OGO 6 Bennett Ion Mass Spectrometer Data 
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bilitza@gsfc.nasa.gov - September 6, 2001

This are data from the OGO 6 BIMS experiment for the time 
period from June 12, 1969 to December 31, 1970 in ASCII
format. There are 15 monthly files (filename format: 
yyyy_mm_ogo6_bims.asc). Each file consists of a varying 
number of data records. The total volume is about 200 MByte.

The instrument measures the ion densities of seven ion
species (H+, He+, N+, O+, N2+, NO+, O2+). The cycle time
is about 40 seconds. Each data record lists the density
and orbit parameters for one specific density measurement.

In reprocessing these data from the original PI-provided
data set the following was done: (i) converting from binary
to ASCII, (ii) computing L values using the IGRF model,
(iii) verifying the dip values with IGRF model, (iv) adding
Ap, Kp, F10.7, and R, (v) dividing the ion densities by the
PI-provided calibration factors, (vi) densities are provided 
in two variables, the first (word #21) only provides "good" 
values (zeros and negative values are set to fill values), 
the second (word #22) provides all values including zeros and 
"bad" data marked in the original data set with a '-' before 
the density value (word #22 stores the absolute value).

The digit '9' is used for fill values, e.g. the fill value 
for the densities is 9.9999E+09 and for the L value 99.99.
A blank space was added between parameters for viewing 
convenience (not shown in Format column).
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#  Parameter	Format	Description
_____________________________________________________________
1  Year   	I3
2  Day      	I4
3  Hour    	I3
4  Minute      	I3
5  Seconds      I3
6  Milliseconds I4
7  Mass index   I2      =1 to 7 for amu=1,4,14,16,28,30,32 
                        (H+,He+,N+,O+,N2+,NO+,O2+)
8  MLT     	F6.2	Magnetic Local Time in decimal hours
9  Geod Lati.   F7.2	in degrees
10 Geod Longi.  F7.2	in degrees (0-360)
11 Geomag Lat.  F7.2	in degrees
12 Altitude   	F8.2	in km
13 Dip  	F6.1	Magnetic inclination in degrees
14 L-shell     	F6.2 	L value computed with the IGRF model +
15 L-code    	I2  	(=1  L is correct; =2  L is not correct; 
			=3  an approximation is used) +
16 Ap (3hour)  	I4	3-hourly Ap magnetic index +
17 Kp (3hour)  	I3	3-hourly Kp magnetic index (3- = 27, 3+ =33, 3o = 30)+
18 F10.7(daily) I4  	Daily solar radio flux at 10.7 cm +
19 R (daily)  	I4	Daily sunspot number +
20 AMU    	I3	Atomic Mass Number for which density is given
21 Ion Density  1X,1PE10.4	Density of ions with AMU in cm-3 (only good data) 
22 Ion Density  1X,2PE11.4	Density of ions with AMU in cm-3 (all data)
23 S/C Charge   F7.2	in Volts
24 Velocity     F7.2 	in km/sec
25 Orbit number I6
26 Eclipse Flag I2	0 - not in eclipse; 1 - in eclipse
27 Current    	1X,2PE11.4	Amperes
28 Voltage     	F6.1	in Volts
29 Shaft Angle  F7.2	in degrees
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+ Newly added parameters
* In preparing this data set from the original data the PI-recommended
  correction factors were applied to the ion density measurements:
     Species   AMU     Density was divided by 
	H+ 	1	2.67
	He+	4	1.61
	N+	14	1.72
	O+	16	1.26
	N2+	28	1.48
	NO+	30	1.48
	O2+	32	1.48