| Date: | 1998-06-05 02:00:00 | |
| Sender: | Richard Eanes, University of Texas, Center for Space Research <[Mailed Richard Eanes <byab350@charon.cc.utexas.edu>]> | |
| Subject: | [SLR-Mail] No. 120: New Lageos Ephemeris | |
| Author: | Richard Eanes, University of Texas, Center for Space Research | |
| Content: | ******************************************************************************** SLR Electronic Mail 1998-06-05 02:00:00 UTC Message No. 120 ******************************************************************************** Author: Richard Eanes, University of Texas, Center for Space Research Subject: New Lageos Ephemeris The Lageos-1 long-term prediction continues to degrade faster than in the past. New predictions have been needed for some time, but I have just now mananged to get them done. My apologies to all that this lapse may have inconvenienced. The new predictions for Lageos-1, Lageos-2 span Jun 1998 through Aug 1999 The ephemerides are distributed in the form of daily ”tuned IRV´s” suitable for use in the IRVINT tracking software or its derivatives. This is the 29´th ephemeris distributed for Lageos-1 (GSFC ID 1155). For Lageos-2 (GSFC ID 5986) this is the 5´th ephemeris distributed. New Etalon-1 and Etalon-2 predictions will follow in the next several days. A leap second at the end of Dec 1999 has been predicted. This prediction is fairly certain, but should it prove incorrect, new tuned IRV´s will be issued (if the ephemeris holds up that long!). When uncompressed, each of the IRV files has 3408 lines and 116062 bytes. They are available via anonymous ftp at CSR. Use ftp.csr.utexas.edu (129.116.190.30) and cd to pub/slr/ephemeris. The files are lg1irv29_tune, and lg2irv05_tune for Lageos-1 and Lageos-2 respectively. They are compressed using the unix command ”compress”, so the names listed above are followed by .Z in each case. Another file (irv29_pole) contains the Earth rotation predictions used in the generation of the new IRV´s. The columns in these files are: Modified Julian Date, x and y components of polar motion in arcsec, TAI-UTC and UT1R-TAI in seconds. There is a point every day. These files together with up-to-date UT1-TAI values from IERS should be used to derive the UT1 correction for SLR tracking operations. The files will also be made available at the EUROLAS Data Center and at the NASA CDDIS. You can request the files from Wolfgang Seemueller at the EUROLAS Data Center using e-mail address: edc@dgfi.badw-muenchen.de, or from Carey Noll at CDDIS using e-mail address: noll@cddis.gsfc.nasa.gov. I will be glad to respond to any questions about these predictions. I can be reached at e-mail address: eanes@csr.utexas.edu , or by phone at (512)471-7560, or fax at (512)471-3570. -- [Mailed From: Richard Eanes ******************************************************************************** |