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*** SPoCA Coronal Hole *** This service provides a catalog of Coronal Holes obtained with the Spatial Possibilitistic Clustering Algorithm (SPoCA). Level 2 AIA 19.3nm images (calibrated and corrected for degradation) are used, at a cadence of one AIA image every 6 hours. Only coronal holes older than three days are being reported. Bounding box and characteristics such as areas and pixel intensity statistics, on AIA 19.3nm and HMI magnetogram images are provided.

USET CaIIK Solar Images

Uccle Solar Equatorial Table (USET) Calcium II-K observations. Full disk solar images taken at the Royal Observatory of Belgium.
USET Drawings

*** USET sunspot drawing *** The Uccle Solar Equatorial Table (USET) facility at the Royal Observatory of Belgium has gathered an uninterrupted series of sunspot drawings since year 1941. This collection continues to be updated when weather permits. This table provides information about these drawings.
USET Drawings

USET links drawings and sunspots
USET Drawings form

USET Drawing form
USET Group form

USET Group form
USET Groups

*** USET Groups *** Values in the USET sunspot group catalog are derived from the solar drawings obtained by the Uccle Solar Equatorial Table (USET) facility that is located at the Royal Observatory of Belgium. The USET sunspot group catalog covers 82 years of observations in 2021, and is updated every day. A home-made software (DigiSun) written in Python is used to derive quantities such as location and areas from the sunspot drawings.

ROB Virtual Observatory Data Center