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Laboratory for Atmospheric and Space Physics

Level 0D

Level 0D Science Data Description

Version 3.1.0


This is the final stage of low-level data processing. It cleans up the MinXSS telemetry and adds ancillary data in preparation for processing to a usable science product at Level 1. The variety of MinXSS packet types (housekeeping, log, etc.) are not, in general, generated at the same time as the science packet, nor do we necessarily downlink the packets that were generated nearest in time to each other. However, some of that non-science telemetry is needed for the conversion to Level 1 and higher. We interpolate the non-science packet telemetry to the mid-point of the science integration periods, provided that the time step does not exceed a given threshold (presently 5 minutes for ADCS data and 1 minute for all other types). We also generate ancillary data such as the orbital position and the spacecraft’s relation to the sun based on our best estimate from an interpolated combination of the publically available two line elements. All of these data are merged into a single structure at each time interval, resulting in a single array of identically-defined structures. Level 0D will be released to the public soon, as well as the IDL code we use to process it to Level 1. That will enable users to e.g., change the threshold on time interpolation of telemetry.

Special note about Level 0D:

All spacecraft data is interpolated to the midpoint of the science packet times. This requires that data from those other packets (hk, adcs) be downlinked at sufficient cadence to result in a reliable interpolation between points. Level 0D will not do the interpolation if those points are further away than some threshold from the science packet time. In these cases the bad data flag is used for those telemetry items but the science data remains.

Externally derived data is also interpolated to the midpoint of the science packets, but this should be trivial since it can be generally be generated for arbitrary points in time.

What’s in Level 0D Data

minxsslevel0d 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.

Level 0D structure definition

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/??/?? – ??

spacecraft_mode 1: Phoenix (ADCS off, X123 off)

2: Safe (ADCS off)

4: Science (All on)

adcs_mode 0: Coarse sun point

1: Fine sun point

eclipse 0: when spacecraft in sunlight

1: when spacecraft in eclipse

radio_transmitted bytes Number of bytes transmitted by the flight radio
radio_received bytes Number of bytes received by the flight radio
eps_5v_cur mA


Current draw on the 5V line, which only powers the X123
eps_5v_volt V


Voltage level of the 5V line, which only powers the X123
sps_xps_pwr_3v V


Measured voltage on the 3V line entering the SPS/XP
sps_xps_pwr_a5v V


Measured analog voltage on the 5V line entering the SPS/XP
sps_xps_pwr_d5v V


Measured digital voltage on the 5V line entering the SPS/XP
switch_sps 0: SPS/XP is powered off

1: SPS/XP is powered on

switch_adcs 0: Attitude Determination and Control System (ADCS) is powered off

1: ADCS is powered on

switch_battery_heater 0: Battery heater is powered off

1: Battery heater is powered on

measured_attitude_valid 0: ADCS attitude knowledge is invalid

1: ADCS attitude knowledge is valid

xact_wheel1_measured_speed rad/s

(radians per second)

Speed of the reaction wheels
attitude_quaternion1 Defines rotation of spacecraft
xact_measured_sun_body_vector_x unit vector ADCS measured relative vector to the sun
xact_sun_point_angle_error º


ADCS computed relative angle to sun
orbit_position_ECI1 km


Earth Centered Inertial position in space
orbit_position_ECEF1 km


Earth Centered Earth Fixed position in space
longitude º


Spacecraft location relative to Earth
altitude km


Spacecraft height above the Earth’s surface
sun_right_ascension º


Relative angle to sun as determined from ground computation based on TLE
earth_sun_distance AU

(astronomical units)

Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light
spacecraft_in_saa 0: Spacecraft is not in the South Atlantic Anomaly

1: Spacecraft is in South Atlantic Anomaly (possibility for more noise in science measurements)

sps_xps_temperature ºC


Temperature measured on the power board of the secondary science instrument
sps_dark_data_hk DN/s

(data numbers per second)

Dark diode reading from the secondary science instrument as logged by the housekeeping system
sps_dark_data_sci DN/integration

(data numbers per integration time)

The total signal recorded in the dark diode during the science integration time
sps_sum_hk fC/s

(femtocoulombs per second)

The sum of the four fine sun sensor diodes with gain scaling to get physical units, as logged by the housekeeping system
sps_xps_count counts/s

(counts per second)

X-ray photometer (secondary science instrument) diode reading
sps_x_hk Measured relative position of the sun in dimensionless units to be converted to degrees
sps_x_deg º (degrees) = (sps_x_hk/10,000)*3.0
sps_y_deg º (degrees) = (sps_y_hk/10,000)*3.0
sps_data_sci DN/integration

(data numbers per integration time)

The total signal recorded in the 4 fine sun sensor diodes during the science integration time (4 element array)
xps_fov_map % deviation from the center Percent deviation in response from the center (boresight – optical axis)
xps_data_hk DN/s

(data numbers per second)

Measurement from the XP as logged by the housekeeping system
xps_data_sci DN / integration

(data numbers per integration period)

Measurement from the XP over its integration time
x123_board_temperature ºC


Temperature of the X123 electronics box
x123_detector_temperature ºC


Temperature of the X123 detector
x123_accum_time ms


Integration period for the X123
x123_live_time ms


Measured time that the slow counter of the X123 was not overrun with photons to count
x123_real_time ms


Another measurement of the time that the slow counter of the X123 was not overrun with photons to count
x123_cmp_info Information from the X123 processor
x123_flags Flags set by the X123 processor
x123_read_errors Read errors detected by X123 processor
x123_write_errors Write errors detected by the X123 processor
x123_gp_count counts X123 General Purpose Counter
x123_group_count Count for the X123 Data: 0 = First
x123_high_voltage V


Voltage applied across the X123 silicon drift detector
x123_radio_flag 0: Flight radio was not transmitting during X123 integration period

1 or greater: Flight radio was transmitting “”

x123_spect_len B
Length of the spectrum from the X123
x123_fast_count counts / integration Total number of counts in the fast counter of the X123 during the integration period
x123_slow_count counts / integration Total number of counts in the slow counter of the X123 during the integration period
x123_spectrum counts/s/ bin

(counts per second per bin)

The 1024 bins of X123  data. Per intergration period per 0.03 keV bin
xps_fov_map % deviation from the center Percent deviation in response from the center (boresight – optical axis)
goes_xrs_1_8_A_flux W/m2 GOES 0.1 – 0.8 A flux
goes_xrs_05_4_A_flux W/m2 GOES 0.05 – 0.4 A flux
flare_flag 1 or 0 Boolean – 1 means flare and 0 means no flare
Time (structure)

  1. fod
  2. hhmmss
  3. human
  4. iso
  5. jd
  6. sod
  7. spacecraftgpsformat
  8. yyyydoy
  9. yyyymmdd
Time in a variety of formats

  1. Fraction of day
  2. Hours minutes seconds
  3. yyyy-mm-dd hh:mm:ss
  4. International standards organization time format (yyyy-mm-ddThh:mm:ssZ)
  5. Julian date
  6. Second of day
  7. Flight clock in GPS format
  8. Year day of year
  9. Year month day