IMFV1.23 INTERMAGNET GIN Dissemination Format for Minute Values

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Magnetic data, with tenth-nanotesla resolution, are organized on a day file basis. One file contains 24 one-hour blocks, each containing 60 minutes worth of values. Blocks of 60 minutes of data are transmitted. Blocks are padded with 9's if incomplete. Information is coded in ASCII.

File name: To remain compatible with all operating systems, the file name is limited to 8 characters and will contain the date and the three-letter code as an extension. eg: MAR1591.BOU for Boulder, March 15, 1991; and JUN2391.OTT for June 23, 1991 at Ottawa.

Description of the block header (64 characters including CrLf)


Description of the block header
Parameter Description
IDC Indicates the IAGA three letter observatory identification(ID) code eg: BOU for Boulder, OTT for Ottawa, LER for Lerwick, etc.
DDDDDDD Indicates the date, eg: FEB1591 for February 15, 1991.
DOY Indicates day of the year (1-366)
HH Indicates the Hour (0-23). The first line following the header will contain the values corresponding to minute 0 and 1 of this hour. The first value of the day file is hour 0 minute 0.
COMP Order in which the components are listed, can be HDZF, XYZF. All components excluding D must be in tenths of nT. D must be in hundredths of minutes, east.
T One-letter code for data type. R=Reported, A=Adjusted, D=Definitive data.
  • Reported data are defined as: the raw data obtained from the IMO, either by satellite, computer link, or other means. It will be formatted in either version IMFV2.8N (binary) or IMFV1.2N (ASCII,) without any BRM (Baseline Reference Measurements), or other modifications applied to it.
  • Adjusted data are defined as: the Reported data with BRM, spike removal, timeshifts, and/or other modifications applied to it. It is emphasized that only one (1) adjusted version of the data would be allowed, to be completed within 7 days of receipt of the Reported data to prevent the proliferation of multiple versions of the Adjusted data.
  • Quasi-definitive data are defined as data that have been corrected using provisional baselines. Produced soon after their acquisition, their accuracy is intended to be very close to that of an observatory's definitive data product. 98% of the differences between quasi-definitive and definitive data (X, Y, Z) monthly mean values should be less than 5nT.
  • Definitive data are defined as the final adopted data values. Definitive data will only be distributed by the institution responsible for the observatory.
GIN Three-letter code for GIN responsible for processing the station (IMO) data eg: EDI(Edinburgh), GOL(Golden), OTT(Ottawa), PAR(Paris).
COLALONG Colatitude and east longitude of the observatory in tenths of degrees.
DECBAS Baseline declination value in tenths of minutes East (0-216,000). Declination baseline values to be provided annually. If components are X,Y,Z then DECBAS=000000.
RRR..RRR Reserved 16 bytes of R-characters for future use.
_ Indicates a space character.
CrLf ndicates a Carriage return, Line feed.

Description of data space (64 characters per line including CrLf)

Component values are coded as signed integers, right-justified with a field width of 7. Total field (F) values are coded as unsigned integers, right-justified with a field width of 6. The field widths must be maintained, either through zero-filling or space-filling. The '+' sign for positive values is optional.

Two (2) minutes of data are concatenated on the same line


Description of data space
Parameter Description
AAAAAAA Indicates Component 1 data field (H,X, etc.).
BBBBBBB Indicates Component 2 data field (D,Y, etc.).
CCCCCCC Indicates Component 3 data field (Z,I, etc.).
FFFFFFF Indicates Total Field data field.
_ Indicates space character.
CrLf Indicates Carriage Return and Line Feed.