Katie Auchettl
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View article: JWST Observations of SN 2024ggi. I. Interpretation and Model Comparison of the Type II Supernova 2024ggi at 55 Days past Explosion
JWST Observations of SN 2024ggi. I. Interpretation and Model Comparison of the Type II Supernova 2024ggi at 55 Days past Explosion Open
We present panchromatic 0.4–21 μ m observations of the nearby (∼7.2 Mpc) Type II supernova (SN) 2024ggi, obtained during the plateau phase at ∼55 days past explosion. Our data set includes JWST spectra spanning 1.7–14 μ m, mid-infrared (MI…
View article: A Panchromatic View of Late-time Shock Power in the Type II Supernova 2023ixf
A Panchromatic View of Late-time Shock Power in the Type II Supernova 2023ixf Open
We present multiwavelength observations of the Type II supernova (SN II) 2023ixf during its first 2 yr of evolution. We combine ground-based optical/near-infrared spectroscopy with Hubble Space Telescope far- and near-ultraviolet spectrosc…
View article: Spectral Diversity in Type Ibn Supernovae and the Large Host Offset of SN2024acyl
Spectral Diversity in Type Ibn Supernovae and the Large Host Offset of SN2024acyl Open
In this paper, we first present observations of SN~2024acyl, a normal Type Ibn supernova with a large projected offset ($\sim$35~kpc) from its host galaxy. The low star-formation rate measured at the explosion site raises the possibility t…
View article: JWST Observations of SN 2023ixf. II. The Panchromatic Evolution between 250 and 720 Days after the Explosion
JWST Observations of SN 2023ixf. II. The Panchromatic Evolution between 250 and 720 Days after the Explosion Open
We present the nebular phase spectroscopic and photometric observations of the nearby hydrogen-rich core-collapse supernova (CCSN) SN 2023ixf, obtained through our JWST programs. These observations, combined with ground-based optical and n…
View article: JWST Spectroscopy of SN Ia 2022aaiq and 2024gy: Evidence for Enhanced Central Stable Ni Abundance and a Deflagration-to-Detonation Transition
JWST Spectroscopy of SN Ia 2022aaiq and 2024gy: Evidence for Enhanced Central Stable Ni Abundance and a Deflagration-to-Detonation Transition Open
We present optical + near-infrared (NIR) + mid-infrared (MIR) observations of the normal Type Ia supernovae (SN Ia) 2022aaiq and 2024gy in the nebular phase, continuously spanning 0.35-28 microns. Medium-resolution JWST spectroscopy reveal…
View article: Final Moments. III. Explosion Properties and Progenitor Constraints of CSM-interacting Type II Supernovae
Final Moments. III. Explosion Properties and Progenitor Constraints of CSM-interacting Type II Supernovae Open
We present analysis of the plateau and late-time phase properties of a sample of 39 Type II supernovae (SNe II) that show narrow, transient, high-ionization emission lines (i.e., “IIn-like”) in their early-time spectra from interaction wit…
View article: Pan-STARRS follow-up of the gravitational-wave event S250818k and the lightcurve of SN 2025ulz
Pan-STARRS follow-up of the gravitational-wave event S250818k and the lightcurve of SN 2025ulz Open
Kilonovae are the scientifically rich, but observationally elusive, optical transient phenomena associated with compact binary mergers. Only a handful of events have been discovered to date, all through multi-wavelength (gamma ray) and mul…
View article: SN 2019tsf: Evidence for Extended Hydrogen-poor CSM in the Three-peaked Light Curve of Stripped Envelope of a Type Ib Supernova
SN 2019tsf: Evidence for Extended Hydrogen-poor CSM in the Three-peaked Light Curve of Stripped Envelope of a Type Ib Supernova Open
We present multiband ATLAS and ZTF photometry for SN 2019tsf, a Type Ib stripped-envelope supernova (SESN). The slow spectral evolution could be associated with an uncommon explosion mechanism specific to this SN. Possible explanations inc…
View article: SN 2022acko and the Properties of its Red Supergiant Progenitor: Direct Detection, Light Curves, and Nebular Spectroscopy
SN 2022acko and the Properties of its Red Supergiant Progenitor: Direct Detection, Light Curves, and Nebular Spectroscopy Open
We present ultraviolet, optical, and infrared observations of the Type II-P supernova SN 2022acko in NGC 1300, located at a distance of 19.0 +/- 2.9 Mpc. Our dataset spans 1-350 days post-explosion in photometry, complemented by late-time …
View article: The ultraviolet spectra of 2003fg-like Type Ia supernovae
The ultraviolet spectra of 2003fg-like Type Ia supernovae Open
2003fg-like Type Ia supernovae (03fg-like SNe Ia) are rare sub-type of SNe Ia, photometrically characterized by broader optical light curves and bluer ultraviolet (UV) colours compared to normal SNe Ia. In this work, we study four 03fg-lik…
View article: Seeing the Outer Edge of the Infant Type Ia Supernova 2024epr in the Optical and Near Infrared
Seeing the Outer Edge of the Infant Type Ia Supernova 2024epr in the Optical and Near Infrared Open
We present optical-to-near-infrared (NIR) photometry and spectroscopy of the Type Ia supernova (SN~Ia) 2024epr, including NIR spectra observed within two days of first light. The early-time optical spectra show strong, high-velocity Ca and…
View article: ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event
ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event Open
We discuss ASASSN-24fw, a 13th-magnitude star that optically faded by mag starting in September 2024 after over a decade of quiescence in ASAS-SN. The dimmimg lasted $$8 months before returning to quiescence in late May 2025. The spectral…
View article: ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event
ASASSN-24fw: An 8-month long, 4.1 mag, optically achromatic and polarized dimming event Open
We discuss ASASSN-24fw, a 13th-magnitude star that optically faded by mag starting in September 2024 after over a decade of quiescence in ASAS-SN. The dimmimg lasted $$8 months before returning to quiescence in late May 2025. The s…
View article: Early and Extensive Ultraviolet through Near Infrared Observations of the Intermediate-luminosity Type Iax Supernovae 2024pxl
Early and Extensive Ultraviolet through Near Infrared Observations of the Intermediate-luminosity Type Iax Supernovae 2024pxl Open
We present ultraviolet (UV) through near-infrared (NIR) photometric and spectroscopic observations of the nearby SN 2024pxl, the third Type Ia supernova (SN Ia) in NGC 6384. SN 2024pxl is a Type Iax supernova (SN Iax) with an intermediate …
View article: Expanding the parameter space of 2002es-like type Ia supernovae: on the underluminous ASASSN-20jq / SN 2020qxp
Expanding the parameter space of 2002es-like type Ia supernovae: on the underluminous ASASSN-20jq / SN 2020qxp Open
We present optical photometric and spectroscopic observations of the peculiar Type Ia supernovae (SNe Ia) ASASSN-20jq/SN 2020qxp. It is a low-luminosity object, with a peak absolute magnitude of MB = −17.1 ± 0.5 mag, while its post-peak li…
View article: Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS
Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS Open
We report initial observations aimed at the characterization of a third interstellar object. This object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered on 2025 July 1 UT and has an orbital eccentricity of $e\sim6.1$, perihelion of $q\sim 1…
View article: Characterizing the standardization properties of type ia supernovae in the <i>z</i> band with hierarchical Bayesian modelling
Characterizing the standardization properties of type ia supernovae in the <i>z</i> band with hierarchical Bayesian modelling Open
Type Ia supernovae (SNe Ia) are standardizable candles: their peak magnitudes can be corrected for correlations between light-curve properties and their luminosities to precisely estimate distances. Understanding SN Ia standardization acro…
View article: The most energetic transients: Tidal disruptions of high-mass stars
The most energetic transients: Tidal disruptions of high-mass stars Open
We present the class of extreme nuclear transients (ENTs), including the most energetic single transient yet found, Gaia18cdj. Each ENT is coincident with its host-galaxy nucleus and exhibits a smooth (<10% excess variability), luminous (2…
View article: Characterising the Standardisation Properties of Type Ia Supernovae in the z band with Hierarchical Bayesian Modelling
Characterising the Standardisation Properties of Type Ia Supernovae in the z band with Hierarchical Bayesian Modelling Open
Type Ia supernovae (SNe Ia) are standardisable candles: their peak magnitudes can be corrected for correlations between light curve properties and their luminosities to precisely estimate distances. Understanding SN Ia standardisation acro…
View article: Expanding the parameter space of 2002es-like type Ia supernovae: On the underluminous ASASSN-20jq/SN 2020qxp
Expanding the parameter space of 2002es-like type Ia supernovae: On the underluminous ASASSN-20jq/SN 2020qxp Open
We present optical photometric and spectroscopic observations of the peculiar Type Ia supernovae (SNe Ia) ASASSN-20jq/SN 2020qxp. It is a low-luminosity object, with a peak absolute magnitude of M B = −17.1 ± 0.5 mag, while its post-peak l…
View article: The <tt>BTSbot-nearby</tt> Discovery of SN 2024jlf: Rapid, Autonomous Follow-up Probes Interaction in an 18.5 Mpc Type IIP Supernova
The BTSbot-nearby Discovery of SN 2024jlf: Rapid, Autonomous Follow-up Probes Interaction in an 18.5 Mpc Type IIP Supernova Open
We present observations of the Type IIP supernova (SN) SN 2024jlf, including spectroscopy beginning just 0.7 days (∼17 hr) after first light. Rapid follow-up was enabled by the new BTSbot-nearby program, which involves autonomously trigger…
View article: A Large-scale Search for Photometrically Variable Active Galactic Nuclei in Dwarf Galaxies Using the Young Supernova Experiment
A Large-scale Search for Photometrically Variable Active Galactic Nuclei in Dwarf Galaxies Using the Young Supernova Experiment Open
We conduct an analysis of over 60,000 dwarf galaxies ( ) in search of photometric variability indicative of active galactic nuclei (AGNs). Using data from the Young Supernova Experiment, a time domain survey on the Pan-STA…
View article: Large Cold Dust Reservoir Revealed in Transitional SN Ib 2014C by James Webb Space Telescope Mid-infrared Spectroscopy
Large Cold Dust Reservoir Revealed in Transitional SN Ib 2014C by James Webb Space Telescope Mid-infrared Spectroscopy Open
Supernova (SN) 2014C is a rare transitional event that exploded as a hydrogen-poor, helium-rich Type Ib SN and subsequently interacted with a hydrogen-rich circumstellar medium (CSM) a few months postexplosion. This unique interacting obje…
View article: JWST and Ground-based Observations of the Type Iax Supernovae SN 2024pxl and SN 2024vjm: Evidence for Weak Deflagration Explosions
JWST and Ground-based Observations of the Type Iax Supernovae SN 2024pxl and SN 2024vjm: Evidence for Weak Deflagration Explosions Open
We present panchromatic optical $+$ near-infrared (NIR) $+$ mid-infrared (MIR) observations of the intermediate-luminosity Type Iax supernova (SN Iax) 2024pxl and the extremely low-luminosity SN Iax 2024vjm. JWST observations provide unpre…
View article: Photometry and Spectroscopy of SN 2024pxl: A Luminosity Link Among Type Iax Supernovae
Photometry and Spectroscopy of SN 2024pxl: A Luminosity Link Among Type Iax Supernovae Open
We present extensive ultraviolet to optical photometric and optical to near-infrared (NIR) spectroscopic follow-up observations of the nearby intermediate-luminosity ($M_V = -$16.81$\pm$0.19~mag) Type Iax supernova (SN) 2024pxl in NGC 6384…
View article: AT 2020nov: Evidence for Disk Reprocessing in a Rare Tidal Disruption Event
AT 2020nov: Evidence for Disk Reprocessing in a Rare Tidal Disruption Event Open
We present a detailed analysis of AT 2020nov, a tidal disruption event (TDE) in the center of its host galaxy, located at a redshift of z = 0.083. AT 2020nov exhibits unique features, including double-peaked Balmer emission lines, a broad …
View article: An optically led search for kilonovae to <i>z</i>∼0.3 with the Kilonova and Transients Programme (KNTraP)
An optically led search for kilonovae to <i>z</i>∼0.3 with the Kilonova and Transients Programme (KNTraP) Open
Compact binary mergers detectable in gravitational waves can be accompanied by a kilonova, an electromagnetic transient powered by radioactive decay of newly synthesised r-process elements. A few kilonova candidates have been observed duri…
View article: The BTSbot-nearby discovery of SN 2024jlf: rapid, autonomous follow-up probes interaction in an 18.5 Mpc Type IIP supernova
The BTSbot-nearby discovery of SN 2024jlf: rapid, autonomous follow-up probes interaction in an 18.5 Mpc Type IIP supernova Open
We present observations of the Type IIP supernova (SN) 2024jlf, including spectroscopy beginning just 0.7 days ($\sim$17 hours) after first light. Rapid follow-up was enabled by the new $\texttt{BTSbot-nearby}$ program, which involves auto…
View article: GRB 220831A: a hostless, intermediate gamma-ray burst with an unusual optical afterglow
GRB 220831A: a hostless, intermediate gamma-ray burst with an unusual optical afterglow Open
GRB 220831A is a gamma-ray burst (GRB) with a duration and spectral peak energy that places it at the interface between the distribution of long-soft and short-hard GRBs. In this paper, we present the multiwavelength follow-up campaign to …
View article: The AGN Optical Variability Fundamental Plane
The AGN Optical Variability Fundamental Plane Open
We investigate the relationship between AGN optical variability timescales, amplitudes, and supermassive black hole (SMBH) masses using homogeneous light curves from the All-Sky Automated Survey for SuperNovae (ASAS-SN). We fit a damped ra…