NAGUs (Notice Advisory to Galileo Users) | European GNSS Service Centre

NAGU Definition

The Notice Advisory to Galileo Users (NAGU) aims to inform about any activity/event in the Galileo system with impact on the Signal in Space (SiS) and/or on the performance levels for Open Service (OS) and High Accuracy Service (HAS) as committed in the applicable Open Service-Service Definition Document. and HAS Service Definition Document respectively.

NAGU Categories

Planned: all activities/events that have been scheduled and that could potentially have an impact on the SiS and/or the performance levels. Planned NAGUs aim to inform users about the activity/event with a reasonable advance notice, ahead of their occurrence.
Unplanned: all activities/events that have an impact on the SiS and/or the performance levels that have not been scheduled and could not be foreseen in advance, before their occurrence. The aim of unplanned NAGUs is to inform users about the activity/event within a reasonable time, after their occurrence.
Service Availability: all events related to the restoration of service provision, following the end of a planned outage or the recovery of an unplanned outage.
General: all activities performed on the Galileo system, or any occurring events, that potentially or substantially have an impact on the SiS and/or on the performance levels, which would not be already covered by a planned or an unplanned NAGU.

NAGU Types and Format

There are different NAGU types defined within each NAGU category:

The following table explains the NAGU types currently in use:

NAGU Type	NAGU Type (abbreviation)	NAGU Description	NAGU Format
PLANNED MANOEUVRE	PLN_MANV	Planned activity affecting the attitude and/or orbit (e.g., satellite relocation to a new slot). It includes the planned outage start time and end time.	Template
PLANNED OUTAGE	PLN_OUTAGE	Planned activity, in space or ground segment, that can potentially cause an outage of the broadcast satellite Signal in Space. It includes the planned outage start time and end time.	Template
CANCELLATION	CANCEL	Cancellation of published NAGUs.	Template
RESCHEDULE	RESCH	Provision of new start/end times for an already published NAGU of the “PLANNED” category.	Template
EXTENSION	EXTNS	Provision of new end time for an already published NAGU of the “PLANNED” category, or notification of the planned outage end time for a published NAGU of the “UNPLANNED” category (UNP_UNUFN).	Template
SATELLITE DECOMMISSIONED	DECOMMSNG	Beginning of decommissioning phase. The end time for the nominal provision of service is specified.	Template
START OF THE EXTENDED OPERATION MODE	EOM_START	Start time of the Galileo Extended Operation Mode is communicated through this NAGU.	Template
END OF THE EXTENDED OPERATION MODE	EOM_END	Upon recovery of the nominal operation mode, this NAGU is issued to communicate the end time of the Galileo Extended Operation Mode.	Template
UNAVAILABLE UNTIL FURTHER NOTICE	UNP_UNUFN	Unscheduled outage of the broadcast satellite Signal in Space, characterised by an undefined duration.	Template
SHORT TERM OUTAGE RECOVERED	UNP_SHTRCVR	Outage events that have been already recovered, before a dedicated NAGU could be published to notify their occurrence.	Template
SATELLITE FIRST TIME USABLE	USABINIT	Satellite enters its active service provision, contributing to the constellation service delivery. It is used for satellites that enter their service provision for the first time, indicating that the space vehicle is providing a Signal In Space in line with the applicable OS SIS ICD, as well as the published OS SDD and the related service performance commitment.	Template
USABLE FOR SERVICE PROVISION	USABLE	The satellite restarts transmitting healthy Signal in Space, concluding a planned outage period or the recovery after an unplanned outage. It includes also a reminder about the exact outage start time, along with the precise outage end time. It includes also the type of clock being used to drive the navigation payload. This NAGU type is also used following Service Declaration, in order to recall the list of space vehicles that are expected to broadcast a Signal in Space aligned with the applicable OS SDD during the specified service provision phase.	Template
GENERAL NOTICE	GENERAL (NOTICE)	General notifications such as announcing the IOV campaign, Service validations, announcement of Service declarations, introduction of services, IOC, FOC, etc.	Template
LAUNCH	GENERAL (LAUNCH)	Notification of satellite launch.	Template - 2 satellites Template - 4 satellites
LEAP SECOND	GENERAL (LEAP SECOND)	Notification of a leap second adjustment affecting UTC time scale, following the related announcement by IERS.	Template
PLANNED OUTAGE TIMING SERVICES	GENERAL (TIMING PLN_OUTAGE)	Notification of a planned operation entailing an outage of timing related services, consisting of GGTO and UTC determination capabilities at user level.	Template
AVAILABILITY OF TIMING SERVICES	GENERAL (TIMING USABLE)	Notification of availability of timing services following the end of a planned operation/ recovery of an unplanned outage with an impact only affecting the timing services.	Template
CANCELLATION OF PLANNED OUTAGE TIMING SERVICES	GENERAL (TIMING CANCEL)	Cancellation of a published general NAGU notification for a planned operation entailing an outage only affecting the timing services.	Template
RESCHEDULE OF PLANNED OUTAGE TIMING SERVICES	GENERAL (TIMING RESCH)	Provision of new start/end times for published general NAGU notification for a planned operation entailing an outage only affecting the timing services.	Template
EXTENSION OF PLANNED OUTAGE TIMING SERVICES	GENERAL (TIMING EXTNS)	Provision of new end time for published general NAGU entailing an outage only affecting the timing services.	Template
UNPLANNED OUTAGE TIMING SERVICES	GENERAL (TIMING UNP_UNUFN)	This general NAGU provides notification of an unplanned outage related to timing services.	Template
SHORT TERM OUTAGE TIMING SERVICES	GENERAL (TIMING UNP_SHTRCVR)	This general NAGU provides notification of a short-term timing services outage event that have been recovered before a NAGU could be published.	Template
PLANNED OUTAGE HAS SERVICES	GENERAL (HAS PLN_OUTAGE)	This general NAGU provides notification of a planned operation entailing an outage of HAS related service, consisting of the complete absence of valid HAS orbit and/or clock corrections for all satellites in the HAS SIS (C/NAV message) . A GENERAL (HAS USABLE) NAGU will be issued following the end of a planned outage of HAS service.	Template
USABILITY OF HAS SERVICES	GENERAL (HAS USABLE)	This general NAGU provides notification of availability of HAS service following the end of a planned operation or the recovery of an unplanned outage, with an impact only affecting the HAS services.	Template
CANCELLATION OF PLANNED OUTAGE HAS SERVICES	GENERAL (HAS CANCEL)	Cancellation of a published GENERAL NAGU notification related to a planned operation, entailing an outage only affecting the HAS service.	Template
RESCHEDULE OF PLANNED OUTAGE HAS SERVICES	GENERAL (HAS RESCH)	Provision of new start/end times for a published GENERAL NAGU notification related to a planned operation, entailing an outage only affecting the HAS service. A GENERAL (HAS USABLE) NAGU will be Issued following the end of a planned outage of HAS service.	Template
EXTENSION OF PLANNED OUTAGE HAS SERVICES	GENERAL (HAS EXTNS)	Provision of new end time for a published, PLANNED NAGU. A GENERAL (HAS USABLE) NAGU will be issued following the end of a planned outage affecting HAS service.	Template
UNPLANNED OUTAGE HAS SERVICES	GENERAL (HAS UNP_UNUFN)	This general NAGU provides notification of an unplanned outage related to HAS service. A GENERAL (HAS USABLE) NAGU will be issued following the recovery of an unplanned outage affecting HAS service.	Template
SHORT TERM OUTAGE HAS SERVICES	GENERAL (HAS UNP_SHTRCVR)	This general NAGU provides notification of a short term HAS service outage event that has been already recovered, before a dedicated NAGU could be published to announce its occurrence.	Template

The following table shows the NAGU types that were used in the past (e.g., prior to declaration of OS Initial Services) and are not currently in use:

NAGU Type	NAGU Type (abbreviation)	NAGU Description
SATELLITE FIRST TIME AVAILABLE	AVAILINIT	Satellite first time available. This NAGU type was used prior to the OS Initial Services Declaration. As of 15^th of December, 2016, the OS Initial Services Declaration has taken place and USABINIT NAGU will be published instead of AVAILINIT NAGU.
AVAILABLE FOR TESTING	AVAILABLE	Satellite available for testing purposes. This NAGU type was used prior to the Initial Services Declaration. As of 15^th of December, 2016, the OS Initial Services Declaration has taken place and USABLE NAGU will be published instead of AVAILABLE NAGU.

DEFINITION OF NAGU FIELDS

Header: the first line of the text field includes the title “NOTICE ADVISORY TO GALILEO USERS (NAGU)”, which is followed by the NAGU SPECIFIC number given in the format YYYYNNN, where YYYY is the Gregorian year and NNN is the sequential number of NAGU, starting with 001 on the 1^st of January every year and incrementing by 1 at each subsequent NAGU.
Date generated (UTC): the second line contains the date at which the NAGU was generated on the GSC website, in UTC time scale, format YYYY-MM-DD hh:mm where YYYY is the Gregorian year, MM is the number of the month from 1-12 in sequence starting with 1 being January and finishing with 12 being December, DD is the day within the Gregorian month, hh is the hour in the 24 hour format and mm is the minute.
NAGU type: as per NAGU definition. See NAGU types table in the section above.
NAGU number: this is defined in the format YYYYNNN (previously defined).
NAGU subject: subject of the NAGU summarizing the information provided in the “Event Description”. The text to be used in the subject is defined by the template of each NAGU.
NAGU referenced to: if the current NAGU refers to previous NAGU then the previous NAGU will be in this field in the form of YYYYRRR where YYYY is the Gregorian year the NAGU was issued and RRR is the number of the NAGU for that year. If there is no reference to previous NAGU then “N/A” (not applicable) will appear here instead.
Start date event (UTC): the start date of the event notified in this NAGU in the UTC time scale with format YYYY-MM-DD hh:mm (see the definition of time in “2.” above).
End date event (UTC): the end date of the event notified in this NAGU in UTC time scale with format YYYY-MM-DD hh:mm (see the definition of time in “2.” above).
Satellite affected: GSAT (Galileo SATellite) name of the satellite affected.
Space vehicle ID: SVID of the satellite affected.
Signal(s) affected: the signal(s) affected by the satellite referenced in the NAGU. The signals affected will be contained within a bracket after the word SIGNAL and can be one or a combination of the following: E1, E5a, E5b, E6-B, E6-C, ALL. Partial outage/availability of the signals is indicated in the NAGU subject if ALL signals are not affected.
Event description: the event description following the templates defined for each NAGU.

NAGU Timeliness

The timely publication of NAGUs refers to the time intervals within which Galileo NAGUs are published, before any planned event or after any unplanned event. The minimum performance level for the timely publication of NAGUs are specified in the applicable Open Service-Service Definition Document and High Accuracy Service-Service Definition Document .