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Data Access
FTPS from SPDF (not with most browsers)
HTTPS from SPDF
Helios 2 Hourly Trajectory Data
ResourceID
spase://NASA/NumericalData/Helios2/Ephemeris/PT1H
Description
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.
Metadata Rights
CC0-1.0:
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available SPASE metadata descriptions. The actual data/software may be subject to a different license.
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Details
Version:2.7.1
NumericalData
ResourceID
spase://NASA/NumericalData/Helios2/Ephemeris/PT1H
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
Helios 2 Hourly Trajectory Data
ReleaseDate
2026-07-21 12:05:04Z
RevisionHistory
RevisionEvent
ReleaseDate
2021-03-11 18:39:11Z
Note
Only known prior ReleaseDate of the metadata
RevisionEvent
ReleaseDate
2025-12-04 13:29:21Z
Note
Added MetadataRightsList and RightsList(s). Added ResourceType and NamingAuthority. Updated to 2.7.1. ZCB
RevisionEvent
ReleaseDate
2026-07-21 12:05:04Z
Note
Added HelioData InformationURL. JWL
Description
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.
Acknowledgement
Please acknowledge the National Space Science Data Center(NSSDC).
Contacts
Role
Person
StartDate
StopDate
Note
1.
MetadataContact
spase://SMWG/Person/Jan.Merka
InformationURL
Name
Readme file at SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/helios/helios2/traj/hour/he2trjhr_fmt.txt
InformationURL
Name
HelioData
URL
https://helio.data.nasa.gov/dataset/Helios2_Ephemeris_PT1H
Description
The HelioData dataset page provides an overview of the dataset with access links, associated variables, and more.
PriorIDs
spase://VSPO/NumericalData/P_HELIOS2_HDR_EPHEMERIS_1HR
spase://VSPO/NumericalData/Helios2/Ephemeris/PT1H
AccessInformation
RepositoryID
spase://SMWG/Repository/NASA/GSFC/SPDF
Availability
Online
AccessRights
Open
RightsList
Rights
SchemeURI
https://spdx.org/licenses/
RightsIdentifierScheme
SPDX
RightsIdentifier
CC0-1.0
RightsURI
https://spdx.org/licenses/CC0-1.0.html
RightsName
Creative Commons Zero v1.0 Universal
Note
CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products
AccessURL
Name
FTPS from SPDF (not with most browsers)
URL
ftps://spdf.gsfc.nasa.gov/pub/data/helios/helios2/traj/hour/
Description
Via ftp in ASCII from SPDF
AccessURL
Name
HTTPS from SPDF
URL
https://spdf.gsfc.nasa.gov/pub/data/helios/helios2/traj/hour/
Description
In CDF via HTTP from SPDF
Format
Text
Encoding
ASCII
InstrumentIDs
spase://SMWG/Instrument/Helios2/Ephemeris
MeasurementType
Ephemeris
TemporalDescription
TimeSpan
StartDate
1976-01-15 00:00:00.000Z
StopDate
1980-03-04 00:00:00.000Z
Cadence
PT1H
ObservedRegion
Heliosphere.Inner