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(Abridged) Using the Zwicky Transient Facility alert stream, we are conducting a large campaign to spectroscopically classify all transients occurring in galaxies in the Census of the Local Universe (CLU) catalog. The aim of the experiment is to construct a spectroscopically complete, volume-limited sample of transients coincident within 100" of CLU galaxies out to 200 Mpc, and to a depth of 20 mag. We describe the survey design and spectroscopic completeness from the first 16 months of operations. We present results from a systematic search for Calcium rich gap transients in the sample of 22 low luminosity (peak absolute magnitude $M > -17$), hydrogen poor events found in the experiment (out of 754 spectroscopically classified SNe). We report the detection of eight Calcium rich gap transients, and constrain their volumetric rate to be at least $\approx 15\pm5$% of the SN Ia rate. Combining this sample with ten events from the literature, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations of events distinguished by their red ($g - r \approx 1.5$ mag) or green ($g - r \approx 0.5$ mag) spectral colors at $r$-band peak, wherein redder events show strong line blanketing signatures, slower light curves, weaker He lines and lower [Ca II]/[O I] in the nebular phase. Together, we find that the spectroscopic continuum, volumetric rates and striking old environments are consistent with the explosive burning of He shells on low mass white dwarfs. We posit that Ca-Ia and red Ca-Ib/c objects are consistent with the double detonation of He shells with high He burning efficiency, while green Ca-Ib/c objects could arise from less efficient He burning scenarios such as detonations in low density He shells or He shell deflagrations., 30 figures, 6 tables. Submitted to ApJ

Introduction Planetary Radio Interferometry and Doppler Experiment (PRIDE) will exploit the signal recording and processing technology developed originally for Very Long Baseline interferometric (VLBI). The essence of PRIDE is in observing the spacecraft radio signal with a network of Earth-based radio telescopes. The PRIDE technique developed at the Joint Institute for VLBI ERIC (JIVE) together with its partners was used for several experiments with several ESA planetary science missions. It has been chosen by ESA as one of the eleven experiments of the Jupiter Icy Moons Explorer (JUICE), the first Large-class mission in the ESA’s Cosmic Vision 2015–2025 program. The mission is scheduled for launch in 2022. Figure 1: A typical PRIDE Experiment 1. PRIDE for JUICE Mission PRIDE is a multidisciplinary component of the JUICE science suite. The main measured deliverables of PRIDE are lateral coordinates L(φ, θ) of spacecraft and the radial velocity of spacecraft. The former (main) measurable of PRIDE requires the phase-referencing VLBI observations (see Duev et al. [1]). The latter employs the Doppler extraction technique described in [7,8]. Its prime deliverable will be used primarily for improvement of the Jovian system ephemerides in support to a variety of applications, ranging from gravimetry to geodynamics to fundamental physics. A typical PRIDE experiment is shown in Figure 1. PRIDE observations are carried out by the ground segment when the spacecraft emits a radio signal for communication or radio science purposes. The methodology of PRIDE has been demonstrated with the ESA's Venus Express & Mars Express by Duev et al. 2012 [1], Molera Calvés et al. 2014 [2], Duev et al. 2016 [4], Molera Calvés et al. 2017 [8], Bocanegra et al. 2018 [7], Bocanegra et al. 2019 [8]. In addition to nominal science objectivities, the team is considering ad hoc observations around the Venus and Mars flybys during the cruise phase. A covariance analysis for a broad scope of the PRIDE measurable and Jovian system parameters have been performed to optimize the observation planning and the overall science impact of the JUICE mission (Dirkx. D et al. 2016 [4] & Dirkx. D et al. 2017 [5]). 2. Ongoing PRIDE observing projects In 2020, we have begun a campaign to gather PRIDE tracking data of the InSight lander, with up to three tracking epochs scheduled for each of the three 2020 EVN sessions. The primary goal of these experiments is to serve as a preparatory activity for more intensive operations for ExoMars-LaRa [9]. The primary manner in which PRIDE will be able to contribute to the science objectives of LaRa is through the use of the Doppler data obtained by all receiving stations. As shown by the analysis of Bocanegra et al. 2018 [7], PRIDE Doppler data at X-band is similar, and in some cases, higher quality compared to regular closed-loop tracking data. One advantage of PRIDE lies in its diversity of receiving stations, making the data quality much less dependent on the meteorological or operational conditions at a single telescope. Figure 2: Frequency detections of Mars Insight (NASA) as seen from the University of Tasmania network of radio telescopes. The spacecraft signal was detected at the sky frequency of 8407.25 MHz and Doppler shift of 50 kHz along 70 minutes of tracking Besides, we propose to merge the three-way Doppler data generated at each receiving station, to fully exploit the data encoded in all downlinks. This would allow an improved calibration of receiving station noise levels, as the noise incurred locally at the receiving ground station (including Earth tropospheric and ionospheric noise on the downlink) is independent for each station. We will use the InSight tracking data to test different practical approached to achieving this conceptual aim, and apply these ‘lessons learned’ to ExoMars-LaRa data analysis. In particular, we will apply the InSight tracking data to investigate different manners in which to weigh the data, considering the fact that the three-way Doppler noise generated at all receiving stations is highly correlated, and to investigate how inter-station biases and drifts can best be calibrated for. The results of the ongoing PRIDE observations of NASA's InSight probe will be reported elsewhere (Dirkx. D, Le Maistre. S, Dehant. V et al., in preparation). References D. A. Duev. et al.: Spacecraft VLBI and Doppler tracking: algorithms and implementation, Astronomy & Astrophysics, 541, A43, 2012 G. Molera Calves. et al.: Observations and analysis of phase scintillation of spacecraft signal on the interplanetary plasma". In: A&A 564, A4, 2014 D. A. Duev. et al.: Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique: A test case of the Mars Express Phobos fly-by, Astronomy & Astrophysics, Vol. 593, 2016 Dirkx D. et al.: Dynamical modeling of the Galilean moons for the JUICE mission, Planetary and Space Science 134 (2016) 82–95 Dirkx D. et al.: On the contribution of PRIDE JUICE to Jovian system ephemerides, Planetary and Space Science, 14–27, 2017 G. Molera Calves. et al.: Analysis of an Interplanetary Coronal Mass Ejection by a Spacecraft Radio Signal: A Case Study, Space Weather, 15 T. M. Bocanegra-Bahamón. et al.: Planetary Radio Interferometry and Doppler Experiment (PRIDE) technique: A test case of the Mars Express Phobos Flyby II. Doppler tracking: Formulation of observed and computed values, and noise budget, Astronomy & Astrophysics, 609, A59, 2018 T.M. Bocanegra-Bahamón. et al.: Venus Express radio occultation observed by PRIDE, Astronomy & Astrophysics, 624, A59, 2019 Dehant V. et al.: The radioscience LaRa instrument onboard ExoMars 2020 to investigate the rotation and interior of Mars, Planetary and Space Science 180, 104776, 2020

Context. Closed-loop Doppler data obtained by deep space tracking networks (e.g., NASA's DSN and ESA's Estrack) are routinely used for navigation and science applications. By "shadow tracking" the spacecraft signal, Earth-based radio telescopes involved in Planetary Radio Interferometry and Doppler Experiment (PRIDE) can provide open-loop Doppler tracking data when the dedicated deep space tracking facilities are operating in closed-loop mode only. Aims. We explain in detail the data processing pipeline, discuss the capabilities of the technique and its potential applications in planetary science. Methods. We provide the formulation of the observed and computed values of the Doppler data in PRIDE tracking of spacecraft, and demonstrate the quality of the results using as a test case an experiment with ESA's Mars Express spacecraft. Results. We find that the Doppler residuals and the corresponding noise budget of the open-loop Doppler detections obtained with the PRIDE stations are comparable to the closed-loop Doppler detections obtained with the dedicated deep space tracking facilities.

A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of $4\times10^{-4}$. We expect to reach $2.5\times10^{-5}$ with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission., Submitted to the 14th Marcel Grossmann Meeting Proceedings

International audience; The European program FP7-ESPaCE is a collaborative activity, which aims at exploiting space and ground-based data for providing new ephemerides of several natural satellites and spacecraft. New technologies applied to the positioning of spacecraft are also studied. ESPaCE addresses also data related to gravity and shape modeling, control point network and rotational parameters of natural satellites. The accuracy improvement of these ephemerides makes them a powerful tool for the analysis of space missions or the preparation of future missions, or for the determination of some physical parameters. This communication gives the preliminary results obtained at the mid-term of this program.