GOES X-ray Flux

The GOES X-ray plots shown here are used to track solar activity and solar flares. Large solar X-ray flares can change the Earth’s ionosphere, which blocks high-frequency (HF) radio transmissions on the sunlit side of the Earth. Solar flares are also associated with Coronal Mass Ejections (CMEs) which can ultimately lead to geomagnetic storms. SWPC sends out space weather alerts at the M5 (5x10^-5 Watts/mw) level. Some large flares are accompanied by strong radio bursts that may interfere with other radio frequencies and cause problems for satellite communication and radio navigation (GPS).

The latest event is the latest X-ray flare detected by the GOES satellites, either automatically or manually entered if the detection algorithm fails, without regard to any earlier events. 

The particulars for defining the begin, maximum, and end-time of an X-ray event are:

• The begin time of an X-ray event is defined as the first minute, in a sequence of 4 minutes, of steep monotonic increase in 0.1-0.8 nm flux.
• The X-ray event maximum is taken as the minute of the peak X-ray flux.
• The end time is the time when the flux level decays to a point halfway between the maximum flux and the pre-flare background level.

Sometimes the algorithm will not trigger on a flare with a gradual rise-time (common for limb events), and the forecaster will have to enter the particulars manually.

The GOES X-ray flux 6-hour and three-day plots contain 1-minute averages of solar X-rays in the 1-8 Angstrom (0.1-0.8 nm) and 0.5-4.0 Angstrom (0.05-0.4 nm) passbands. Data from the SWPC primary and secondary GOES X-ray satellites is shown. Some data dropouts occur during instrument calibrations and satellite eclipses when the Earth or the moon comes between the satellite and the sun, especially during the spring and fall. The Earth Eclipse seasons around the spring and fall equinoxes last for about 45 to 60 days and ranges from minutes to just over an hour. The plots on this page update dynamically every minute.

GOES X-ray flux measurements (1 - 8 Angstrom flux) have been made since 1986 and, prior to that, on the NOAA SMS satellites since 1974. SWPC has used this data to produce a variety of data sets including 1-minute averages and flare lists. For more information on the GOES satellites and their X-ray measurements from before 2010 see: GOES measurement data information

The dynamic plot above can be downloaded in multiple image formats using the menu at the upper right. The menu also offers the ability to download the displayed numerical data in JSON format.

Numerical data are also available directly from SWPC's data service at: 

https://services.swpc.noaa.gov/json/goes/

In that directory the file instrument-sources.json provides the mapping of primary and secondary measurements from each instrument to the satellite from which that measurement is made. The file satellite-longitudes.json provides the longitudes of the satellites. Observation data are found under the primary and secondary subdirectories.

A notable change between the GOES-R (16-19) and previous GOES SWPC data is that the GOES-R XRS irradiances are provided with a different irradiance calibration than for earlier satellites, and this impacts flare magnitudes. 

Both operational and science-quality reprocessed XRS data for GOES 13 through the current GOES satellites is available at https://www.ncei.noaa.gov/products/satellite/goes-r. The science quality data has calibrations consistent with the GOES-R data for the irradiance magnitudes and includes multiple products as described in    https://data.ngdc.noaa.gov/platforms/solar-space-observing-satellites/goes/goes16/l2/docs/GOES-R_EUVS_L2_Data_Users_Guide.pdf. In 2022, XRS data from GOES 1-12 will be reprocessed and become available at this website.

Older SWPC historical 3-day plots and text files from 1996 through January 2020 are available at: 

ftp://ftp.swpc.noaa.gov/pub/warehouse/

Access to the warehouse is provided by copying the above link in a file explorer and downloading data of interest.

The official archive for this older GOES data which has not yet been reprocessed, including daily forecast reports, can be found under "Data Access" at:

https://www.ncei.noaa.gov/products/satellite/goes-r

Users of this older data should consult https://www.ngdc.noaa.gov/stp/satellite/goes/doc/GOES_XRS_readme.pdf for information on how to correct this data.