Planning experiment with the Spektr-UF observatory: the first webversion of exposure time calculator

Planned for the launch in late 20s Spektr-UF space observatory, being created in Russia, is designed to obtain images and spectra of space objects in the ultraviolet region of the electromagnetic spectrum (115 – 310 nm). An important part of the observatory is a special software - an exposure time calculator (ETC). This software is necessary for planning and implementing the observatory's scientific program. It allows not only to evaluate the possibility of registering a signal from an astronomical object of interest, but also to prepare and select applications, as well as draw up an observation program. In preparation for the launch of Spektr-UF, an exposure calculator for this observatory was developed, with which users can plan photometric and spectral observations of various astronomical objects. When developing this program, the experience of other missions, primarily the Hubble Space Telescope (HST), was used. The work reviews the main capabilities of the Spektr-UF ETC and also presents a mathematical model of this calculator that characterizes the signal recording process. Based on real examples, the possibility of implementing photometry and spectroscopy modes for astronomical objects using various scientific instruments of the observatory is discussed. And some observational limits are shown. Plans for the improvement of the ETC are discussed too.