Data Providers:
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210:  This is the 210 E longitude chain from Dr K. Yumoto of Solar-Terrestrial Environmental 
  Laboratory, Nagoya University, Japan (yumoto@stelab.nagoya-u.ac.jp. The original data are
  variation data in XYZ coordinates in 0.1nT. 
AT&T:  The original data are 1 min averages from L.J. Lanzerotti and Carol Maclennan of AT&T 
  (cgm@physics.att.com) of variation data in EHZ coordinates.  
  Original data are often 2 sec for TKN and PTA, 5 sec for IQA, and 10 sec for MCM and SPA.
AT&T/UMD:  The original data are from AT&T, but are processed into 1 minute average variation
  data in EHZ coordinates by Dan Detrick of the University of Maryland (detrick@uap.umd.edu)
AT&T/UMD:  The original data are from AT&T, but are processed into 1 minute average variation
  data in EHZ coordinates by Dan Detrick of the University of Maryland (detrick@uap.umd.edu)
CANOPUS:  The original data is XYZ 5 second data from Terry Hughes (hughes@canott.dan.sp-agency.ca)
  of CANOPUS.  
DMI/UMI:  The original data is from the Danish Meteorological Institute (DMI) in  binary .gdf
  files of 20 second data in EHZ coordinates.  The contact is Eigil Friis-Christensen at
  metoefc@uts.uni-c.dk.  The data were converted by Bob Sitar of the University of Michigan
  (sitar@pitts.sprl.umich.edu) into 1 minute averages with the constant quiet values for the
  month removed, and converted from EHZ to XYZ coordinates. 
IMAGE:  The original data are from Hermann Luehr (luehr@geophys.nat.tu-bs.de) at the Institute for
  for Geomagnetism and Meteorology.  The data are variation data in XYZ coordinates.  The data
  were every 60 seconds, but finer resolution of 20 seconds is available. 
ING:  The original data is from Lili Cafarella of ING in Rome, Italy (cafarella@in8800.ingrm.it).
  It is one minute absolute data in DHZ, where D is in degrees.
INTERMAGNET:  This data is 1 minute data in NGDC format from the 1993 INTERMAGNET CDROM
  The original sources can be obtained from Al Green (awgreen@gldfs.cr.usgs.gov)
MACCS/BU:  The original MACCS data can be obtained in 5 second or 1 minute averages from
  Mark Engebretson of Augsburg College (engebretson@auggie.dnet.nasa.gov) or from
  Jeff Hughes of Boston University (hughes@buasta.bu.edu).  The data are in EHZ coordinates
  but are usually labelled as XYZ.  The November 1993 data were the 60 second averages
  obtained from Boston University in binary format, which was converted by US Air Force Academy 
  personnel to ascii format. 
NGDC:  This data is 1 minute data in NGDC format from Les Morris (lmorris@ngdc.noaa.gov) at
  the National Geophysical Data Center (NGDC).  The original sources can be obtained from
  Les Morris. 
NGDC/RGON:  This data is 1 minute data in NGDC format from Les Morris (lmorris@ngdc.noaa.gov)
  at the National Geophysical Data Center (NGDC).  The original data is downloaded from a
  satellite link to the Space Environment Center (SEC) in Boulder.  The data are thus not
  quality controlled, and can have numerous calibration or other spikes, especially in the
  Alaskan chain, which is unattended and has been running since the IGY.  The only RGON
  data used in November 1993 is in the Alaskan chain whose contact is John Olson of the
  University of Alaska (jvo@maxwell.gi.alaska.edu).  The data are variation data in EHZ
  coordinates.  (Canadian RGON data is usually in XYZ coordinates.)
SAMNET:  This data comes from David Milling of the University of York (dave@aurora.york.ac.uk).
  The original variation data are 5 second values in ZDH coordinates in units of quarter nT.