| Date: | 2023-11-15 11:08:28 | |
| Sender: | Robert Sherwood - BGS <rshe@bgs.ac.uk> | |
| Subject: | [SLR-Mail] No.2822: HERL replacement data issued | |
| Author: | unknown | |
| Content: | Dear Colleagues, We discovered over the summer that a mistake had been made with the reintegration of the signals from our Active Hydrogen maser on its return from repair in February 2022. This created a sign error in the correction that we apply to our raw maser epochs to keep them close to UTC, meaning we were introducing an epoch error to all SLR measurements. As the maser naturally drifts with respect to UTC the size of this difference increased over time, reaching a maximum of around 4us in June 2023. Since this error is the correction applied it is recorded in the header of every CRD file produced. This has enabled us to issue replacement data for the period 10/02/2022 - 29/06/2023 where the epochs have been corrected. These replacement files (both normal point and full rate CRD v1 and v2) with release flag incremented are now available at EDC, and will be the default files you get when downloading the standard monthly combined files. Synchronisation of the replacement data with CDDIS is ongoing, but expected to be complete very soon. We have spent some time checking and analysing the replacement data in comparison to the original in an attempt to characterise what the scale of the effect might be. None of the QC type checks routinely undertaken by the community had flagged any issue. In our initial NSGF Analysis centre results we don´t see any significant differences in the final results, though the scatter of the residuals with respect to the orbit does increase over time until the error is corrected. A similar effect on the rms of the NP residuals was identified by colleagues from GMV at the Copernicus POD Service. Many thanks to them for their invaluable confirmation of the diagnosis and solution to the problem. Obviously, we can only apologise for any inconvenience caused. We would suggest redownloading the new data currently available and repeating any critical analysis undertaken using data from this period. If there are any specific questions or anyone sees interesting results please don´t hesitate to get in touch. Best regards, Rob Sherwood NERC Space Geodesy Facility Herstmonceux England BN27 1RN 01323 833888 This email and any attachments are intended solely for the use of the named recipients. If you are not the intended recipient you must not use, disclose, copy or distribute this email or any of its attachments and should notify the sender immediately and delete this email from your system. UK Research and Innovation (UKRI) has taken every reasonable precaution to minimise risk of this email or any attachments containing viruses or malware but the recipient should carry out its own virus and malware checks before opening the attachments. UKRI does not accept any liability for any losses or damages which the recipient may sustain due to presence of any viruses. Dear Colleagues, We discovered over the summer that a mistake had been made with the reintegration of the signals from our Active Hydrogen maser on its return from repair in February 2022. This created a sign error in the correction that we apply to our raw maser epochs to keep them close to UTC, meaning we were introducing an epoch error to all SLR measurements. As the maser naturally drifts with respect to UTC the size of this difference increased over time, reaching a maximum of around 4us in June 2023. Since this error is the correction applied it is recorded in the header of every CRD file produced. This has enabled us to issue replacement data for the period 10/02/2022 – 29/06/2023 where the epochs have been corrected. These replacement files (both normal point and full rate CRD v1 and v2) with release flag incremented are now available at EDC, and will be the default files you get when downloading the standard monthly combined files. Synchronisation of the replacement data with CDDIS is ongoing, but expected to be complete very soon. We have spent some time checking and analysing the replacement data in comparison to the original in an attempt to characterise what the scale of the effect might be. None of the QC type checks routinely undertaken by the community had flagged any issue. In our initial NSGF Analysis centre results we don’t see any significant differences in the final results, though the scatter of the residuals with respect to the orbit does increase over time until the error is corrected. A similar effect on the rms of the NP residuals was identified by colleagues from GMV at the Copernicus POD Service. Many thanks to them for their invaluable confirmation of the diagnosis and solution to the problem. Obviously, we can only apologise for any inconvenience caused. We would suggest redownloading the new data currently available and repeating any critical analysis undertaken using data from this period. If there are any specific questions or anyone sees interesting results please don’t hesitate to get in touch. Best regards, Rob Sherwood NERC Space Geodesy Facility Herstmonceux England BN27 1RN 01323 833888 This email and any attachments are intended solely for the use of the named recipients. If you are not the intended recipient you must not use, disclose, copy or distribute this email or any of its attachments and should notify the sender immediately and delete this email from your system. UK Research and Innovation (UKRI) has taken every reasonable precaution to minimise risk of this email or any attachments containing viruses or malware but the recipient should carry out its own virus and malware checks before opening the attachments. UKRI does not accept any liability for any losses or damages which the recipient may sustain due to presence of any viruses. |