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Jupiter’s decimeter-wavelength flux density is dominated by synchrotron emission from magnetically trapped ∼5–50 MeV electrons in the radiation belts. Synchrotron radio emission remains the most useful diagnostic of the radiation belts, and a global picture is provided by ground-based observations. Monitoring of the long-term variations of Jupiter’s Synchrotron Radiation (JSR) flux density is crucial to understanding its relationship with the solar wind. The GAVRT (Goldstone-Apple Valley Radio Telescope) program operates two retired Deep Space Network (DSN) antennas, and as part of their K-12 program and Juno support, GAVRT has been collecting data to monitor JSR radio emission at 2280 MHz (13 cm wavelength). We present new results from 2019 August to 2021 December GAVRT monitoring observations. As viewed from Earth the JSR varies systematically (by about 10%) with Jupiter’s 9.9 hr rotation period, and our observations were typically much shorter than 9.9 hr. To estimate the daily flux density of JSR, we took advantage of recent progress in modeling the radiation belt, scaling individual observations by the predicted relative variation due to Jupiter’s rotation as viewed from Earth. We discuss the JSR variability from 2015 to 2021, combining our results with previous GAVRT data. Our new results show a marked decrease (∼1 Jy) in JSR flux density between 2018 and 2021, while earlier observations showed an increase from 2015 to 2018. These results are remarkably consistent with long-term variability shown by the simulations of Han et al. based on models driven by the solar wind ram pressure.

Goldstone Apple Valley Radio Telescope (GAVRT) is a science education partnership among NASA, the Jet Propulsion Laboratory (JPL), and the Lewis Center for Educational Research (LCER), offering unique opportunities for K -12 students and their teachers. As part of a long-term Jupiter synchrotron radiation (JSR) flux density monitoring program, LCER has been carrying out Jupiter observations with some student participation. In this paper we present the results of processed data sets observed between March 6, 2015 and April 6 2018. The data are divided into 5 epochs, grouped by time. We derive JSR beaming curves at different epochs and Earth declinations. We present a comparison of the observed beaming curves with those derived from most recent models for the radiation belts. Our results show an increasing trend of the JSR flux density which seem consistent with the models for the magnetospheric solar wind interactions., Comment: 24 pages; 9 figures To be published in PASP

This paper describes a radio astronomy programfor schools, the Goldstone-AppleValley Radio Telescope,GAVRT. The GAVRT program is designed to bring the inspiration and enthusiasm to a younger generation of teachers and children who learn about science by doing real science, just as Iosif Shklovsky brought to an older generation.

Goldstone Apple Valley Radio Telescope (GAVRT) is a science education partnership among NASA, the Jet Propulsion Laboratory (JPL), and the Lewis Center for Educational Research (LCER), offering unique opportunities for K -12 students and their teachers. The GAVRT program operates a 34-m radio telescope with a wide-band, low noise receiver, which is tunable in four independent dual-polarization bands from 3 to 14 GHz. The annular eclipse of the Sun on 2012 May 20 was observed by GAVRT as part of education outreach. In this paper we present the results of this eclipse data and discuss the multi-wavelength strip scan brightness distribution across three active regions. We derive the source brightness temperatures and angular sizes as a function of frequency and interpret the results in terms of the gyroresonance mechanism. We show examples of the increasing brightness and widening of source size (isogauss surface) with wavelength as evidence for gyroresonance emission layers of broader (diverging ) isogauss surfaces of the magnetic field geometry in the corona above solar surface. We present an example how the derived frequency - brightness temperature relationship is translated to a magnetic field - brightness temperature relationship under the frame-work of gyroresonance emission. Our results demonstrate the usefulness of GAVRT bands as excellent probes to study the layers of the corona above the active regions (sun spots), in particular the prevalence of the gyroresonance mechanism. Our results provide a frame-work for multiwavelength cm-wavelength eclipse observations and illustrate how the GAVRT program and K- 12 student/teacher participation can produce science data useful to the scientific community and science missions., Comment: 21 pages; 8 figures To be published in PASP

We have recently equipped the 34-meter DSS-28 radio telescope at the Goldstone Deep Space Communications Complex with a novel wide bandwidth radiometer and digital signal processor as part of the Goldstone Apple Valley Radio Telescope (GAVRT) educational outreach program operated by the Jet Propulsion Laboratory and the Lewis Center for Educational Research. The system employs a cryogenically cooled wide bandwidth quad-ridge feed and InP low noise amplifiers to achieve excellent noise performance from 2.7 to 14 GHz; a fractional bandwidth better than 4:1. Four independently tunable dual-polarization receivers each down-convert a 2 GHz block to baseband, providing access to 8 GHz of instantaneous bandwidth. A flexible FPGA-based signal processor has been constructed using CASPER FPGA hardware and tools to take advantage of this enormous bandwidth. This system demonstrates many of the enabling wide bandwidth technologies that will be crucial to maximizing the utility of future large centimeter-wavelength arrays, in particular the Square Kilometer Array. The GAVRT program has previously used narrow bandwidth total power radiometers to study flux variability of quasars and the outer planets. The versatility of DSS-28 will enable other projects including spectroscopy and SETI. Finally, the wide instantaneous bandwidth available makes this system uniquely suited for studying transient radio pulses. A configuration of the digital signal processor has been developed which provides the capability of recording a burst of raw baseband voltage data triggered by a real-time incoherent dedispersion system which is very sensitive to pulses from a known source, such as the Crab Nebula pulsar.