Fast Spectroscopy And Imaging With The FORS2 HIT Mode

The HIgh-Time resolution (HIT) mode of FORS2 has 3 sub-modes that allow for imaging and spectroscopy over a range of timescales from milliseconds up to seconds. It is the only high time resolution spectroscopy mode available on an 8 m class telescope. In imaging mode, it can be used to measure the pulse of pulsars and spinning white dwarfs in a variety of high throughput broadand narrowband filters. In spectroscopy mode it can take up to 10 spectra per second using a novel “shift-and-wait” clocking pattern for the CCD. It takes advantage of the userdesigned masks which can be inserted into FORS2 to allow any two targets within the 6.8’ × 6.8’ field of view of FORS2 to be selected. A number of integration, or more precisely ‘wait’, times are available, which together with the high throughput GRISMs can observe the entire optical spectrum on a range of timescales.