PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM RELEASE_ID = 0001 REVISION_ID = 0000 OBJECT = TEXT PUBLICATION_DATE = 2007-05-31 NOTE = "Description of the CALIB directory contents for an ASPERA-3 release." END_OBJECT = TEXT END CALIB Directory Contents The CALIB directory contains calibration tables for a MEX ASPERA-3 archive volume. The files listed below are found in this directory. CALINFO.TXT - The file you are reading. NPINORM_CAL.TAB - The ASPERA-3 Neutral Particle Imager (NPI) Calibration Table. This table provides the calibration values per NPI sensor to convert count rate (cnts/second) into scientific units (number flux). NPINORM_CAL.LBL - PDS label that describes the ASPERA-3 Neutral Particle Imager (NPI) Calibration Table. ******************************* IMPORTANT NOTE ******************************* As expected for all types of ENA instruments, NPI data contain both an ENA component and a UV component. THE CALIBRATIONS PROVIDED ARE ONLY FOR THE ENA COMPONENT. Thus, the UV signals must be separated from the ENA signals before applying the calibrations described in this document. The signals from each component are intermixed and there is no prescribed way to separate each component. Extraction is complicated because both components are model dependent. In some cases, the ASPERA-3 NPI team have not identified even the type of model to use and, definitely, there is no and will be no standard approach to separate the two signals. ** Please contact ASPERA-3 Co-PI and NPI Scientist, Dr. Stas Barabash, for more information before using NPI data. His contact information is found in the AAREADME.TXT file. ********************************** END NOTE ********************************** Description of calibration table formulation and use: This is the calibration table formulation for NPI science data from the normal mode data packets (NPINORM). This table provides calibration values (columns) for each sector (32 rows) with a description of each calibration value and how to apply the value to the data for converting count rate data [cnts/second] to number flux [cnts/(cm**2-sr-s)]. To convert cnts/second to cnts/(cm**2-sr-s): CNTS_SEC NUM_FLUX = -------------------------------------------- EFFICIENCY * GEOM_FACTOR * RESPONSE_FACTOR where, CNTS_SEC = Data Value (cnts/sec) - DARK_CNT (cnts/sec) EFFICIENCY = (EFF_ENERGY[keV] * EFF_SLOPE[1/keV]) + EFF_OFFSET Basic information: The instrument cycle (INST_CYCLE) is 0.03125 seconds. The accumulation time (ACCUM_TIME) of the instrument is fixed at 1 second except during a couple of time periods early on during Near Earth Verification (NEV or EV) where it was set to 0.25 seconds. Therefore, the raw counts are the count rate (cnts/sec) except for these test periods. The MODE Data Accumulation Time value in the data (CSV) files is used to determine the accumulation time: ACCUM_TIME = INST_CYCLE * 2**N where N is the MODE DATA Accumulation Time value in the data (CSV) files, and depends on the instrument mode. For example, if the MODE DATA Accumulation Time is 5, then 2**5 = 32 and ACCUM_TIME = 0.03125 * 32 = 1 second and if MODE DATA Accumulation Time is 3, then ACCUM_TIME = 0.03125 * 2**3 = 0.25 seconds When the MODE DATA Accumulation Time value is 3, then the associated data values in the CSV files are simply divided by ACCUM_TIME (0.25) to get cnts/sec. The columns of the calibration table, NPINORM_CAL.TAB, and how to apply the values are decribed below. COLUMN 1 of CAL TABLE: SENSOR_NAME This column is the NPI sector name: "Sector xx ", where xx = 0-31. COLUMNS 2, 3, 4: DARK_CNT_X (X = '0_1', '2_3', or '4_5') These columns contain the sector dependent dark count/sec and the column to use (2, 3, or 4) depends on the MCP voltage: An additional mode was added on August 18, 2004 to drive the flux calibration values. This mode is based on the MCP voltage and the calibration tables are dependent on this mode. The MCP mode is an integer number that ranges from 0 to 5 and computed from the MCP monitor value as follows: NPI MCP Mode Value NPI MCP Voltage 0 greater than -2350V 1 -2350V to -2450V 2 -2450V to -2550V 3 -2550V to -2650V 4 -2650V to -2750V 5 less than -2750V COLUMN 2 of CAL TABLE: DARK_CNT_0_1 Subtract the sector dependent dark count/sec (data correction) Use this column for MODE DATA NPI MCP Mode = 0 or 1 Values for Sectors 0 - 31 from left to right: 0.666667, 1.016670, 1.150000, 1.133330, 0.916667, 0.950000, 1.183330, 0.716667, 0.916667, 0.933333, 1.150000, 0.916667, 0.816667, 1.016670, 1.000000, 0.733333, 0.783333, 0.850000, 0.850000, 0.816667, 0.766667, 0.700000, 0.883333, 0.816667, 0.766667, 1.050000, 1.216670, 1.100000, 1.266670, 1.233330, 1.066670, 1.300000 COLUMN 3 of CAL TABLE: DARK_CNT_2_3 Subtract the sector dependent dark count/sec (data correction) Use this column for MODE DATA NPI MCP Mode = 2 or 3 Values for Sectors 0 - 31 from left to right: 0.650000, 1.100000, 1.616670, 1.666670, 1.933330, 1.966670, 1.933330, 1.850000, 1.566670, 1.816670, 2.116670, 1.950000, 1.750000, 1.733330, 1.916670, 1.850000, 1.983330, 1.783330, 1.833330, 1.866670, 1.550000, 1.933330, 1.916670, 1.583330, 1.700000, 1.916670, 2.166670, 2.283330, 1.916670, 2.016670, 2.216670, 4.266670 COLUMN 4 of CAL TABLE: DARK_CNT_4_5 Subtract the sector dependent dark count/sec (data correction) Use this column for MODE DATA NPI MCP Mode = 4 or 5 Values for Sectors 0 - 31 from left to right: 0.483333, 0.716667, 1.266670, 1.633330, 2.000000, 2.133330, 2.483330, 2.500000, 2.316670, 2.416670, 2.316670, 2.283330, 2.616670, 2.200000, 2.866670, 2.416670, 2.333330, 2.283330, 2.433330, 2.633330, 2.416670, 2.450000, 2.466670, 1.916670, 1.950000, 2.066670, 2.333330, 2.083330, 2.216670, 2.300000, 2.533330, 7.916670 After applying COLUMN 2, 3, or 4, (DARK_CNT) the 'corrected' cnts/sec portion is determined (CNTS_SEC): CNTS_SEC = Data Value (cnts/sec) - DARK_CNT (cnts/sec) Any values less than 0 (negative) should be set to 0. This is because values that are negative mean that the signal is less than the noise generated by the MCP (i.e., the data value is all noise). Next, the efficiency is determined: EFFICIENCY = (EFF_ENERGY[keV] * EFF_SLOPE[1/keV]) + EFF_OFFSET The efficiency energy (EFF_ENERGY[keV]) is found in column 5. The efficiency slope (column 6, 7, 8, or 9) and the efficiency offset (column 10, 11, 12, or 13) to use depend on the MCP voltage: An additional mode was added on August 18, 2004 to drive the flux calibration values. This mode is based on the MCP voltage and the calibration tables are dependent on this mode. The MCP mode is an integer number that ranges from 0 to 5 and computed from the MCP monitor value as follows: NPI MCP Mode Value NPI MCP Voltage 0 greater than -2350V 1 -2350V to -2450V 2 -2450V to -2550V 3 -2550V to -2650V 4 -2650V to -2750V 5 less than -2750V COLUMN 5 of CAL TABLE: EFF_ENERGY (keV) This column contains the energy values for the sectors. The energy used here is the average energy for the efficiency of the MCP in keV. Same value for all Sectors = 1.0000 COLUMNS 6, 7, 8, 9: EFF_SLOPE_X (X = '0', '1', '2', or '3_4_5') These columns contain the efficiency slope [1/keV], and the column to use (7, 8, 9, or 10) depends on the MCP voltage. COLUMN 6 of CAL TABLE: EFF_SLOPE_0 (units of keV**-1) The efficiency slope to use when MODE DATA NPI MCP Mode = 0 Same value for all Sectors = 0.0001205 COLUMN 7 of CAL TABLE: EFF_SLOPE_1 (units of keV**-1) The efficiency slope to use when MODE DATA NPI MCP Mode = 1 Same value for all Sectors = 0.0005261 COLUMN 8 of CAL TABLE: EFF_SLOPE_2 (units of keV**-1) The efficiency slope to use when MODE DATA NPI MCP Mode = 2 Same value for all Sectors = 0.0007423 COLUMN 9 of CAL TABLE: EFF_SLOPE_3_4_5 (units of keV**-1) The efficiency slope to use when MODE DATA NPI MCP Mode = 3, 4, or 5 Same value for all Sectors = 0.0007567 COLUMNS 10, 11, 12, 13: EFF_OFFSET_X (X = '0', '1', '2', or '3_4_5') These columns contain the efficiency offset, and the column to use (10, 11, 12, or 13) depends on the MCP voltage. COLUMN 10 of CAL TABLE: EFF_OFFSET_0 (unitless) The efficiency offset to use when MODE DATA NPI MCP Mode = 0 Same value for all Sectors = -0.00001346 COLUMN 11 of CAL TABLE: EFF_OFFSET_1 (unitless) The efficiency offset to use when MODE DATA NPI MCP Mode = 1 Same value for all Sectors = -0.0001008 COLUMN 12 of CAL TABLE: EFF_OFFSET_2 (unitless) The efficiency offset to use when MODE DATA NPI MCP Mode = 2 Same value for all Sectors = -0.0001509 COLUMN 13 of CAL TABLE: EFF_OFFSET_3_4_5 (unitless) The efficiency offset to use when MODE DATA NPI MCP Mode = 3, 4, or 5 Same value for all Sectors = -0.0001625 Now take cnts/sec and divide ((eff_energy*slope) + offset). So far, we have: CNTS_SEC = Data Value (cnts/sec) - DARK_CNT (cnts/sec) EFFICIENCY = (EFF_ENERGY[keV] * EFF_SLOPE[1/keV]) + EFF_OFFSET CNTS_SEC TMP_VAL = ------------ EFFICIENCY COLUMN 14 of CAL TABLE: GEOM_FACTOR (cm**2-sr) Divide TMP_VAL (result so far) by the geometric factor. This column contains the geometric factors for each sector [cm**2-sr]. Values for Sectors 0 - 31 from left to right: 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027, 0.0027 From above, the VALUE at this point is: CNTS_SEC VALUE = -------------------------- EFFICIENCY * GEOM_FACTOR COLUMN 15 of CAL TABLE: RESPONSE_FACTOR Divide result so far by the relative amplitude response factor. This column contains the relative amplitude response factors. Values for Sectors 0 - 31 from left to right: 1.11, 1.07, 1.09, 1.07, 1.00, 0.99, 1.10, 1.04, 1.00, 1.31, 1.30, 1.16, 1.05, 0.85, 0.88, 1.00, 1.00, 0.65, 0.69, 0.58, 0.64, 0.64, 0.84, 0.97, 0.99, 0.98, 1.15, 1.28, 1.30, 1.44, 1.09, 0.86 From above, the VALUE at this point is: CNTS_SEC VALUE = -------------------------------------------- EFFICIENCY * GEOM_FACTOR * RESPONSE_FACTOR COLUMN 16 of CAL TABLE: TRANSMIT_FACTOR Multiply result so far by the sector dependent transmission factor. A value of 1 indicates full transmission and a 0 means that the sector is physically blocked. This column contains the transmission factor per sector. Values for Sectors 0 - 31 from left to right: 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 RESULT: For those sectors that are physically blocked, NUM_FLUX = 0.0 For those sectors that are not blocked: CNTS_SEC NUM_FLUX = -------------------------------------------- EFFICIENCY * GEOM_FACTOR * RESPONSE_FACTOR EXAMPLE Using Data from File: NPINORM20031762025C_ACC01.CSV Time Range: 2003-176T21:30:52.221 - 2003-176T21:30:52.471 MODE DATA Accumulation Time for these data: N = 3 ACCUM_TIME = INST_CYCLE (COLUMN 1) * 2**N = 0.03125 * 2**3 = 0.25 secs MODE DATA NPI MCP Mode for these data = 1 Use DARK_CNT_0_1 (COLUMN 2) Use EFF_SLOPE_1 (COLUMN 7) Use EFF_OFFSET_1 (COLUMN 11) COLUMN 2 (cnts/sec - Adj. Sector Data MCP Mode = 1 dark cnt/sec) (< 0) Number Values cnts/sec DARK_CNT_0_1 CNTS_SEC CNTS_SEC -------------------------------------------------------------------- 0 2 8 0.666667 7.333333 7.333333 1 2 8 1.016670 6.983330 6.983330 2 1 4 1.150000 2.850000 2.850000 3 4 16 1.133330 14.866670 14.866670 4 1 4 0.916667 3.083333 3.083333 5 1 4 0.950000 3.050000 3.050000 6 3 12 1.183330 10.816670 10.816670 7 1 4 0.716667 3.283333 3.283333 8 6 24 0.916667 23.083333 23.083333 9 5 20 0.933333 19.066667 19.066667 10 4 16 1.150000 14.850000 14.850000 11 1 4 0.916667 3.083333 3.083333 12 0 0 0.816667 -0.816667 0.000000 13 0 0 1.016670 -1.016670 0.000000 14 0 0 1.000000 -1.000000 0.000000 15 0 0 0.733333 -0.733333 0.000000 16 0 0 0.783333 -0.783333 0.000000 17 1 4 0.850000 3.150000 3.150000 18 0 0 0.850000 -0.850000 0.000000 19 1 4 0.816667 3.183333 3.183333 20 0 0 0.766667 -0.766667 0.000000 21 0 0 0.700000 -0.700000 0.000000 22 0 0 0.883333 -0.883333 0.000000 23 0 0 0.816667 -0.816667 0.000000 24 1 4 0.766667 3.233333 3.233333 25 0 0 1.050000 -1.050000 0.000000 26 0 0 1.216670 -1.216670 0.000000 27 3 12 1.100000 10.900000 10.900000 28 2 8 1.266670 6.733330 6.733330 29 0 0 1.233330 -1.233330 0.000000 30 0 0 1.066670 -1.066670 0.000000 31 2 8 1.300000 6.700000 6.700000 The EFFICIENCY is the same for all sectors: ( COLUMN 5 * COLUMN 7 ) + COLUMN 11 (EFF_ENERGY * EFF_SLOPE_1) + EFF_OFFSET_1 = EFFICIENCY ( 1.0000 * 0.0005261 ) + -0.0001008 = 0.0004253 Adj. CNTS_SEC (cnts/sec) Sector (< 0) ------------ ------------ Number CNTS_SEC EFFICIENCY GEOM_FACTOR GEOM_FACTOR RESPONSE_FACTOR ------------------------------------------------------------------------------ 0 7.333333 17242.7298 0.0027 6386196.2222 1.11 1 6.983330 16419.7743 0.0027 6081397.8889 1.07 2 2.850000 6701.1521 0.0027 2481908.1852 1.09 3 14.866670 34955.7254 0.0027 12946564.9630 1.07 4 3.083333 7249.7837 0.0027 2685105.0741 1.00 5 3.050000 7171.4084 0.0027 2656077.1852 0.99 6 10.816670 25433.0355 0.0027 9419642.7778 1.10 7 3.283333 7720.0400 0.0027 2859274.0741 1.04 8 23.083333 54275.4126 0.0027 20102004.6667 1.00 9 19.066667 44831.1004 0.0027 16604111.2593 1.31 10 14.850000 34916.5295 0.0027 12932047.9630 1.30 11 3.083333 7249.7837 0.0027 2685105.0741 1.16 12 0.000000 0.0000 0.0027 0.0000 1.05 13 0.000000 0.0000 0.0027 0.0000 0.85 14 0.000000 0.0000 0.0027 0.0000 0.88 15 0.000000 0.0000 0.0027 0.0000 1.00 16 0.000000 0.0000 0.0027 0.0000 1.00 17 3.150000 7406.5366 0.0027 2743161.7037 0.65 18 0.000000 0.0000 0.0027 0.0000 0.69 19 3.183333 7484.9118 0.0027 2772189.5556 0.58 20 0.000000 0.0000 0.0027 0.0000 0.64 21 0.000000 0.0000 0.0027 0.0000 0.64 22 0.000000 0.0000 0.0027 0.0000 0.84 23 0.000000 0.0000 0.0027 0.0000 0.97 24 3.233333 7602.4759 0.0027 2815731.8148 0.99 25 0.000000 0.0000 0.0027 0.0000 0.98 26 0.000000 0.0000 0.0027 0.0000 1.15 27 10.900000 25628.9678 0.0027 9492210.2963 1.28 28 6.733330 15831.9539 0.0027 5863686.6296 1.30 29 0.000000 0.0000 0.0027 0.0000 1.44 30 0.000000 0.0000 0.0027 0.0000 1.09 31 6.700000 15753.5857 0.0027 5834661.3704 0.86 [(cnts/sec)/geom] Sector ----------------- RESULT Number RESPONSE_FACTOR TRANSMIT_FACTOR [cnts/(cm**2-sr-s)] -------------------------------------------------------------------- 0 5753329.9299 1.0 5753329.9299 1 5683549.4289 1.0 5683549.4289 2 2276979.9864 1.0 2276979.9864 3 12099593.4234 1.0 12099593.4234 4 2685105.0741 1.0 2685105.0741 5 2682906.2477 1.0 2682906.2477 6 8563311.6162 1.0 8563311.6162 7 2749301.9943 1.0 2749301.9943 8 20102004.6667 1.0 20102004.6667 9 12674894.0911 1.0 12674894.0911 10 9947729.2023 1.0 9947729.2023 11 2314745.7535 1.0 2314745.7535 12 0.0000 1.0 0.0000 13 0.0000 1.0 0.0000 14 0.0000 1.0 0.0000 15 0.0000 0.0 0.0000 16 0.0000 0.0 0.0000 17 4220248.7749 1.0 4220248.7749 18 0.0000 1.0 0.0000 19 4779637.1648 1.0 4779637.1648 20 0.0000 1.0 0.0000 21 0.0000 1.0 0.0000 22 0.0000 1.0 0.0000 23 0.0000 1.0 0.0000 24 2844173.5503 1.0 2844173.5503 25 0.0000 1.0 0.0000 26 0.0000 1.0 0.0000 27 7415789.2940 1.0 7415789.2940 28 4510528.1766 1.0 4510528.1766 29 0.0000 1.0 0.0000 30 0.0000 1.0 0.0000 31 6784489.9656 1.0 6784489.9656