1. IAU GA XXV Sydney AC/CdC WG Report Sean E. Urban U.S. Naval Observatory, Washington DC

2. IAU GA XXV Sydney Website Much of the WG activities & info on AC/CdC found at: http://astro.u-strasbg.fr/~fresneau/workgroup.html

3. IAU GA XXV Sydney Working Group Members Carlos Abad I. Bustos Fierro M. Odenkirchen Robert Argyle M. Geffert R. Orellana James Biggs E. Glushkova T. Pauwels Noah Brosch M. Irwin T. Rafferty B. Bucciarelli D. Jones M. Sanchez G. Coyne K. Kuimov J. Sanner E. Davoust A. Kuzmin M. Tsvetkov J.P. De Cuyper Chen Li S. Urban E. van Dessel K. Lumme A. Vaughan C. Ducourant J.L. Muinos A. Fresneau (Chair)

4. IAU GA XXV Sydney Brief Overview Astrographic Catalogue (AC) –All stars to b=11.0; Ep. ~1907 –Over 22,000 plates; 2x2 degrees; 2-fold overlap; scale=60”/mm –Multi-institutional, forerunner of IAU Carte du Ciel (CdC) –All stars to b=14.5; Ep. ~1912 –Same instrument as AC; same 2x2 deg plates; same overlap, scale –Goal: odd zones w/ 1 exp.; even zones w/ 3 exposures –Paper charts to be made w/ even zone plates –~7500 plates

5. IAU GA XXV Sydney Valuable data? AC –Plates measured by hand; published; keypunched –Data reduced (AC 2000.2); used in Tycho-2, UCAC2 –Errors ~200 to 400 mas/image –Some improvement gained in re-measurment; worthwhile? –Currently available for future use CdC –Most plates never measured –At 200 mas, p.m. ~2 mas/yr –Better than anything currently available

6. IAU GA XXV Sydney Example of CdC plate

7. IAU GA XXV Sydney Programs in Progress Bordeaux zone (+11 to +17) –500 plates w/ APM (Cambridge); combined w/ current epoch TC data Sydney (-65 to –51) –500 plates w/ APM (Cambridge); San Fernando (-10 to –2) –400 plates w/ scanned, available on CD Toulouse (+4 to +10) –Rapid scanner in search of lp variables Cordoba/Uccle –Testing measuring machines

8. IAU GA XXV Sydney Results

9. IAU GA XXV Sydney Results From Sydney and Bordeaux CdC Positional errors: –120 to 180 mas “internal” –150 to 300 mas global Photometric errors: –0.1 mag internal Variablity of stars on short periods detected and believed real –0.35 mag external Plates aging: –Degradation in reaching faintest stars

10. IAU GA XXV Sydney Discussion Plates currently in jeopardy; age, apathy Who to save plates/digitize images? –Sub-micron measuring not needed (“fast scanners?) –Identify unique set of plates to test machines? –Archive raw images or only save (x,y)s? Keep the WG active in Comm 8? Join the Preservation and Digitization of Photographic Plate WG?