| 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 |
| 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 |
| Schaller, Emily Lauren | I. Seasonal changes in Titan's cloud activity. II. Volatile ices on outer solar system objects | 2008 | California Institute of Technology | NIRI+ALTAIR | USA |
| Schaefer, Gail Helen | Dynamical masses of pre-main sequence stars | 2004 | State University of New York at Stony Brook | NIRI+ALTAIR | USA |
| Scarano, Sérgio | Rotation Curves and Metallicity Gradients of Spiral Galaxies: The Role of the Corotation Radius and New Observations | 2008 | University of Sao Paulo | GMOS-N | Brazil |
| Sanmartim, David | População estelar e cinemática de quasares post | 2013 | Federal University of Rio Grande do Sul | GMOS-N/GMOS-S | Brazil |
| Sanders, Nathan Edward | Core-collapse Supernova Progenitors in the Era of Untargeted Transient Searches | 2014 | Harvard University | GMOS-N | USA |
| Salinas, Ricardo | Dark matter in central and isolated galaxies | 2011 | Universidad de Concepcion | GMOS-S | Chile |
| Sales, Dinalva Aires de | Propriedades físicas dos silicatos e hidrocarbonetos aromáticos policíclicos presentes na região nuclear das galáxias Seyferts e Starburst | 2012 | Federal University of Rio Grande do Sul | MICHELLE/TRECS | Brazil |
| Rose, Marvin | On the nature of the red, 2MASS-selected AGN in the local Universe | 2012 | University of Sheffield | GMOS-S | UK |
