Results for "S. B. Cenko"

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Discovery of the Very Red Near-Infrared and Optical Afterglow of the Short-Duration GRB 070724AAug 07 2009[Abridged] We report the discovery of the near-infrared and optical afterglow of the short-duration gamma-ray burst GRB070724A. The afterglow is detected in i,J,H,K observations starting 2.3 hr after the burst with K=19.59+/-0.16 mag and i=23.79+/-0.07 ... More
Probing the distance and morphology of the Large Magellanic Cloud with RR Lyrae starsMay 05 2014May 07 2014We present a Bayesian analysis of the distances to 15,040 Large Magellanic Cloud (LMC) RR Lyrae stars using $V$- and $I$-band light curves from the Optical Gravitational Lensing Experiment, in combination with new $z$-band observations from the Dark Energy ... More
Spectroscopy of GRB 050505 at z=4.275: A logN(HI)=22.1 DLA Host Galaxy and the Nature of the ProgenitorNov 16 2005We present the discovery of the optical afterglow of GRB 050505 and an optical absorption spectrum obtained with the Keck I 10-m telescope. The spectrum exhibits three redshifted absorption systems with the highest, at z=4.2748, arising in the GRB host ... More
Observational Limits on X-ray Bursts from RRAT J1911+00Sep 04 2006(abridged) The high radio-flux brightness temperature of the recently discovered class of sources known as Rotating RAdio Transients (RRATs) motivates detailed study in the X-ray band. We describe analyses of historical X-ray data, searching for X-ray ... More
Discovery of SN 2009nz Associated with GRB 091127May 26 2010Oct 04 2010We report SMARTS, Gemini and Swift-UVOT observations of the optical transient (OT) associated with gamma-ray burst (GRB) 091127, at redshift 0.49, taken between 0.9 hr and 102 days following the Swift trigger. In our early-time observations, the OT fades ... More
The short-hard GRB 051103: Observations and implications for its natureSep 20 2006The bright short-hard GRB 051103 was triangulated by the inter-planetary network and found to occur in the direction of the nearby M81/M82 galaxy group. Given its possible local-Universe nature, we searched for an afterglow associated with this burst. ... More
Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic BinariesApr 07 2011We present orbital parameters for six double-lined spectroscopic binaries (iota Pegasi, omega Draconis, 12 Bootis, V1143 Cygni, beta Aurigae, and Mizar A) and two double-lined triple star systems (kappa Pegasi and eta Virginis). The orbital fits are based ... More
Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. I. Instrument Description and Orbits of Single-lined Spectroscopic BinariesSep 17 2009We have designed and constructed a second-generation version of the Dispersed Fourier Transform Spectrograph, or dFTS. This instrument combines a spectral interferometer with a dispersive spectrograph to provide high-accuracy, high-resolution optical ... More
A high angular-resolution search for the progenitor of the type Ic Supernova 2004gtJun 21 2005Aug 03 2005We report the results of a high-spatial-resoltion search for the progenitor of type Ic supernova SN 2004gt, using the newly commissioned Keck laser-guide star adaptive optics system (LGSAO) along with archival Hubble Space Telescope data. This is the ... More
Preliminary Results from the Caltech Core-Collapse Project (CCCP)Nov 29 2006We present preliminary results from the Caltech Core-Collapse Project (CCCP), a large observational program focused on the study of core-collapse SNe. Uniform, high-quality NIR and optical photometry and multi-epoch optical spectroscopy have been obtained ... More
The First Systematic Study of Type Ibc Supernova Multi-band Light CurvesNov 22 2010Nov 13 2011We present detailed optical photometry for 25 Type Ibc supernovae within d\approx150 Mpc obtained with the robotic Palomar 60-inch telescope in 2004-2007. This study represents the first uniform, systematic, and statistical sample of multi-band SNe Ibc ... More
Gemini Spectroscopy of the Short GRB 130603B Afterglow and HostJun 09 2013Jul 29 2013We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst GRB 130603B discovered by the Swift satellite. Using the Gemini South telescope, our prompt optical spectra reveal a strong ... More
A Case Study of On-the-Fly Wide-Field Radio Imaging Applied to the Gravitational-wave Event GW 151226Mar 19 2018We apply a newly-developed On-the-Fly mosaicing technique on the NSF's Karl G. Jansky Very Large Array (VLA) at 3 GHz in order to carry out a sensitive search for an afterglow from the Advanced LIGO binary black hole merger event GW 151226. In three epochs ... More
Late-time observations of the relativistic tidal disruption flare candidate Swift J1112.2-8238Aug 31 2017We present late-time follow-up of the relativistic tidal disruption flare candidate Swift J1112.2-8238. We confirm the previously determined redshift of $z=0.8900\pm0.0005$ based on multiple emission line detections. {\em HST} imaging of the host galaxy ... More
Photometric Typing Analyses of Three Young Supernovae with the Robotic Palomar 60-Inch TelescopeNov 11 2004Dec 08 2004We present photometric typing analyses of three young supernovae observed with the Robotic 60-inch Telescope at Palomar Observatory (P60). This represents the first time that such photo-typing has been attempted, in a blind fashion, on newly-discovered ... More
The Caltech Core-Collapse Project (CCCP)Oct 01 2004The cosmological utility of type Ia Supernovae (SNe) prompted numerous studies of these events, and they are now well characterized observationally, both as individual objects and as a population. In contrast, all other types of SNe (i.e., core-collapse ... More
The double-peaked radio light curve of PTF11qcjFeb 27 2018We present continued radio follow-up observations of PTF11qcj, a highly energetic broad-lined Type Ic supernova (SN), with a radio peak luminosity comparable to that of the $\gamma$-ray burst (GRB) associated SN 1998bw. The latest observations, carried ... More
Discovery of Bright Galactic R Coronae Borealis and DY Persei Variables: Rare Gems Mined from ACVSApr 18 2012Aug 08 2012We present the results of a machine-learning (ML) based search for new R Coronae Borealis (RCB) stars and DY Persei-like stars (DYPers) in the Galaxy using cataloged light curves from the All-Sky Automated Survey (ASAS) Catalog of Variable Stars (ACVS). ... More
Discovery of a new photometric sub-class of faint and fast classical novaeMar 08 2010We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60-inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1-day) and deep (g < ... More
The Luminous Infrared Host Galaxy of Short-Duration GRB 100206ADec 16 2011The known host galaxies of short-hard gamma-ray bursts (GRBs) to date are characterized by low to moderate star-formation rates and a broad range of stellar masses. In this paper, we positionally associate the recent unambiguously short-hard Swift GRB ... More
The Quasar SDSS J1536+0441: An Unusual Double-Peaked EmitterJun 04 2009Dec 13 2009The quasar SDSS J153636.22+044127.0, exhibiting peculiar broad emission-line profiles with multiple components, was proposed as a candidate sub-parsec binary supermassive black hole system. More recently, imaging revealed two spatially distinct sources, ... More
The Incidence of Dwarf Novae in Large Area Transient SearchesNov 30 2006Apr 28 2007Understanding and quantifying the contribution of known classes of transient and variable sources is an important lesson to be learned from the manifold of pre-cursors programs of the near-future large synoptic sky survey programs like SkyMapper, Pan-STARRS ... More
A long and homogeneous optical monitoring of the 'naked-eye' burst GRB 080319B with the Palomar-60 telescopeDec 19 2009GRB 080319B is one of the brightest and most extensively sampled bursts. It has good coverage at many wavelengths. Here we present the optical observations of the Palomar 60 inch telescope, which spans a long time interval after the burst. We augment ... More
HST and Spitzer Observations of the Host Galaxy of GRB 050904: A Metal-Enriched, Dusty Starburst at z=6.295Mar 27 2006We present deep Hubble Space Telescope and Spitzer Space Telescope observations of the host galaxy of GRB 050904 at z=6.295. The host is detected in the H-band and marginally at 3.6 micron. From these detections, and limits in the z'-band and 4.5 micron, ... More
Did the progenitor of SN2011dh have a binary companion?Sep 20 2015We present late-time Hubble Space Telescope (HST) ultraviolet (UV) and optical observations of the site of SN 2011dh in the galaxy M51, ~1164 days post-explosion. At the SN location, we observe a point source that is visible at all wavelengths, that is ... More
Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apdNov 09 2016Apr 17 2017We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift ... More
Swift J1112.2-8238: A Candidate Relativistic Tidal Disruption FlareJul 13 2015We present observations of Swift J1112.2-8238, and identify it as a candidate relativistic tidal disruption flare (rTDF). The outburst was first detected by Swift/BAT in June 2011 as an unknown, long-lived (order of days) $\gamma$-ray transient source. ... More
Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apdNov 09 2016We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift ... More
Connecting GRBs and ULIRGs: A Sensitive, Unbiased Survey for Radio Emission from Gamma-Ray Burst Host Galaxies at 0<z<2.5Jul 16 2014Feb 03 2015Luminous infrared galaxies and submillimeter galaxies contribute significantly to stellar mass assembly and the frequency of GRBs in these systems provides an important test of the connection between the gamma-ray burst rate and that of overall cosmic ... More
Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor starsOct 13 2010Type IIn Supernovae (SNe IIn) are rare events, constituting only a few percent of all core-collapse SNe, and the current sample of well observed SNe IIn is small. Here, we study the four SNe IIn observed by the Caltech Core-Collapse Project (CCCP). The ... More
A Spectroscopic Study of the Extreme Black Widow PSR J1311-3430Mar 17 2015We report on a series of spectroscopic observations of PSR J1311-3430, an extreme black-widow gamma-ray pulsar with a helium-star companion. In a previous study we estimated the neutron star mass as M_NS= 2.68+/-0.14M_Sun (statistical error), based on ... More
An Energetic Afterglow From A Distant Stellar ExplosionApr 27 2006We present the discovery of radio afterglow emission from the high redshift (z=6.295) burst GRB 050904. The peak flux density for this burst is similar to typical low-redshift gamma-ray bursts (GRB). We further show that beyond a redshift of order unity, ... More
2FGL J1653.6-0159: A New Low in Evaporating Pulsar Binary PeriodsAug 13 2014Aug 26 2014We have identified an optical binary with orbital period P_b=4488s as the probable counterpart of the Fermi source 2FGL J1653.6-0159. Although pulsations have not yet been detected, the source properties are consistent with an evaporating millisecond ... More
An unusually brilliant transient in the galaxy Messier 85May 24 2007Historically, variable and transient sources have both surprised astronomers and provided new views of the heavens. Here we report the discovery of an optical transient in the outskirts of the lenticular galaxy Messier 85 in the Virgo Cluster. With a ... More
The Caltech-NRAO Stripe 82 Survey (CNSS) Paper I: The Pilot Radio Transient Survey In 50 deg$^2$Jan 07 2016We have commenced a multi-year program, the Caltech-NRAO Stripe 82 Survey (CNSS), to search for radio transients with the Jansky VLA in the SDSS Stripe 82 region. The CNSS will deliver five epochs over the entire $\sim$270 deg$^2$ of Stripe 82, an eventual ... More
The Afterglow, Energetics and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221aJan 20 2006Aug 31 2006We present detailed optical, X-ray and radio observations of the bright afterglow of the short gamma-ray burst 051221a obtained with Gemini, Swift/XRT, and the Very Large Array, as well as optical spectra from which we measure the redshift of the burst, ... More
The Progenitors of Short-Hard Gamma-Ray Bursts from an Extended Sample of EventsSep 29 2005Nov 09 2005The detection of the afterglow emission and host galaxies of short-hard gamma-ray bursts (SHBs) is one of the most exciting recent astronomical discoveries. Indications that SHB progenitors belong to old stellar populations, in contrast to those of the ... More
Dark Bursts in the Swift Era: The Palomar 60 inch-Swift Early Optical Afterglow CatalogAug 29 2008We present multi-color optical observations of long-duration gamma-ray bursts (GRBs) made over a three year period with the robotic Palomar 60 inch telescope (P60). Our sample consists of all 29 events discovered by Swift for which P60 began observations ... More
The Afterglow and Environment of the Short GRB111117AMay 31 2012Jul 16 2012We present multi-wavelength observations of the afterglow of the short GRB111117A, and follow-up observations of its host galaxy. From rapid optical and radio observations we place limits of r \gtrsim 25.5 mag at \deltat \approx 0.55 d and F_nu(5.8 GHz) ... More
Late time multi wavelength observations of Swift J1644+5734: A luminous optical/IR bump and quiescent X-ray emissionSep 29 2015We present late-time multi-wavelength observations of Swift J1644+57, suggested to be a relativistic tidal disruption flare (TDF). Our observations extend to >4 years from discovery, and show that 1.4 years after outburst the relativistic jet switched-off ... More
SN 2006gy: An extremely luminous supernova in the galaxy NGC 1260Dec 14 2006Feb 07 2007With an extinction-corrected V-band peak absolute magnitude of about -22, supernova (SN) 2006gy is probably the brightest SN ever observed. We report on multi-wavelength observations of this SN and its environment. Our spectroscopy shows an H alpha emission ... More
SN2007ax : An Extremely Faint Type Ia SupernovaJul 03 2008We present multi-band photometric and optical spectroscopic observations of SN2007ax, the faintest and reddest Type Ia supernova (SNIa) yet observed. With M_B = -15.9 and (B-V)max = 1.2, this SN is over half a magnitude fainter at maximum light than any ... More
On the progenitor of SN 2005gl and the nature of Type IIn supernovaeAug 02 2006We present a study of the type IIn supernova (SN) 2005gl, in the relatively nearby (d~66 Mpc) galaxy NGC 266. Photometry and spectroscopy of the SN indicate it is a typical member of its class. Pre-explosion Hubble Space Telescope (HST) imaging of the ... More
Revisiting optical tidal disruption events with iPTF16axaMar 03 2017May 15 2017We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at $z=0.108$, and present its broadband photometric and spectroscopic evolution from 3 months of follow-up observations ... More
The rise and fall of the Type Ib supernova iPTF13bvn - Not a massive Wolf-Rayet starMar 26 2014May 15 2014We investigate iPTF13bvn, a core-collapse (CC) supernova (SN) in the nearby spiral galaxy NGC 5806. This object was discovered by the intermediate Palomar Transient Factory very soon after the explosion and was classified as a stripped-envelope CC SN, ... More
The Environment of M85 optical transient 2006-1: constraints on the progenitor age and massOct 16 2007M85 optical transient 2006-1 (M85 OT 2006-1) is the most luminous member of the small family of V838 Mon-like objects, whose nature is still a mystery. This event took place in the Virgo cluster of galaxies and peaked at an absolute magnitude of I~-13. ... More
The peculiar Type Ia supernova iPTF14atg: Chandrasekhar-mass explosion or violent merger?Apr 19 2016iPTF14atg, a subluminous peculiar Type Ia supernova (SN Ia) similar to SN 2002es, is the first SN Ia for which a strong UV flash was observed in the early-time light curves. This has been interpreted as evidence for a single-degenerate (SD) progenitor ... More
Automating Discovery and Classification of Transients and Variable Stars in the Synoptic Survey EraJun 27 2011The rate of image acquisition in modern synoptic imaging surveys has already begun to outpace the feasibility of keeping astronomers in the real-time discovery and classification loop. Here we present the inner workings of a framework, based on machine-learning ... More
SN 2004A: Another Type II-P Supernova with a Red Supergiant ProgenitorMar 24 2006Mar 28 2006We present a monitoring study of SN 2004A and probable discovery of a progenitor star in pre-explosion HST images. The photometric and spectroscopic monitoring of SN 2004A show that it was a normal Type II-P which was discovered in NGC 6207 about two ... More
Caltech Core-Collapse Project (CCCP) Observations of Type II Supernovae: Evidence for Three Distinct Photometric SubtypesJun 10 2012Jun 15 2012We present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Project (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three ... More
Discovery of the Ultra-Bright Type II-L Supernova 2008esAug 21 2008Nov 18 2008We report the discovery by the Robotic Optical Transient Experiment (ROTSE-IIIb) telescope of SN 2008es, an overluminous supernova (SN) at z=0.205 with a peak visual magnitude of -22.2. We present multiwavelength follow-up observations with the Swift ... More
Optimisation of the Swift X-ray follow-up of Advanced LIGO and Virgo gravitational wave triggers in 2015--16Jun 04 2015Sep 22 2015One of the most exciting near-term prospects in physics is the potential discovery of gravitational waves by the advanced LIGO and Virgo detectors. To maximise both the confidence of the detection and the science return, it is essential to identify an ... More
The dark GRB080207 in an extremely red host and the implications for GRBs in highly obscured environmentsSep 14 2011[Abridged] We present comprehensive X-ray, optical, near- and mid-infrared, and sub-mm observations of GRB 080207 and its host galaxy. The afterglow was undetected in the optical and near-IR, implying an optical to X-ray index <0.3, identifying GRB 080207 ... More
Radio follow-up of gravitational wave triggers during Advanced LIGO O1Aug 23 2016Oct 31 2016We present radio follow-up observations carried out with the Karl G. Jansky Very Large Array during the first observing run (O1) of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). A total of three gravitational wave triggers were ... More
Radio follow-up of gravitational wave triggers during Advanced LIGO O1Aug 23 2016We present radio follow-up observations carried out with the Karl G. Jansky Very Large Array during the first observing run (O1) of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). A total of three gravitational wave triggers were ... More
GRBs 070429B and 070714B: The High End of the Short-Duration Gamma-Ray Burst Redshift DistributionFeb 07 2008We present optical spectra of the host galaxies of the short-duration gamma-ray burst GRB 070429B and the likely short-duration with extended emission GRB 070714B. In both cases, we find a single emission line that we identify as O II lambda 3727 at z ... More
The J-band Light Curve of SN 2003lw, Associated with GRB 031203Mar 25 2004At z=0.1055, the gamma-ray burst GRB 031203 is one of the two nearest GRBs known. Using observations from the Very Large Array (VLA) and Chandra X-ray Observatory, we derive sub-arcsecond localizations of the radio and X-ray afterglow of this GRB. We ... More
The 105 month Swift-BAT all-sky hard X-ray surveyJan 05 2018We present a catalog of hard X-ray sources detected in the first 105 months of observations with the Burst Alert Telescope (BAT) coded mask imager on board the Swift observatory. The 105 month Swift-BAT survey is a uniform hard X-ray all-sky survey with ... More
Photometrically Triggered Keck Spectroscopy of Fermi BL Lac ObjectsAug 13 2013We report on Keck spectra of ten Fermi blazars. J0622+3326, previously unobserved, is shown to be a flat-spectrum radio quasar at redshift z=1.062. The others are known BL Lac-type objects that have resisted previous attempts to secure redshifts. Using ... More
The unusual radio afterglow of the ultra-long gamma-ray burst GRB 130925AJun 01 2015GRB 130925A is one of the recent additions to the growing family of ultra-long GRBs (T90$ \gtrsim 1000$ s). While the X-ray emission of ultra-long GRBs have been studied extensively in the past, no comprehensive radio dataset has been obtained so far. ... More
The gamma-ray burst GRB060614 requires a novel explosive processAug 11 2006Over the past decade our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (T < 2 s) GRBs are associated with the explosive deaths of ... More
Deja Vu All Over Again: The Reappearance of Supernova RefsdalDec 15 2015Apr 18 2016In Hubble Space Telescope (HST) imaging taken on 10 November 2014, four images of supernova (SN) "Refsdal" (redshift z=1.49) appeared in an Einstein-cross--like configuration (images S1-S4) around an early-type galaxy in the cluster MACS J1149.5+2223 ... More
GRB070125: The First Long-Duration Gamma-Ray Burst in a Halo EnvironmentDec 17 2007We present the discovery and high signal-to-noise spectroscopic observations of the optical afterglow of the long-duration gamma-ray burst GRB070125. Unlike all previously observed long-duration afterglows in the redshift range 0.5 < z < 2.0, we find ... More
An Independent Measurement of the Incidence of MgII Absorbers along Gamma-Ray Burst Sightlines: the End of the Mystery?Nov 28 2012In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sightlines to gamma-ray bursts (GRBs) relative to the in- cidence of such absorption along quasar sightlines. This counterintuitive ... More
Evidence for Dust Destruction from the Early-time Colour Change of GRB 120119AMay 08 2013We present broadband observations and analysis of Swift gamma-ray burst (GRB) 120119A. Our early-time afterglow detections began under 15 s after the burst in the host frame (redshift z = 1.73), and they yield constraints on the burst energetics and local ... More
Late Time Radio Emission from X-ray Selected Tidal Disruption EventsSep 28 2012Nov 29 2012We present new observations with the Karl G. Jansky Very Large Array of seven X-ray-selected tidal disruption events (TDEs). The radio observations were carried out between 9 and 22 years after the initial X-ray discovery, and, thus, probe the late-time ... More
The Discovery of the Optical and Near-IR Afterglows of the First Swift Gamma-Ray BurstsFeb 23 2005We present optical and near-infrared searches for afterglow emission from the first four Swift bursts with accurate positions from the X-ray Telescope (XRT). Using telescopes at Las Campanas, Keck, and Palomar observatories we rapidly identified and followed ... More
The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916CFeb 04 2009The detection of GeV photons from gamma-ray bursts (GRBs) has important consequences for the interpretation and modelling of these most-energetic cosmological explosions. The full exploitation of the high-energy measurements relies, however, on the accurate ... More
Photometry of Some Recent Gamma-ray BurstsDec 07 2011We present the results of the optical, X-ray and gamma-ray analysis of some recent GRBs. The data were obtained by the automated P60 telescope and the Swift telescope (UVOT, XRT and BAT). We present some example fits for the lightcurves. The data reduction ... More
The Type II Superluminous SN 2008es at Late Times: Near-Infrared Excess and Circumstellar InteractionJul 20 2018SN 2008es is one of the rare cases of a Type II superluminous supernova (SLSN) showing no relatively narrow features in its early-time spectra, and therefore its powering mechanism is under debate between circumstellar interaction (CSI) and magnetar spin-down. ... More
Early-time VLA observations and broad-band afterglow analysis of the Fermi-LAT detected GRB 130907ANov 26 2014Jul 21 2015We present multi-wavelength observations of the hyper-energetic gamma-ray burst (GRB) 130907A, a Swift-discovered burst with early radio observations starting at $\approx 4$ hr after the $\gamma$-ray trigger. GRB 130907A was also detected by the Fermi/LAT ... More
Going the Distance: Mapping Host Galaxies of LIGO and Virgo Sources in Three Dimensions Using Local Cosmography and Targeted Follow-upMar 23 2016Sep 22 2016The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) discovered gravitational waves (GWs) from a binary black hole merger in 2015 September and may soon observe signals from neutron star mergers. There is considerable interest in searching ... More
Large Highly-Ionized Nebulae Around Ultra-luminous X-ray SourcesMar 14 2011We present the results of deep optical spectroscopic observations using the LRIS spectrograph on the Keck I 10-m telescope of three ultra-luminous X-ray sources (ULXs), Ho IX X-1; M81 X-6; and Ho II X-1. Our observations reveal the existence of large ... More
Evidence for High-Frequency QPOs with a 3:2 Frequency Ratio from a 5000 Solar Mass Black HoleJan 11 2016Following the discovery of 3:2 resonance quasi-periodic oscillations (QPOs) in M82X-1 (Pasham et al. 2014), we have constructed power density spectra (PDS) of all 15 (sufficiently long) {\it XMM-Newton} observations of the ultraluminous X-ray source NGC1313X-1 ... More
The afterglow and elliptical host galaxy of the short gamma-ray burst GRB 050724Aug 04 2005Nov 22 2005Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness -- the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing ... More
A multi-wavelength investigation of the radio-loud supernova PTF11qcj and its circumstellar environmentJul 09 2013Feb 04 2014We present the discovery, classification, and extensive panchromatic (from radio to X-ray) follow-up observations of PTF11qcj, a supernova discovered by the Palomar Transient Factory. PTF11qcj is located at a distance of dL ~ 124 Mpc. Our observations ... More
Opportunities for Multimessenger Astronomy in the 2020sMar 11 2019Electromagnetic observations of the sky have been the basis for our study of the Universe for millennia, cosmic ray studies are now entering their second century, the first neutrinos from an astrophysical source were identified three decades ago, and ... More
Supplement: Going the Distance: Mapping Host Galaxies of LIGO and Virgo Sources in Three Dimensions Using Local Cosmography and Targeted Follow-upMay 13 2016Sep 22 2016This is a supplement to the Letter of Singer et al. (https://arxiv.org/abs/1603.07333), in which we demonstrated a rapid algorithm for obtaining joint 3D estimates of sky location and luminosity distance from observations of binary neutron star mergers ... More
A New Population of High Redshift Short-Duration Gamma-Ray BurstsNov 03 2006Mar 23 2007The redshift distribution of the short-duration GRBs is a crucial, but currently fragmentary, clue to the nature of their progenitors. Here we present optical observations of nine short GRBs obtained with Gemini, Magellan, and the Hubble Space Telescope. ... More
Optical Follow-Up Observations of PTF10qts, a Luminous Broad-Lined Type Ic Supernova Found by the Palomar Transient FactoryMay 20 2014We present optical photometry and spectroscopy of the broad-lined Type Ic supernova (SNIc-BL) PTF10qts, which was discovered as part of the Palomar Transient Factory. The supernova was located in a dwarf galaxy of magnitude $r=21.1$ at a redshift $z=0.0907$. ... More
GRB 070201: A possible Soft Gamma Ray Repeater in M31Dec 20 2007The gamma-ray burst (GRB) 070201 was a bright short-duration hard-spectrum GRB detected by the Inter-Planetary Network (IPN). Its error quadrilateral, which has an area of 0.124 sq. deg, intersects some prominent spiral arms of the nearby M31 (Andromeda) ... More
The Fast and Furious Decay of the Peculiar Type Ic Supernova 2005ekJun 10 2013Jul 11 2013We present extensive multi-wavelength observations of the extremely rapidly declining Type Ic supernova, SN 2005ek. Reaching a peak magnitude of M_R = -17.3 and decaying by ~3 mag in the first 15 days post-maximum, SN 2005ek is among the fastest Type ... More
Early Observations of the Type Ia Supernova iPTF 16abc: A Case of Interaction with Nearby, Unbound Material and/or Strong Ejecta MixingAug 23 2017May 22 2018Early observations of Type Ia supernovae (SNe Ia) provide a unique probe of their progenitor systems and explosion physics. Here we report the intermediate Palomar Transient Factory (iPTF) discovery of an extraordinarily young SN Ia, iPTF 16abc. By fitting ... More
The Swift Gamma-Ray Burst Host Galaxy Legacy Survey - I. Sample Selection and Redshift DistributionApr 09 2015Jan 20 2016We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey ("SHOALS"), a multi-observatory high-redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst hosts yet assembled (119 in total). We describe the motivations ... More
Swift follow-up of gravitational wave triggers: results from the first aLIGO run and optimisation for the futureJun 15 2016Dec 20 2018During its first observing run, in late 2015, the advanced LIGO facility announced 3 gravitational wave (GW) triggers to electromagnetic follow-up partners. Two of these have since been confirmed as being of astrophysical origin: both are binary black ... More
The Afterglows, Redshifts, and Properties of Swift Gamma-Ray BurstsMay 06 2005We present optical, near-IR, and radio follow up of sixteen Swift bursts, including our discovery of nine afterglows and a redshift determination for three. These observations, supplemented by data from the literature, provide an afterglow recovery rate ... More
Swift follow-up of gravitational wave triggers: results from the first aLIGO run and optimisation for the futureJun 15 2016During its first observing run, in late 2015, the advanced LIGO facility announced 3 gravitational wave (GW) triggers to electromagnetic follow-up partners. Two of these have since been confirmed as being of astrophysical origin: both are binary black ... More
A Multimessenger Picture of the Flaring Blazar TXS 0506+056: implications for High-Energy Neutrino Emission and Cosmic Ray AccelerationJul 12 2018Detection of the IceCube-170922A neutrino coincident with the flaring blazar TXS 0506+056, the first and only 3-sigma high-energy neutrino source association to date, offers a potential breakthrough in our understanding of high-energy cosmic particles ... More
X-ray emission from supernovae in dense circumstellar matter environments: A search for collisionless shocksJun 04 2012(Abridged). The optical light curve of some SNe may be powered by the outward diffusion of the energy deposited by the explosion shock in optically thick circumstellar matter (CSM). Recently, it was shown that the radiation-mediated and -dominated shock ... More
Constraining GRB Emission Physics with Extensive Early-Time, Multiband Follow-upJul 18 2011Sep 08 2011Understanding the origin and diversity of emission processes responsible for Gamma-ray Bursts (GRBs) remains a pressing challenge. While prompt and contemporaneous panchromatic observations have the potential to test predictions of the internal-external ... More
GRB 060505: A possible short-duration gamma-ray burst in a star forming region at redshift of 0.09Mar 08 2007On 2006 May 5, a four second duration, low energy, ~10^49 erg, Gamma-Ray Burst (GRB) was observed, spatially associated with a z=0.0894 galaxy. Here, we report the discovery of the GRB optical afterglow and observations of its environment using Gemini-south, ... More
Multi-Wavelength Observations of GRB 050820A: An Exceptionally Energetic Event Followed from Start to FinishAug 08 2006We present observations of the unusually bright and long gamma-ray burst GRB 050820A, one of the best-sampled broadband data sets in the Swift era. The gamma-ray light curve is marked by a soft precursor pulse some 200 s before the main event; the lack ... More
A Spectacular Radio Flare from XRF 050416a at 40 days and Implications for the Nature of X-ray FlashesJul 23 2006Apr 20 2007We present detailed optical, near-infrared, and radio observations of the X-ray flash 050416a obtained with Palomar and Siding Springs Observatories as well as HST and the VLA, placing this event among the best-studied X-ray flashes to date. In addition, ... More
GRB171205A/SN2017iuk: A local low-luminosity gamma-ray burstOct 08 2018Gamma-ray bursts (GRBs) occurring in the local Universe constitute an interesting sub-class of the GRB family, since their luminosity is on average lower than that of their cosmological analogs. We aim to contribute to the study of local bursts by reporting ... More
The sub-energetic GRB 031203 as a cosmic analogue to GRB 980425Aug 04 2004Over the six years since the discovery of the gamma-ray burst GRB 980425, associated with the nearby (distance, ~40 Mpc) supernova 1998bw, astronomers have fiercely debated the nature of this event. Relative to bursts located at cosmological distances, ... More
GRB070610 : A Curious Galactic TransientAug 02 2007Oct 22 2007GRB 070610 is a typical high-energy event with a duration of 5s.Yet within the burst localization we detect a highly unusual X-ray and optical transient, SwiftJ195509.6+261406. We see high amplitude X-ray and optical variability on very short time scales ... More
Relativistic ejecta from XRF 060218 and the rate of cosmic explosionsApr 18 2006Aug 14 2006Over the last decade, long-duration gamma-ray bursts (GRBs) including the subclass of X-ray flashes (XRFs) have been revealed to be a rare variety of Type Ibc supernova (SN). While all these events result from the death of massive stars, the electromagnetic ... More
A UV Resonance Line Echo from a Shell Around a Hydrogen-Poor Superluminous SupernovaAug 14 2018Aug 18 2018Hydrogen-poor superluminous supernovae (SLSN-I) are a class of rare and energetic explosions discovered in untargeted transient surveys in the past decade. The progenitor stars and the physical mechanism behind their large radiated energies ($\sim10^{51}$ ... More
iPTF16asu: A Luminous, Rapidly-Evolving, and High-Velocity SupernovaJun 15 2017Jan 09 2018Wide-field surveys are discovering a growing number of rare transients whose physical origin is not yet well understood. Here, we present optical and UV data and analysis of iPTF16asu, a luminous, rapidly-evolving, high velocity, stripped-envelope supernova. ... More
Time-Varying Sodium Absorption in the Type Ia Supernova 2013ghMay 05 2016Temporal variability of narrow absorption lines in high-resolution spectra of Type Ia supernovae (SNe Ia) is studied to search for circumstellar matter. Time series which resolve the profiles of absorption lines such as Na I D or Ca II H&K are expected ... More