0 Assigned ID: 690 ----- Attempting Submission 1 (Fri Mar 06 19:22:44 GMT 2020) ----- HST Phase I Proposal 690 successfully submitted. Receipt: # 690-1 Resubmit with the target confirmation run correctly 257660594 ----- Attempting Submission 1 (Thu Jun 04 02:53:33 GMT 2020) ----- HST Phase II Proposal 16220 successfully submitted. Receipt: # 16220-1 ----- Attempting Submission 2 (Thu Jun 04 20:49:32 GMT 2020) ----- We wish to use 5 orbits of HST/WFC3 time to observe an eclipse spectrum of the only known transiting brown dwarf that has all of its physical properties independently measured at high precision, and that receives a negligible amount of external irradiation. Brown dwarfs evolve in both radius and temperature as they age, changing their atmospheric spectral emission with time. Understanding this evolution is important because it informs us about their interior structure, which ultimately helps constrain where the dividing line is between brown dwarfs that form through "star-like" Jeans-collapse or "planet-like" accretion. However, a fundamental problem in brown dwarf evolution and atmosphere models has been our inability to directly measure their basic physical properties, and no one has yet observed the atmosphere of a non-irradiated brown dwarf where we know all of them. The discovery of our target system finally allows us to conduct just this sort of observation using HST/WFC3 -- in conjuntion with archival Spitzer eclipse observations at 3.6um and 4.5um. Measuring the emission spectrum will allow us to perform a set of tests on brown dwarf evolution and atmospheres models with an an over-constrained physical system with no major free parameters. The results will provide a one-of-a-kind observational anchor for brown dwarfs. These observations are to observe a secondary eclipse of AD 3116b using WFC3/G141. These observations will require 5 orbits to complete. The eclipse duration of AD 3116b is 3.1 hours, so we wish to observe for a minimum of 6.2 hours to see a suffcient amount of out-of-transit baseline. 6.2 hours of observations can be completed using 4 orbits, but we are also including 1 additional orbit at the beginning of each visit to allow the spacecraft and detector to settle and remove the initial systematic noise typical in observations using WFC3. We are using staring mode -- rather than scanning -- because AD 3116 is relatively faint. Dr. Thomas Beatty Expert in the data reduction and analysis of WFC3 spectroscopic eclipse observations. Dr. John Gizis Expert in spectroscopy of very-low-mass stars and brown dwarfs. Dr. Michael Line Expert in transiting exoplanet spectral/retrieval/chemical modeling and brown dwarf forward and retrieval modeling. Dr. Mark Marley Modeler of extrasolar planet and brown dwarf atmospheres, clouds, spectra, and evolution. Dr. Daniel Stevens Expert in modeling eclipsing binaries and SED/parallax determinations of stellar properties. Stellar Physics and Stellar Types Exoplanets and Exoplanet Formation 6 false false false false false false false SUPPORTED STAR BROWN DWARF EXTRA-SOLAR PLANETARY SYSTEM M V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. EPIC-211946007 J2000 J2000 J=14.348, H=13.769, K = 13.499 WFC3/IR Spectroscopic No No G141 C:\Users\tgbea\AppData\Local\Temp\OPVisit10255674666699781600.xml 1591303696250 The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. 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