International Laser Ranging Service

Station Change Quarantine Procedure

When a station decides to make changes to hardware or software in their system's measurement path, they must notify the ILRS Central Bureau (CB) with a plan of their anticipated actions. The communication shall include enough detail to allow an informed decision on quarantine. Once the station has notified the ILRS CB, the CB, in coordination with the Networks and Engineering Working Group, will determine whether the proposed actions warrant the quarantine of the post-change data, and it will notify the station and the Operations Centers (OCs) accordingly. If the case has been designated to require validation of the data, then, upon the completion of the station changes, the OC receiving data from the “modified” station will withhold those data from the operational data flow. The OC will hold the data outside of the operational data stream but will deliver it to the CDDIS and EDC in a specified (quarantine) directory so that the data are available for the Analysis Working Group (AWG) to analyze . The OC will notify the CB, AWG, station and other OC that the data are being routed to the quarantine directory.  The OC will also send the station the procedure to be followed during quarantine: observe at least 20 good LAGEOS-1 and -2, and LARES passes within a 60-day sliding window. If there are problems with the data, the AWG will work with the station until the problems are resolved. General guideline for approval: data quality as good or better than before the changes were made.  When the data are approved, the AWG will notify the analysts the station and the OC.  The OC will coordinate with the other OC and Data Centers (DC’s), and all received and approved passes will be submitted to the operational data stream and the data will become publicly available at the data centers.

To summarize, the standard operating procedure is:

• the station preparing to make changes notifies the ILRS CB and both OCs of the planned changes and schedule, if possible, at least one week prior to the initiation of the work;
• the ILRS CB decides whether or not to quarantine the data after the changes and notifies the station, the AWG, and the OCs;
• the station initiates work on the system (possibly delivering data throughout this period);
• the station notifies the OCs when data will begin to be sent again (if they were discontinued during the work), preferably a day or two before the first data distribution to allow the AWG Analysis Centers time to prepare. If suspect data are collected by the station, the station may elect to vet the data through the normal screening process with the data flag incremented by one and proper notification to the AWG. Alternatively, the station may hold back the data while investigation is underway but must inform the CB and AWG that data will be withheld.
• the station documents the changes in the site log, system change log file, and the CRD data configuration records;
• the OC receiving the data will hold the data and notify the AWG, the other OC, the DCs, and the CB that the station's data are being submitted for analysis (if quarantine was necessary);
• the receiving OC coordinates and begins sending the quarantined data to the CDDIS and EDC in a separate data flow for AWG analysis;
• when the AWG approves the station's data after receiving and analyzing at least 20 good LAGEOS-1, and -2 and LARES passes within a 60 day sliding window, it lifts the quarantine by notifying the ILRS CB and OCs; and
• the receiving OC submits all approved station passes into the operational data flow where the other OC also picks up the data. Each OC then delivers the data to their associated Data Center using standard daily delivery of production data.

If there are any questions, please contact your OC or the ILRS CB.