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Mag Conj w/Vik-Sweden 3x80 Bins on Microfiche


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1986-03-01 to 1986-06-30


This data set provides times of magnetic field conjunctions for a specified lead spacecraft with one or more other spacecraft. The lead spacecraft data are entered in the first pair of lines, and the data for the other spacecraft are entered in the following pair of lines. As the lead spacecraft moves in its orbit, its magnetic field foot point is calculated every 1 min, in the same hemisphere in which its subsatellite point is located. At each minute, a rectangular bin of x deg in geographic latitude and y deg in longitude encloses the point. Typically, this will be 6 deg by 12 deg, but the adopted values are indicated in the file, after the command "MOVING." If the other spacecraft happened to have its foot point within this rectangle near that time, it will be accepted as a conjunction. The data for each spacecraft will then be written in a pair of lines, beginning with that of the lead spacecraft. If there was no conjunction at that bin, a new bin is constructed in the next minute and checked for conjunction. The first column, SATID, lists the spacecraft names. The next column, DDDHH.H, lists the day number, DDD, and decimal hour, HH.H of the lead spacecraft's entry into and exit from the bin. The column labeled SLAT/SLON provides the geograghic coordinates of the subsatellite points of the two spacecraft at those four instants. ALT> GEOID provides the altitudes of the spacecraft at those times, in kilometers. The geographic latitude and longitude of the center of the bin and then a pair of identical numbers, which are the lines of sight distance (in RE) between the two spacecraft at that instant, are listed under the GSEP label. The column ARCLEN lists the lengths of the magnetic field line (again, in RE) between the spacecraft and their field line foot points, at the pair of entry/exit times. The foot points are mapped into the same (north or south) hemisphere over which the lead spacecraft was on. Finally, corresponding to those pairs of times, the geographic latitudes and longitudes of the foot points of the field lines are listed under TLAT/TLON. The program allows a choice from a variety of internal and external field models. The chosen models are indicated just above the listing, under the letters IE. As is well known, the auroral and polar cap field lines are severly stretched into the tailward direction and eventually tend to reach out to the sun. (See, for instance, Planet. Space Sci., vol. 15, 917, 1967.) None of the available field models account for the phenomenon satisfactorily; accordingly, the magnetic field conjunctions may not be reliable enough if the foot points are listed to be in these regions; unless both the spacecraft happen to be in the same (north or south) hemisphere and at low (<6 RE) altitudes.

Alternate Names

  • Mag Conj w/Vik-Swed 3X80 Bns Fich


  • Ancillary: Ephemeris/Orbit/Attitude


  • 81-070A-00H
  • 81-070A-00I
  • 84-088A-00D
  • 84-088A-00E
  • 86-019B-00E
  • 86-019B-00F
  • 86-019B-00G
  • 86-019B-00H

Additional Information


Questions and comments about this data collection can be directed to: Coordinated Request and User Support Office



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