... Through development of in-depth knowledge of spectrographs on HST, the ST-ECF has established physical modelling of spectrometers, applied to FOS and STIS, and slitless spectroscopy, as applied to NICMOS and ACS, as its areas of instrument science expertise. WFC3 grism mode (@STSCI) . ACS grism mode (@STSCI) . NICMOS grism mode (@STSCI) . STIS Calibration Enhancement (@STSCI) . FOS . Slitless Spectroscopy Simulations (@STSCI) . TinyTim with WFC3 support (@STSCI) . ...