| DATA_SET_DESCRIPTION |
Data Set Overview
=================
The Ulysses spacecraft was occulted by the Io Plasma Torus
(IPT) during its Jupiter encounter on 8 February 1992. The
Ulysses dual-frequency radio subsystem used by the Ulysses
Solar Corona Experiment (SCE) was utilized to measure the
electron content (column density) of the IPT [BIRDETAL1992B].
In the nominal mode for radio-sounding observations
[BIRDETAL1992A], both downlinks (S-band: f_s = 2.3 GHz;
X-band: f_x = 8.4 GHz) are phase coherent with the uplink
(S-band: f_u = 2.1 GHz). The dual-frequency radio-sounding
technique exploits the dispersive nature of ionized media on
the propagation of the two downlinks. The tiny Doppler shift
due to plasma moving in and out of the ray path is greater at
S-band than at the higher frequency X-band.
The SCE data are obtained from the Radio Science Support group
at JPL. There are basically two types of data: Ranging and
Doppler (Frequency), recorded as a function of UT Ground
Received Time. The raw data are delivered in special binary
files called ATDFs (Archival Tracking Data Files), containing
Ranging and Doppler data from the standard DSN tracking
receivers. There are high-time resolution Doppler data from
special radio science receivers (so-called 'open loop' data)
as well. These are in files called ODRs (Original Data
Records).
ATDFs are files of radiometric data produced by the Network
Operations Control Center (NOCC) Navigation Subsystem (NAV).
They are derived from Intermediate Data Records by NAV and
contain all radiometric measurements received from the DSN
station including signal levels (`AGC' = automatic gain
control in dBm), antenna pointing angles, frequency (often
referred to simply as `Doppler'), range, and residuals.
Doppler data are often used to infer spacecraft radial motion
relative to the tracking antenna. Data values in ATDFs are
reported at rates no higher than 10 per second. For the
Ulysses Jupiter encounter the received frequencies at S-Band
and X-band were recorded at a sample time of one per second.
Each ATDF data record contains 117 parameters, stored in
records of 288 bytes. The ATDF is described in section
TRK-2-25 of the JPL Document 820-13 [DSN820-13].
The ATDFs have been analyzed for the Jupiter encounter and a
detailed report has been published [BIRDETAL1993]. Data
files have been generated which contain the Ranging and
Doppler data at various stages of processing. Stage #1 is
generally just stripping the Ranging/Doppler data from the
ATDFs. Stage #2 is to 'clean' the data files by weeding out
obviously bad data. Stage #3 is to produce a 'final data
set', a table of the measured data plus physically relevant
quantities as function of time.
Data
====
The following table gives an idea about the size and coverage
of the ranging data set:
Ulysses SCE Ranging data at Jupiter:
Stage# start stop ASCII size gzip size
doy:hh:mm doy:hh:mm (kB) (kB)
1 36:15:54 41:14:44 116 17
2 36:20:30 40:18:44 88 13
3 36:21:44 40:18:44 22 4
All stage #3 ranging data from the Ulysses Jupiter encounter
have been provided to this archive in the ALLRANGE directory.
No ranging data were taken during the Jupiter encounter pass
at DSS 43 on February 8, 1992. Here are the first few lines
of the ASCII table:
set no dss doy:hh:mm:ss difrng econt
1 1 61 36:21:44:24 6 22
1 2 61 36:21:54:24 53 210
1 3 61 36:22: 4:24 16 62
1 4 61 36:22:14:25 38 150
1 5 61 36:22:44:24 67 266
1 6 61 36:23: 4:24 47 186
1 7 61 36:23:14:24 27 106
1 8 61 36:23:24:24 60 238
1 9 61 36:23:34:24 56 222
where:
set = running number for each DSN tracking pass during
Jupiter encounter
no = running number for range measurement within each
tracking pass
dss = DSN station number
doy = Day of year in 1992
hh:mm:ss = hours, minutes seconds (UT, ground received)
difrng = differential range delay in `range units' [DSN810-5]
econt = electron content in `hexems' [BIRDETAL1992B]
|
.png)
.png)
