VII BSAC  "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 Wide field plates observations of stars from Earth Orientation Catalogs (EOC) Yavor Chapanov1, Katya Tsvetkova2, Milcho Tsvetkov2, Jan Vondrák3, Cyril Ron3, Vojtéch Štefka3 1 – Central Laboratory for Geodesy, Bulgarian Academy of Sciences 2 – Astronomical Institute, Bulgarian Academy of Sciences 3 – Astronomical Institute, Academy of Sciences of Czech Republic

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 DATA SOURCE EARTH ORIENTATION CATALOGUE EOC-4 - 4418 objects, determined from 4.5 million observations of latitude/universal time WIDE-FIELD PLATE DATABASE WFPDB - Catalogues of Wide-Field Plates with more than 600000 entries

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 DECLINATION EPOCHS - significant number of stars with mean epochs before 1990 - long observational series

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 RA EPOCHS - small number of stars with mean epochs between 1975 and 1990 - short observational series

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 Proper motion in declination - stars with pmDE>0.05”/a are potential source of systematics

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 Proper motion in RA - stars with pmRA>0.05”/a are potential source of systematics

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 Parallax - non-linear proper motion is more visible for stars with greater parallax

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 EARTH ORIENTATION CATALOGUE EOC-4 STAR MAGNITUDE - between 0 and 12 mean magnitude 6.5 - significant number of bright stars star images cover more pixels - better accuracy

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 WFPDB – Telescopes and plates VIEW ANGLE [degree] - 1, 3, 5, 7, 20, … APERTURE [cm] - 10, 12, 14, 16, 34, 40, 60, 67, … PLATE SCALE ["/mm] - 830, 295, 860, 258, 300, 102, 115, 96, … SCAN RESOLUTION [dpi] - 300, 600, 1200, 2400, 4800, 9600, …

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 WFPDB – Star position accuracy ACCORDING PLATE SCALE (emulsion corn 10m) 100"/mm - ±0.5" 60"/mm - ±0.3" 13"/mm - ±0.06" (Rozhen) ACCORDING SCAN RESOLUTION 300dpi=12d/mm+scale 13”/mm - ±0.5" 600dpi=24d/mm+scale 13”/mm - ±0.3" 1200dpi=47d/mm+scale 60"/mm - ±0.6" 2400dpi=94d/mm+scale 100"/mm - ±0.5" 4800dpi=189d/mm+scale 100"/mm – (±0.3“) 9600dpi=378d/mm+scale 100"/mm – (±0.1“)

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 WFPDB – Plates: position accuracy PLATE CENTER - current accuracy (1”,1”), necessary (0.1”, 0.1”), determined by 7-parameter transformation PLATE ORIENTATION - determined by 7-parameter transformation ANGULAR DISTANCE FROM THE CENTER - max 5°

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 WFPDB – Plates: Access FREE ACCESS - compressed images SCAN RESOLUTION - as high, as possible (interpolation) SEARCH - by the scale parameter (<100”/mm) TOOLS - 7-parameter transformation (plate center) - distortion model improving - star identification and coordinates extraction

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 CONCLUSIONS The WFPDB provide significant number of plates, containing a given star. The observation epochs cover century time span, which is useful to improve star catalogs. It is necessary to improve the free access to the digitized plates and to add some new options in the search engine and tools: - improve resolution to 4800dpi or more and compress the images - search for plates with scale <100arcsec/mm - online tool for identification of a group of stars from a given plate sequence - accurate determination of the plate centers and their orientation by 7-parameter transformation

VII BSAC "ASTROINFORMATICS" – Chepelare, 1-4 June 2010 THANK YOU FOR ATTENTION