1 / 20

Status of the International Celestial Reference Frame

Status of the International Celestial Reference Frame. Alan L. Fey 3 rd IVS General Meeting February 9-11, 2004. Outline. Brief ICRF Timeline The ICRF ICRF Ext.1 ICRF Ext.2 ICRF Maintenance. Brief ICRF Timeline. 1988 IAU sets up working group to establish new CRF

susan
Download Presentation

Status of the International Celestial Reference Frame

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Status of the International Celestial Reference Frame Alan L. Fey 3rd IVS General Meeting February 9-11, 2004

  2. Outline • Brief ICRF Timeline • The ICRF • ICRF Ext.1 • ICRF Ext.2 • ICRF Maintenance

  3. Brief ICRF Timeline • 1988 IAU sets up working group to establish new CRF • 1991 IAU establishes theoretical basis for new CRF • 1994 IAU defines fiducial points for CRF as EG objects • 1995 sub-group of IAU WGRF tasked to construct CRF • 1997 IAU establishes the ICRS and adopts the ICRF • 1998 ICRF replaces FK5 as fundamental frame • 1999 ICRF Ext.1 completed • 2004 ICRF Ext.2 completed

  4. The ICRF(Ma et al. 1998, AJ, 116, 516)http://www.iers.org/iers/pc/icrs/ • Compact extragalactic radio sources • Dual frequency 2.3/8.4 GHz MkIII VLBI • All available data through July 1995 • 1.6 million observations • Global solution using CALC/SOLVE • Not a combination catalog

  5. The ICRF continued(Ma et al. 1998, AJ, 116, 516)http://www.iers.org/iers/pc/icrs/ • 608 total sources • 212 Defining sources • 294 Candidate sources • 162 Other sources • Defines ICRS Axes to ~20 micro-arcsec • ICRS axes have independent existence • ICRF is just one “realization”

  6. Sky Distribution of 212 ICRF Defining Sources

  7. Sky Distribution of 608 ICRF Sources

  8. ICRF Ext.1(1998 IERS Annual Report)http://www.iers.org/iers/pc/icrs/ • “Maintenance” Release • Refine positions of candidate/other sources • Provide positions of new sources • Added available data through April 1999 • Additional 0.6 million observations • 461 sessions • ICRF Solution parameterization

  9. ICRF Ext.1 continued(1998 IERS Annual Report)http://www.iers.org/iers/pc/icrs/ • 667 total sources • 212 Defining (same positions as ICRF) • 294 Candidate (refined positions) • 102 Other (refined positions) • 59 New sources

  10. Sky Distribution of 59 New ICRF Ext.1 Sources

  11. ICRF Ext.2(Fey et al. 2004, submitted to the Astronomical Journal)soon to be available at http://www.iers.org/iers/pc/icrs/ • “Maintenance” Release • Refine positions of candidate/other sources • Provide positions of new sources • Added available data through May 2002 • Additional 1.2 million observations • 400 sessions • Includes VLBA RDV data (30 sessions) • ICRF Solution parameterization

  12. ICRF Ext.2 continued(Fey et al. 2004, submitted to the Astronomical Journal)soon to be available at http://www.iers.org/iers/pc/icrs/ • 717 total sources • 212 Defining (same positions as ICRF) • 294 Candidate (refined positions) • 102 Other (refined positions) • 59 New from ICRF Ext.1 (refined positions) • 50 New sources

  13. Sky Distribution of 50 New ICRF Ext.2 Sources

  14. Sky Distribution of 717 ICRF Ext.2 Sources

  15. ICRF Maintenance • IERS charged by IAU with maintenance • Maintenance activities are run jointly by • IERS ICRS Product Center • International VLBI Service • In coordination with • IAU Working Group on ICRS

  16. ICRF Maintenance continued • Active Observing programs • IVS CRF Series of Experiments • Concentrate on Southern Hemisphere for monitoring • Increase source density of defining sources in South • VLBA RDV Series of Experiments • Cycle through Northern Hemisphere sources for monitoring • Joint GSFC/USNO/NRAO program • In ICRF Ext.2, RDV data account for ~20% of all data!

  17. ICRF Maintenance continued • Active Observing programs continued • IVS Geodetic/EOP Experiments • Concentrates primarily on brightest, most stable sources • IVS coordinated activity • VLBA Calibrator Surveys (VCS) • Expand list of geodetic sources • Expand list of phase reference calibrators for imaging • Joint NRAO/GSFC program

  18. Sky Distribution of 1332 VCS-1 Sources(Beasley et al. 2002, ApJS,141,13)

  19. ICRF Maintenance continued • Active Observing Programs continued • EVN Experiments • Increase source density of defining sources in Northern Hemisphere • Primarily Bordeaux Observatory program • LBA CRF Series of Experiments • New sources for densification of Southern Hemisphere • Joint USNO/ATNF program

  20. Sky Distribution of 22 New Southern Sources(Fey et al. 2004, submitted to the Astronomical Journal)

More Related