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The study of cometary composition is important for understanding our solar system's early evolutionary processes. Carbon dioxide (CO2) is a common hypervolatile in comets that can drive activity but is more difficult to study than other hypervolatiles due to severe telluric absorption. CO2 can only be directly observed from space-borne assets. Therefore, a proxy is needed to measure CO2 abundances in comets using ground-based observations. The flux ratio of the [O I] 5577 A line to the sum of the [O I] 6300 A and [O I] 6364 A lines (hereafter referred to as the [O I] line ratio) has, with some success, been used in the past as such a proxy. We present an [O I] line ratio analysis of comet 45P/Honda-Mrkos-Pajdu\v{s}\'akov\'a (HMP), using data obtained with the Tull Coud\'e Spectrograph on the 2.7-meter Harlan J. Smith telescope at McDonald Observatory, taken from UT February 21-23, 2017 when the comet was at heliocentric distances of 1.12-1.15 AU. HMP is a hyperactive Jupiter family comet (JFC). Icy grains driven out by CO2 sublimation have been proposed as a driver of hyperactivity, but the CO2 abundance of HMP has not been measured. From our [O I] line ratio measurements, we find a CO2/H2O ratio for HMP of 22.9 +/- 1.4%. We compare the CO2/H2O ratios to the active fractions of the nine comets (including HMP) in the literature that have data for both values. We find no correlation. These findings imply that CO2 sublimation driving out icy grains is not the only factor influencing active fractions for cometary nuclei., Comment: 17 pages, 8 figures. To be published in The Planetary Science Journal

TU Tau (= HD 38218 = HIP 27135) is a binary system consisting of a C-N carbon star primary and an A-type secondary. We report on new photometry and spectroscopy which tracked the recent disappearance of the A-star secondary. The dimming of the A-star was gradual and irregular, with one or more brief brightenings, implying the presence of nonhomogeneities in the carbon star outflow. We also present evidence that the A-star is actively accreting s-process enriched material from the carbon star and suggest that it will therefore eventually evolve into a Barium giant. This is an important system as well because the A-type star can serve as a probe of the outer atmosphere of the carbon star., Comment: 9 pages, 9 figures, 4 tables, a number of amateur observatories made significant contributions to this research. Paper accepted for publication in The Astronomical Journal

The extraordinary 2021 September-October outburst of Centaur 29P/Schwassmann-Wachmann 1 afforded an opportunity to test the composition of primitive Kuiper disk material at high sensitivity. We conducted nearly simultaneous multi-wavelength spectroscopic observations of 29P/Schwassmann-Wachmann 1 using iSHELL at the NASA Infrared Telescope Facility and nFLASH at the Atacama Pathfinder EXperiment (APEX) on 2021 October 6, with follow-up APEX/nFLASH observations on 2021 October 7 and 2022 April 3. This coordinated campaign between near-infrared and radio wavelengths enabled us to sample molecular emission from a wealth of coma molecules and to perform measurements that cannot be accomplished with either wavelength alone. We securely detected CO emission on all dates with both facilities, including velocity-resolved spectra of the CO (J=2-1) transition with APEX/nFLASH and multiple CO (v=1-0) rovibrational transitions with IRTF/iSHELL. We report rotational temperatures, coma kinematics, and production rates for CO and stringent (3-sigma) upper limits on abundance ratios relative to CO for CH4, C2H6, CH3OH, H2CO, CS, and OCS. Our upper limits for CS/CO and OCS/CO represent their first values in the literature for this Centaur. Upper limits for CH4, C2H6, CH3OH, and H2CO are the most stringent reported to date, and are most similar to values found in ultra CO-rich Oort cloud comet C/2016 R2 (PanSTARRS), which may have implications for how ices are preserved in cometary nuclei. We demonstrate the superb synergy of coordinated radio and near-infrared measurements, and advocate for future small body studies that jointly leverage the capabilities of each wavelength.

The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to: (1) to systematically monitor a sample of Dynamically New Comets over the whole sky, and (2) use alerts from existing sky surveys to rapidly respond to and characterize detected outburst activity in all small bodies. The data gathered on outbursts helps to characterize each outburst's evolution with time, assess the frequency and magnitude distribution of outbursts in general, and contributes to the understanding of outburst processes and volatile distribution in the Solar System. The LOOK Project exploits the synergy between current and future wide-field surveys such as ZTF, PanSTARRS, and LSST as well as rapid-response telescope networks such as LCO, and serves as an excellent testbed for what will be needed the much larger number of objects coming from Rubin Observatory. We will describe the LOOK Project goals, the planning and target selection (including the use of NEOexchange as a Target and Observation Manager or "TOM"), and results from the first phase of observations, including the detection of activity and outbursts on the giant comet C/2014 UN271 (Bernardinelli-Bernstein) and the discovery and follow-up of outbursts on comets. Within these outburst discoveries, we present a high cadence of 7P/Pons-Winnecke with days, a large outburst on 57P/duToit-Neujmin-Delporte, and evidence that comet P/2020 X1 (ATLAS) was in outburst when discovered., Comment: 35 pages, 11 figures, accepted for publication in PSJ

Based on the occurrence rates implied by the discoveries of 1I/`Oumuamua and 2I/Borisov, the forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST) should detect $\ge1$ interstellar objects every year (Hoover et al. 2021). We advocate for future measurements of the production rates of H$_2$O, CO$_2$ and CO in these objects to estimate their carbon to oxygen ratios, which traces formation locations within their original protoplanetary disks. We review similar measurements for Solar System comets, which indicate formation interior to the CO snowline. By quantifying the relative processing in the interstellar medium and Solar System, we estimate that production rates will not be representative of primordial compositions for the majority of interstellar comets. Preferential desorption of CO and CO$_2$ relative to H$_2$O in the interstellar medium implies that measured C/O ratios represent lower limits on the primordial ratios. Specifically, production rate ratios of ${\rm Q}({\rm CO})/{\rm Q}({\rm H_2O})<.2$ and ${\rm Q}({\rm CO})/{\rm Q}({\rm H_2O})>1$ likely indicate formation interior and exterior to the CO snowline, respectively. The high C/O ratio of 2I/Borisov implies that it formed exterior to the CO snowline. We provide an overview of the currently operational facilities capable of obtaining these measurements that will constrain the fraction of ejected comets that formed exterior to the CO snowline. This fraction will provide key insights into the efficiency of and mechanisms for cometary ejection in exoplanetary systems., Comment: Accepted for publication at PSJ, 33 pages, 14 figures, preprint for reference at Exoplanets IV Program Number 405.03

The study of comets affords a unique window into the birth, infancy, and subsequent history of the solar system. There is strong evidence that comets incorporated pristine interstellar material as well as processed nebular matter, providing insights into the composition and prevailing conditions over wide swaths of the solar nebula at the time of planet formation. Dynamically new Oort cloud comets harbor primitive ices that have been stored thousands of astronomical units from the Sun and have suffered minimal thermal or radiative processing since their emplacement ~4.5 Gyr ago. Periodic, more dynamically evolved comets such as the Halley-type and Jupiter-family comets reveal the effects of lives spent over a range of heliocentric distances, including perihelion passages into the very inner solar system. Systematically characterizing the information imprinted in the native ice compositions of these objects is critical to understanding the formation and evolution of the solar system, the presence of organic matter and water on the terrestrial planets, the chemistry present in protoplanetary disks around other stars, and the nature of interstellar interlopers such as 2I/Borisov. Although comet rendezvous and sample return missions can provide remarkable insights into the properties of a few short-period comets, the on-sky capacity necessary to perform population-level comet studies while simultaneously remaining sensitive to the paradigm-challenging science that individual comets can reveal can only be provided by remote sensing observations. Here we report the state-of-the-art in ground- and space-based remote sensing of cometary volatiles, review the remarkable progress of the previous decade, articulate the pressing questions that ground- and space-based work will address over the next ten years, and advocate for the technology and resources necessary to realize these aspirations., Comment: White paper for the National Academies of Sciences, Engineering, and Medicine Planetary Science and Astrobiology Decadal Survey 2023-2032

In its 16 years of scientific measurements, the Spitzer Space Telescope performed a number of ground breaking and key infrared measurements of Solar System objects near and far. Targets ranged from the smallest planetesimals to the giant planets, and have helped us reform our understanding of these objects while also laying the groundwork for future infrared space-based observations like those to be undertaken by the James Webb Space Telescope in the 2020s. In this first Paper, we describe how the Spitzer Space Telescope advanced our knowledge of Solar System formation and evolution via observations of small outer Solar System planetesimals, i.e., Comets, Centaurs, and Kuiper Belt Objects (KBOs). Relics from the early formation era of our Solar System, these objects hold important information about the processes that created them. The key Spitzer observations can be grouped into 3 broad classes: characterization of new Solar System objects (comets D/ISON 2012 S1, C/2016 R2, 1I/`Oumuamua); large population surveys of known object sizes (comets, Centaurs, and KBOs); and compositional studies via spectral measurements of body surfaces and emitted materials (comets, Centaurs, and KBOs)., Comment: Published in Nature Astronomy, Volume 4, page 930. This arXiv version pre-dates the proofs corrections; the final published version is availabe at https://rdcu.be/b8fgx

We present high spectral resolution optical observations of comet 21P/Giacobini-Zinner from six nights in 2018. The observations were obtained with the Tull coude spectrograph on the 2.7m Harlan J. Smith Telescope of McDonald Observatory. This comet's spectrum shows strong depletions in C$_2$, C$_3$, CH, and NH$_2$ relative to CN. We explore what it means for a comet to be depleted and show that all of the species are present in the spectrum at similar relative line intensities within a a molecular band compared with a typical comet. The depletions represent a much lower abundance of the species studied., Comment: Accepted for publication in The Planetary Science Journal; 2 tables; 8 figures

The study of comets affords a unique window into the birth, infancy, and subsequent history of the solar system. There is strong evidence that comets incorporated pristine interstellar material as well as processed nebular matter, providing insights into the composition and prevailing conditions over wide swaths of the solar nebula at the time of planet formation. Dynamically new Oort cloud comets harbor primitive ices that have been stored thousands of astronomical units from the Sun and have suffered minimal thermal or radiative processing since their emplacement ~4.5 Gyr ago. Periodic, more dynamically evolved comets such as the Halley-type and Jupiter-family comets reveal the effects of lives spent over a range of heliocentric distances, including perihelion passages into the very inner solar system. Systematically characterizing the information imprinted in the native ice compositions of these objects is critical to understanding the formation and evolution of the solar system, the presence of organic matter and water on the terrestrial planets, the chemistry present in protoplanetary disks around other stars, and the nature of interstellar interlopers such as 2I/Borisov. Although comet rendezvous and sample return missions can provide remarkable insights into the properties of a few short-period comets, the on-sky capacity necessary to perform population-level comet studies while simultaneously remaining sensitive to the paradigm-challenging science that individual comets can reveal can only be provided by remote sensing observations. Here we report the state-of-the-art in ground- and space-based remote sensing of cometary volatiles, review the remarkable progress of the previous decade, articulate the pressing questions that ground- and space-based work will address over the next ten years, and advocate for the technology and resources necessary to realize these aspirations., Comment: White paper for the National Academies of Sciences, Engineering, and Medicine Planetary Science and Astrobiology Decadal Survey 2023-2032

We present high spectral resolution optical spectra obtained with the ARCES instrument at Apache Point Observatory showing detection of the [OI]6300 A line in interstellar comet 2I/Borisov. We employ the observed flux in this line to derive an H$_2$O production rate of (6.3$\pm$1.5)$\times$10$^{26}$ mol s$^{-1}$. Comparing to previously reported observations of CN, this implies a CN/H$_2$O ratio of $\sim$0.3-0.6%. The lower end of this range is consistent with the average value in comets, while the upper end is higher than the average value for Solar System comets, but still within the range of observed values. C$_2$/H$_2$O is depleted, with a value likely less than 0.1%. The dust-to-gas ratio is consistent with the normal value for Solar System comets. Using a simple sublimation model we estimate an H$_2$O active area of 1.7 km$^2$, which for current estimates for the size of Borisov suggests active fractions between 1-150%, consistent with values measured in Solar System comets. More detailed characterization of 2I/Borisov, including compositional information and properties of the nucleus, is needed to fully interpret the observed H$_2$O production rate., Comment: 8 pages, 2 figures, 1 table, Accepted in ApJ Letters

Comet C/2016 R2 (PanSTARRS) has a peculiar volatile composition, with CO being the dominant volatile as opposed to H$_2$O and one of the largest N$_2$/CO ratios ever observed in a comet. Using observations obtained with the \textit{Spitzer Space Telescope}, NASA's Infrared Telescope Facility, the 3.5-meter ARC telescope at Apache Point Observatory, the Discovery Channel Telescope at Lowell Observatory, and the Arizona Radio Observatory 10-m Submillimeter Telescope we quantified the abundances of 12 different species in the coma of R2 PanSTARRS. We confirm the high abundances of CO and N$_2$ and heavy depletions of H$_2$O, HCN, CH$_3$OH, and H$_2$CO compared to CO reported by previous studies. We provide the first measurements (or most sensitive measurements/constraints) on H$_2$O, CO$_2$, CH$_4$, C$_2$H$_6$, OCS, C$_2$H$_2$, and NH$_3$, all of which are depleted relative to CO by at least one to two orders of magnitude compared to values commonly observed in comets. The observed species also show strong enhancements relative to H$_2$O, and even when compared to other species like CH$_4$ or CH$_3$OH most species show deviations from typical comets by at least a factor of two to three. The only mixing ratios found to be close to typical are CH$_3$OH/CO$_2$ and CH$_3$OH/CH$_4$. While R2 PanSTARRS was located at a heliocentric distance of 2.8 AU at the time of our observations in January/February 2018, we argue that this alone cannot account for the peculiar observed composition of this comet and therefore must reflect its intrinsic composition. We discuss possible implications for this clear outlier in compositional studies of comets obtained to date, and encourage future dynamical and chemical modeling in order to better understand what the composition of R2 PanSTARRS tells us about the early Solar System., Comment: 36 pages, 12 figures, 7 tables, accepted for publication in AJ

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Actor RAMI MALEK. He's nominated for an Oscar for best actor for his role as Freddie Mercury in the film Bohemian Rhapsody, about the band Queen. The film is also nominated for Best Picture as well as Best Sound Editing and Best Sound Mixing. MALEK is probably best known for his starring role in the TV series Mr. Robot, as a withdrawn hacker, with social anxiety disorder. (REBROADCAST from 11.21.18) (THIS INTERVIEW CONTINUES THRU THE END OF THE SHOW). (2.) Writer and film director ADAM MCKAY. He's been nominated for Oscars for Best Director and Best Original Screenplay for his film Vice, about Dick Cheney. The film has also been nominated for Best Picture as well. And Christian Bale who transforms himself into Cheney has been nominated for Best Actor. MCKAY's other films include The Big Short, Anchorman, and Talladega Nights. He's former head writer for Saturday Night Live. He also cofounded Funny or Die, and the improv group Upright Citizens Brigade. (REBROADCAST from 1.3.2019) (THIS INTERVIEW CONTINUES INTO THE SECOND HALF OF THE SHOW).

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Writer and film director ADAM MCKAY. His new film Vice, is about Dick Cheney, and it stars Christian Bale who transforms himself into Cheney. The film has been nominated for six Golden Globes. MCKAY's other films include The Big Short, Anchorman, and Talladega Nights. He's former head writer for Saturday Night Live. He also cofounded Funny or Die, and the improv group Upright Citizens Brigade. (THIS INTERVIEW CONTINUES INTO THE SECOND HALF OF THE SHOW). (2.) Linguist GEOFF NUNBERG considers the lack of understanding about indigenous languages and cultures south of the U.S. border.

Comet C/2016 R2 (PanSTARRS) has a peculiar volatile composition, with CO being the dominant volatile as opposed to H$_2$O and one of the largest N$_2$/CO ratios ever observed in a comet. Using observations obtained with the \textit{Spitzer Space Telescope}, NASA's Infrared Telescope Facility, the 3.5-meter ARC telescope at Apache Point Observatory, the Discovery Channel Telescope at Lowell Observatory, and the Arizona Radio Observatory 10-m Submillimeter Telescope we quantified the abundances of 12 different species in the coma of R2 PanSTARRS. We confirm the high abundances of CO and N$_2$ and heavy depletions of H$_2$O, HCN, CH$_3$OH, and H$_2$CO compared to CO reported by previous studies. We provide the first measurements (or most sensitive measurements/constraints) on H$_2$O, CO$_2$, CH$_4$, C$_2$H$_6$, OCS, C$_2$H$_2$, and NH$_3$, all of which are depleted relative to CO by at least one to two orders of magnitude compared to values commonly observed in comets. The observed species also show strong enhancements relative to H$_2$O, and even when compared to other species like CH$_4$ or CH$_3$OH most species show deviations from typical comets by at least a factor of two to three. The only mixing ratios found to be close to typical are CH$_3$OH/CO$_2$ and CH$_3$OH/CH$_4$. While R2 PanSTARRS was located at a heliocentric distance of 2.8 AU at the time of our observations in January/February 2018, we argue that this alone cannot account for the peculiar observed composition of this comet and therefore must reflect its intrinsic composition. We discuss possible implications for this clear outlier in compositional studies of comets obtained to date, and encourage future dynamical and chemical modeling in order to better understand what the composition of R2 PanSTARRS tells us about the early Solar System., Comment: 36 pages, 12 figures, 7 tables, accepted for publication in AJ

We present high spectral resolution optical spectra obtained with the ARCES instrument at Apache Point Observatory showing detection of the [OI]6300 A line in interstellar comet 2I/Borisov. We employ the observed flux in this line to derive an H$_2$O production rate of (6.3$\pm$1.5)$\times$10$^{26}$ mol s$^{-1}$. Comparing to previously reported observations of CN, this implies a CN/H$_2$O ratio of $\sim$0.3-0.6%. The lower end of this range is consistent with the average value in comets, while the upper end is higher than the average value for Solar System comets, but still within the range of observed values. C$_2$/H$_2$O is depleted, with a value likely less than 0.1%. The dust-to-gas ratio is consistent with the normal value for Solar System comets. Using a simple sublimation model we estimate an H$_2$O active area of 1.7 km$^2$, which for current estimates for the size of Borisov suggests active fractions between 1-150%, consistent with values measured in Solar System comets. More detailed characterization of 2I/Borisov, including compositional information and properties of the nucleus, is needed to fully interpret the observed H$_2$O production rate., Comment: 8 pages, 2 figures, 1 table, Accepted in ApJ Letters

We report on imaging and spectroscopic observations of comet C/2016~R2 (Pan-STARRS) obtained with the 0.8\,m and 2.7\,m telescopes of McDonald Observatory in November and December 2017 respectively. The comet was at a heliocentric distance greater than 3\,{\sc au} during both sets of observations. The images showed a well-developed tail with properties that suggested it was an ion tail. The spectra confirmed that we were observing well-developed bands of CO$^+$ and N$_2^+$. The N$_2^+$ detection was unequivocally cometary and was one of the strongest bands of N$_2^+$ detected in a comet spectrum. We derived the ratio of these two ions and from that we were able to derive that N$_2$/CO = 0.15. This is the highest such ratio reported for a comet. Note erratum - N2/CO=0.06 not 0.15., Comment: Published in ApJL 9 February 2018. This version includes an erratum on the last page after references (accepted by ApJL) on the value of N2/CO

We present H$_2$O production rates for comet C/2012 S1 (ISON) derived from observations of [OI] and OH emission during its inbound leg, covering a heliocentric distance range of 1.8-0.44 AU. Our production rates are in agreement with previous measurements using a variety of instruments and techniques and with data from the various observatories greatly differing in their projected fields of view. The consistent results across all data suggest the absence of an extended source of H$_2$O production, for example sublimation of icy grains in the coma, or a source with spatial extent confined to the dimensions of the smallest projected field of view (in this case $<$ 1,000 km). We find that ISON had an active area of around 10 km$^2$ for heliocentric distances R$_h$ > 1.2 AU, which then decreased to about half this value from R$_h$=1.2-0.9 AU. This was followed by a rapid increase in active area at about R$_h$=0.6 AU, corresponding to the first of three major outbursts ISON experienced inside of 1 AU. The combination of a detected outburst in the light curve and rapid increase in active area likely indicates a major nucleus fragmentation event. The 5-10 km$^2$ active area observed outside of R$_h$=0.6 AU is consistent with a 50-100% active fraction for the nucleus, larger than typically observed for cometary nuclei. Although the absolute value of the active area is somewhat dependent on the thermal model employed, the changes in active area observed are consistent among models. The conclusion of a 50-100+% active fraction is robust for realistic thermal models of the nucleus. However the possibility of a contribution of a spatially unresolved distribution of icy grains cannot be discounted., Comment: 26 pages, 5 figures, 5 tables, accepted for publication in Icarus

We present H$_2$O production rates for comet C/2012 S1 (ISON) derived from observations of [OI] and OH emission during its inbound leg, covering a heliocentric distance range of 1.8-0.44 AU. Our production rates are in agreement with previous measurements using a variety of instruments and techniques and with data from the various observatories greatly differing in their projected fields of view. The consistent results across all data suggest the absence of an extended source of H$_2$O production, for example sublimation of icy grains in the coma, or a source with spatial extent confined to the dimensions of the smallest projected field of view (in this case $<$ 1,000 km). We find that ISON had an active area of around 10 km$^2$ for heliocentric distances R$_h$ > 1.2 AU, which then decreased to about half this value from R$_h$=1.2-0.9 AU. This was followed by a rapid increase in active area at about R$_h$=0.6 AU, corresponding to the first of three major outbursts ISON experienced inside of 1 AU. The combination of a detected outburst in the light curve and rapid increase in active area likely indicates a major nucleus fragmentation event. The 5-10 km$^2$ active area observed outside of R$_h$=0.6 AU is consistent with a 50-100% active fraction for the nucleus, larger than typically observed for cometary nuclei. Although the absolute value of the active area is somewhat dependent on the thermal model employed, the changes in active area observed are consistent among models. The conclusion of a 50-100+% active fraction is robust for realistic thermal models of the nucleus. However the possibility of a contribution of a spatially unresolved distribution of icy grains cannot be discounted., Comment: 26 pages, 5 figures, 5 tables, accepted for publication in Icarus

We report on imaging and spectroscopic observations of comet C/2016~R2 (Pan-STARRS) obtained with the 0.8\,m and 2.7\,m telescopes of McDonald Observatory in November and December 2017 respectively. The comet was at a heliocentric distance greater than 3\,{\sc au} during both sets of observations. The images showed a well-developed tail with properties that suggested it was an ion tail. The spectra confirmed that we were observing well-developed bands of CO$^+$ and N$_2^+$. The N$_2^+$ detection was unequivocally cometary and was one of the strongest bands of N$_2^+$ detected in a comet spectrum. We derived the ratio of these two ions and from that we were able to derive that N$_2$/CO = 0.15. This is the highest such ratio reported for a comet. Note erratum - N2/CO=0.06 not 0.15., Comment: Published in ApJL 9 February 2018. This version includes an erratum on the last page after references (accepted by ApJL) on the value of N2/CO

Recent observations have suggested that there is water ice present on the surfaces of 24 Themis and 1 Ceres. We present upper limits on the H$_2$O production rate on these bodies derived using a search for [OI]6300 Angstrom emission. For Themis, the water production is less than 4.5 $\times$ 10$^{27}$ mol s$^{-1}$, while for Ceres our derived upper limit is 4.6 $\times$ 10$^{28}$ mol s$^{-1}$. The derived limits imply a very low fraction of the surface area of each asteroid is active ($<$ 2 $\times$ 10$^{-4}$), though this estimate varies by as much as an order of magnitude depending on thermal properties of the surface. This is much lower than seen for comets, which have active areas of 10$^{-2}$ - 10$^{-1}$. We discuss possible implications for our findings on the nature of water ice on Themis and Ceres., Comment: 15 pages, 3 figures, accepted for publication in Icarus

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Filmmaker TOM McCARTHY - he directed and co-wrote the film Spotlight - which has been nominated for an oscar for best feature, best supporting actor and actress, direction, and original screenplay. It's about a group of journalists at the Boston Globe who in 2002 published a groundbreaking investigation of child sexual abuse by Catholic priests. One of those reporters was WALTER ROBINSON, who also joins us. "Spotlight" stars , who also joins us. "Spotlight" stars Mark Ruffalo, Rachel McAdams, Liev Schreiber and Michael Keaton who plays ROBINSON. (REBROADCAST from 10.29.15) INTERVIEW BY DAVE DAVIES) (2.) ADAM MCKAY talks about directing the new film The Big Short which has been nominated for an oscar for best feature, direction, supporting actor, and original screenplay. It's about the economic collapse of 2008. McKay also directed Anchorman and Talladega Nights. He is a co-founder of the website Funny or Die. (REBROADCAST FROM 12.23.15)

Recent observations have suggested that there is water ice present on the surfaces of 24 Themis and 1 Ceres. We present upper limits on the H$_2$O production rate on these bodies derived using a search for [OI]6300 Angstrom emission. For Themis, the water production is less than 4.5 $\times$ 10$^{27}$ mol s$^{-1}$, while for Ceres our derived upper limit is 4.6 $\times$ 10$^{28}$ mol s$^{-1}$. The derived limits imply a very low fraction of the surface area of each asteroid is active ($<$ 2 $\times$ 10$^{-4}$), though this estimate varies by as much as an order of magnitude depending on thermal properties of the surface. This is much lower than seen for comets, which have active areas of 10$^{-2}$ - 10$^{-1}$. We discuss possible implications for our findings on the nature of water ice on Themis and Ceres., Comment: 15 pages, 3 figures, accepted for publication in Icarus

We present analysis of observations of CO2 and OI emission in three comets to measure the CO2 abundance and evaluate the possibility of employing observations of OI emission in comets as a proxy for CO2. We obtained NIR imaging sensitive to CO2 of comets C/2012 K1 (PanSTARRS), C/2012 K5 (LINEAR), and 290P/Jager with the IRAC instrument on Spitzer. We acquired observations of OI emission in these comets with the ARCES echelle spectrometer mounted on the 3.5-meter telescope at Apache Point Observatory and observations of OH with the Swift observatory (PanSTARRS) and with Keck HIRES (Jager). The CO2/H2O ratios derived from the Spitzer images are 12.6 +/- 1.3% (PanSTARRS), 28.9 +/- 3.6% (LINEAR), and 31.3 +/- 4.2% (Jager). These abundances are derived under the assumption that contamination from CO emission is negligible. The CO2 abundance for PanSTARRS is close to the average abundance measured in comets at similar heliocentric distance to date, while the abundances measured for LINEAR and Jager are significantly larger than the average abundance. From the coma morphology observed in PanSTARRS and the assumed gas expansion velocity, we derive a rotation period for the nucleus of about 9.2 hours. Comparison of H2O production rates derived from ARCES and Swift data, as well as other observations, suggest the possibility of sublimation from icy grains in the inner coma. We evaluate the possibility that the OI emission can be employed as a proxy for CO2 by comparing CO2/H2O ratios inferred from the OI lines to those measured directly by Spitzer. We find that for PanSTARRS we can reproduce the observed CO2 abundance to an accuracy of ~20%. For LINEAR and Jager, we were only able to obtain upper limits on the CO2 abundance inferred from the OI lines. These upper limits are consistent with the CO2 abundances measured by Spitzer., Comment: 30 pages, 6 tables, 7 figures, accepted for publication in Icarus

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We present analysis of observations of CO2 and OI emission in three comets to measure the CO2 abundance and evaluate the possibility of employing observations of OI emission in comets as a proxy for CO2. We obtained NIR imaging sensitive to CO2 of comets C/2012 K1 (PanSTARRS), C/2012 K5 (LINEAR), and 290P/Jager with the IRAC instrument on Spitzer. We acquired observations of OI emission in these comets with the ARCES echelle spectrometer mounted on the 3.5-meter telescope at Apache Point Observatory and observations of OH with the Swift observatory (PanSTARRS) and with Keck HIRES (Jager). The CO2/H2O ratios derived from the Spitzer images are 12.6 +/- 1.3% (PanSTARRS), 28.9 +/- 3.6% (LINEAR), and 31.3 +/- 4.2% (Jager). These abundances are derived under the assumption that contamination from CO emission is negligible. The CO2 abundance for PanSTARRS is close to the average abundance measured in comets at similar heliocentric distance to date, while the abundances measured for LINEAR and Jager are significantly larger than the average abundance. From the coma morphology observed in PanSTARRS and the assumed gas expansion velocity, we derive a rotation period for the nucleus of about 9.2 hours. Comparison of H2O production rates derived from ARCES and Swift data, as well as other observations, suggest the possibility of sublimation from icy grains in the inner coma. We evaluate the possibility that the OI emission can be employed as a proxy for CO2 by comparing CO2/H2O ratios inferred from the OI lines to those measured directly by Spitzer. We find that for PanSTARRS we can reproduce the observed CO2 abundance to an accuracy of ~20%. For LINEAR and Jager, we were only able to obtain upper limits on the CO2 abundance inferred from the OI lines. These upper limits are consistent with the CO2 abundances measured by Spitzer., Comment: 30 pages, 6 tables, 7 figures, accepted for publication in Icarus

We present analysis of high spectral resolution NIR spectra of CO and H$_2$O in comet C/2009 P1 (Garradd) taken during its 2011-2012 apparition with the CSHELL instrument on NASA's Infrared Telescope Facility (IRTF). We also present analysis of observations of atomic oxygen in comet Garradd obtained with the ARCES echelle spectrometer mounted on the ARC 3.5-meter telescope at Apache Point Observatory and the Tull Coude spectrograph on the Harlan J. Smith 2.7-meter telescope at McDonald Observatory. The observations of atomic oxygen serve as a proxy for H$_2$O and CO$_2$. We confirm the high CO abundance in comet Garradd and the asymmetry in the CO/H$_2$O ratio with respect to perihelion reported by previous studies. From the oxygen observations, we infer that the CO$_2$/H$_2$O ratio decreased as the comet moved towards the Sun, which is expected based on current sublimation models. We also infer that the CO$_2$/H$_2$O ratio was higher pre-perihelion than post-perihelion. We observe evidence for the icy grain source of H$_2$O reported by several studies pre-perihelion, and argue that this source is significantly less abundant post-perihelion. Since H$_2$O, CO$_2$, and CO are the primary ices in comets, they drive the activity. We use our measurements of these important volatiles in an attempt to explain the evolution of Garradd's activity over the apparition., Comment: 35 pages, 10 figures, 9 tables, accepted for publication in Icarus

We present analysis of high spectral resolution NIR spectra of CO and H$_2$O in comet C/2009 P1 (Garradd) taken during its 2011-2012 apparition with the CSHELL instrument on NASA's Infrared Telescope Facility (IRTF). We also present analysis of observations of atomic oxygen in comet Garradd obtained with the ARCES echelle spectrometer mounted on the ARC 3.5-meter telescope at Apache Point Observatory and the Tull Coude spectrograph on the Harlan J. Smith 2.7-meter telescope at McDonald Observatory. The observations of atomic oxygen serve as a proxy for H$_2$O and CO$_2$. We confirm the high CO abundance in comet Garradd and the asymmetry in the CO/H$_2$O ratio with respect to perihelion reported by previous studies. From the oxygen observations, we infer that the CO$_2$/H$_2$O ratio decreased as the comet moved towards the Sun, which is expected based on current sublimation models. We also infer that the CO$_2$/H$_2$O ratio was higher pre-perihelion than post-perihelion. We observe evidence for the icy grain source of H$_2$O reported by several studies pre-perihelion, and argue that this source is significantly less abundant post-perihelion. Since H$_2$O, CO$_2$, and CO are the primary ices in comets, they drive the activity. We use our measurements of these important volatiles in an attempt to explain the evolution of Garradd's activity over the apparition., Comment: 35 pages, 10 figures, 9 tables, accepted for publication in Icarus

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., 1.) Actor WILL FERRELL & director ADAM MCKAY, the two co-wrote the long awaited follow-up to Anchorman, Anchorman 2. It's set in the 1980s, when CNN made it's debut. This time Ron Burgundy is anchoring a new 24-hour news show. (THIS INTERVIEW CONTINUES INTO THE SECOND HALF OF THE SHOW). (2.) Linguist GEOFF NUNBERG on the "word" of the year.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) The late folklorist ALAN LOMAX. He spent more than a half century recording the folk music and customs of the world. Here in America, he's responsible for priceless recordings of Leadbelly, Woody Guthrie, Jelly Roll Morton, and many others. There's a new biography of him written by John Szwed, Alan Lomax: The Man Who Recorded the World. (REBROADCAST from 7/9/90) (2.) TV critic DAVID BIANCULLI previews three new series premiering Sunday: Episodes and Shameless on Showtime, and Downton Abbey on PBS. He says they're all well-acted, cleverly written, fun to watch, and a little unusual. (3.) Actor WILL FERRELL and director ADAM MCKAY. Their comedy action film The Other Guys which spoofs the buddy-cop genre is now out on DVD. Ferrell plays a nerdy, forensic accountant and detective who is mismatched with a gung-ho detective played by Mark Wahlberg. FERRELL and MCKAY previously worked together on the films Anchorman, Talladega Nights, and Step Brothers. (REBROADCAST from 8/5/10) (4.) Film critic DAVID EDELSTEIN reviews Blue Valentine starring Ryan Gosling and Michelle Williams.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Actor WILL FERRELL and director ADAM MCKAY. The two have collaborated on the new comedy action film The Other Guys which spoofs the buddy-cop genre. Ferrell plays a nerdy, forensic accountant and detective who is mismatched with a gung-ho detective played by Mark Wahlberg. FERRELL and MCKAY previously worked together on the films Anchorman, Talladega Nights, and Step Brothers. (2.) Novelist DAVID MITCHELL is the author of the new book The Thousand Autumns of Jacob de Zoet (Random House). It's set on an island near Nagasaki, Japan in 1799, where Dutch traders are allowed into the otherwise closed Japanese society. A young Dutch clerk arrives to earn his fortune. Our book critic Maureen Corrigan says it is a 'beautiful novel, full of life and authenticity, atmosphere and characters that breathe. It manages to do what the best historical fiction always does - make a reader melancholy, thinking about all those other, true-life stories from the past that have melted into air.' MITCHELL has twice been short-listed for the Man Booker Prize. His previous novels include Number9Dream, Cloud Atlas, and Black Swan Green.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Actors WILL FERRELL and JOHN C. REILLY, and writer/director ADAM MCKAY. The three have teamed up for the new comedy 'Step Brothers' about two underemployed, underachieving middle-aged men who each live with their single parent until they are forced to be step brothers when their parents marry. The three teamed up for the comedy 'Talladega Nights: The Ballad of Ricky Bobby.' MCKAY and FERRELL also worked on 'Anchorman: The Legend of Ron Burgundy.' (THIS INTERVIEW CONTINUES INTO THE SECOND HALF OF THE SHOW). (2.) Rock critic KEN TUCKER reviews 'Lookout Mountain, Lookout Sea' the new album by the group the Silver Jews, led by singer-songwriter poet David Berman. (3.) Book critic MAUREEN CORRIGAN reviews two insider books about China: 'The Last Days of Old Beijing' (Walker & Co.) by Michael Meyer, and 'Serve the People: A Stir-Fried Journey Through China' (Harcourt) by Jen Lin Liu.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Animator, director and writer ANDREW STANTON. He co-wrote and directed the Pixar animated film 'Wall-E.' Stanton also wrote and directed 'Finding Nemo,' which was awarded an Oscar for Best Animated Feature Film in 2004. STANTON also co-wrote 'Monster's Inc,' 'Toy Story,' and 'A Bug's Life.' STANTON joined Pixar in 1990 and was the company's second animator and ninth employee. (REBROADCAST from 07.10.08). (2.) Actors WILL FERRELL and JOHN C. REILLY, and writer/director ADAM MCKAY. The three have teamed up for the comedy 'Step Brothers' about two underemployed, underachieving middle-aged men who each live with their single parent until they are forced to be step brothers when their parents marry. The three teamed up for the comedy 'Talladega Nights: The Ballad of Ricky Bobby.' MCKAY and FERRELL also worked on 'Anchorman: The Legend of Ron Burgundy.' (REBROADCAST from 07.23.08) (3.) Rock historian ED WARD tells the story of the Staples Singers.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Film director ADAM MCKAY. He directed the movie 'Anchorman,' starring Will Ferrell. It's now out on DVD. It's a spoof of local TV news shows. McKay was the head writer for the T-V show Saturday Night Live from 1997 to 2001. During that time, McKay made a number of short film segments. 'Anchorman' is his first feature length work. McKay was one of the founding members of the Upright Citizens Brigade comedy troupe. He's an alum of the Second City Improv in Chicago, and he's also had many bit parts on SNL. (REBROADCAST from 7/8/04) (2.) Oscar winning British actor JEREMY IRONS talks about his life and career. His newest film is 'Merchant of Venice.' IRONS has appeared in numerous films, television programs and stage productions. His films include: "Reversal of Fortune," "Dead Ringers," "The French Lieutenant's Woman," "Nijinski," and "Die Hard with a Vengeance,' "Man in the Iron Mask' and 'Lolita.' (REBROADCAST from 3/30/98) (3.) Film critic DAVID EDELSTEIN reviews 'Merchant of Venice' starring Jeremy Irons and Al Pacino.

Since its national debut in 1987, Fresh Air with Terry Gross has been a highly acclaimed and much adored weekday magazine among public radio listeners. Each week, nearly 4.8 million people turn to Peabody Award-winning host Terry Gross for insightful conversations with the leading voices in contemporary arts and issues. The renowned program reaches a global audience, with over 620 public radio stations broadcasting Fresh Air, and 3 million podcast downloads each week. Fresh Air has broken the mold of 'talk show' by weaving together superior journalism and intimate storytelling from modern-day intellectuals, politicians and artists alike. Through probing questions and careful research, Gross's interviews are lauded for revealing a fresh perspective on cultural icons and trends. Her thorough conversations are often complemented by commentary from well-known contributors. Fresh Air is produced at WHYY-FM in Philadelphia and broadcast nationally by NPR., (1.) Film director ADAM MCKAY. He directed the new movie 'Anchorman,' starring Will Ferrell. It's about a news anchor from the 1970s and his wacky adventures when a female anchor joins the staff. McKay was the head writer for the T-V show Saturday Night Live from 1997 to 2001. During that time, McKay made a number of short film segments. 'Anchorman' is his first feature length work. McKay was one of the founding members of the Upright Citizens Brigade comedy troupe. He's an alum of the Second City Improv in Chicago, and he's also had many bit parts on SNL. (THIS INTERVIEW CONTINUES INTO THE SECOND HALF OF THE SHOW.) (2.) T-V producer JAMAL DAJANI (zha-MAHL da-ZHAH-nee) He's a co-producer of the show 'Mosaic' on the satellite network Link TV. Dajani is a Palestinian-American. The show's mission is to bring world perspectives to American viewers. They translate Arab programming from Abu Dhabi, Beirut and Damascus into English, bringing viewers news rarely seen on American airwaves. The idea is to improve relations between countries with cultural exchange. The network is available to Dish and DirecTV network subscribers only. (3.) Book critic MAUREEN CORRIGAN reviews 'An Unfinished Season,' by Ward Just.

The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to (1) systematically monitor a sample of previously discovered over the whole sky, to assess the evolutionary state of these distant remnants from the early solar system, and (2) use alerts from existing sky surveys to rapidly respond to and characterize detected outburst activity in all small bodies. The data gathered on outbursts helps to characterize each outburst’s evolution with time, helps to assess the frequency and magnitude distribution of outbursts in general, and contributes to the understanding of outburst processes and volatile distribution in the solar system. The LOOK Project exploits the synergy between current and future wide-field surveys such as ZTF, Pan-STARRS, and LSST, as well as rapid-response telescope networks such as LCO, and serves as an excellent test bed for what will be needed for the much larger number of objects coming from Rubin Observatory. We will describe the LOOK Project goals, the planning and target selection (including the use of NEOexchange as a Target and Observation Manager or “TOM”), and results from the first phase of observations, including the detection of activity and outbursts on the giant comet C/2014 UN271 (Bernardinelli–Bernstein) and the discovery and follow-up of 28 outbursts on 14 comets. Within these outburst discoveries, we present a high-cadence light curve of 7P/Pons–Winnecke with 10 outbursts observed over 90 days, a large outburst on 57P/duToit–Neujmin–Delporte, and evidence that comet P/2020 X1 (ATLAS) was in outburst when discovered.