Planetary Radio Confusion Tool
IR HST image
(Erich Karkoschka)
This is a tool set up to help Mike Klein and his students investigate the effects of confusing sources on radio wavelength observations of the planets, both past and current. The old observations were mostly done by Mike with the JPL DSN 70-m antenna (DSS14), while the newer ones are done by the students using the Goldstone Apple Valley Radio Telescope (GAVRT). More details for the observations of Uranus can be found in Mike's 2002 DPS talk.
This tool uses the source list from the NRAO VLA Sky Survey (NVSS) to determine what background sources might be near the planet at some past time when it was observed. The position of the planet at any given time is retrieved from the JPL Horizons ephemeris. Given that position, the tool calculates the increase in received flux density from the background sources, and from that calculates a correction to the estimated brightness temperature of the planet. There are some caveats to the use of the numbers produced when running this tool:
- It assumes a spectral index of -0.7 for the confusing sources (appropriate for synchrotron radiation);
- It does not account for smooth background radiation (especially galactic);
- It does not use a "real" beam shape, but rather a theoretical one (Gaussian);
- For beam-switched observations, it should really calculate the confusing sources (and smooth background) in the "off" position and use the difference for the correction, which it does not do.