BCTE & BCIN - Terrace and Invermere Active Control Stations
Warning Bulletin - July 2019
From March 1st at 13:00 PST (21:00 UTC) to July 22nd, 2019 RINEX files for BCTE and BCIN posted on the BCACS FTP were corrupt. This was incorrectly identified as an antenna mast modification; please disregard previous communications which stated this as the cause. An investigation found that no such physical site modifications had been made to either of these stations. Regardless, files during this date range would have yielded erroneous vertical results by ~12cm in magnitude. The magnitude of horizontal error yielded from these corrupt files was found to be near-zero/negligible.
GeoBC advises all users of BCIN and BCTE to review all projects between those dates to verify whether this error adversely impacted their GNSS-derived results. “Clean” RINEX files are available upon request for those stations within that date range; users have the ability to reprocess their rover data to assess and correct adversely impacted post-processed datasets. Additionally, GeoBC plans to repost these clean RINEX files onto the BCACS FTP for that date range in the near future.
As a part of the investigation, new observations were made to surrounding passive GCMs in Terrace. These new observations will be used to refresh the published hybrid ellipsoid height of BCTE. This refreshed value will replace the existing one that was determined based on GPS observations made circa 1998. The refreshed values will account for building subsidence during that 21-year period, which is expected to be ~4cm. As a result of this refresh, end users will arrive at ellipsoidal heights that are more accurate within the CGVD28 datum and will also have a better fit with the passive GCM network in the immediate vicinity of the station. However, users must be aware that this will introduce an inconsistency with heights derived using BCTE in recent years. Users are advised to be mindful of this when working with BCTE-derived heights especially for circumstances where agreement with historic projects might be more important than absolute accuracy within the CGVD28 datum.
GeoBC will be implementing measures to detect antenna disturbances or corrupted BCACS data in a timelier manner going forward.
Click on the red triangles below for the latest station information sheets.