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The responsibility for the production of this data set is with Dr. Rainer Schwenn and Kevin Ivory (MPAe). Parts of the data may be different or missing (compared to other data sets), due to various processing routines used over the years.
Katlenburg-Lindau, January 22, 1996
Max-Planck-Institut fuer Aeronmomie (MPAe) Max-Planck-Strasse 2 D-37191 Katlenburg-Lindau GERMANY
HELIOSCD
|
+---- BIN -- HELIOS1 contains binary data files
| +------ HELIOS2
|
+---- DOC contains documentation on directory and
| file structures on the CD-ROM
|
+---- PROG contains Fortran programs (used to generate
| the files and usable to read the binary files)
|
+---- TAB -- HELIOS1 contains table data files (ASCII text)
+------ HELIOS2
All files were created on a DEC Alpha system running under DEC Unix.
That means that the binary data is stored in little-endian IEEE
format and the ASCII data is stored with LF denoting the end-of-line.
For systems that denote the end-of-line with CRLF, the GNU free
software program 'recode' can be used to transform the notation.
The CD-ROM was written in accordance to the ISO 9660 filesystem standard
with Rock Ridge extension attributes.
We were able to successfully read all files from the CD-ROM with the operating systems DEC Unix, OpenVMS and MS-DOS/Windows. On each of these systems we were also successful in reading the binary files with Fortran programs.
Some operating system dependent hints:
CRLF.COM or RECODE.EXE).
tab directory of this CD-ROM.
If no data is available for a particular day, there is no file for
that day. The files are named something like h178_058.tab,
where h1 or h2 stands for the spacecraft
Helios 1 or Helios 2, 78 stands for the year 1978,
followed by a single underline and the day of year written
with three digits. Each file has the extension .tab.
The files were created on DEC Alpha system running under DEC Unix
with the Fortran program cd_tab (cd_tab.f)
supplied in prog directory of the CD-ROM. They are in ASCII
text format and the end of line is denoted by LF
(for DOS/Windows systems convert to CRLF).
Each file begins with two comment lines (the first 8 characters of the first line give year and day of year of the following lines). Each data spectrum is stored in a 159 byte (=column) record (plus LF) of the following format:
Column Format Type Parameter 1- 2 i2 INTEGER hour (time format: hh:mm:ss) 4- 5 i2 INTEGER minute 7- 8 i2 INTEGER second 9- 13 f5.2 REAL heliocentric distance of s/c [AU] 14- 20 f7.2 REAL earth-sun-s/c angle [deg] 21- 27 f7.2 REAL Carrington longitude of s/c [deg] 28- 33 f6.2 REAL Carrington latitude of s/c [deg] 34- 38 i5 INTEGER Carrington rotation # 39- 45 f7.2 REAL I1A proton density [cm-3] 46- 53 f8.1 REAL I1A proton velocity [km/s] 54- 61 f8.0 REAL I1A proton temperature [K] 62- 67 f6.2 REAL I1A proton azimuthal flow angle [deg] 68- 73 f6.2 REAL I1A proton elevational flow angle [deg] 74- 80 f7.2 REAL E2 magnetic field, Bx [nT] 81- 87 f7.2 REAL E2 magnetic field, By [nT] 88- 94 f7.2 REAL E2 magnetic field, Bz [nT] 95- 99 f5.2 REAL E2 magnetic field, sigma Bx [nT] 100-104 f5.2 REAL E2 magnetic field, sigma By [nT] 105-109 f5.2 REAL E2 magnetic field, sigma Bz [nT] 110-115 f6.2 REAL I1A alpha density [cm-3] 116-121 f6.1 REAL I1A alpha velocity [km/s] 122-129 f8.0 REAL I1A alpha temperature [K] 130-135 f6.2 REAL I1B proton density [cm-3] 136-141 f6.1 REAL I1B proton velocity [km/s] 142-149 f8.0 REAL I1B proton temperature [K]Missing plasma parameters have the value -1, missing magnetic data have the value 0.
With VMS, the CD-ROM will have to be mounted with an option specifying
stream records with a maximum of 159 bytes to successfully read/copy
the *.tab files:
$ MOUNT/MEDIA=CDROM/UNDEF=(STREAM_LF:159) device [volume] [logical]
(the volume-label is HELIOSCD)
bin directory of this CD-ROM.
If no data is available for a particular day, there is no file for
that day. The files are named something like h178_058.cd,
where h1 or h2 stands for the spacecraft
Helios 1 or Helios 2, 78 stands for the year 1978,
followed by a single underline and the day of year written
with three digits. Each file has the extension .cd.
The files were created on DEC Alpha system running under DEC Unix, which means that the binary data is stored in little-endian IEEE format. This is the same format used on systems based on the Intel x86-series and on Digital DECstations. On HP, Sun, IBM and other similar workstations, big-endian IEEE format is common, so byteswapping may be necessary with such systems.
Each data spectrum is stored in a 80 byte record of the following format (byte count starts with 1, bit counts start with 0):
Bytes (1-80) Type Parameter
1 - 4 INTEGER*4 datetime
Bits 0-30 datetime, seconds since Jan 1, 1964
time = MOD(datetime,86400) sec of day
date = datetime/86400 days since 010164
31 spacecraft (0: Helios 1, 1: Helios 2)
5 - 8 INTEGER*4 imode
Bits 0 I1A protons (0: available, 1: not)
1 I1A alphas (0: available, 1: not)
2 I1B protons (0: available, 1: not)
3 E2 magnetic field (0: available, 1: not)
4 I1B electrons (0: available, 1: not)
5 alternating shift (0: no, 1: yes)
6 perihel shift (0: no, 1: yes)
7 data mode (0: normal, 1: high)
8- 9 format (0: 5, 1: 1, 2: 2, 3: 3)
10-13 log2(bitrate) (3: 8, ... , 12: 4096)
14-15 unused
16 distribution mode 7 (0: no, 1: yes)
17-23 unused
24-31 Carrington rotation # - 1600
9 - 24 REAL*4 orbit(4) orbital parameters of the Helios s/c
array element 1 heliocentric distance of s/c [AU]
2 earth-sun-s/c angle [deg]
3 Carrington longitude of s/c [deg]
4 Carrington latitude of s/c [deg]
25 - 44 REAL*4 p_i1a(5) I1A proton parameters
array element 1 density [cm-3]
2 velocity [km/s]
3 temperature [K]
4 azimuthal flow angle [deg]
5 elevational flow angle [deg]
45 - 56 REAL*4 a_i1a(3) I1A alpha parameters
array element 1 density [cm-3]
2 velocity [km/s]
3 temperature [K]
57 - 68 REAL*4 p_i1b(3) I1B proton parameters
array element 1 density [cm-3]
2 velocity [km/s]
3 temperature [K]
69 - 80 INTEGER*2 m_e2(6) E2 magnetic field
array element 1 Bx [100 nT]
2 By [100 nT]
3 Bz [100 nT]
4 sigma Bx [100 nT]
5 sigma By [100 nT]
6 sigma Bz [100 nT]
Missing plasma parameters have the value -1, missing magnetic data
have the value 0.
The Fortran open statement may differ depending on the compiler and system used. If the record length has to be given in bytes, the open statement will be
OPEN (15, FILE='h178_058.cd', ACCESS='DIRECT', RECL=80,
& STATUS='OLD')
If the record length has to be given in words, the open statement will be
OPEN (15, FILE='h178_058.cd', ACCESS='DIRECT', RECL=20,
& STATUS='OLD')
With DEC Fortran for OpenVMS you may also have to use the option
CONVERT='LITTLE_ENDIAN'.
With VMS, the CD-ROM may either have to be mounted with an option specifying the fixed record length of 80 bytes:
$ MOUNT/MEDIA=CDROM/UNDEF=(FIXED:NONE:80) device [volume] [logical]
(the volume-label is HELIOSCD)
or with OpenVMS 6.0 or higher, the file attributes may be changed
later with the following command:
$ SET FILE/ATTRIBUTE=LRL:80 *.CD