This directory provides access to one file of 1968-1971
hourly averaged solar wind plasma parameters from the
Jet Propulsion Laboratory plasma instruments (Faraday
Cup plus Electrostatic Analyzer) flown on the geocentric
OGO 5 spacecraft.  Principal Investigator was Dr. Marcia
Neugebauer.

The directory consists of (1) this aareadme text, intended to
give orientation to a user and a little background in this
data set; (2) a text file (ogo5_pla_doc.txt) having more detail
about the instruments,data processing and the data record format;
and (3) the data file itself (ogo5_pla.dat).

The detailed text (item 2 above) was created at NSSDC by
scanning and OCR'ing the key parts of a paper document
created by Marcia Neugebauer and Barbara Weber in 1973.

In the early 1970's, Dr. Neugebauer provided to NSSDC
several OGO 5 plasma data sets: full resolution and hourly
averaged plasma parameters on magnetic tapes and as
plots and listings on microfilm.  Hourly averages on tape
were used in the creation of the original OMNI data set in
the mid-1970's.  They are the data newly made electronically
accessible through this ftp directory tree.  (If interest emerges,
the full resolution data set could also be made electronically
accessible by NSSDC.)

A unique characteristic of this data set is that its data for
March 13, 1971 - April 30, 1971 represent the only solar
wind plasma data overlap between the multiplicity of solar
wind spacecraft launched in the 1960's and those launched in
March 1971 (IMP 6) and later (IMPs 7, 8, ISEE 3, Wind,
ACE, etc.).  In preparing OMNI originally, and in the
~2002-3 preparation of  OMNI 2, much normalization of
pre-1971 plasma data across source spacecraft was done,
as were post-1971 cross normalizations.  However, it
was judged that there was insufficient OGO 5 - IMP 6
overlap to cross-normalize plasma parameters across the
1971 boundary.

Making the OGO 5 hourly averages electronically
accessible is motivated in part to enable the space physics
community to make independent assessments of the
cross-normalizing of pre-1971 and post-1971 solar
wind plasma data.

IMP 6 solar wind plasma hourly averages are available at
https://spdf.gsfc.nasa.gov/pub/data/imp/imp6/plasma_lanl/solarwind_1hr/

and at http://nssdc.gsfc.nasa.gov/ftphelper/pla_imp_678.html.

General OMNI documentation is available from
http://nssdc.gsfc.nasa.gov/omniweb
Text from the mid-1970's addressing the then-perceived
impossibility of cross-normalizing OMNI's pre-1971 and
post-1971 plasma data is found at
http://nssdc.gsfc.nasa.gov/omniweb/om_book/main/main.html

JHK, April 22, 2004