Level 1
Level 1 Science Data Description
MinXSS Version 3.1.0 | DAXSS Version 1.0.0
Description
Level 1 MinXSS & DAXSS data focuses on the science product and telemetry related to the science. The raw count spectrum from Level 0D is converted into irradiance units and NIST/SURF calibration applied. The nominal integrations are 10 seconds. The resultant array of structures (variable name = minxsslevel1_x123, for X123 data) is stored as an IDL saveset and netCDF, which can be directly restored in IDL or read into python (see How to Load and Plot Data). The definition of the structure is provided in the table below.
What’s in Level 1 Data
The Level 1 data file for X123 is a variable minxsslevel1_x123 (minxss) and data (DAXSS), which is an array of anonymous structures (“anonymous structures” is IDL lingo that is the equivalent of dictionaries in other languages). Each element in the array is a point in time. The definition of the structure is provided in the table below.
Note: Bad data flag for bytes is 255 i.e. byte(-1). For strings it’s empty (‘’). For all other types it’s NaN.
Note: The primary science instrument is called the X123. The secondary science instruments are the SPS and XP. The attitude determination and control system (ADCS) is called XACT.
There are four main data structures for MinXSS, level1_x123 (X123 science observations), level1_x123_dark (eclipse data corresponding to the level1_x123 data), level1_xp (XP science observations), level1_xp_dark (eclipse data corresponding to the level1_xp data). DAXSS has just the one structure, data. There are also two ancillary structures in the IDL saveset, minxsslevel1_x123_meta and minxsslevel1_xp_meta, which essentially include the tag name descriptions listed in the tables in this document. This information is contained in the netCDF meta as well.
Level 1 structures definition
level1_x123 Structure
| Tag Name | Units | Description |
| flight_model | — | 1: MinXSS-1 in ISS orbit from 2016-05-16 to 2017-05-06
2: MinXSS-2 in 575 km sun-sync orbit from 2018-12-03 to 2019-01-07 3. INSPIRESat-1/DAXSS in 550 km sun-sync dawn-dusk orbit from 2022-02-14 to present |
| irradiance | photons/sec/cm^2/keV | Float Array of 1024 elements. The photon flux array. |
| irradiance_uncertainty | photons/sec/cm^2/keV | Float Array of 1024 elements. The estimated uncertainty on the irradiance (photon flux array). |
| energy | keV | Float Array of 1024 elements. The range is about 0 to 30 keV. The values < 0 are an artifact of the gain calibration, which results in a slight negative offset on the energy bins. |
| spectrum_cps | counts/s (cps) | Float Array of 1024 elements. This is the count rate measured that is used to estimate the photon irradiance. |
| spectrum_cps_accuracy | counts/s (cps) | Float Array of 1024 elements. It provides estimate of the measurement accuracy which includes pre-flight calibration and measurement precision. |
| spectrum_cps_precision | counts/s (cps) | Float Array of 1024 elements. It provides an estimate of the measurement precision, which is dependent on the number of spectra used to create the count rate. |
| spectrum_cps_stddev | counts/s (cps) | Float Array of 1024 elements. If more than one integration time is used to create the spectra (Nx123 > 1), then this is the standard deviation of the binned spectra data. If only one spectrum is used, then this is equal to 0. |
| deadtime_correction_factor | Float | Float number indicating the number used to scale UP the spectra due to detector timer dead-time losses. |
| valid_flag | Boolean | Float Array of 1024 elements. Flag indicating if the irradiance value is considered “valid” after the conversion. 1 is considered a valid inversion; data corresponding to a valid_flag value of 0 should be analyzed with STRONG caution. Values with a value of 0 can vary by many orders of magnitude from the “true” value. |
| spectrum_total_counts | counts | Float Array of 1024 elements. This is the summed counts (per energy bin) measured over the all included integration periods used to create the data product. |
| spectrum_total_counts_accuracy | counts | Float Array of 1024 elements. It provides estimate of the measurement accuracy on spectrum_total_counts which includes pre-flight calibration and measurement precision. |
| spectrum_total_counts_precision | counts | Float Array of 1024 elements. It provides an estimate of the measurement precision on spectrum_total_counts, which is dependent on the total number of spectra used to create the count rate. |
| integration_time | sec | Integration time. It can range from 10 sec for one X123 spectrum to about 60 sec. |
| number_spectra | — | The number of spectra used to create the spectrum_cps and hence the irradiance quantities.. |
| x123_fast_count | counts/sec | This is the spectrum summed count rate from the X123 fast channel. |
| x123_slow_count | counts/sec | This is the spectrum summed count rate from the X123 slow channel. This channel is used to create the X-ray spectra. The summation of the signal_cps array should equal the x123_slow_count value. |
| SPS_on | — | Flag that says if the SPS unit is On or Off |
| SPS_sum | fC | SPS total signal from four quadrants |
| SPS_X | degrees | Offset from SPS optical center. The SPS_X_HK is also provided but it is not as accurate as the SPS_X tag. |
| SPS_Y | degrees | Offset from SPS optical center. The SPS_Y_HK is also provided but it is not as accurate as the SPS_Y tag. |
| longitude | º
(degrees) |
Spacecraft location relative to Earth |
| latitude | ||
| altitude | km
(kilometers) |
Spacecraft height above the Earth’s surface |
| sun_right_ascension | º
(degrees) |
Relative angle to sun as determined from ground computation based on TLE |
| sun_declination | ||
| earth_sun_distance | AU
(astronomical units) |
Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light |
| solar_zenith_angle | º
(degrees) |
The solar zenith angle at the time of the measurement |
| tangent_ray_height | km
(kilometers) |
The tangent ray height in Earth atmosphere at the time of the measurement |
| correct_au | unitless | Correction factor used to scale the irradiance to the annual averaged Earth-Sun distance (1 AU) |
| Time
[Time (structure) is same as used in Level 0D and is:
|
— | Time in a variety of formats
|
level1_x123_dark Structure
| Tag Name | Units | Description |
| flight_model | — | 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??
2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ?? |
| energy | keV | Float Array of 1024 elements. The range is about 0 to 30 keV. |
| spectrum_cps | counts/s (cps) | Float Array of 1024 elements. |
| spectrum_cps_accuracy | counts/s (cps) | Float Array of 1024 elements. It provides estimate of the measurement accuracy which includes pre-flight calibration and measurement precision. |
| spectrum_cps_precision | counts/s (cps) | Float Array of 1024 elements. It provides an estimate of the measurement precision, which is dependent on the number of spectra used to create the count rate. |
| spectrum_cps_stddev | counts/s (cps) | Float Array of 1024 elements. If more than one integration time is used to create the spectra (Nx123 > 1), then this is the standard deviation of the binned spectra data. If only one spectrum is used, then this is equal to 0. |
| deadtime_correction_factor | Float | Float number indicating the number used to scale UP the spectra due to detector timer dead-time losses. |
| valid_flag | Boolean | Float Array of 1024 elements. Flag indicating if the irradiance value is considered “valid” after the conversion. 1 is considered a valid inversion; data corresponding to a valid_flag value of 0 should be analyzed with STRONG caution. Values with a value of 0 can vary by many orders of magnitude from the “true” value. |
| spectrum_total_counts | counts | Float Array of 1024 elements. This is the summed counts (per energy bin) measured over the all included integration periods used to create the data product. |
| spectrum_total_counts_accuracy | counts | Float Array of 1024 elements. It provides estimate of the measurement accuracy on spectrum_total_counts which includes pre-flight calibration and measurement precision. |
| spectrum_total_counts_precision | counts | Float Array of 1024 elements. It provides an estimate of the measurement precision on spectrum_total_counts, which is dependent on the total number of spectra used to create the count rate. |
| integration_time | sec | Integration time. It can range from 10 sec for one X123 spectrum to about 60 sec. |
| number_spectra | — | The number of spectra used to create the spectrum_cps and hence the irradiance quantities.. |
| x123_fast_count | counts/sec | This is the spectrum summed count rate from the X123 fast channel. |
| x123_slow_count | counts/sec | This is the spectrum summed count rate from the X123 slow channel. This channel is used to create the X-ray spectra. The summation of the signal_cps array should equal the x123_slow_count value. |
| SPS_on | — | Flag that says if the SPS unit is On or Off |
| SPS_sum | fC | SPS total signal from four quadrants |
| SPS_X | degrees | Offset from SPS optical center. The SPS_X_HK is also provided but it is not as accurate as the SPS_X tag. |
| SPS_Y | degrees | Offset from SPS optical center. The SPS_Y_HK is also provided but it is not as accurate as the SPS_Y tag. |
| longitude | º
(degrees) |
Spacecraft location relative to Earth |
| latitude | ||
| altitude | km
(kilometers) |
Spacecraft height above the Earth’s surface |
| sun_right_ascension | º
(degrees) |
Relative angle to sun as determined from ground computation based on TLE |
| sun_declination | ||
| earth_sun_distance | AU
(astronomical units) |
Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light |
| correct_au | unitless | Correction factor used to scale the irradiance to the annual averaged Earth-Sun distance (1 AU) |
| Time
[Time (structure) is same as used in Level 0D and is:
|
— | Time in a variety of formats
|
level1_xp and level1_xp_dark Structure
| Tag Name | Units | Description |
| flight_model | — | 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??
2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ?? |
| signal_fc | fC/s | Float. Background (dark diode) subtracted averaged signal from XP. The average is over the number of integrations (Nxp). |
| signal_fc_accuracy | femtoCoulombs/s (fC/s) | Float. Estimate of the measurement accuracy on xp_fc_background_subtracted which includes pre-flight calibration and measurement precision. |
| signal_fc_precision | femtoCoulombs/s (fC/s) | Float. Estimate of the measurement precision on xp_fc_background_subtracted, which is dependent on the total number of spectra used to create the count rate. |
| signal_fc_stddev | femtoCoulombs/s (fC/s) | Float. If more than one integration time is used to create the signal (N > 1), then this is the standard deviation of the signal data. If only one integration time is used, then this is equal to 0. |
| x123_estimated_xp_fc | femtoCoulombs/s (fC/s) | Float. Estimated XP signal in fC/s from the measured X123 spectrum. |
| x123_estimated_xp_fc_uncertainty | femtoCoulombs/s (fC/s) | Float. Uncertainty on the estimated XP signal in fC/s from the measured X123 spectrum. |
| fractional_difference_x123_estimated_xp_fc | Float | Float. Fractional difference between the actual XP signal (xp_fc_background_subtracted) and the estimated XP signal from the measured X123 spectrum (x123_estimated_xp_fc). |
| number_xp_samples | Integer | Number of XP 1-second samples. |
| Time
[Time (structure) is same as used in Level 0D and is:
|
— | Time in a variety of formats
|
