NSSDC Makes IMP 8 LANL Plasma Data Uniform

Volume 15, Number 4, December 1999


By Joseph King and Natalia Papitashvili


For many years NSSDC has offered electronic access through the Space Physics Catalog (SPyCAT) to two sets of solar wind plasma parameter data from the Los Alamos National Laboratory (LANL) electrostatic analyzer on the Interplanetary Monitoring Platform (IMP) 8 spacecraft. These are called LANL16 and LANL19 and covered the intervals 1973-1986 and 1986-current, respectively. The numbers 16 and 19 reflect the numbers of data words per two-minute data record. The difference of three was because in the early years of data preparation at LANL spacecraft position information was not included, in part because IMP moves very little in two minutes. The judgement was that such information was otherwise accessible with sufficient convenience.

As the result of interactions between Principal Investigator Dr. Jack Gosling and NSSDC in the late 1980s, it was determined that adding the spacecraft position information to the plasma data records would be worth the effort. So data past April 1986 started arriving at NSSDC with three extra words per record.

When these data were first made network-accessible through SPyCAT and the NASA Data Archive and Distribution Service (NDADS) some years ago, the 16-word and 19-word versions were made accessible for their respective coverage periods. While NSSDC never received any complaints about this duality, NSSDC judged that it would be user-ineffective for the long term. Accordingly, in anticipation of the migration of data from the NDADS near-line environment to a magnetic disk-based on-line environment, NSSDC added IMP position information to the 1973-1986 data records, thereby creating a single uniformly formatted set of LANL solar wind plasma data. Each record now has time, location, and proton and alpha particle flow speed, direction, density, and temperature information.

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Author:Miranda Beall
Curator:Lori Persichitti
Responsible Official: Dr. Joseph H. King, Code 633
Last Revised: 15 MARCH 2000 [LAP]