**NSSDCA ID:** PSFP-00580

**Availability:** Archived at NSSDC, accessible from elsewhere

**Time span:** 1989-08-22 to 1989-08-29

This description was generated automatically using input from the Planetary Data System.

Data Set Overview ================= This data set includes data from the Low Field Magnetometer (LFM) during the inbound Neptune encounter beginning in the solar wind and continuing until the first magnetopause crossing. The magnetometer are given in Heliographic coordinates and the data have been averaged from the resample 9.6 second sample rate to a 48.0 second rate. The dataset consists of the following columns: 1) ctime (decimal seconds since 1966-01-01T00:00:00.000), 2) pdstime (ISO standard time format), 3-5) spacecraft clock (m65536,m60,fds-line), 6) magnetometer id (1 = LFM, 2 = HFM), 7), Br (radial component), 8) Bt (tangential component), 9) Bn (normal component), 10) Bmag (magnitude of the average components), 11) avg_Bmag (average of the magnitude of the raw components), 12) Lambda (longitude = tan^-1(Bt/Br)), 13) Delta (latitude = sin^-1(Bn/avg_Bmag) ), 14-16) rms vector (Pythagorean root mean square deviation of the component averages), 17) npts (number of points in average), 18) flag a character string which indicates software or s/c hardware intervention which reduces confidence in the data (NULL flags represent 'good' data). Parameters ========== Derived Parameters -----------------Sampling Parameter Name : time Sampling Parameter Resolution : 0.06 seconds Minimum Sampling Parameter : 0.06 seconds Maximum Sampling Parameter : 0.06 seconds Sampling Parameter Interval : 48.0 seconds Minimum Available Sampling Interval : 48.0 seconds Data Set Parameter Name : magnetic field vector Noise Level : 0.006 nT Data Set Parameter Unit : nanotesla Magentic field vector: A derived parameter which combines the 3 orthogonal magnetic field component measurements. Measured Parameters ------------------Magentic field component: A measured parameter equaling the magnetic field strength (e.g. in nanoteslas) along a particular axis direction. Usually the three orthogonal axis components are measured by three different sensors. Ancillary Data ============== An ancillary data file containing the derived spacecraft magnetic field is provided with this data at a 48 second sample rate. These data provide zero level offsets used in the data processing. S/C field data is provided in spacecraft coordinates. Coordinate System ================= Mean Inertial Heliographic 1950 (HG) Coordinates -----------------------------------------------COORDINATE_SYSTEM_CENTER_NAME : SUN COORDINATE_SYSTEM_REFERENCE_EPOCH : UNK /* 09-23-1950 */ The Heliographic coordinate system is defined in the reference epoch of 1950. The unit vectors which define the coordinate system are as follows: X points away from the Sun towards the ascending node, in the solar equatorial plane, Z points along the Sun's spin axis, positive above the equatorial plane, and Y completes the right handed set. Position is given in terms of the following: RANGE (R) - The range or R component of the spherical Heliographic coordinate system is the distance from the Sun's position at the reference epoch to the spacecraft measured in AU. LATITUDE (LAT) - The latitude component of the spherical Heliographic coordinate system is the angle between the solar equatorial plane of the reference epoch measured in the plane that contains the solar spin axis of that epoch. LONGITUDE (LONG) - The longitude component of the spherical Heliographic coordinate system is zero in the direction of the ascending node at the reference epoch (X direction) and increases for a body orbiting the Sun as the Earth does. X - The X component of the Heliographic coordinate system points away from the Sun, towards the ascending node, and lies in the solar equatorial plane. Y - The Y vector of the Heliographic coordinate system is formed by the righthanded cross product of the X and Z unit vectors. It lies in the solar equatorial plane and it points away from the Sun, but does not extend in the direction of any particular body. Z - The Z component of the Heliographic coordinate system is parallel to the Sun's spin axis, taken as positive above the equatorial plane of the Sun.

These data are available on-line from the Planetary Data System (PDS) at:

https://pds-ppi.igpp.ucla.edu/data/VG2-N-MAG-4-SUMM-HGCOORDS-48SEC-V1.0/

- VG2-N-MAG-4-SUMM-HGCOORDS-48SEC-V1.0

- Planetary Science: Fields and Particles

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

Name | Role | Original Affiliation | |
---|---|---|---|

Dr. Norman F. Ness | Data Provider | University of Delaware | |

Dr. John E. P. Connerney | General Contact | NASA Goddard Space Flight Center | jec@lepjec.gsfc.nasa.gov |