0 See Proposal Description for comments on Phase II setup. This revision of my first Phase II submittal incorporates Dan Welty's comments to improve the target ACQ exposure and now uses the STIS CCD LP filter for ACQ with a shorter exposure time of 0.4 s. The G230L exposures in Orbit #1 have been increased slightly to fill up the orbit. The STIS.ta. and STIS.sp. run numbers have been updated corresponding to new ETC runs. The target B magnitude has been corrected to B = 13.42 (Simbad). 912310212 ----- Attempting Submission 1 (Wed Jun 10 22:16:19 GMT 2020) ----- HST Phase II Proposal 16290 successfully submitted. Receipt: # 16290-1 ----- Attempting Submission 2 (Sat Jun 27 21:45:34 GMT 2020) ----- Observational studies of planet-hosting T Tauri stars (TTS) provide crucial insight into the earliest evolutionary stages of planet formation at ages of a few Myr. In a exciting new discovery, two giant protoplanets have been directly imaged orbiting in the disk gap of the nearby (113 pc) TTS PDS 70. The gap is gas-depleted, directly exposing the protoplanets to UV and X-ray irradiation from the star. PDS 70 is the closest planet-hosting TTS discovered so far and viewed through very low extinction, making it an exceptional target for UV spectroscopy with HST. We propose to obtain the first UV spectra of PDS 70 using STIS FUV (G140L) and NUV (G230L) gratings. Our main objectives are to determine the star's accretion rate (which remains controversial) and use the UV spectra, along with existing X-ray spectra, to assess the impact of UV/X-ray irradiation on disk and protoplanet atmosphere ionization and heating. Stellar UV and X-ray emission influence disk dissipation and mass-loss, thus affecting the timescale for planet-formation, a key constraint for planet-formation models. We propose to obtain STIS/MAMA long-slit (52 x 0.2 arcsec aperture) spectra of the T Tauri star PDS 70 with G140L (1 orbit) and G230L (1 orbit). We prefer that the two spectra be obtained contemporaneously and we have thus packaged them into one Visit (2 orbits) in Phase II. There are no Orient or explicit Timing constraints. In Phase II, we have used G140L and G230L exposure times of 887 and 739 s respectively with 3 iterations to fill the orbits. We want to use these shorter exposures to check for possible spectral variability across exposures, which may be present in our target since T Tauri stars often vary in the UV. We have requested the G140L exposure to be placed in the second orbit since it provides more usable exposure time and we anticipate lower fluxes in the FUV than in NUV. For the representative STIS ETC G230L simulation (number entered in APT template) we have assumed a Pickles K7V spectral type normalized to B = 13.42 mag (Simbad), and have added a representative Mg II doublet line (2799 A.) using a line flux of 1.0e-13 erg/cm2/s (sum of the doublet components) typical of T Tauri stars. For the G140L ETC simulation we have assumed a faint flat continuum and have added a C IV doublet line (1549 A.) using a typical T Tauri star doublet line flux of 1.65e-14 erg/cm2/s (sum of the doublet components). We will perform a target ACQ but since we are using a 0.2 arcsec slit width we have not inserted a PEAK-up in the Phase II observing plan. We have selected the STIS LP filter (F28X50LP) for ACQ. We have set the ACQ exposure time to 0.4 s which ETC simulations indicate will provide SNR = 178 - 289, depending on what input values we use to normalize the target flux for Pickles K7V spectral template , i.e. B=13.42, V = 12.18, R = 11.71, or F_lambda = 2.2e-15 ergs/cm2/s/A from Swift U-filter (center=3465 A.) flux density. Using B=13.42 gives SNR=289 in 0.4 s (t_sat = 1.6 s), V = 12.18 gives SNR = 270 (t_sat= 1.83 s), R=11.71 gives SNR=204 (t_sat = 3.21 s), and the Swift U-filter flux density gives SNR=178 (t_sat = 4.17 s). Our team has extensive experience analyzing observational data for T Tauri stars, including STIS UV spectra and modeling disk irradiation of TTS hosting exoplanets. Representative publications are: i) Skinner, S., Schneider, P., Audard, M., and Guedel, M., 2018, ApJ, 855,143 'Resolving the Inner Arcsecond of the RY Tau Jet with HST' ii) Skinner, S. and Guedel, M., 2020, ApJ, 888, 15 ' X-ray Emission and Disk Irradiation of HL Tau and HD 100546' iii) Skinner, S. and Guedel, M., 2017, ApJ, 839, 45 ' XMM-Newton X-ray Observations of LkCa 15: A T Tauri Star with a Formative Planetary System' Stellar Physics and Stellar Types Exoplanets and Exoplanet Formation 6 false false true false false false false SUPPORTED STAR K V-IV T TAURI STAR RA, Dec are from Simbad (referenced to Gaia DR2). RA, Dec errors, Proper Motion, Radial Velocity are from Gaia DR2. V mag and uncertainty are from range given in Simbad. CD-408434 GSC07811-01917 J2000 J2000 B=13.42 (Simbad); Swift uvw2 (1599-2256 A.) = 1.5e-13 ergs/cm^2/s; uvwI (2253-2946 A.) = 2.7e-13 ergs/cm^2/s (ref. Joyce et al. 2020) STIS/FUV-MAMA Spectroscopic No No G140L 1425 STIS/NUV-MAMA Spectroscopic No No G230L 2376 1593279053404 /Users/skinners/Downloads/OP-cache/pds70_cyc28_phase2_ver4-v01.xml The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. 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