The celestron nexstar 90 slt computerised telescope has the high quality 90mm maksutov cassegrain optical design it comes with a fully computerised altazimuth mount and starpointer finderscope to help with alignment and accurately locating objects powered by 8 aa user supplied batteries or an optional ac adapter 18778 the nexstar love to travel the internal battery compartment provides power to the high precision servo motors for rigid low vibration performance while eliminating cor