The future of the “positioning and earth orientation” project was discussed next, including requirements of the client (IERS) and practical restrictions for the ILRS analysts. After a lengthy debate, it was decided to modify the current Call for Participation into one with a weekly processing schedule, which better matches the frequency of the IERS Bulletin A, its first customer (action item Noomen/Appleby/Shelus). The exact deadline for such analyses needs to be assessed, and depends on the date of release of the Bulletins A (action item Noomen). Although different ideas were brought to light, it was agreed to leave the current elements of the proposal intact (28 days, 1-day EOPs i.e. x/y-pole and LOD, station coordinates at mid-point, provide full covariance information) since this gives the widest range of opportunities to optimize the final solution. New deadlines for contributions are: handing in of analysis solutions on May 31 at latest, test period running until October 1, evaluation of results in first 3 weeks of October and selection of analysis contributors (i.e. the outcome of the benchmark project) and prime/backup combination center during the next workshop in Wettzell (last week of October).
Rothacher stressed the importance and uniqueness of SLR when it comes to determining geocenter and scale. He repeated the invitation that was already expressed during the IERS Retreat (cf. agenda item 4.2), for an official ILRS contribution to the new IERS Combination Pilot Project. Here, ILRS is asked to contribute with weekly solutions covering station coordinates and daily EOPs (the latter including epoch values plus time derivatives), each individual solution being based on 7 days of tracking data. Although the exact details need to be worked out, and it was strongly emphasized that for the SLR technique a 28-day period would be preferable for high-quality station coordinates and geocenter determination, the solution requirements posed by this new IERS project were honored by the AWG. Noomen volunteered to participate in the new IERS Combination Working Group, and will initiate an official response to the formal invitation that ILRS can expect to come from IERS (action item Noomen/Appleby/Shelus).