Document title: ISIS-1 and -2 Topside Sounder electron density profiles -- 
Format description 
Project: ISIS 
NDADS Datatype: TOPS_NE_ASCII
Super-EID: DOCUMENT                      
There may be other documents also identified by this super-EID.
NDADS filename: TOPS_NE_READ_ME_ISIS.DOC
TRF entry: b46548.txt in NSSDC's controlled digital document library, Mar. 1998.
Document text follows:
----------------------

          ISIS-1 AND -2 TOPSIDE SOUNDER ELECTRON DENSITY PROFILES
          ------------------ Format Description -----------------

This data were generated at NSSDC from a data set original produced at the
Communication Research Center (CRC) in Ottawa, Canada and archived at NSSDC
(69-009A-01F).  The CRC had computed the electron density profiles from the
frequencies and virtual heights scaled from the orginal topside sounder
ionograms.

There were six files with ISIS-1 data and seven files with ISIS-2 data.
Within each file the data are in chronological order, there is, however,
time overlap between the different files.  There is even a few cases where
we found two profiles (in different files) with identical recording time;
these most likely were recorded at different telemetry ground stations.

At NSSDC the data were converted to ASCII format and grouped into daily
files.  A parameter (FILE) was added to identify the file from which the
data point originated (to help separate profiles with identical time but
different ground stations).  In addition heights were computed for each
data point from the coefficients given in the orginal data files using the
formulas described by J.E.  Jackson (Proceedings of the IEEE, pp 960, June
1969).

The data are in ASCII format and include the following parameters:

FILE	I1,1X	File Identifier: ISIS-1: 1=T2F0001, 2=T2F0002, 3=T2F0003,
		4=T3F0001, 5=T3F0002, 6=T3F0003; ISIS-2: 1=F0001, 2=F0002,
		3=F0003, 4=F0004, 5=F0005, 6=F0006, 7=F0007

TYPE	I1	=4 The data are electron density profiles.
 
TRACE	A1	=X extra-ordinary trace was used, =O ordinary trace was used.

T/B	A1	=T topside sounding, 	=B bottomside sounding

DIP	I3,1X	Magnetic inclination at the satellite in degree

Q	I1,1X	Quality flag: 4-best, 9-minimal information, 0-tabulation was 
		made before code was established; use Q=7-9 with caution.

YEAR	I2,1X	Last two digits of year

DOY	I3,1X	Day of year (Jan 1 = 1)

HOUR	I2	Hours Universal Time when the ionogram was recorded (the time 
		given 3.0 +/- 1 sec before the occurrence of the 0.5 MHz 
		frequency marker)

MIN/	I2,A1	Minutes Universal Time, Slash/

SEC	I2	Seconds Universal Time

X	A3	For internal use by observers

FOF2*	I7	The ordinary wave frequency (in MHz) corresponding to the 
		highest number density computed for the ionogram. This is 
		always less than, or equal to, the ordinary wave penetration 
		frequency of the F layer. [absent in most cases]

HMAX	F5.1	The height corresponding to FOF2*. [absent for the majority 
		of profiles]

TEC	E11.4,1X  Electron content (in cm-2) from the satellite down 
		  to the height corresponding to FOF2*.

N	I2,1X	Number of profile points.

FH	F4.2,1X	Gyrofrequency at the satellite in MHz.

Long	F6.1,1X	Longitude in degrees.

Lat	F6.2,1X	Latitude in degrees.

XHI	I3	Solar zenith angle in degrees.

--------------- followed by N pairs of Ne and H, format: 4(F11.2,F9.2):

Ne	F11.2	Electron density in cm-3.

H	F9.2	height in km.