Regulation 13 Certificates

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A Regulation 13 Certificate is a legal document which displays a station’s coordinate and the uncertainty of that coordinate. The certificates are generally requested by Continuously Operating Reference Stations (CORS) operators as a means of providing their users with an accurate connection to the Australian Datum - the Geocentric Datum of Australia 2020 (GDA2020). Geoscience Australia is appointed as a verifying authority under the National Measurement Act, 1960, to provide this legal chain of traceability for position measurement.

Requesting Regulation 13 Certificates

Geoscience Australia provides a fee-free service to obtain Regulation 13 Certificates on Continuously Operating Reference Stations (CORS).

For a CORS to be considered for Regulation 13 certification it must be accepted in the Asia Pacific Reference Frame (APREF) project. See the guidelines for becoming an APREF participant. Note that only the CORS site owner can submit the application for Regulation 13 Certification unless a signed consent letter is issued by the CORS owner for a secondary party to submit on their behalf.

What you need to provide us:

Cover letter (on a letterhead) formally requesting a "Certificate of Verification of a Reference Standard of a Position-Measurement in Accordance with Regulation 13 of the National Measurement Regulations 1999" for your station/s. The letter should include:

The number of stations that you require certificates for and their 4-character site names.
Clearly indicate who you are, including your address and contact details.
This letter should be addressed to:
Reg13 Laboratory contact
GNSS Analysis Section
Geoscience Australia
GPO Box 378
Canberra, ACT, 2601
This letter can also be emailed to: dl-reg13@ga.gov.au

What we will provide you with after our analysis is:

A Certificate of Verification of a Reference Standard of a Position-Measurement in Accordance with Regulation 13 of the National Measurement Regulations 1999 for each station. The certificate will be valid for five years and will apply to the station mark, but only has validity if the station is continuously operated with the identical equipment. Critically, this means the same antenna as listed on the certificate.
All Reg 13 certificates are available for the public access from the link: https://ga-gnss-products-v1.s3.amazonaws.com/index.html. Upon visiting the page, either search for ‘reg13’ in the Search tool on the top right corner, or navigate to the last page using the buttons located in the bottom right corner; then, click on the folder labelled “reg13/” to access the certificates.

Procedure for cessation of Regulation 13 Certificates

Regulation 13 Certificates are only valid for five years, unless the analysis shows that a site coordinate is no longer within the Positional Uncertainty (PU) values, at which point a site will be assessed for suitability of re-verification.
In accordance with Regulation 22 of the National Measurement Regulations 1999 the verification of a standard of measurement ceases to have effect at the end of the period stated in the certificate of verification.
When the cessation date is reached, Geoscience Australia advises that the Regulation 13 Certificate coordinates are no longer supplied to the public. Please note, this may include removing coordinate information from public access websites.
We advise that a new Regulation 13 Certificate is requested approximately six weeks prior to the current certificate expiry date.

Procedure for cancellation of Regulation 13 Certificates

In accordance with Regulation 23 of the National Measurement Regulations 1999, if the data in the Regulation 13 Certificate is found to be a) incorrect, or b) exceeding the maximum permissible variation for the standard, the Certificate may be cancelled.
- Please note, this includes an antenna change.
Geoscience Australia advises that the Regulation 13 Certificate coordinates are no longer supplied to the public. Please note, this may include removing coordinate information from public access websites.
Geoscience Australia also requests that the Certificate is removed from public access.

Prerequisites for issuing a Regulation 13 certificate

For a Regulation 13 certificate to be issued for a station, there are a few prerequisites, which impact the processing time of issuing a certificate. The processing requires the IGS final products to be available, usually 2-3 weeks latency. The station data needs to be available for at least seven consecutive days, and the station coordinate solution needs to be of adequate quality (e.g. weekly coordinate repeatability of better than 5 mm horizontal and 10 mm vertical). In addition, station metadata (e.g. equipment used in the station) needs to be verified.

Processing times

Noting the above prerequisites, the processing time for issuing a Regulation 13 certificate varies and depends on the quality of the data provided by the station. However, a minimum of 4-6 weeks is generally required to issue a Regulation 13 certificate. Further delays apply when there are quality issues with the data and/or metadata inconsistencies.

Procedure for determining the uncertainty of the Regulation 13 coordinates

The uncertainties of the Regulation 13 positions are determined by considering both Type A (statistical) and Type B uncertainty sources according to the Guide to the expression of uncertainty in measurement - BIPM. While Type A uncertainties are derived from the propagation of errors to the estimated parameters in the estimation process, Type B uncertainties include error sources that cannot be estimated from the statistical analysis of short-period observations. As a result, and based on several factors including e.g. environmental effects, long-term station loading (deformation) processes, monument stability and signal multipath, a total uncertainty is assigned to the site coordinates.
Table 1 below shows the major uncertainty sources for GPS analysis. Based on the analysis carried out by the authorized analyst, the total uncertainty is calculated as:

$𝜎_{t o t a l} = \sqrt[]{𝜎_{1}^{2} + 𝜎_{2}^{2} + \dots + 𝜎_{N}^{2}}$

where $𝜎_{i} ((i = 1, N))$ are each of Type A and Type B uncertainties listed in Table 1.

Table 1. Uncertainty sources (95% C.L.) for position, determined from GPS, and the total uncertainty, assuming the normal distribution of the uncertainty sources, high degrees of freedom and a coverage factor, k, of 2.

Uncertainty Source	Position Uncertainty Horizontal (mm)	Position Uncertainty Vertical (mm)
Type A – Experimental Error	2	6
Type B - Antenna phase centre	3	10
Type B^* - Monument stability	1 to 20	1 to 40
Type B – Other sources including un-modelled crustal loading, satellite orbit variations, atmosphere, tectonics, signal multi-path	6	10
Total	7 to 21	15 to 43

* An authorized analyst at their discretion may apply an appropriate monument stability uncertainty that reflects the station’s stability.

When giving consideration to the assignment of Type B uncertainty sources, an authorized analyst follows a defined decision-making process:
- Based on all available data (including time series data available from APREF), is the site likely to remain within normal uncertainties for the two years following certification?
  - If yes, proceed with certification using normal uncertainties
  - If no, is the site likely to remain within above-normal uncertainties for the two years following certification?
    - If yes, proceed with certification with above-normal uncertainties
    - If no, decline certification but provide official coordinates with above-normal uncertainties.