IonoWatch shows a UTC clock and a map of HF propagation from your own QTH. Principle: cautious rather than euphoric – uncertain paths are shown yellow at most.
SP (short path) is the shorter part of the great circle between two stations. LP (long path) is the other, longer part of the same great circle (40,000 km minus the SP distance), in the opposite direction (bearing + 180°). LP is often open only briefly, mostly along the grey line or across the night side.
The SP/LP buttons choose which path is rated. For a clicked call the map draws both great-circle paths: SP solid (blue), LP dashed (orange); the selected path is strong, the other faint.
On LP and beyond 9000 km: a single strong own spot with P.533 support gives yellow at most; green needs at least three independent confirmations.
ITU-R P.533 (ITURHFProp), NOAA SWPC (Kp, Bz, X-ray, D-RAP, OVATION aurora), KC2G (eSSN), wspr.live, PSKReporter (FT8) and RBN (CW skimmers). Own spots weigh most. An active skimmer that hears other stations from your area but not your signal lowers the rating there moderately.
If a source cannot be reached, a red notice appears below the gear. Clicking it shows each source's status with the reason; for TLS/certificate errors "More info" gives hints for your Windows version, and "Copy error" copies the details. IonoWatch never changes anything on your PC.
From spots on 15/12/10/6 m over 300–2300 km (one Es hop) that F2 cannot explain. An Es MUF is estimated per cloud from the hop geometry; a seasonal factor is included. Es is "possible/fluctuating": yellow at most, fading after 15–20 min. Single unanswered CQs count half; FT8-only evidence is marked in the tooltip (FT8 decodes 15–20 dB weaker than CW). Spots beyond 3000 km count as F2.
Mouse wheel: zoom around the pointer; drag to pan; double-click or "1:1" to reset. Mouse over the map: SNR, distance, bearing. ⓘ Info: all details of the rating, hold-out hit rates with n and confidence, learned antenna correction. Gear: call, locator, power, antenna, accuracy, skimmer display, language (applies immediately).