The extraordinary colors of trans-neptunian objects 1994 TB and 1993 SC

We present B-V and V-R colors for trans-neptunian objects (TNOs) 1994 TB and 1993 SC. We have found that these TNOs have colors almost as red as 5145 Pholus which are therefore consistent with surfaces rich in complex organic molecules. We have measured B-V colors of 1.10 ± 0.15 and 1.27 ± 0.11 for 1994 TB and 1993 SC, respectively, as well as V-R colors of 0.68 ± 0.06 and 0.70 ± 0.04 for 1994 TB and 1993 SC, respectively. Currently, there are only four TNOs with published broadband colors (1992 QB1, 1993 FW, 1993 SC, and 1994 TB). TNO colors range from solar (a single V-R measurement of 1993 FW in the literature) to nearly the reddest objects in the solar system (our measurements of 1993 SC and 1994 TB). Although we have concluded 1993 SC is a very red TNO, a measurement in the literature has suggested that there is nothing special about the color of 1993 SC. Because there are so few TNOs with color measurements and because colors for 1993 SC are inconsistent, we cannot say yet with any certainty whether the surfaces of TNOs exhibit a diversity of colors and hence a diversity of surface compositions.