernando
  Dafydd Evams, Jose (Pepe) Muinos et al.
  - CMC14  catalog complete and published
  - observations -40 to -15 deg Dec in progress

  Automated Transit Circle, El Leoncito (Argentina)
  Jose (Pepe) Muinos et al.
  - observation of -55 to +35 deg Declination
  - partial catalog publication in 2007
  - final catalog by 2009

  Bordeaux, PM2000
  Christine Ducourant et al.
  - recent transit circle observations of Bordeaux zone
  - re-work Astrographic Catalogue data for proper motions
  - accurate, rigorous reductions of all, catalog published

  Tie to ICRF, extragalactic sources
  - Bordeaux work (Christine Ducourant et al.)
  - Brazilian group (Marcello Assafin, Alexandre Andrei et al.)
  - Paris observatory, CFHT (Jean Souchay et al.)
  - Torino observatory (Ricky Smart, Beatrice Bucciarelli)
  - USNO work (Norbert Zacharias et al.)

  SPM
  Terry Girard, Bill van Altena (Yale) et al.
  - re-processing early epoch data
  - continue observing program El Leoncito (50cm astrograph + CCD)
  - plan on proper motion catalog construction 2007

  GSC2 / GSPC2
  Beatrice Bucciarelli et al.
  - work on re-reduction of Guide Star Catalog data

  DAS = Deep Astrometric Standards
  Imants Platais (PI)
  - limiting magnitude about R=24,  4 fields, each 10 sq.deg.
  - first round of optical observations at 4-meter tel. done
  - new extragalactic radio sources on observing list for tie to ICRF
  - plan for second epoch observations for proper motions

  URAT, detector development
  Norbert Zacharias (PI)
  - primary mirror on order, expect delivery Oct. 2007
  - no funding identified yet to finish telescope construction
  - plan to go forward with focal plane development
  - phase I of URAT might involve the USNO astrograph
  - successful production of world largest, single CCD chip
   in 2006 (10,560 x 10,560 pixels, 9 um, 95 mm on a side),
   USNO will receive complete camera (dewar, backside) in June 2007

  Double stars
  Brian Mason, Bill Hartkopf et al.
  - maintain WDS and other catalogs
  - active observing program at several telescopes
  - stand by for "UCAC avalanche" (UCAC3 will output double stars)

  Photographic plate measurements
  - PMM (Schmidt plates, NPM, SPM) scans done some time ago (Dave Monet)
  - astrograph plates (Hamburg, Black Birch, Lick, AGK2)
   just completed this spring (Norbert Zacharias, Gary Wycoff et al.)
  - new machine for Royal Brussels Observatory (Jean-Pierre de Cuyper)
     currently being built by AeroTech (Pittsburgh), deliver this summer

  Software development and tie to other projects
  - WFCAM and VISTA  (Dafydd Evans)
  - transfer into Gaia (photometry) in 2007  (Dafydd Evans)
  - PanSTARRs and LSST  (Dave Monet)
  - Gaia at large (Francois Mignard)

  Consulting
  Sean Urban, Chief of the Nautical Almanac Office, USNO
  - particularly regarding coordinate conversions,
     precession-nutation-frame bias or solar system objects


Ideas for WG work and future collaborations:

 - Produce combined, astrometric catalog including 
     UCAC, USNO-B, 2MASS, TC catalogs, Bordeaux data, SPM ...
     to extend beyond Hipparcos/Tycho-2 = NOMAD ?
    (general consensus about concept and scope)

 - Make such a catalog accessible in VO format  (J.Muinos)

 - Support of Deep Astrometric Standard project (I.Platais et al.)

 - "... I see the strong need for a new observing program, 
   such as URAT.  I am sure I do not need to tell you the 
   benefits about adding recent-epoch positions to keep the 
   proper motion errors from accumulating, higher confidence 
   in astrometry, pushing the astrometry to fainter magnitudes, 
   etc.  Although clearly USNO should take the lead on this, 
   the support still is lacking.  Maybe it is time to open
   it up to international partners."  (Sean Urban)

 - "... small institutions trying to conduct astrometric 
   programs should attach themselves to large, relatively
   well-funded, survey type programs and provide expertise 
   in return for data. 
   ... working group would seem like a good vehicle for connecting
   underfunded, astrometric programs with large surveys since it
   carries the authority of the IAU.  Thus, I would hope it could
   both help institutions get modest amounts of funding for 
   participation and bring the usefulness of these institutions 
   to the attention of the program managers of some of the large 
   surveys."  (Tom Corbin)

In summary, the task at hand is to produce an astrometric standard
catalog, covering all-sky, all-mags, and incorporating all 
applicable data sets.  To accomplish this goal USNO need
to finish the UCAC3 reductions first.  After dealing with image
profile fitting issues for a year, I am now in the process of
integrating and testing the pipeline code to re-run the pixel
data (4.5 TB compressed files spread over 3 computers).  In
parallel we are working on primary proper motion data.  The
plan is to include new measures of AGK2, ZA, BB plates at the 
bright end in addition to the catalogs already used for UCAC2.

Any comments, suggestions, progress reports and other material
relevant to this working group, please submit to me at any
time to be included in a future newsletter.

Norbert