Ulysses Cospin - Cosmic Ray and Solar Particle Investigation Bundle Ulysses Jupiter Encounter Cospin Anisotropy Telescope (AT) Data Description PDS3 DATA_SET_ID = ULY-J-COSPIN-AT-4-FLUX-256SEC-V1.0 ORIGINAL DATA_SET_NAME = ULY JUP COSPIN ANISOTROPY TELESCOPE 25 SEC. PARTICLE FLUX START_TIME = 1992-01-25T00:02:08.000 STOP_TIME = 1992-02-17T23:55:44.000 PDS3 DATA_SET_RELEASE_DATE = 1998-05-01 PRODUCER_FULL_NAME = ROBERT J. HYNDS DATA DESCRIPTION ================ Data Overview ============= The Imperial College Anisotropy Telescope ----------------------------------------- (Last updated: 17 March 1995) This document describes the Anisotropy Telescopes, the data they provide, and the format of the data files provided by Imperial College to the Ulysses Data System. NB. Please take careful note of the following points: (1) The Anisotropy Telescope pointing directions were given incorrectly in the Astronomy and Astrophysics paper, and the energy channel widths quoted there have since been updated. (2) See the Ulysses Data System guidelines for restrictions on the use of this data. 1. The Anisotropy Telescopes ---------------------------- The Anisotropy Telescope (AT) experiment is a two-telescope device. The telescopes are nominally identical with Telescope T1 pointing at 60 degrees to the spacecraft spin axis (i.e. in the Earthward looking hemisphere) and telescope T2 pointing at 145 degrees (i.e. in the anti-Earthward looking hemisphere). They have a full-cone opening aperture of 70 degrees and a geometric factor of 0.7 cm^2 sr. Together they provide 80% coverage of the full sky. The most significant gap in the coverage is a cone with a half angle of 25 degrees centered on the Earthward pointing line along the spacecraft spin-axis. There is also a 5 degree gap in coverage between the two telescopes. 2. The full AT Bundle ----------------------- Spin-averaged and sectored data in a variety of energy channels is produced by the ATs, as follows: Channel Energy range Energy Range Sectored / number /MeV (protons) /MeV (alphas) Spin-averaged 1 0.7 - 0.9 2.3 - 2.5 Spin-averaged 2 0.9 - 1.3 2.5 - 2.7 Spin-averaged 3 1.3 - 2.2 2.7 - 3.0 Spin-averaged 4 2.2 - 3.6 - Spin-averaged 5 3.6 - 6.5 24.0 - 28.0 Spin-averaged 6 0.7 - 1.3 2.3 - 2.7 Sectored (8) 7 1.3 - 2.2 2.7 - 3.0 Sectored (8) 8 2.2 - 3.6 - Sectored (8) 9 3.6 - 6.5 24.0 - 28.0 Sectored (8) 10 - 3.0 - 7.5 Spin-averaged 11 - 7.5 - 12.0 Spin-averaged 12 - 12.0 - 26.0 Spin-averaged 13 - 3.0 - 7.5 Sectored (4) 3. AT data provided to the Ulysses Data System ---------------------------------------------- The AT data provided in these files is a subset of the total bundle which is held at Imperial College. The format of these files is as follows: There is one data file per day. Each data file contains data records for every ten minute interval in the day, except during the Jupiter encounter (1992, days 25 to 48 inclusive) where data at 256s resolution is provided. Each record contains 17 fields of information, the first being a time-stamp referring to the centre time of the data contained in the remaining 16 fields. The definition of these fields, including their FORTRAN format, is given below. N.B. Fluxes quoted are from telescope T1, which points at 60 degrees to the spacecraft spin axis. Field FORTRAN Definition Format 1 a24 Time in format yyyy-mm-ddThh:mm:ss.sssZ 2 1pe10.4 Flux from channel 1 3 1pe10.4 Flux from channel 2 4 1pe10.4 Flux from channel 3 5 1pe10.4 Flux from channel 4 6 1pe10.4 Flux from channel 5 7 1pe10.4 Flux from channel 10 8 1pe10.4 Flux from channel 11 9 1pe10.4 Flux from channel 12 10 1pe10.4 Flux from channel 7, sector 1 11 1pe10.4 Flux from channel 7, sector 2 12 1pe10.4 Flux from channel 7, sector 3 13 1pe10.4 Flux from channel 7, sector 4 14 1pe10.4 Flux from channel 7, sector 5 15 1pe10.4 Flux from channel 7, sector 6 16 1pe10.4 Flux from channel 7, sector 7 17 1pe10.4 Flux from channel 7, sector 8 Each record can be read using the FORTRAN format '(i4,4(1x,i2),1x,f6.3,16(1x,1pe10.4))' or 1x,a24,16(1x,1pe10.4) [please note that time-stamp and record format have been changed by the PDS/PPI Node for the sake of consistency with other data collections found on this volume] 3.1 Definition of flux ---------------------- in this table, flux means differential flux in units of (cm^2 sr s MeV)^-1 (NB. per MeV, not per MeV per nucleon). The fluxes have been computed by dividing the observed count rates by the geometric factor and the energy channel width. The energy channel width depends on species. Where a channel is sensitive to alpha particles and protons (i.e., channels 1, 2, 3, 5, 6, 7 and 9), the proton width has been used since normally the alpha contribution is insignificant. However, sufficient information has been given above to reconstruct the channel count-rates if necessary. All AT channels exhibit a 'background' which may originate from electronic noise or from activation of the material of the telescopes or of the spacecraft. These background fluxes have been subtracted from the data provided in these files. Channel 3 and channel 7 are the channels least affected by background and it is for this reason that channel 7 has been selected to provide the sectored data included in these files. The data have also been 'despiked', although it is not guaranteed that all spikes have been removed. 3.2 Definition of sectors ------------------------- All sectored channels except channel 13 have eight 45 degree sectors. Channel 13 has only 4 sectors. Sector 1 of channel 13 is a 90 degree sector equivalent to sectors 1 & 2 of any of the other sectored channels. Similarly, sector 2 of channel 13 is equivalent to sectors 3 & 4 of any other sectored channel, etc. The sectoring scheme is defined relative to the 'sun crossing line'. The sun-crossing line is the line in the plane defined by the Sun, the Earth and Ulysses, which is perpendicular to the Ulysses-Earth line and which makes an angle of less than 90 degrees to the Ulysses-Sun line. For channels with 8 sectors, sector 1 is the 45 degree sector which starts from the sun-crossing line and extends in the sense of spacecraft rotation. Sector 2 begins at the angle that sector 1 ends and continues in the sense of spacecraft rotation, etc, continuing through to sector 8 which ends at the the sun-crossing line. References: ======== Cowley, S.W.H., and K. Staines, Ulysses Observations of Antisunward Flow on Jovian Polar Cap Field Lines, Planet. Space Sci, 41(11/12), 987, 1993. (https://doi.org/10.1016/0032-0633(93)90103-9) Simpson, J.A., J.D. Anglin, A. Balogh, M. Bercovitch, J.M. Bouman, E.E. Budzinski, J.R. Burrows, R. Carvell, J.J. Connell, R. Ducros, P. Ferrando, J. Firth, M. Garcia-Munoz, J. Henrion, R.J. Hynds, B. Iwers, R. Jacquet, H. Kunow, G. Lentz, R.G. Marsden, R.B. McKibben, R. Mueller-Mellin, D.E. Page, M. Perkins, A. Raviart, T.R. Sanderson, H. Sierks, L. Treguer, A.J. Tuzzolino, K.-P. Wenzel, and G. Wibberenz, The Ulysses cosmic ray and solar particle investigation, Astron. Astrophys. Suppl. Set: 92, 365-399, 1992. Staines, K., A. Balogh, S.W.H. Cowley, R.J. Forsyth, T.M. Edwards, and R.J. Hynds, Ulysses Observations of Non- Corotational Flows in the Outer Dayside Jovian Magnetosphere, Planet. Space Sci, 41(11/12), 927, 1993. (https://doi.org/10.1016/0032-0633(93)90098-M) Staines, K., A. Balogh, S.W.H. Cowley, T.M Edwards, R.J. Forsyth, R.J. Hynds, and N.F. Laxton, An Overview of the Anisotropy Telescope Observations of MeV Ions During the Ulysses Jupiter Encounter, Planet. Space Sci., 44, 341-369, 1996. (https://doi.org/10.1016/0032-0633(95)00131-X)