Mark Gurwell - CfA

Mark Gurwell
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Mark Gurwell

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High Energy Astrophysical Phenomena (23)
Cosmology and Nongalactic Astrophysics (14)
Astrophysics of Galaxies (7)
Astrophysics (6)
Instrumentation and Methods for Astrophysics (5)
Earth and Planetary Astrophysics (1)
Physics - Physics and Society (1)

Publications Authored By Mark Gurwell

S5 0716+714 is a well known BL Lac object, one of the brightest and most active blazars. The discovery in the Very High Energy band (VHE, E > 100 GeV) by MAGIC happened in 2008. In January 2015 the source went through the brightest optical state ever observed, triggering MAGIC follow-up and a VHE detection with 13{\sigma} significance (ATel 6999). Read More

Affiliations: 1ALMA Time-domain Special Interest Group, 2ALMA Time-domain Special Interest Group, 3ALMA Time-domain Special Interest Group, 4ALMA Time-domain Special Interest Group, 5ALMA Time-domain Special Interest Group, 6ALMA Time-domain Special Interest Group, 7ALMA Time-domain Special Interest Group, 8ALMA Time-domain Special Interest Group, 9ALMA Time-domain Special Interest Group, 10ALMA Time-domain Special Interest Group, 11ALMA Time-domain Special Interest Group, 12ALMA Time-domain Special Interest Group, 13ALMA Time-domain Special Interest Group, 14ALMA Time-domain Special Interest Group, 15ALMA Time-domain Special Interest Group, 16ALMA Time-domain Special Interest Group, 17ALMA Time-domain Special Interest Group, 18ALMA Time-domain Special Interest Group, 19ALMA Time-domain Special Interest Group, 20ALMA Time-domain Special Interest Group, 21ALMA Time-domain Special Interest Group, 22ALMA Time-domain Special Interest Group, 23ALMA Time-domain Special Interest Group, 24ALMA Time-domain Special Interest Group, 25ALMA Time-domain Special Interest Group, 26ALMA Time-domain Special Interest Group, 27ALMA Time-domain Special Interest Group, 28ALMA Time-domain Special Interest Group, 29ALMA Time-domain Special Interest Group, 30ALMA Time-domain Special Interest Group, 31ALMA Time-domain Special Interest Group, 32ALMA Time-domain Special Interest Group, 33ALMA Time-domain Special Interest Group, 34ALMA Time-domain Special Interest Group, 35ALMA Time-domain Special Interest Group, 36ALMA Time-domain Special Interest Group, 37ALMA Time-domain Special Interest Group

While the Atacama Large Millimeter/submillimeter Array (ALMA) is a uniquely powerful telescope, its impact in certain fields of astrophysics has been limited by observatory policies rather than the telescope's innate technical capabilities. In particular, several observatory policies present challenges for observations of variable, mobile, and/or transient sources --- collectively referred to here as "time-domain" observations. In this whitepaper we identify some of these policies, describe the scientific applications they impair, and suggest changes that would increase ALMA's science impact in Cycle 6 and beyond. Read More

Authors: Demitri Muna, Michael Alexander, Alice Allen, Richard Ashley, Daniel Asmus, Ruyman Azzollini, Michele Bannister, Rachael Beaton, Andrew Benson, G. Bruce Berriman, Maciej Bilicki, Peter Boyce, Joanna Bridge, Jan Cami, Eryn Cangi, Xian Chen, Nicholas Christiny, Christopher Clark, Michelle Collins, Johan Comparat, Neil Cook, Darren Croton, Isak Delberth Davids, Éric Depagne, John Donor, Leonardo A. dos Santos, Stephanie Douglas, Alan Du, Meredith Durbin, Dawn Erb, Daniel Faes, J. G. Fernández-Trincado, Anthony Foley, Sotiria Fotopoulou, Søren Frimann, Peter Frinchaboy, Rafael Garcia-Dias, Artur Gawryszczak, Elizabeth George, Sebastian Gonzalez, Karl Gordon, Nicholas Gorgone, Catherine Gosmeyer, Katie Grasha, Perry Greenfield, Rebekka Grellmann, James Guillochon, Mark Gurwell, Marcel Haas, Alex Hagen, Daryl Haggard, Tim Haines, Patrick Hall, Wojciech Hellwing, Edmund Christian Herenz, Samuel Hinton, Renee Hlozek, John Hoffman, Derek Holman, Benne Willem Holwerda, Anthony Horton, Cameron Hummels, Daniel Jacobs, Jens Juel Jensen, David Jones, Arna Karick, Luke Kelley, Matthew Kenworthy, Ben Kitchener, Dominik Klaes, Saul Kohn, Piotr Konorski, Coleman Krawczyk, Kyler Kuehn, Teet Kuutma, Michael T. Lam, Richard Lane, Jochen Liske, Diego Lopez-Camara, Katherine Mack, Sam Mangham, Qingqing Mao, David J. E. Marsh, Cecilia Mateu, Loïc Maurin, James McCormac, Ivelina Momcheva, Hektor Monteiro, Michael Mueller, Roberto Munoz, Rohan Naidu, Nicholas Nelson, Christian Nitschelm, Chris North, Juan Nunez-Iglesias, Sara Ogaz, Russell Owen, John Parejko, Vera Patrício, Joshua Pepper, Marshall Perrin, Timothy Pickering, Jennifer Piscionere, Richard Pogge, Radek Poleski, Alkistis Pourtsidou, Adrian M. Price-Whelan, Meredith L. Rawls, Shaun Read, Glen Rees, Hanno Rein, Thomas Rice, Signe Riemer-Sørensen, Naum Rusomarov, Sebastian F. Sanchez, Miguel Santander-García, Gal Sarid, William Schoenell, Aleks Scholz, Robert L. Schuhmann, William Schuster, Peter Scicluna, Marja Seidel, Lijing Shao, Pranav Sharma, Aleksandar Shulevski, David Shupe, Cristóbal Sifón, Brooke Simmons, Manodeep Sinha, Ian Skillen, Bjoern Soergel, Thomas Spriggs, Sundar Srinivasan, Abigail Stevens, Ole Streicher, Eric Suchyta, Joshua Tan, O. Grace Telford, Romain Thomas, Chiara Tonini, Grant Tremblay, Sarah Tuttle, Tanya Urrutia, Sam Vaughan, Miguel Verdugo, Alexander Wagner, Josh Walawender, Andrew Wetzel, Kyle Willett, Peter K. G. Williams, Guang Yang, Guangtun Zhu, Andrea Zonca

The Astropy Project ( is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Read More

The Galactic Center black hole Sagittarius A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve the 1.3 mm emission from this source on angular scales comparable to that of the general relativistic shadow. Previous EHT observations have used visibility amplitudes to infer the morphology of the millimeter-wavelength emission. Read More

We present observations of the $^{12}$CO(6-5) line and 686GHz continuum emission in NGC253 with the Submillimeter Array at an angular resolution of ~4arcsec. The $^{12}$CO(6-5) emission is clearly detected along the disk and follows the distribution of the lower $^{12}$CO line transitions with little variations of the line ratios in it. A large-velocity gradient analysis suggests a two-temperature model of the molecular gas in the disk, likely dominated by a combination of low-velocity shocks and the disk wide PDRs. Read More

We present a source-plane reconstruction of a ${\it Herschel}$ and ${\it Planck}$-detected gravitationally-lensed dusty star-forming galaxy (DSFG) at $z=1.68$ using {\it Hubble}, Sub-millimeter Array (SMA), and Keck observations. The background sub-millimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at $z=0. Read More

Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizon-scale magnetic-field structure. We report interferometric observations at 1. Read More

We analyze the light curves of 413 radio sources at submillimeter wavelengths using data from the Submillimeter Array calibrator database. The database includes more than 20,000 observations at 1.3 and 0. Read More

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between October 2012 and November 2014. Read More

We present high angular resolution Submillimeter Array observations ofthe outbursting Jupiter family comet 17P/Holmes on 2007 October 26-29, achieving a spatial resolution of 2.5", or ~3000 km at the comet distance. The observations resulted in detections of the rotational lines CO 3-2, HCN 4-3, H$^{13}$CN 4-3, CS 7-6, H$_2$CO 3$_{1,2}$-2$_{1,1}$, H$_2$S 2$_{2,0}$-2$_{1,1}$, and multiple CH$_3$OH lines, along with the associated dust continuum at 221 and 349 GHz. Read More

The blazar 1156+295 was active at gamma-ray energies, exhibiting three prominent flares during the year 2010. Here, we present results using the combination of broadband (X-ray through mm single dish) monitoring data and radio band imaging data at 43 GHz on the connection of gamma-ray events to the ejections of superluminal components and other changes in the jet of 1156+295. The kinematics of the jet over the interval 2007. Read More

We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164 in 2008. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array (VLBA) images at 7mm with ~0.15 milliarcsecond resolution. Read More

A subset of ultraluminous X-ray sources (those with luminosities < 10^40 erg/s) are thought to be powered by the accretion of gas onto black holes with masses of ~5-20 M_solar, probably via an accretion disc. The X-ray and radio emission are coupled in such Galactic sources, with the radio emission originating in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium precludes determining the causal sequence of events that leads to the ejection of the jet. Read More

Approximately 10% of active galactic nuclei exhibit relativistic jets, which are powered by accretion of matter onto super massive black holes. While the measured width profiles of such jets on large scales agree with theories of magnetic collimation, predicted structure on accretion disk scales at the jet launch point has not been detected. We report radio interferometry observations at 1. Read More

We present multiwavelength data of the blazar 3C 454.3 obtained during an extremely bright outburst from November 2010 through January 2011. These include flux density measurements with the Herschel Space Observatory at five submillimeter-wave and far-infrared bands, the Fermi Large Area Telescope at gamma-ray energies, Swift at X-ray, ultraviolet (UV), and optical frequencies, and the Submillimeter Array at 1. Read More

We have observed 3C~279 in a gamma-ray flaring state in November 2008. We construct quasi-simultaneous spectral energy distributions (SEDs) of the source for the flaring period of 2008 and during a quiescent period in May 2010. Data have been compiled from observations with Fermi, Swift, RXTE, the VLBA, and various ground-based optical and radio telescopes. Read More

We locate the gamma-ray and lower frequency emission in flares of the BL Lac object AO 0235+164 at >12pc in the jet of the source from the central engine. We employ time-dependent multi-spectral-range flux and linear polarization monitoring observations, as well as ultra-high resolution (~0.15 milliarcsecond) imaging of the jet structure at lambda=7mm. Read More

We present multiwavelength spectral analyses of two Fermi-LAT blazars, OJ 287 and 3C 279, that are part of the Boston University multiwaveband polarization program. The data have been compiled from observations with Fermi, RXTE, the VLBA, and various ground-based optical and radio telescopes. We simulate the dynamic spectral energy distributions (SEDs) within the framework of a multi-slice, time-dependent leptonic jet model for blazars, with radiation feedback, in the internal shock scenario. Read More

We report on the location of the gamma-ray emission region in flares of the BL Lacertae object OJ287 at >14pc from the central supermassive black hole. We employ data from multi-spectral range (total flux and linear polarization) monitoring programs combined with sequences of ultra-high-resolution 7mm VLBA images. The correlation between the brightest gamma-ray and mm flares is found to be statistically significant. Read More

Affiliations: 1Yale, 2Boston U., 3Boston U., 4UCSD, 5UCSD, 6UCSD, 7U. Southampton, UK, 8U. Michigan, 9U. Michigan, 10Metsahovi Radio Observatory, Finland, 11Metsahovi Radio Observatory, Finland, 12Boston U., 13Instituto de Astrofisica de Andalucia, Spain, 14Instituto de Astrofisica de Andalucia, Spain, 15Lowell Observatory, 16CfA

We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4--10 keV), optical (R band), and radio (14.5, 37, and 230 GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Read More

We combine time-dependent multi-waveband flux and linear polarization observations with sub-milliarcsecond-scale polarimetric images at lambda=7mm of the BL Lacertae-type blazar OJ287 to locate the gamma-ray emission in prominent flares in the jet of the source >14pc from the central engine. We demonstrate a highly significant correlation between the strongest gamma-ray and millimeter-wave flares through Monte-Carlo simulations. The two reported gamma-ray peaks occurred near the beginning of two major mm-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Read More

Sagittarius A*, the ~4 x 10^6 solar mass black hole candidate at the Galactic Center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength Very Long Baseline Interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the ARO/SMT on Mt. Read More

Authors: Asantha Cooray, Steve Eales, Scott Chapman, David L. Clements, Olivier Dore, Duncan Farrah, Matt J. Jarvis, Manoj Kaplinghat, Mattia Negrello, Alessandro Melchiorri, Hiranya Peiris, Alexandra Pope, Mario G. Santos, Stephen Serjeant, Mark Thompson, Glenn White, Alexandre Amblard, Manda Banerji, Pier-Stefano Corasaniti, Sudeep Das, Francesco de_Bernardis, Gianfranco de_Zotti, Tommaso Giannantonio, Joaquin Gonzalez-Nuevo Gonzalez, Ali Ahmad Khostovan, Ketron Mitchell-Wynne, Paolo Serra, Yong-Seon Song, Joaquin Vieira, Lingyu Wang, Michael Zemcov, Filipe Abdalla, Jose Afonso, Nabila Aghanim, Paola Andreani, Itziar Aretxaga, Robbie Auld, Maarten Baes, Andrew Baker, Denis Barkats, R. Belen Barreiro, Nicola Bartolo, Elizabeth Barton, Sudhanshu Barway, Elia Stefano Battistelli, Carlton Baugh, Alexander Beelen, Karim Benabed, Andrew Blain, Joss Bland-Hawthorn, James~J. Bock, J. Richard Bond, Julian Borrill, Colin Borys, Alessandro Boselli, Francois R. Bouchet, Carrie Bridge, Fabrizio Brighenti, Veronique Buat, David Buote, Denis Burgarella, Robert Bussmann, Erminia Calabrese, Christopher Cantalupo, Raymond Carlberg, Carla Sofia Carvalho, Caitlin Casey, Antonio Cava, Jordi Cepa, Edward Chapin, Ranga Ram Chary, Xuelei Chen, Sergio Colafrancesco, Shaun Cole, Peter Coles, Alexander Conley, Luca Conversi, Jeff Cooke, Steven Crawford, Catherine Cress, Elisabete da Cunha, Gavin Dalton, Luigi Danese, Helmut Dannerbauer, Jonathan Davies, Paolo de Bernardis, Roland de Putter, Mark Devlin, Jose M. Diego, Herve Dole, Marian Douspis, Joanna Dunkley, James Dunlop, Loretta Dunne, Rolando Dunner, Simon Dye, George Efstathiou, Eiichi Egami, Taotao Fang, Patrizia Ferrero, Alberto Franceschini, Christopher C. Frazer, David Frayer, Carlos Frenk, Ken Ganga, Raphael Gavazzi, Jason Glenn, Yan Gong, Eduardo Gonzalez-Solares, Matt Griffin, Qi Guo, Mark Gurwell, Amir Hajian, Mark Halpern, Duncan Hanson, Martin Hardcastle, Evanthia Hatziminaoglou, Alan Heavens, Sebastien Heinis, Diego Herranz, Matt Hilton, Shirley Ho, Benne W. Holwerda, Rosalind Hopwood, Jonathan Horner, Kevin Huffenberger, David H. Hughes, John P. Hughes, Edo Ibar, Rob Ivison, Neal Jackson, Andrew Jaffe, Timothy Jenness, Gilles Joncas, Shahab Joudaki, Sugata Kaviraj, Sam Kim, Lindsay King, Theodore Kisner, Johan Knapen, Alexei Kniazev, Eiichiro Komatsu, Leon Koopmans, Chao-Lin Kuo, Cedric Lacey, Ofer Lahav, Anthony N. Lasenby, Andy Lawrence, Myung Gyoon Lee, Lerothodi L. Leeuw, Louis R. Levenson, Geraint Lewis, Nicola Loaring, Marcos Lopez-Caniego, Steve Maddox, Tobias Marriage, Gaelen Marsden, Enrique Martinez-Gonzalez, Silvia Masi, Sabino Matarrese, William G. Mathews, Shuji Matsuura, Richard McMahon, Yannick Mellier, Felipe Menanteau, Michal~J. Michalowski, Marius Millea, Bahram Mobasher, Subhanjoy Mohanty, Ludovic Montier, Kavilan Moodley, Gerald H. Moriarty-Schieven, Angela Mortier, Dipak Munshi, Eric Murphy, Kirpal Nandra, Paolo Natoli, Hien Nguyen, Seb Oliver, Alain Omont, Lyman Page, Mathew Page, Roberta Paladini, Stefania Pandolfi, Enzo Pascale, Guillaume Patanchon, John Peacock, Chris Pearson, Ismael Perez-Fournon, Pablo G. Perez-Gonz, Francesco Piacentini, Elena Pierpaoli, Michael Pohlen, Etienne Pointecouteau, Gianluca Polenta, Jason Rawlings, Erik~D. Reese, Emma Rigby, Giulia Rodighiero, Encarni Romero-Colmenero, Isaac Roseboom, Michael Rowan-Robinson, Miguel Sanchez-Portal, Fabian Schmidt, Michael Schneider, Bernhard Schulz, Douglas Scott, Chris Sedgwick, Neelima Sehgal, Nick Seymour, Blake~D. Sherwin, Jo Short, David Shupe, Jonathan Sievers, Ramin Skibba, Joseph Smidt, Anthony Smith, Daniel J. B. Smith, Matthew W. L. Smith, David Spergel, Suzanne Staggs, Jason Stevens, Eric Switzer, Toshinobu Takagi, Tsutomu Takeuchi, Pasquale Temi, Markos Trichas, Corrado Trigilio, Katherine Tugwell, Grazia Umana, William Vacca, Mattia Vaccari, Petri Vaisanen, Ivan Valtchanov, Kurt van der Heyden, Paul P. van der Werf, Eelco van_Kampen, Ludovic van_Waerbeke, Simona Vegetti, Marcella Veneziani, Licia Verde, Aprajita Verma, Patricio Vielva, Marco P. Viero, Baltasar Vila Vilaro, Julie Wardlow, Grant Wilson, Edward L. Wright, C. Kevin Xu, Min S. Yun

A large sub-mm survey with Herschel will enable many exciting science opportunities, especially in an era of wide-field optical and radio surveys and high resolution cosmic microwave background experiments. The Herschel-SPIRE Legacy Survey (HSLS), will lead to imaging data over 4000 sq. degrees at 250, 350, and 500 micron. Read More

We monitored the flaring blazar 3C 454.3 during 2005 June-July with the Spitzer Infrared Spectrograph (IRS: 15 epochs), Infrared Array Camera (IRAC: 12 epochs) and Multiband Imaging Photometer (MIPS: 2 epochs). We also made Spitzer IRS, IRAC, and MIPS observations from 2006 December-2007 January when the source was in a low state, the latter simultaneous with a single Chandra X-ray observation. Read More

Affiliations: 1ICC, Durham, 2ICC, Durham, 3CfA, Harvard, 4Maryland, 5Rutgers, 6ESO, Germany, 7ICC, Durham, 8ICC, Durham, 9UK-ATC, 10CfA, Harvard, 11ICC, Durham, 12IRAM, 13CfA, Harvard, 14Maryland, 15IRAM, 16ESO, Chile, 17IRAM, 18Caltech, 19IfA Cambridge, 20CfA, Harvard, 21Princeton

Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimeter (sub-mm) wavelengths and which may be forming stars at rates upto 1,000Mo/yr. These intense bursts of star formation are believed to be driven by mergers between gas rich galaxies. Read More

We present multi-epoch observations from the Submillimeter Array (SMA) for a sample of 171 bright blazars, 43 of which were detected by Fermi during the first three months of observations. We explore the correlation between their gamma-ray properties and submillimeter observations of their parsec-scale jets, with a special emphasis on spectral index in both bands and the variability of the synchrotron component. Subclass is determined using a combination of Fermi designation and the Candidate Gamma-Ray Blazar Survey (CGRaBS), resulting in 35 BL Lac objects and 136 flat-spectrum radio quasars (FSRQs) in our total sample. Read More

We used the Extended Submillimeter Array (eSMA) in its most extended configuration to investigate the innermost (within a radius of 290 R* from the star) circumstellar envelope (CSE) of IRC+10216. We imaged the CSE using HCN and other molecular lines with a beam size of 0."22 x 0. Read More

Affiliations: 1Leiden Observatory, Leiden University, 2Harvard-Smithsonian Center for Astrophysics, 3Leiden Observatory, Leiden University, 4Harvard-Smithsonian Center for Astrophysics, 5Caltech Submillimeter Observatory, 6Joint Astronomy Center, 7Harvard-Smithsonian Center for Astrophysics, 8Harvard-Smithsonian Center for Astrophysics, 9Joint Institute for VLBI in Europe, 10Leiden Observatory, Leiden University, 11Harvard-Smithsonian Center for Astrophysics, Submillimeter Array, 12Caltech Submillimeter Observatory, 13Caltech Submillimeter Observatory
Category: Astrophysics

We report the first science observations and results obtained with the "extended" SMA (eSMA), which is composed of the SMA (Submillimeter Array), JCMT (James Clerk Maxwell Telescope) and CSO (Caltech Submillimeter Observatory). Redshifted absorptions at z=0.886 of CI (^3P_1 - ^3P_0) were observed with the eSMA with an angular resolution of 0. Read More


We have used the Submillimeter Array (SMA) to make the first interferometric observations (beam size ~1") of the 12CO J=6-5 line and 435 micron (690 GHz) continuum emission toward the central region of the nearby ULIRG Arp 220. These observations resolve the eastern and western nuclei from each other, in both the molecular line and dust continuum emission. At 435 micron, the peak intensity of the western nucleus is stronger than the eastern nucleus, and the difference in peak intensities is less than at longer wavelengths. Read More

The eSMA ("extended SMA") combines the SMA, JCMT and CSO into a single facility, providing enhanced sensitivity and spatial resolution owing to the increased collecting area at the longest baselines. Until ALMA early science observing (2011), the eSMA will be the facility capable of the highest angular resolution observations at 345 GHz. The gain in sensitivity and resolution will bring new insights in a variety of fields, such as protoplanetary/transition disks, high-mass star formation, solar system bodies, nearby and high-z galaxies. Read More

We present high resolution submillimeter interferometric imaging of two of the brightest high-redshift submillimeter galaxies known: GN20 and AzTEC1 at 0.8 and 0.3 arcsec resolution respectively. Read More

We have used the Submillimeter Array to image a flux limited sample of seven submillimeter galaxies, selected by the AzTEC camera on the JCMT at 1.1 mm, in the COSMOS field at 890um with 2" resolution. All of the sources - two radio-bright and five radio-dim - are detected as single point-sources at high significance (> 6\sigma), with positions accurate to 0. Read More

Interferometric observations of the atmosphere of Titan were performed with the Submillimeter Array on two nights in February 2004 to investigate the global average vertical distributions of several molecular species above the tropopause. Rotational transitions of CO, isomers of HCN, and HC3N were simultaneously recorded. The abundance of CO is determined to be 51+/-4 ppm, constant with altitude. Read More