Electronic timer switch with astro program for rail mounting, 1 changeover contact for 16 A / 250 V AC (AC1), LCD display, joystick programming or programming via an NFC-enabled smartphone with the Finder Toolbox app (Android and iOS). After installing the Finder app, an existing program can be read out or a new program can be created with maximum flexibility. To transfer data, the timer switch is touched with the smartphone. Astronomical time control through automatic switching at sunrise and sunset using postal code or geographic coordinates, selectable time offset for sunrise and sunset, as well as turning on and off during the astro on-time. Contact material AgSnO2, maximum inrush current 120 A for 5 ms, pulse function from 1 second to 59 minutes, shortest switching time 1 minute, maximum switching power at 230 V AC1: 4000 VA. Lamp loads: incandescent and halogen lamps 2000 W, energy-saving lamps 400 W, LED (230 V AC) 400 W, low-voltage halogen lamps or LED with electronic ballast 400 W, low-voltage halogen lamps or LED with magnetic ballast 800 W, fluorescent lamps with electronic ballast 1000 W, fluorescent lamps with magnetic ballast 750 W, safe isolation between power supply and contact.