GOES Particle Intracalibration Toolkit William Rowland NOAA/NESDIS/STAR, GMU Robert Weigel, PhD George Mason University Changyong Cao, PhD NOAA/NESDIS/STAR
MAGED • Solid State Detector, collimator, and electronics • Determines energy of electrons based on energy deposited. • Energy range in table below. GOES-NOP Data book
GOES MAGED EPS HEPAD Handbook
GOES MAGED Energy Captured EPS HEPAD Handbook
Pre-launch • Initial factors determined during ground calibration. • No standards between beamlines • Full energy/flux range may not be calibrated • Only one telescope generally characterized
On-orbit • In-flight Calibration • Should track electronics degradation • Not useful in some channels of current generation • Currently not performed even for useful channels • During Post-Launch testing comparisons are sometimes performed • Between telescopes on a single GOES satellite • Between GOES satellites
On-orbit (continued) • After Post-launch testing • Generally no resources have been devoted to following changes in cal factors due to different rates of degradation • Neither SWPC nor NSOF has the resources necessary
STAR’s Role • Stewards of L1b Data Quality • Analyze and trend performance of instruments • Recommend adjustments to calibration factors as necessary • Participate in anomaly resolution as necessary • Limited manpower necessitates development of tools • GOES Particle Intercalibration Toolkit • Permit intracalibration of telescopes aboard the same satellite. • Permit intercalibration of satellites. • Make the data obtained publicly available, so that others involved in the process (like NSOF) and the user community can track performance as desired.
Phase space consists of 3 position vectors, 3 velocity vectors, a scalar number density. • Phase space coordinates express this in terms of 3 adiabatic invariants (μ, K, L*), 3 phases, and a scalar. • For intracalibration • Position is the same for all telescopes on a satellite. • K and L* depend on the magnetic field. All telescopes are in the same magnetic field.
B1=B2, vTot1~VTot2, m1 = m2 • Therefore, if α1=α2 then μ1= μ2 • In this case all adiabatic invariants are the same for the particles measured by the two telescopes. • These data may be useful for calibration.
Calculate representative pitch angles using • Magnetic Field measurements • Knowledge of the orientation of the particle sensors • Currently spacecraft reference frame is utilized • Any common frame works
Pitch Angle “match” is defined as the angles matching to within 1 degree. • Particle sensor orientation knowledge is no better. • This may be overly restrictive • Less stringent requirements yielded visually similar results, at least to several degrees
Additional constraints • Magnetic field vector direction changing quickly • Necessary for the First Adiabatic Invariant to be meaningful • Used a limit of 1 degree per integration cycle for the current plots • Parameter is included in metadata • User can view different results if desired
Additional constraints or possible confounds which are being considered • Dst values • Did not appear to make a large difference • Rate of change in count rates • Have not examined the current data set to see if an impact is noticeable. • Local time • Have not examined data set for impact • This may have more of an impact at lower energies (S/C charging)
Current tasks • Quantify impact of additional effects • Dst, changes in count rate, local time, etc… • Obtain further peer review • Automate code • Currently can manually order it to retrieve and analyze a month’s worth of data • Make results available to SWPC • STAR does not have a mandate to calibrate GOES-NOP
Software issues • File sizes are getting too large. Need to either • Optimize code • Change platforms • Bundle datasets into 3 month sets