IAGA format
Format for one-minute and more dense values. Number of characters are marked in bold-face.
- Record length 4 [1440]
- Length of one record 3 [in minutes]
- Type of data 2 [00 = observatory; 01 = temporary station]
- Station identification 6 [e.g. 3 numbers, 3 letters]
- Geographic latitude 5 [in 0.01o (space or sign and 4 numbers)]
- Geographic longitude 5 [in 0.01oE]
- Free 23
- Year 4
- Month 2
- Day 2
- Hour 2 [00...23 UT]
- Minute 2 [00...59. The first minute of the record]
- Interval between datapoints 2 [in seconds]
- How produced 1 [0 = digital recording; 1 = digitized from primary recordings; 2 = digitized from supplementary recording; 9 = unknown]
- Filter breakpoint 4 [0000 if values are means between datapoints. Otherwize period in seconds at which low pass filter is 3 db down (0.7 amplitude). 9999 if no filtering was employed.]
- Filter slope 2 [Number of db per octave, i.e. 6, 12, 18 db/octave or measured equivalent for numerical filter.]
- Base line information 1 [1 = final data, absolute base line, accuracy about 1 nT; 2 = final data but no absolute measurements; 3 = preliminary data; 4 = data relative to quiet day night values.]
- Probable base line change 2 [in 0.1 nT within one day]
- Components 1 [1 = X ,Y, Z; 2 = H, D (0.1), Z; 3 = A, B, Z]
- Character of the day 1 [0 = normal; 1 = one of the 5 international quietest days; 2 = one of the 5 international disturbed days]
- Free 85
- X1, Y1, Z1,...,X60, Y60, Z60 7x180 [in 0.1 nT (0.1' if D). The first character from left is the sign, which is minus or, for positive values, space. Missing = 999999.]
- Hourly mean of X 7 [000000 if not the last part of the hour]
- Hourly mean of Y 7 [as above]
- Hourly mean of Z 7 [as above]
Time definition
The value of the interval is its mean. For example, the value of the first minute of an hour is the mean value from XXh00m00s to XXh01m00s, etc. However, the practice is not standard everywhere, but centred mean values are also used. Then the value of the second minute of an hour is the mean value from XXh00m30s to XXh01m30s, etc. The first convention is used for EISCAT and IMAGE data.
One record contains 1440 characters. For merged tapes the stations follow each other by record. Leading zeros have to be used for too long fields. One record = one hour of one-minute values. The code used: ASCII.