OOREADME.TXT for <ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/isis/topside_sounder>

ISIS Topside Sounder

This directory groups data from the ISIS 1 and 2 topside sounder instruments. The 
data were obtained through NASA/OSS/AISRP-funded data restoration projects at GSFC 
(digitization: R. Benson, PI) and at the University of Massachusetts Lowell (TOPIST: 
B. Reinisch, PI). More information about these projects can be found at 
<http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html>.

A search page <http://nssdc.gsfc.nasa.gov/space/isis/isis_menu4.html> lets users
locate data for specified dates, times, locations and other search criteria 
(currently only ISIS-2 data are considered).

In addition to the standard resolution ionograms provided in these subdirectories in
OS2 binary, NSSDC also archives a higher resolution data product with a 
3.75 km apparent-range resolution instead of 15 km for the standard ionograms. 
These data are available from NSSDC on request <mailto:request@nssdca.gsfc.nasa.gov> 
in OS2 binary format. Also available are telemetry-level Pulse Code Modulation (PCM) 
data for all ISIS 2 instruments (a description can be found at 
<http://nssdc.gsfc.nasa.gov/space/isis/documents/pcm_doc/des_pcm.html>). 

NOTE: The standard resolution ionograms in CDF format are no longer served from 
these directories. They can be downloaded from CDAWeb <http://cdaweb.gsfc.nasa.gov/>.


Subdirectories:
/crc_ne_profile_ascii    
	Electron density profiles deduced from selected ionograms at the 
	Communications Research Center (CRC) in Ottawa, Canada in the seventies 
/ionogram_cdf   
	These data have been moved to CDAWeb <http://cdaweb.gsfc.nasa.gov>.
/ionogram_examples
	Examples of ionogram images in color or grey_scale
/ionogram_header_ascii	
	Header file with header information for all ionograms recorded during a 
	specific satellite pass (a format description can be found at 
	http://nssdc.gsfc.nasa.gov/space/isis/header.html).
/ionogram_os2bin   
	Ionograms in OS2 binary format with orbit information included (a format
	description can be found at 
	http://nssdc.gsfc.nasa.gov/space/isis/des_av_i1.html and
	http://nssdc.gsfc.nasa.gov/space/isis/des_av_i2.html
/topist_ne_profile_ascii
    Electron density profiles produced by the Topist software operating on
    all of the "/ionogram_os2bin" ionograms. As of July 31, 2002, all of the
    ISIS 2 data had been finished, and ISIS 1 was yet to start.

Additional related information and data services on NSSDC's ISIS home 
page: <http://nssdc.gsfc.nasa.gov/space/isis.html>

Software related to these data sets can be found at
ftp://nssdcftp.gsfc.nasa.gov/spacecraft_data/isis/software
/orbit_worldmap_program
	Program to generate orbit parameters
/ionogram_inversion_jackson
	John Jackson's program to invert an ionogram trace into an electron 
	density profile.
/interactive_tracing_inversion
	An interactive widget-based program to trace and invert an ionogram; 
	requires IDL and X terminal (X-windows, MACX, Sun).

NSSDC Contact: <mailto:request@nssdca.gsfc.nasa.gov> or phone 1-301-286-6695

Please acknowledge the NASA National Space Science Data Center and the Principal
Investigator Robert Benson of Goddard Space Flight Center for data usage.

Keywords: ionosphere, topside, sounder, ionogram

[Dec 18, 2000/dieter.bilitza@gsfc.nasa.gov]