ISIS Topside Sounder

This directory groups data from the Alouette 2, 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://spdf.gsfc.nasa.gov/isis/isis-status.html>.

A search page <http://spdf.gsfc.nasa.gov/isis/isis_menu4.html> lets users
locate ISIS-2 data for specified dates, times, locations and other search criteria. 
The ISIS-1 search page is found at <http://spdf.gsfc.nasa.gov/isis/isis1_menu4.html>

In addition to the standard resolution ionograms provided in these subdirectories in
OS2 binary, NSSDC 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://spdf.gsfc.nasa.gov/isis/documents/pcm_doc/des_pcm.html>). 

Subdirectories:
/crc_ne_profile_ascii    
	Electron density profiles deduced from ISIS-1 and -2 ionograms by manual scaling  
	at the Communications Research Center (CRC) in Ottawa, Canada in the seventies in 
	ASCII format 
/crc_ne_profile_cdf
    Same data in CDF format grouped by year and also available on 
    CDAWeb (http://cdaweb.gsfc.nasa.gov).    
/ionogram_cdf   
	Ionogram data in CDF format also available on CDAWeb (http://cdaweb.gsfc.nasa.gov).
	ISIS-1 and -2 data grouped by ground station, year, and day of year. 
/ionogram_examples
	Examples of ionogram images in JPG or GIF format in color or grey_scale.
/ionogram_header_ascii	
	Header file with header information for all ionograms recorded during a 
	specific satellite pass in ASCII format (a format description can be found at 
	http://spdf.gsfc.nasa.gov/isis/header.html).
/ionogram_os2bin   
	High-resolution ionograms in OS2 binary format with orbit information included 
	(a format description can be found at 
	http://spdf.gsfc.nasa.gov/isis/des_av_i1.html and
	http://spdf.gsfc.nasa.gov/isis/des_av_i2.html
/ionogram_new_i1_cdf   
	Ionogram data in CDF format also available on CDAWeb (http://cdaweb.gsfc.nasa.gov).
	This are the newest version ionograms currently only available for ISIS-1 and the
	Ottawa ground station. Data are grouped by year. See the file 
	Description_Improved_ISIS-1_files.docx for details about the difference to the 
	earlier version stored in ionogram_cdf.
/ISIS_images_USU
	JPG and PNG images of ISIS 1 and 2, and Alouette 1 and 2 topside sounder ionograms 
	that were scanned from the original rolls of microfilm: 1 roll each from Alouette 
	1, 2, and ISIS 1, 35 rolls from ISIS 2, and 2 rolls from the Resolute Bay ionosonde. 
/software
	Software related to these data sets: 
	/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).
/topist_ne_profile_ascii
    Electron density profiles produced by the Topist software operating on
    all of the "/ionogram_os2bin" ionograms from ISIS 2. Grouped by ground
    station and year.
/topist_ne_profile_cdf
    Same data in CDF format and also available on CDAWeb. Data are for all ground
    stations combined in one large yearly CDF file (30-60 MB).  

Please acknowledge the NASA Space Physics Data Facility and the instrument's Principal
Investigator for data usage.

Keywords: ionosphere, topside, sounder, ionogram

Data contact: Dieter.Bilitza-1@nasa.gov>
NASA Official: Dr. Robert McGuire <robert.e.mcguire@nasa.gov>