AKEBONO RDM SDB DATA DESCRIPTION ================================ 'readme.rdm' version 1.3 http://www.darts.isas.ac.jp/akbn/readme/readme.rdm.txt initial version written by Takagi revised on Jul. 07, 2000 by Sessai ------------------------------------------------------------------------------ Welcome to the AKEBONO RDM Science Data Base! RDM (Radiation Monitor) on AKEBONO consists of HPM (High energy particle monitor) and RIC (monitor for Radiation effect on IC). RDM data files here on this SDB(Science Data Base) are summary files for HPM data. This is a brief description for them. HPM observes fluxes of electrons in three energy channels, protons in three energy channels and alpha particles in one energy channel. --------------------------------------- channel particle energy range name --------------------------------------- E1 electron > 2.5MeV E2 electron 0.95 - 2.5MeV E3 electron 0.3 - 0.95MeV P1 proton 29 - 62MeV P2 proton 15 - 29MeV P3 proton 6.3 - 15MeV AA alpha 16 - 52MeV --------------------------------------- 1. FILE NAME Each RDM SDB file has its file name, YYMMDDHH.rdm where YY: 2-digit year, MM: month, DD: day of month, HH: hour which indicates the start time of each observation in UTC. Each file contains RDM data for 3 hours or less. 2. FILE STRUCTURE Each file consists of a header and data blocks. The header size and each data block size are both 631 bytes. a header (631bytes) 1st data block (631bytes) 2nd data block (631bytes) ... M'th data block (631bytes) ... 3. HEADER FORMAT(631bytes) ------------------------------------------------------------ byte position | contents ------------------------------------------------------------ 1 - 12 | YYMMDDhhmmss (start date and time in ASCII) 13 - 16 | 4bytes of NULL 17 - 19 | 'RDM' (3 characters in ASCII) 20 - 631 | all NULL ------------------------------------------------------------ 4. DATA BLOCK FORMAT(631bytes) Each data block contains 15 sets of counting rates. --------------------------------------------------- byte position | contents --------------------------------------------------- 1 | start time of the data block (**1) 2 - 43 | 1st data sets(42bytes) 44 - 85 | 2nd data sets(42bytes) ... | ... | N'th data sets ... | ... 590 - 631 | 15th data sets(42bytes) --------------------------------------------------- (**1) The start time of each data block is indicated by the following: (start time of data block) = (start time in the header block) + (1st byte integer of data block) * 120 seconds 5. DATA SETS Each data set has 21 values. These values are counting rates of 7 particle channels that are further divided by pitch angle range; 45, 90, 135 degrees. Each value is expressed with 2 bytes integer (**2,**3). --------------------------------------------------- data position channel name pitch angle --------------------------------------------------- 1st E1 45 deg. 2nd E1 90 deg. 3rd E1 135 deg. 4th - 6th E2 45, 90, 135 deg. 7th - 8th E3 45, 90, 135 deg. 9th - 12th P1 45, 90, 135 deg. 13th - 15th P2 45, 90, 135 deg. 16th - 18th P3 45, 90, 135 deg. 19th - 21th AA 45, 90, 135 deg. --------------------------------------------------- (**2) Byte order is "little endian", i.e. "lower byte, first", compatible with intel CPUs(e.g. Linux on x86 and Windows). If you read them on "big endian" platforms, you have to swap them! (**3) Missing data items are indicated by 0xFFFF. Flux can be obtained by multiplying the following conversion factors. --------------------------------------------------- channel conversion unit name factor --------------------------------------------------- E1 43.5 /cm2/sec/sr E2 28.1 /cm2/sec/sr/MeV E3 66.9 /cm2/sec/sr/MeV P1 1.32 /cm2/sec/sr/MeV P2 3.11 /cm2/sec/sr/MeV P3 5.00 /cm2/sec/sr/MeV AA 0.146 /cm2/sec/sr/MeV --------------------------------------------------- 6. OBSERVATION TIME The observation time period of values in N'th data set of M'th data block is indicated by the following. From (start time of data block) + (8sec.) * ( N - 1 ) - (4sec.) To (start time of data block) + (8sec.) * ( N - 1 ) + (4sec.) 7. INFORMATION If you have any problem in the data or need any further information, please let us know. Akira Sessai Yukimatu Upper Atmosphere Physics Group, National Institute of Polar Research (NIPR) 1-9-10, Kaga, Itabasi, Tokyo 173-8515, Japan fax : +81-3-3962-5742 Tsugunobu Nagai Earth and Planetary Sciences Tokyo Institute of Technology Tokyo 152-8551, Japan fax : +81-3-5734-3537 email to both above: akebono-rdm@uap.nipr.ac.jp 8. REFERENCES 1. S.Takagi, T.Nakamura, T.Kohno, N.Shiono, K.Hayashi, F.Makino, "Observation of Particle Flux and Damage on IC Devices in the Radiation Belt with AKEBONO Satellite", The Institute of Space and Astronautical Science Report, No.75, The Institute of Space and Astronautical Science, 1992 (in Japanese) 2. S.Takagi, T.Nakamura, T.Kohno, F.Makino, "Flux Distribution and Modulation of Charged Particles in the Radiation Belt Observed with AKEBONO", The Institute of Space and Astronautical Science Report, No.80, The Institute of Space and Astronautical Science, 1995 (in Japanese) 3. S.Takagi, T.Nakamura, T.Kohno, N.Shiono, F.Makino, "Observation of Space Radiation Environment with EXOS-D", IEEE Trans. Nucl. Sci., NS-40,pp.1491-1497(1993) ------------------------------------------------------------------------------