Control Files Werner Gurtner Astronomical Institute University of Bern ILRS Workshop 3-7 October 2005 Eastbourne

Control files/mails used by ILRS u Manoeuvre predictions: Special header u Standard time bias files u Drag function files u Time bias server u EUROLAS status exchange u Go-Nogo file u Dynamic priorities u URGENT mail

Manoeuvre predictions u Special mail subject u Special header u Manoeuvre epoch triggers replacement of prediction elements... MANOEUVRE... The following state vectors are valid after the 1 manoeuvre(s) which will be executed as 1 burns, as follows: yyyy mm dd HH MM SS.S Start End Subj: ERS-2 man preds 05/09/23,03:09

Standard time bias files u Special mail subject u Distributed daily u Time bias functions for all IRV sets currently in use Subj: Standard Time Bias Functions RGO ERS GFZ605 GFZ Ajisai 1500 HON270 RGO Ajisai 1500 HON271 RGO Ajisai 1500 JAX260 RGO Ajisai 1500 NER271 RGO BeaconC 317 HON270 RGO BeaconC 317 HON271 RGO

Drag function files u Distributed for some satellites (Champ, Grace A,B) u Used to compute additional time bias Subj: CHAMP FR drag function IRV SET EPHEM NO 5016 SATELLITE 8002 MAXEPOCH EPOCH DRAG FRCO NMAX 20 EPOCH DRAG FRCO NMAX 20

Time bias server u Downloads hourly updates of the time bias function file from NSGF u Computes on request current time biases u Accessed  by TCP/IP: telnet://aiuas3.unibe.ch:7840  web page : u Hosted by Zimmerwald ! Time biases at 30-Sep :13 UT ! ! Satellite Total IRVset LstObs Passes SIC Drag Dyn ! TB[ms] [hhh:mm] used [ms] Prio ! Ajisai -4 HON271 16: Ajisai -4 HON272 16: Ajisai 0 NER272 16: BeaconC -6 HON271 24: Champ -44 GFZ016 0:

EUROLAS status exchange u Exchange of status and current time bias u Every 15 seconds u Server hosted by Zimmerwald Graz :17:32 Glonass87 LST 0 HON Potsdam :18:01 OUT Zimmerwald :18:48 Glonass87 CUR 0 COD Wettzell :18:41 OUT (Tracking Idle) Grasse_slr :06:10 Lageos2 LST 653 NER Herstmonceux :18:26 OUT Ajaccio_ftlr :59:00 OUT

Go-Nogo Flag  File kept at CSR/UTX ftp://ftp.csr.utexas.edu/pub/icesat/slr/icesat.gng u Automatically downloaded per ftp immediately before each pass u Contains flag u go: allowed to track u nogo: not allowed to track u Example: icesat go check interval

Dynamic priorities u In- or decrease priority for a small number of satellites u Code inserted into time bias server output  Available as web page

URGENT Mail u Short (and understandable) mails to operators u To be used for (unexpected) events important for proper operation u E.g. u Satellites in non-standard mode (like, e.g., safe mode) u Urgent increase of tracking priorities u Manoeuvres u Problems with predictions Subj: URGENT MAIL: Envisat Orbit Manoeuvre Announcement To all concerned, an Envisat maintenance manoeuvre will be performed in the next 24 hours. The TIRV file taking this into account will be sent imminently. With kind regards, ESOC Envisat Flight Dynamics Operations Team

Who is using what? u Are these files actually used? u By whom? u Are they useful? u Is it too much? u Same questions could be asked regarding the various data and analysis reports