Analysis of 32 years of Arecibo planetary-radar observations of Venus (1988–2020) to measure its rotation elements and build a registered global radar image.
Writeup: Amateur Estimates of the Rotational Elements of Venus using 32 years of Arecibo Planetary Radar
Planetary radar astronomy maps
celestial bodies with active radar. From 1988 to 2020 Arecibo intermittently observed
Venus in delay-Doppler mode; the data are
archived at the PDS Geosciences Node
(Bruce A. Campbell & Donald B. Campbell 2022, Planet. Sci. J. 3 55,
doi:10.3847/PSJ/ac4f43). This repository projects each coherent look into a Venus
body-fixed frame, finds the spin (period and pole) under which all looks co-register,
and stacks them into a global image — the rotation elements and the crisp image are
two readouts of the same registration (see project_goal.md).
- Sidereal rotation period: P = 243.0206 ± 0.0007 d, pole adopted from IAU (RA 272.76°, Dec 67.16°) — consistent with Campbell 2019 (243.0212) and Margot 2020 (243.0226), above the Magellan/IAU 243.0185.
- Global stack of all 916 looks, both latitude hemispheres (−85°…+83°), at up to
~1.2 km/px (
results/figures/global_*,results/session_stacks/global_*.npz).
Coverage is both north and south but only the Earth-facing ~185° of longitude — Earth-based radar sees only the sub-Earth disk, and the six inferior-conjunction epochs sample a limited longitude range.
See REPORT.md for methods, conventions, validation, and the full result.
venera/— tested library (cspyce + DE440s geometry, projection, registration, rotation fit, stacking). The durable code; run.conda/bin/python test/run_all.py.scripts/— drivers (project all looks → stack → period estimate → global map); seescripts/README.md.PLAN.md— remaining/optional refinements.
Example delay-Doppler image:
