| Spolaor, Max | Radial gradients in elliptical galaxies | 2009 | Swinburne University of Technology | GMOS-S | Australia |
| Spengler, Chelsea | Nuclear star clusters in the Virgo Cluster of galaxies | 2018 | University of Victoria | GMOS-S | Canada |
| Smith, Rachel | The Evolution of Debris Disk Systems: Constraints from Theory and Observation | 2008 | University of Edinburgh | MICHELLE/TRECS | UK |
| Smith, Daniel J. B. | A wide-area search for high redshift Lyman alpha haloes | 2007 | University of Oxford | GMOS-N | UK |
| Smith Castelli, Analia | Poblaciones de galaxias en el cumulo de Antlia | 2008 | Universidad Nacional de La Plata (UNLP) | GMOS-S | Argentina |
| Skemer, Andrew | High spatial resolution mid-infrared studies of planetary systems | 2011 | The University of Arizona | MICHELLE/TRECS | USA |
| Sinnott, Brendan | Spectroscopy and photometry of scattered light echoes from supernovae | 2013 | McMaster University | GMOS-S | Canada |
| Singer, Leo P. | The needle in the hundred square haystack: the hunt for binary neutron star mergers with LIGO and Palomar Transient Factory | 2015 | California Institute of Technology | GMOS-N/GMOS-S | USA |
| Simanton, Lesley Ann | Star Cluster Populations in the Spiral Galaxy M101 | 2015 | University of Toledo | GMOS-N | USA |
| Silge, Julia Dorothea | Sweep the dust away: infrared kinematics of nearby galaxies | 2005 | The University of Texas at Austin | GNIRS | USA |
| Siegler, Nicholas | Discovery of very-low mass binary stars and circumstellar disks in the infrared | 2007 | The University of Arizona | Hokupaa | USA |
| Shih, Hsin-Yi | Radio jet driven outflows: an investigation of extended emission line regions around radio loud AGNs | 2014 | University of Hawaii | GMOS-N | USA |
| Sheppard, Scott S. | Small bodies in the outer solar system: from Kuiper Belt objects to Centaurs to satellites | 2004 | University of Hawaii | GMOS-N | USA |
| Sesto, Leandro | Trazando el mapa magnetico de NGC 1316 a traves de su sistema de cumulos globulares | 2017 | Universidad Nacional de La Plata (UNLP) | GMOS-S | Argentina |
| Secrest, Nathan J. | Supermassive black holes in bulgeless and dwarf galaxies: a multi-wavelength investigation | 2014 | George Mason University | GMOS-N | USA |
| Schwamb, Megan E. | Beyond Sedna: probing the distant solar systems | 2011 | California Institute of Technology | GMOS-N | USA |
| Schonell, Astor J. | Estudo da alimentação e Retro-alimentação de núcleos ativos de galáxias a partir de observações no infravermelho próximo | 2017 | Universidade Federal de Santa Maria (UFSM) | NIFS+ALTAIR | Brazil |
| Schnorr Muller, Allan | Feeding the Super Massive Black Hole in Active Galactic Nuclei | 2013 | Federal University of Rio Grande do Sul | GMOS-N/GMOS-S | Brazil |
| Schlieder, Joshua Edward | New low-mass members of nearby young moving groups | 2011 | State University of New York at Stony Brook | PHOENIX | USA |
| Schimoia, Jáderson da Silva | Double peaked profiles: revealing the presence of accretion disks in the broad line region of active galaxies | 2015 | Federal University of Rio Grande do Sul | GMOS-S | Brazil |
