sentinel-1a

C-band SAR. All-weather, day/night imaging. Gold standard for flood-extent mapping, ship detection, post-event damage assessment, and oil-spill detection. S1A still operational; S1B failed Dec 2021 until S1C launch.

Sensor	C-SAR (C-band Synthetic Aperture Radar)
Resolution	5m × 20m (IW SLC), 10m (GRD)
Revisit (days)	12
STAC	sentinel-1-grd
GEE	COPERNICUS/S1_GRD