See http://sec.noaa.gov/Data/ for tables of all online data 
      at SEC, including links to non-SEC sources for older data.

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May 15, 2003
           Space Environment Center GOES MAGNETOMETER Data Lists


====================================================================== 
May 15, 2003 -- The GOES 10 energetic proton detectors are showing
intermittent, high noise levels in the higher energy proton channels
(greater than about 80 MeV). This problem was first noticed in data
taken April 26, 2003. To ensure continued operational monitoring of
important energetic particle data, it is necessary to reassign
primary/secondary designations for the GOES Space Environment
Monitor (SEM) detectors. As of 1500 UT on May 15, GOES-8 became the
primary satellite for protons. GOES 12 is the primary satellite
for magnetometer, X-ray, and electron measurements. GOES 10 is
the secondary satellite for all SEM sensors - magnetometer, X-ray
sensor, and energetic particle sensor. This short-term solution
(approximately 2 - 3 months) will be in place until we define and
implement a permanent fix.
            
See details at http://www.sec.noaa.gov/GOES.html

====================================================================== 
April 8, SEC stopped using GOES 8 data.
GOES 10 is now SEC's primary GOES satellite, with GOES 12 the backup 
for magnetometer, XRS x-ray measurements, and energetic particle data. 
However, no integral particle and electron flux values are available 
on GOES 12.
 
===========================================================================
===========================================================================

September 1996
               DESCRIPTION OF GOES MAGNETOMETER DATA


SEC designates two GOES satellites as operational, one at about 135 degrees 
geographic west longitude and one at about 75 degrees geographic west 
longitude. The satellite inclination is typically within a few tenths of a 
degree of of the geographic equator. However, the satellites can be moved, 
especially during the six months to one year following launch, and the 
inclination can increase after years of satellite operation. The following 
information is provided as an aid for interpreting and using magnetometer 
data from GOES satellites.

1. Coordinate system:

The three components are: Hp,  perpendicular to the satellite orbital plane 
or parallel to the Earth's spin axis in the case of a zero degree 
inclination orbit; He, perpendicular to Hp and directed earthwards; and Hn, 
perpendicular to both Hp and He and directed eastwards. (This is the same 
coordinate system used for all the GOES magnetic field measurements since 
GOES-5;  prior to GOES-5, Hn was directed westwards.)

2. Effect of three-axis stabilized, rather than spinning spacecraft:

Calibration data are used from ground and on-orbit testing, including a 
one-time 3-axis spacecraft maneuver to determine offsets resulting from the 
spacecraft field and magnetometer electronics.  However, it is important to 
remember that absolute vector magnetic field measurements are difficult to 
determine on non-spinning spacecraft such as GOES 8 and 9.  We will continue 
to evaluate the data, including comparisons with model fields, and provide 
improved knowledge of magnetic field absolute accuracy as it becomes known.

3. Torquer current effects:

A calibration between torquer currents and magnetic field signatures was 
made both on the ground and in space for correcting the magnetic field 
measurement; however, on GOES-8, noise in the torquer current telemetry 
introduced artificial noise in the "corrected" magnetic field at the few 
nanoTesla level.  A correction has been instituted on GOES-8, and will be 
included on following spacecraft, to allow use of torquer command data for 
torquer current correction.  The problem has been further dealt with on 
GOES-9, and future spacecraft, by filtering the torquer current telemetry 
before it is transmitted.  These effects should be insignificant in the vast 
majority of the 1-minute data.

4.GOES 9 eclipse intervals:

GOES-9 is undergoing few degree rotations during the eclipse seasons for 
spacecraft thermal control to extend the life of motors used for the imager 
and sounder.  The first tests were on August 14, 1996, and then rotations 
were performed routinely from August 20, 1996 to September 1, 1996. These 
rotations will be performed again from October 13, 1996 to October 26, 1996. 
The schedule may be cancelled during severe weather monitoring intervals.

The spacecraft, including magnetometer sensors, is rotated 3.5 degrees to 
the east about four hours before local midnight.  At local midnight, the 
spacecraft is rotated to face four degrees west from the usual orientation. 
Approximately four hours later, the spacecraft orientation is returned to 
normal.  For example, on August 14, the first maneuver was about 0430 UT, 
the second at 0840 UT and the final rotaion at 1302 UT.

At present, there is no correction applied to the magnetometer data, but the 
correction should be present by the spring eclipse season.

5. Calibrations:

Calibrations are performed once per week and will result in a few minutes of 
deleted 1 minute average data.

6. Reference:

Singer, H.J., L. Matheson, R. Grubb, A. Newman and S.D. Bouwer, Monitoring 
Space Weather with the GOES Magnetometers, SPIE Conference Proceedings, 
Volume 2812, 4-9 August 1996, in press.

Contacts:

Dr. Howard.Singer@noaa.gov Lead Scientist for GOES SEM Instruments

Dr. Terry.Onsager@noaa.gov   Energetic Particles
Dr. Howard.Singer@noaa.gov    Magnetometer