The Sardinia Radio Telescope (SRT): A large modern radio telescope for observations from meter to mm wavelengths

The Sardinia Radio Telescope (SRT) is a new 64-m across radio astronomical facility located in Sardinia, Italy, and operated by the National Institute for Astrophysics (INAF). It can operate on a broad frequency range -300 MHz to 115 GHz, and is equipped with three different focus solutions: a primary, a Gregorian, and four Beam Wave Guide foci. The primary mirror is an active surface able to compensate the gravitational stress variations at different elevations and keeps the antenna gain flat and optimal at any elevation, as proven by regular observations of the 20-GHz system of the telescope. The optics is shaped and designed to minimise bandpass ripples that can jeopardise deep spectroscopic observations. Tests have delivered stunning results making SRT a world-class instrument for spectro-scopic astrophysical research. Currently, the receiver fleet comprises a P-L-band co-axial receiver (300-410 MHz and 1300-1800 MHz), a C-band system (5.7-7.7 GHz), and a K-band 7-beam array (18-26 GHz). A second C-band receiver (4.2-5.6 GHz), a 7-beam S-band array (3.0-4.5 GHz) and a 19-beam Q-band array (33-50 GHz) are being developed. The P-L-band package has an ultra-broad frequency coverage and its extension to 300 MHz at the low frequency end makes it a unique pulsar research machine in the current international radio astronomical context. The telescope has officially commenced its single-dish operations on 1 February 2016 with the start of an Early Science Program (ESP) that has been delivering stunning results. In this talk we will present the telescope, its main features that make it a unique radio astronomical instrument for several types of astrophysical observations, and results from its ESP campaign.