GOES 1–15 Space Weather Instruments

Energetic Particle Sensor (EPS)

Energetic Particle Sensors (EPS) are solid-state detectors with pulse-height discrimination that measure proton, alpha-particle, and electron fluxes. The EPS telescope (channels P1-P3) and the dome D5 detector designs (channels P6 and P7) were the same from GOES-4 through GOES-15. The dome D3 (channels P4, E1, and E2) and dome D4 detector designs (channels P5 and E3) were the same from GOES-8 through GOES-15.

The E1, E2, E3, and P1 channels respond to trapped outer radiation belt particles. The P2 channel may occasionally respond to trapped particles during magnetically disturbed conditions. P1–P7 measure fluxes that originate outside the magnetosphere–from the sun or the heart of the galaxy. Similarly, the alpha particle channels A1–A6 measure fluxes of solar- and galactic-origin helium-4 nuclei.

The particle data also include significant secondary responses from higher energy particles, other species (especially proton contamination of electron channels E2 and E3), and directions outside the nominal detector entrance aperture. The data also include backgrounds that are caused by instrument noise, not by penetrating radiation. The integral proton fluxes are derived from the instrument channels and have been partially corrected for these effects. E2 (>2 MeV) and E3 (>4 MeV) electron data become unreliable during most solar energetic particle events (solar radiation storms). The alpha particle (helium-4 nuclei) channels are all differential channels.

Magnetospheric Electron Detector (MAGED) and Magnetospheric Proton Detector (MAGPD)

On GOES 13–15, the EPS was renamed the Energetic Proton, Electron and Alpha Detector (EPEAD), and two new instruments (Magnetospheric Electron Detector - MAGED, and Magnetospheric Proton Detector - MAGPD) were added to the suite. MAGED (30-600 keV electrons) and MAGPD (80-800 keV protons) are based on the POES SEM-2 Medium Energy Proton and Electron Detector (MEPED) electron and proton telescope designs, but with different energy channels. MAGED and MAGPD are each composed of nine telescopes of identical design in a cruciform arrangement, with five telescopes forming a fan in the north-south plane and four additional telescopes forming an east-west fan with the central telescope.

High Energy Proton and Alpha Detector (HEPAD)

The HEPAD telescope consists of two silicon detectors and a photomultiplier tube (PMT) illuminated by a Cherenkov radiator. Triple coincidences between the two silicon detectors and the PMT are used to produce four proton channels and two alpha particle channels. There are three proton differential channels between 330 and 700 MeV and an integral channel above 700 MeV. The two alpha particle channels rarely report fluxes above backgrounds. HEPAD data are available from GOES-6 and GOES 8-15 (The GOES-7 instrument failed). The GOES-6 HEPAD first observed a SEP event with a ground level enhancement (GLE) in February 1984 (GLE 39). The final GLE observed by HEPAD (on GOES 13–15) was GLE 72 (September 2017).

SPE list (1976 to date) This table lists the Solar Proton Events Affecting the Earth Environment detected by SWPC and its predecessors using GOES data from 1976 to the present day. Starting in 2021, the events have been detected using GOES-R SEISS/SGPS data.

Science-Quality and Operational Particles Data

When available, we strongly recommend using the science-quality data in your study. These data have been reprocessed to account for new calibrations, to account for dead time, or to flag backgrounds and contamination. The 1-minute averages of the GOES 13–15 EPEAD >0.8 and >2 MeV electron channels (E1 and E2) were reprocessed by NCEI with a science-quality algorithm. Key aspects of this algorithm that distinguished this product from the real-time SWPC product included (1) application of a dead-time correction and (2) replacing near-background values with fill values. NCEI has also calculated pitch angles for MAGED and MAGPD at 1-minute cadence using magnetic field measurements from the GOES 13–15 magnetometers.

The 1-minute average EPAD and MAGED/MAGPD pitch angles monthly files can be accessed from the GOES-SEM averages directory. They are contained in the NetCDF folders for GOES 13–15, and use the following file naming convention:

;gXX_epead_e13ew_1m_yyyymmdd_yyyymmdd_science_v1.0.0.nc.

gXX_pitch_angles_1m_yyymmdd_yyymmdd.nc”

The GOES EPEAD Science-Quality Electron Fluxes Algorithm Theoretical Basis Document and GOES 13–15 MAGE/PD Pitch Angles Algorithm Theoretical Basis Document provide a detailed description of the science-quality algorithm and product.

Operational Particles Data

Magnetometers

Three orthogonal fluxgate magnetometer elements (only two spinning fluxgate elements prior to GOES-8 -1994) provide geomagnetic field measurements at geosynchronous orbit (L = 6.6) with high resolution since 1974.

More Information About Magnetometers

Solar X-ray Imager (SXI)

Until 2001, NOAA monitored three prominent space weather parameters using the SEM instrument suite: energetic particles, magnetic fields and total solar X-ray output. In the summer of 2001, NOAA also began to monitor the structure of the solar atmosphere using an X-ray telescope called the Solar X-ray Imager (SXI). The GOES-12 through 15 spacecrafts each carried a SXI that used a 512 x 512 intensified CCD and broadband filters to obtain solar corona images (once per minute) at several wavelength bands ranging from soft X-rays to extreme ultraviolet (about 6 and 60 Å). 

GOES' geosynchronous orbit allows it to have direct line-of-sight observations of the Sun, 24 hours/day, 7 days/week. The only exception to this, is near the equinox, when GOES enters Earth's shadow for up to one hour each day. SXI will collect an image once per minute and the exposure settings follow a sequence that is optimized to observe three primary phenomena as they are reflected in the Solar atmosphere: coronal structures, active regions, and solar flares.

SXI Data

GOES Science-Quality Data

• GOES 1-15 XRS Science-Quality Data ReadMe
• XRS L2 User Guide
• GOES 13-15 XRS Responsivity
• GOES 13-15 EUVS ChansAB Science-Quality Data ReadMe
• GOES 13-15 EUVS Lyman-alpha Science-Quality Data ReadMe
• GOES 13-15 EUVS v4 NetCDF Readme
• GOES 13-15 EUVS Responsivity
• GOES-14 EPS-HEPAD storage-mode fluxes ReadMe
• GOES 8–15 Magnetometer Readme
• GOES 6-15 Ephemeris Data ReadMe

GOES Operational (Real-Time) Data 

• GOES 1-15 Operational XRS Data Readme
• SXI Readme
• SMS-1 - GOES-7 Full Resolution Data Readme
• SMS-1 - GOES-12 Averaged Data Readme

GOES Data Books: Overview of the Satellite Platform and Instruments

• GOES-8–GOES-12 Data Book
• GOES-N Series DataBook
• GOES-N Series Databook Section5 revD

GOES NOP (13–15) Algorithm Theoretical Basis Documents

• GOES EPEAD Science-Quality Electron Fluxes Algorithm Theoretical Basis Document
• GOES 13-15 MAGE/PD Pitch Angles Algorithm Theoretical Basis Document

GOES NOP (13–15) Engineering Documents

• Electron Calibration Report for EPEAD D3 Dome (2004)
• Electron Calibration Report for MAGED Telescope (2004)
• Proton and Electron Calibration Report for MAGPD Telescope (2004)
• EPS/HEPAD Calilbration and Data Handbook (2011)
• GOES-NOP HEPAD In-Orbit Data Study (2011)

GOES I-M (8–12) Engineering Documents

• EPS Dome Electron Channel Calibration Report (1988)
• EPS Dome Sensor Response to Protons (1995)
• Proton Calibration of HEPAD (1990)
• GOES-G XRS Calibration Document-02 (Jan 1, 985)
• GOES I–M Calibration Document-06 (May, 1986)
• GOES I–M Calibration Document-07 (May, 2000)

GOES DEF (4–6) Engineering Documents

• EPS Telescope Calibration Work (1979)
• EPS Dome Calibration Work (1980)
• Proton Calibration of HEPAD (1986)
• HEPAD Preliminary Data Analysis (1980)
• XRS/EPS Sensor Operation Document-01 (Feb, 1987)
• XRS Calibration Document-03 (May. 1980)
• GOES D Calibration Document-04 (May, 1980)
• GOES E XRS Calibration Document-05 (Feb, 1980)

GOES 1–3 and SMS Engineering Documents

• ERL-SEL-42: Space Environment Subsystem, 1975, R.N. Grubb
• ERL-SEL-48: Solar X-ray Measurements from SMS-1, SMS-1 and GOES-1, Information for Data Users, R.F. Donnelly, et al
• ERL-SEL-56: SMS-GOES Soft X-ray Measurements, July 1, 1974 - December 31, 1976, R.F. Donnelly
• PANA-SEM-4: Effective Proton/Electron Geometric Factors and Comparison of the Electron Channel Responses of the EPS Subsystems on the GOES-4 and GOES-2 satellites (Panametrics, Inc. Dec 7, 1981)
• GOES-PCC-549: Nuclear Calibrations for GOES-2 and -3 EPS (Aeronutronic Ford Corporation, Aug 12, 1976)

GOES Data Announcements

• GOES-14 and 15 Data Discontinuation Announcement (March 4, 2020)
• GOES-13 Data Discontinuation Announcement (December 14, 2017)

Other Documents

• Data Notes: Comments captured in the 1990's about data issues.
• GOES-NOP_QualFlag_Dictionary_v20100218.xls
• GOES-NOP_QualFlag_Dictionary_v20110309.xls
• goes13ReadinessReview-Particles.pdf
• GOES-13_QualityIssues_v20100322.pdf
• Solar Proton Events Affecting the Earth Environment (1976-present)
• EGU2017 - GOES-8-15 HiRes and ULFs - Redmon.pptx
• ERL-SEL-62: A Summary of Solar 1-8 Å Measurements from the SMS and GOES Satellites, 1977 - 1981, S.D. Bouwer, et al
• Monitoring Space Weather with the GOES Magnetometers, SPIE Conference, H.J. Singer, et al
• Comment on the use of GOES Solar Proton Data and Spectra in Solar Proton Dose Calculations, D.F. Smart & M.A. Shea.
• 2010 GOES and POES Data Services Program Review Slides