Comet C/2012 S1 (ISON): Observations of the Dust Grains from SOFIA and of the Atomic Gas from NSO Dunn and McMath-Pierce Solar Telescopes (Invited)

Comet C/2012 S1 (ISON) is unique in that it is a dynamically new cometderived from the Oort cloud reservoir of comets with a sun-grazingorbit. Infrared (IR) and visible wavelength observing campaigns wereplanned on NASA's Stratospheric Observatory For Infrared Astronomy(SOFIA) and on National Solar Observatory Dunn (DST) and McMath-PierceSolar Telescopes, respectively. We highlight our early results. SOFIA(+FORCAST [1]) mid- to far-IR images and spectroscopy (~5-35 μm) ofthe dust in the coma of ISON are to be obtained by the ISON-SOFIA Teamduring a flight window 2013 Oct 21-23 UT (r_h≈1.18 AU). Dustcharacteristics, identified through the 10 μm silicate emissionfeature and its strength [2], as well as spectral features from cometarycrystalline silicates (Forsterite) at 11.05-11.2 μm, and near 16, 19,23.5, 27.5, and 33 μm are compared with other Oort cloud comets thatspan the range of small and/or highly porous grains (e.g., C/1995 O1(Hale-Bopp) [3,4,5] and C/2001 Q4 (NEAT) [6]) to large and/or compactgrains (e.g., C/2007 N4 (Lulin) [7] and C/2006 P1 (McNaught) [8]).Measurement of the crystalline peaks in contrast to the broad 10 and 20μm amorphous silicate features yields the cometary silicatecrystalline mass fraction [9], which is a benchmark for radial transportin our protoplanetary disk [10]. The central wavelength positions,relative intensities, and feature asymmetries for the crystalline peaksmay constrain the shapes of the crystals [11]. Only SOFIA can look forcometary organics in the 5-8 μm region. Spatially resolvedmeasurements of atoms and simple molecules from when comet ISON is nearthe Sun (r_h<0.4 AU, near Nov-20--Dec-03 UT) were proposed for bythe ISON-DST Team. Comet ISON is the first comet since comet Ikeya-Seki(1965f) [12,13] suitable for studying the alkalai metals Na and K andthe atoms specifically attributed to dust grains including Mg, Si, Fe,as well as Ca. DST's Horizontal Grating Spectrometer (HGS) measures 4settings: Na I, K, C2 to sample cometary organics (along with Mg I), and[O I] as a proxy for activity from water [14] (along with Si I and FeI). State-of-the-art instruments that will also be employed include IBIS[15], which is a Fabry-Perot spectral imaging system that concurrentlymeasures lines of Na, K, Ca II, or Fe, and ROSA (CSUN/QUB) [16], whichis a rapid imager that simultaneously monitors Ca II or CN. FromMcMath-Pierce, the Solar-Stellar Spectrograph also will target ISON(320-900 nm, R~21,000, r_h