README for GEOSPACE Orbit Plots (most recent 90 day plots are updated daily)

Orbit plots are created at an 8 hour cadence in both Geocentric Solar Ecliptic (GSE) and Solar Magnetic (SM) coordinates.

1. The SM plots are x-y orbit projections +/-12 RE in the equatorial plane.
2. The GSE plots are x-y orbit projections +/-30 RE in the equatorial plane.
3. The Lagrangian-1 GSE plots are x-y at z=0 and x-z at y=0 orbit projections for an x range of +280 to -60 RE.

Only data that resides in the (SSCWeb database) are plotted. The plotting code calls the SSCWeb web-services API:
1. Makes a query of all spacecraft and their time ranges in the SSCWeb database
2. For time range of the plot, the target spacecraft with an orbit solution within that time range are plotted
3. Spacecraft listed in the legend, but not shown on the plot indicates that an orbit solution exists for that time range but its orbit is outside the plot ranges.
4. The target spacecraft are key NASA/NOAA/ESA/JAXA/ISRO heliophysics missions

Note to SPDF TEAM: the function sab_get_satinfo.pro contains this list and would have to be modified to add new spacecraft.

For spacecraft flying in a constellation like MMS and Cluster only one spacecraft is selected.

The dots on each orbit are spaced by 2 hours. The colors are assigned automatically to each spacecraft and can vary as new missions begin or old missions end.

The model magnetopause[1] and bow shock[2] are parameterized by Solar Wind and IMF GSM. Averages over the plot time span of the Solar Wind dynamic pressure, speed, proton density, and IMF in GSE and GSM are used in the models, and are from the hourly OMNI data[3] if available. Nominal values of 2.6 nPa, 400 km/s, 8 cm^{-3}, [-4, 4, 0] nT GSE are used if OMNI data is not available for that time interval.

Both the bow shock and magnetopause models are corrected for aberration in the x-y plane: atan(30 [km/s]/Solar Speed [km/s]). Note on the SM plot the model MP and BS locations are only correct when the dipole tilt angle is 0 degrees.

On the GSE x-y plot panel the dashed lines outside the bow shock connecting to the bow shock are in the direction of the IMF Bx, By GSE the bow shock normal is shown to help indicate whether that area of the bow shock is quasi-parallel or perpendicular.

Currently the plots are generated once a week over +/- 90 day interval, the starting at -90 days ensures that the OMNI data will be updated.

References
[1] Shue, J.-H., et al. (1998), Magnetopause location under extreme solar wind conditions, J. Geophys. Res., 103(A8), 17691–17700, doi:10.1029/98JA01103.
[2] Chao, J.K., D.J. Wu, C.-H. Lin, Y.-H. Yang, X.Y. Wang, M. Kessel, S.H. Chen, R.P. Lepping (2002), Models for the size and shape of the earth's magnetopause and bow shock, Pergamon, Volume 12, Pages 127-135, ISSN 0964-2749, ISBN 9780080440576, https://doi.org/10.1016/S0964-2749(02)80212-8.
[3] King, J. H., & Papitashvili, N. E. (2020). OMNI Combined Heliopheric Observations (COHO), Merged Magnetic Field, Plasma and Ephermeris, Definitive Hourly Data [Data set]. NASA Space Physics Data Facility. http://doi.org/10.48322/6FFX-3441.

Authors and curators:

Last updated: 2025