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	Gazette IERS Gazette IERS Gazette IERS Gazette IERS Gazette 
                                   ________________________________________
	No 53, 30 January 2000    /
_________________________________/        Contact: iers@obspm.fr
                                     ftp: hpiers.obspm.fr (145.238.100.28)
                                     WWW: http://hpiers.obspm.fr
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        Subject: Submissions for the 1999 IERS Annual Report
        Authors: D. Gambis, L. Castrique 

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                           ----------------------
                           CENTRAL BUREAU OF IERS
                           ----------------------

                                                    Paris, 30 January 2000 


Subject : Submissions for the 1999 IERS Annual Report


	Dear colleagues:

	You are invited to submit Earth orientation and reference frame 
results for the 1999 IERS Annual Report.


CELESTIAL SYSTEMS AND FRAMES
The first realization of the International Celestial Reference Frame, ICRF
(1995 IERS Annual Report), has been updated end extended using all VLBI
observations available until spring 1999. This last realization,
ICRF-Ext.1, published in the 1998 IERS Annual Report is the current
conventional celestial reference frame. No new global celestial reference
frame will be constructed this year, new information will be used to check
the conventional frame. The VLBI catalogues provided by the Analysis
Centers will be analyzed and validated. Individual solutions will be used
to study the effect of models, geometry, etc. We would appreciate that a
special effort be made concerning the modeling and the adoption of the 
IERS Conventions.

TERRESTRIAL SYSTEMS AND FRAMES	
 The ITRF97 conventional terrestrial reference frame is available.
A new terrestrial reference frame ITRF2000 will be constructed this year. 
The call for submission of sets of stations positions and velocities was 
made by the ITRF section (See "http://lareg.ensg.ign.fr/ITRF/ITRF2000/")

 For the forthcoming IERS Annual Report, the Analysis Centers intending to
propose Earth orientation solutions associated with their ITRF2000
submission are invited to send these solutions to the IERS Central Bureau.


EARTH ORIENTATION
        The EOP submission is unchanged with regard to last year submission. 
The usual deterministic and statistical assessments will be performed. They
will be published in the 1999 Annual Report. Analysis centers are invited to
make their solutions using either the ITRF reference frame or deriving their 
own terrestrial frame that should be sent to the ITRF Bureau for consistency 
analyses.
						
	Long time series (over at least five years) tied to well described 
reference frames are extremely useful for the monitoring of the tie of IERS 
EOP and reference frames.

	The 1999 Annual Report will contain the conclusions of these vali-
dations and checks, as well as the usual feedback on the systematic and 
statistical agreement of the Analysis Center solutions with those of the 
IERS. 

	Please adhere as strictly as possible to the formats given in the 
attachments. Specifications for the terrestrial frames submissions are
provided by the ITRF Section :
          http://lareg.ensg.ign.fr/ITRF/ITRF-submit.html
          
	The IERS organisation is such that the activities are coordinated
within each observing technique. It is therefore essential that the yearly
submissions of the Analysis Centres be examined by the IERS Coordinators.
For this reason you are asked to send to the relevant Technique Coordinator
a copy of the files sent to the Central Bureau.

	We hope that you will meet the deadline: 
  _______________________________________________________________________
  |                                                                      |
  |                     Send all files by 31 March 2000,                 |
  |                     as specified in the guidelines.                  |
  |______________________________________________________________________|
  
	This letter and its Attachments, as well as the formats can be 
accessed under anonymous ftp:

		ftp	 	  145.238.100.28 (hpiers.obspm.fr)
		with login	: anonymous
		and password	: your e-mail address
		directory 	: iers/annreport/Call_1999AR                                  

	Your help is highly appreciated. Thank you for your cooperation.

    							
                                                          Daniel Gambis
                                                          Director 
                                                          IERS Central Bureau