Data Set Overview : This data set contains Voyager 1 and 2 measurements of the brightness of Jupiter at H Lyman alpha and in the H2 Lyman and Werner bands shortward of H Lyman alpha. Pointing has been corrected by the C-Smithing process, and these data were derived from the pre-encounter North-South Map sequences. In this sequence, the UVS field of view was located near the central meridian of the planet. The field of view stepped slowly from north to south, and then rapidly repositioned to the north. These scans were repeated until all Jovian longitudes had been sampled. Coverage in longitude was not continuous in time. Rather, some longitude ranges were covered on the preceding or following rotation of Jupiter.  The brightnesses represent integrals over the appropriate passband that have been computed from the full spectrum. The spectra were binned by Flight Data System (FDS) count, so that each record contains the data from one 48-second frame. Because the motion of the scan platform was synchronized with FDS count, each record corresponds to a single pointing position on Jupiter. The first two spectra of each FDS count have been excluded, because the scan platform was moving during those times. In some cases (e.g. during the flyback slews to prepare for another N/S scan) all spectra were flagged with bad pointing status, and no spectra appear in the output bin. The data in each time bin was normalized by dividing by the number of spectra binned, so that the spectra represent counts per 3.84 second interval (the integration time in the GS-3 data mode used for most of the encounter sequences). The final processing step in the spectral analysis stage was a correction for fixed pattern noise (flat fielding).  The brightnesses were computed by summing over the appropriate wavelength channels. These are:  Voyager 1 Emission channel range wavelength range (A) H2 bands 43 - 58 924 - 1072 H Lyman alpha 70 - 78 1174 - 1257  Voyager 2 Emission channel range wavelength range (A) H2 bands 45 - 60 921 - 1069 H Lyman alpha 72 - 80 1171 - 1254  The brightnesses were corrected for dark counts, which arise mainly from the Jovian radiation environment. Because the radiation-induced dark count rate depends rather sensitively on the magnetic latitude of the spacecraft, and hence on time, this correction is made on a spectrum-by-spectrum basis. For the H Lyman alpha emission, the procedure also compensates approximately for H2 band emissions that fall within the H Lyman alpha channel range. This correction procedure consists of subtracting the sum over suitably chosen background channels. These background channels are:  Voyager 1 Emission channel range wavelength range (A) H2 bands 23 - 38 739 - 887 H Lyman alpha 58 - 66 1063 - 1146  Voyager 2 Emission channel range wavelength range H2 bands 25 - 40 736 - 884 H Lyman alpha 60 - 68 1060 - 1143  Each record contains pointing information that consists of the latitude and System III longitude of the two ends of the slit (P2 and P8 points) and the center of the slit (P5 point) projected on Jupiter. In addition, each point has associated with it a status flag. A minus (-) means that the line of sight for the specified point intersects the planet. A plus (+) means that the line of sight is off the planet. In the latter case, the latitude and longitude refer to the point on the planet that is under the point of closest approach to the planet of the line of sight.  Each logical record corresponds to one FDS count, and consists of three lines in the data file. The quantities on each line are:  first line: Spacecraft Event Time, FDS count, S/C to Jupiter range.  second line: P2 latitude, P2 longitude, P5 latitude, P5 longitude, P8 latitude, P8 longitude, P2 status, P5 status, P8 status  third line: H Lyman alpha counts, H2 band counts.  For a detailed description of the data set contents, see [SANDELETAL1979; DESSLERETAL1981; and BROADFOOTETAL1981].   Parameters :  Voyager 1 Encounter Times ------------------------- Start Time : 1979-061/19:58:00 (1979-03-02) Stop Time : 1979-062/09:20:57 (1979-03-03)   Voyager 2 Encounter Times ------------------------- Start Time : 1979-187/11:52:11 (1979-07-07) Stop Time : 1979-188/05:16:05 (1979-07-08)   Data Set Parameter 'H LYMAN ALPHA BRIGHTNESS' --------------------------------------------- Data Set Parameter Name : H LYMAN ALPHA BRIGHTNESS Data Set Parameter Unit : COUNTS Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : 48 Maximum Sampling Parameter : 48 Sampling Parameter Resolution : 48 Sampling Parameter Interval : 48 Minimum Available Sampling Int : 48 Noise Level : UNK   Data Set Parameter 'H2 BAND BRIGHTNESS' --------------------------------------- Data Set Parameter Name : H2 BAND BRIGHTNESS Data Set Parameter Unit : COUNTS Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : 48 Maximum Sampling Parameter : 48 Sampling Parameter Resolution : 48 Sampling Parameter Interval : 48 Minimum Available Sampling Int : 48 Noise Level : UNK

Confidence Level Overview : Bad spectra resulting from telemetry noise and other effects have been omitted from this data set. Spectra acquired when the scan platform was in motion have also been omitted to reduce spatial smearing as much as possible. Some spatial smearing due to s/c limit cycle motions is unavoidable.  The pointing information for the data set was derived by the C-Smithing (image navigation) process at JPL. This improved pointing is believed to be the most accurate pointing information available.