1. Prospective Improvements of IVS Products and Evolvement of Observing Programs Harald Schuh WG2 Chair Vienna University of Technology hschuh@luna.tuwien.ac.at Wolfgang Schlüter IVS Chair Bundesamt für Kartographie und Geodäsie Fundamentalstation Wettzell Nancy Vandenberg IVSCC Director NASA Goddard Space Flight Center

2. I V S - International VLBI Service for Geodesy and Astrometry IVS is a service of n IAG - International Association of Geodesy n IAU - International Astronomical Union FAGS - Federation of Astronomical and Geophysical Data Analysis Services Main tasks of the IVS u Maintenance of the ICRF (International Celestial Reference Frame) F radio source positions and changes u Provision of products for F ITRF (International Terrestrial Reference Frame) station positions and velocities F EOP - Earth Orientation Parameters monitoring the celestial pole (d , dψ) monitoring Universal Time (UT1) and length of day (LOD) monitoring polar Motion (x p, y p )

3. The IVS 1999 - 2001 n IVS inauguration was on 1 st of March, 1999 n Demand for continuity in maintaining the reference frames forced to employ and accept the u existing infrastructure u existing observing programs (NEOS, CORE,....) u related data handling n IVS efforts in 1999 - 2001 u installation of its structure and components u Get used to the new tasks n 2001 review of products and observing programs ==> WG2  Basis for improving products and evolving observing programs to meet service requirements

4. WG2 on Product Specification and Observing Programs WG 2 established at the 5 th IVS DB-Meeting on February 15 th, 2001 The assignment of WG2 was to l review the usefulness and appropriateness of current IVS products, l recommend guidelines for accuracy, timeliness, and redundancy, l review the quality and appropriateness of observing programs, l set goals for improvements of IVS products, l suggest how these may possibly be achieved in the future, l suggest a realistic set of observing programs, taking into account existing agency programs.  Complete report was presented in November 2001 and accepted by the IVS Directing Board on Feb. 14 th, 2002  available: http://ivscc.gsfc.nasa.gov within IVS Annual Report 2001

5. Members of the WG2 n Harald Schuh (chair), TU Vienna (A) n Patrick Charlot, Obs. Bordeaux (F) n Hayo Hase, BKG (D) n Ed Himwich, NASA/GSFC (USA) n Kerry Kingham, USNO (USA) n Calvin Klatt, EMR (Canada) n Chopo Ma, NASA/GSFC (USA) n Zinovy Malkin, IAA (RU) n Arthur Niell, MIT Haystack (USA) n Axel Nothnagel, Univ. Bonn (D) n Wolfgang Schlüter, BKG (D) n Kazuhiro Takashima, GSI (JP) n Nancy Vandenberg, NASA/GSFC (USA)  Experts in various fields of VLBI  Involving many agencies  Different nations  to obtain broad acceptance within IVS

6. Rationale and motivation for the work of WG2 n Fundamental role of VLBI for the realization and maintenance of global reference frames F unique for the ICRF, essential for EOPs and scale of the ITRF n Requirement for precise reference frames (10 -9 ), consistent for decades:  IGGOS - Integrated Global Geodetic Observing System n Demand for combination of all techniques F to achieve the required accuracy F to eliminate systematic errors F to generate reliable and redundant results n Collaboration of all IAG Services (IVS, ILRS, IGS, IDS,...  IERS)

7. IVS products (some examples from WG2 Report) Products StatusGoals(2002-2005) n polar motionaccuracy x p ~100  s, y p ~200  sx p, y p : 50... 25  s latency 1-4 weeks... 4 months4 - 3 days...1day resolution 1 day1 day...1h... 10min freq. of sessions ~3 d/week.........7d/week n UT1accuracy 5... 20  s3.................. 2  s latency 1 week4 - 3 days.... 1day resolution 1 day1 day....... 10min n ,  accuracy 100... 400  arcsec50...25  arcsec latency 1-4 weeks... 4 months4 - 3days... 1 day resolution 1 day1 day freq. of sessions ~3 d/week.......... 7 d/week n TRF (x,x,z)accuracy 5-20 mm5.............. 2 mm............ n CRFaccuracy 0.25-3 mas0.25 mas (improved distribution) freq. of solution 1 y1 y latency 3-6 months3............. 1 month(s) n...........................

8. More IVS products (see WG2 Report) n EOP- dUT1/dt (lod) - dx p /dt, dy p /dt n TRF- x,y,z time series - episodic events - annual solutions - non-linear changes n CRF- source structure - flux density n Geodynamical Parameters- solid Earth tides h, l - ocean loading A,  - atmospheric loading α n Physical Parameters- tropospheric parameters (zenith delays, gradients) - ionospheric mapping - light deflection parameter 

9. New IVS observing programs u IVS Program Committee was established in Sept. 2001 u appropriate observing programs started 2002 for F Earth Orientation Parameters (EOP): IVS-R1... IVS-R4, IVS-INT1 <Two rapid turn-around sessions each week, <Comparable xp, yp results. <Additional sessions employing S2 and K4 techniques (IVS-E3, IVS-INT2) F Terrestrial Reference Frame (TRF): IVS-T2 <Monthly TRF sessions with 8 stations F Celestial Reference Frame (CRF): IVS-CRF <Bi-monthly RDV sessions using the VLBA and 10 geodetic stations, F CONT, annually or semi-annually IVS-CONT02 <14-day continuous sessions to demonstrate the best results that VLBI can offer <in 2002: CONT-session, October 16-31, 2002 F Monthly R&D sessions: IVS-R&D <to investigate instrumental effects, research the network offset problem êObserving program 2002: geodetic VLBI observations will be increased by about 30% êGoal: future increase by ~100% till 2005

10. Improvements required n weekend gaps, automation for unattended observing needed n reduce time delay and reduce expenses u development of a modern disc based recording system (Mk5) u development of data transfer via the Internet (e-VLBI) n global network configuration has to be improved u especially in the southern hemisphere u encourage additional institutions and include the S2 and K4 technologies u more observing time is required overall n timeliness, shorten turn-around time at the correlators (better logistical organization of tape/disc transport) n robustness of the products, more analysis centers with different software

11. Finally.... n To meet the ambitious goals all responsible members of the contributing agencies are kindly asked to support the IVS as much as possible Thank you