User Ephemeris File- UEF

Data Usage Guidance/Restrictions

The operational data for this datatype is available to all registered CLASS users. Pre-operational data may be restricted to authorized users. To become an authorized user, send a request to the CLASS Help Desk.

Dataset Name

A User Ephemeris File (UEF) contains orbit vectors that cover a 10 day time span. An updated UEF file is received each day. The UEF is the foundation for all the navigation data produced in IPD. It is utilized to create the TBUS bulletins, the equator crossing information files, the Search and Rescue (SAR) orbit ephemeris files, and level 1B instrument data files.

Inventory ID

A unique numerical ID assigned to the data set for CLASS inventory purposes.


The satellite that acquired the UEF data.

N12 ND NOAA-12
N14 NJ NOAA-14
N15 NK NOAA-15
N16 NL NOAA-16
N17 NM NOAA-17
N18 NN NOAA-18
N19 NPrime NOAA-19


Refers to the time span of interest to the user. This section of the search page allows the user to define the range of dates/times of interest.


Coordinated Universal Time (UTC) is the international time standard. It is the current term for what was referred to as Greenwich Meridian Time (GMT). Zero (0) hours UTC is midnight in Greenwich England, which lies on the zero longitudinal meridian. Universal time is based on a 24 hour clock, therefore, afternoon hours such as 4 pm UTC are expressed as 16:00 UTC (sixteen hours, zero minutes).

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