spase://NASA/NumericalData/Helios2/Ephemeris/PT1H

This directory includes hourly heliocentric coordinate data for the Helios 1 spacecraft as extracted into the ASCII files HE1TRJyy.asc (yy is the two-digit year) from the merged solar wind magnetic and plasma data set in HELIOS_1/MGD_FREEMAN. All trajectory parameters except solar ecliptic and heliographic inertial coordinates were taken from the original merged dataset. The other parameters were computed and added using the code HELTRJCON in the MGD_FREEMAN directory. Source routines for coordinate conversions in this code were provided by R. Parthasarathy of the Satellite Situation Center at NSSDC. The code READHEL in MGD_FREEMAN was used to read the archived datasets into an intermediate format for input to HELTRJCON. Code HELTRJCN1 was used to correct the solar ecliptic angles as of 6/14/94 (see Note 2 above). HELTRJCON was also corrected as of this date. Data Parameter Description: NY - YEAR OF THE DATA INTERVAL (LAST TWO DIGITS ONLY). ND - DAY OF THE DATA INTERVAL FROM THE FIRST DAY OF THE ABOVE YEAR, JAN. 1= DAY 1. NH - HOUR OF THE DAY OF THE DATA INTERVAL. NCARROT - CARRINGTON ROTATION NUMBER AS SEEN BY AN EARTH BASED OBSERVER AT THE START OF THE DATA INTERVAL. SPAU - SPACECRAFT HELIOCENTRIC DISTANCE IN ASTRONOMICAL UNITS. SECLAT - SOLAR ECLIPTIC LATITUDE IN DEGREES SECLON - SOLAR ECLIPTIC LONGITUDE IN DEGREES HELLAT - SOLAR HELIOGRAPHIC LATITUDE IN DEGREES HELLON - SOLAR HELIOGRAPHIC (CARRINGTON) LONGITUDE IN DEGREES HILLON - SOLAR HELIOGRAPHIC INERTIAL LONGITUDE IN DEGREES WITH RESPECT TO ASCENDING NODE OF SOLAR EQUATOR ON THE ECLIPTIC ESSCSANG - EARTH-SUN-SPACECRAFT SEPARATION ANGLE (IN DEGREES, 0-360). ICODE - DATA CODE: 1 MEANS PLASMA DATA ONLY ARE PRESENT FOR THAT HOURLY INTERVAL; 2 MEANS MAGNETOMETER DATA ONLY; 3 MEANS BOTH PLASMA AND MAGNETOMETER DATA PRESENT. Note 1: The solar ecliptic coordinates are given with respect to true equinox and ecliptic of date. The solar ascending node was located at ecliptic longitude +74.367 degrees as of 1 Jan. 1900 at 1200 UT; this longitude increases by 1.4 degrees/century. Note 2: The solar ecliptic cordinates in this directory before 6/14/94 were calculated incorrectly and have been corrected as of this date. The heliographic angles are from the original source dataset and had no problems.