# Publications

• The Rapid Reddening and Featureless Optical Spectra of the Optical Counterpart of GW170817, AT 2017gfo, during the First Four Days
The Astrophysical Journal Letters, Volume 848, Number 2
• Optical emission from a kilonova following a gravitational-wave-detected neutron-star merger
Nature, 2017, 1476-4687
• Optical Follow-up of Gravitational-wave Events with Las Cumbres Observatory
The Astrophysical Journal Letters, Volume 848, Number 2
• Clues to the Nature of SN 2009ip II: The Continuing Photometric and Spectroscopic Evolution to 1000 Days
eprint arXiv:1704.05868
• Multiwavelength follow-up of a rare IceCube neutrino multiplet
eprint arXiv:1702.06131
• Growing evidence that SNe Iax are not a one-parameter family: the case of PS1-12bwh
Astronomy & Astrophysics, Volume 601, id.A62, 12 pp.
• Confined Dense Circumstellar Material Surrounding a Regular Type II Supernova: The Unique Flash-Spectroscopy Event - SN 2013fs
eprint arXiv:1701.02596
• A Type II Supernova Hubble diagram from the CSP-I, SDSS-II, and SNLS surveys
eprint arXiv:1612.05636
• Two New Calcium-Rich Gap Transients in Group and Cluster Environments
eprint arXiv:1612.00454
• Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj
eprint arXiv:1611.09438
• Constraints on the Progenitor of SN 2016gkg From Its Shock-Cooling Light Curve
eprint arXiv:1611.06451
• The progenitor and early evolution of the Type IIb SN 2016gkg
eprint arXiv:1611.00419
• On the early-time excess emission in hydrogen-poor superluminous supernovae
The Astrophysical Journal, 835:58 (19pp), 2017
• The Superluminous Transient ASASSN-15lh as a Tidal Disruption Event from a Kerr Black Hole
Nature Astronomy 1, Article number: 0002 (2016)
• Optical and Ultraviolet Observations of the Very Young Type IIP SN 2014cx in NGC 337
The Astrophysical Journal, Volume 832, Number 2
• Superluminous supernova 2015bn in the nebular phase: evidence for the engine-powered explosion of a stripped massive star
eprint arXiv:1608.02995
• Type Ibn Supernovae Show Photometric Homogeneity and Evidence for Two Spectral Subclasses
The Astrophysical Journal, Volume 836, Issue 2, article id. 158, 22 pp. (2017)
• 450 Days of Type II SN 2013ej in Optical and Near-Infrared
eprint arXiv:1605.06117
• The multi-faceted Type II-L supernova 2014G from pre-maximum to nebular phase
eprint arXiv:1605.06116
• The volumetric rate of superluminous supernovae at z ˜ 1
Monthly Notices of the Royal Astronomical Society, vol. 464, issue 3, pp. 3568-3579
• On the nature of Hydrogen-rich Superluminous Supernovae
eprint arXiv:1604.01226
• Interacting supernovae and supernova impostors. LSQ13zm: an outburst heralds the death of a massive star
eprint arXiv:1604.00013
• The Diversity of Type II Supernova vs. The Similarity in Their Progenitors
eprint arXiv:1603.08953
• Optical and near infrared observations of SN 2014ck: an outlier among the Type Iax supernovae
eprint arXiv:1603.07084
• SN 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova
eprint arXiv:1603.04748
• Comparative analysis of SN 2012dn optical spectra: days -14 to +114
Monthly Notices of the Royal Astronomical Society, Volume 457, Issue 4, p.3702-3723
• DES14X3taz: A Type I Superluminous Supernova Showing a Luminous, Rapidly Cooling Initial Pre-peak Bump
The Astrophysical Journal Letters, Volume 818, Issue 1, article id. L8, 7 pp. (2016).
• Flash Spectroscopy: Emission Lines from the Ionized Circumstellar Material around <10-Day-Old Type II Supernovae
eprint arXiv:1512.00846
• Type II supernova energetics and comparison of light curves to shock-cooling models
eprint arXiv:1512.00733
• Rapidly Rising Transients in the Supernova - Superluminous Supernova Gap
eprint arXiv:1511.00704
• On type IIn/Ia-CSM supernovae as exemplified by SN 2012ca
eprint arXiv:1510.01109
• Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy: the big brother of SN 1998S
eprint arXiv:1509.05389
• SN 2011fu: a type IIb supernova with a luminous double-peaked light curve
Monthly Notices of the Royal Astronomical Society, Volume 454, Issue 1, p.95-114
• Spectral models for early time SN 2011fe observations
Monthly Notices of the Royal Astronomical Society, Volume 454, Issue 3, p.2549-2556
• SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion
eprint arXiv:1507.07261
• Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra
eprint arXiv:1507.02501
• Science with KRAKENS
eprint arXiv:1506.03458
• The Detection of a Type IIn Supernova in Optical Follow-up Observations of IceCube Neutrino Events
The Astrophysical Journal, Volume 811, Issue 1, article id. 52, 17 pp. (2015).
• A strong ultraviolet pulse from a newborn type Ia supernova
Nature, Volume 521, Issue 7552, pp. 328-331 (2015).
• The rise-time of Type II supernovae
Monthly Notices of the Royal Astronomical Society, Volume 451, Issue 2, p.2212-2229
• Diversity in extinction laws of Type Ia supernovae measured between 0.2 and 2 µm
eprint arXiv:1504.02101
• SN 2013ab: a normal Type IIP supernova in NGC 5669
• Massive stars exploding in a He-rich circumstellar medium - VI. Observations of two distant Type Ibn supernova candidates discovered by La Silla-QUEST
Monthly Notices of the Royal Astronomical Society, Volume 449, Issue 2, p.1954-1966
• Supernova 2013by: A Type IIL Supernova with a IIP-like light curve drop
• Time-Varying Potassium in High-Resolution Spectra of the Type Ia Supernova 2014j
• The Rising Light Curves of Type Ia Supernovae
• OGLE-2013-SN-079: a lonely supernova consistent with a helium shell detonation
• Type Ia Supernova Spectral Features in the Context of Their Host Galaxy Properties
• Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory
• SN Hunt 248: a super-Eddington outburst from a massive cool hypergiant
• Slow-speed Supernovae from the Palomar Transient Factory: Two Channels
• Early Observations and Analysis of the Type Ia SN 2014J in M82
• A Continuum of H- to He-Rich Tidal Disruption Candidates With a Preference for E+A Galaxies
• Super-luminous supernovae from PESSTO
• The Type IIP Supernova 2012aw in M95: hydrodynamical modelling of the photospheric phase from accurate spectrophotometric monitoring
• The rise and fall of the Type Ib supernova iPTF13bvn - Not a massive Wolf-Rayet star
• Clues To The Nature of SN 2009ip from Photometric and Spectroscopic Evolution to Late Times
• The Rise of SN 2014J in the Nearby Galaxy M82
• Low luminosity Type II supernovae - II. Pointing towards moderate mass precursors
• The host galaxies of Type Ia supernovae discovered by the Palomar Transient Factory
• The Very Young Type Ia Supernova 2013dy: Discovery, and Strong Carbon Absorption in Early-time Spectra
• Slowly fading super-luminous supernovae that are not pair-instability explosions
• The superluminous supernova PS1-11ap: bridging the gap between low and high redshift
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Two Superluminous Supernovae from the Early Universe Discovered by the Supernova Legacy Survey
• The first month of evolution of the slow-rising Type IIP SN 2013ej in M74$^*$
• A statistical analysis of circumstellar material in Type Ia supernovae
• Discovery, Progenitor & Early Evolution of a Stripped Envelope Supernova iPTF13bvn
• Dark energy with gravitational lens time delays
• Las Cumbres Observatory Global Telescope Network
• Hubble Space Telescope spectra of the Type Ia supernova SN 2011fe: a tail of low-density, high-velocity material with Z \lt Z$_&sun;$
• Optical and near-infrared observations of SN 2011dh - The first 100 days
• Super Luminous Ic Supernovae: catching a magnetar by the tail
• Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium
• Late-time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx
• An outburst from a massive star 40days before a supernova explosion
• The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements
• PTF 11kx: A Type Ia Supernova with a Symbiotic Nova Progenitor
• Hubble Space Telescope studies of low-redshift Type Ia supernovae: evolution with redshift and ultraviolet spectral trends
• Analysis of the Early-time Optical Spectra of SN 2011fe in M101
• An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts
• Near-infrared observations of Type Ia supernovae: the best known standard candle for cosmology
• Light echoes reveal an unexpectedly cool $\eta$Carinae during its nineteenth-century Great Eruption
• A ground-based measurement of the relativistic beaming effect in a detached double WD binary
• On Type IIn/Ia-CSM supernovae as exemplified by SN 2012ca*
Monthly Notices of the Royal Astronomical Society, Volume 459, Issue 3, p.2721-2740
• Science operations for LCOGT: a global telescope network
• The LCOGT Supernova Key Project
NOAO Proposal ID #2014B-0286
Contact: ahowell@lco.global