Malte Busmann

Follow-up of SN 2025wny IV: Photometric Time-delay Measurements of a Strongly Lensed Superluminous Supernova

Alice Townsend, Suhail Dhawan, Erin E. Hayes +34

We present photometric time-delay measurements of SN 2025wny, the first strongly lensed Type I superluminous supernova (SLSN-I), discovered at $z = 2.015$ . Time-delay measurements…

Follow-up of SN 2025wny III: Spectroscopic Time-delay Measurements of a Strongly Gravitationally Lensed Superluminous Supernova

Joel Johansson, Edvard Mörtsell, Ariel Goobar +30

We present spatially resolved spectra and infer the time-delays between the multiple images of the strongly gravitationally lensed superluminous supernova (SLSN) 2025wny at z=2.015…

Follow-up of SN 2025wny II: Superluminous Supernova Physics at Cosmic Noon

Maggie L. Li, Lin Yan, Anamaria Gkini +46

SN 2025wny is a gravitationally lensed, hydrogen-poor superluminous supernova (SLSN-I) at z = 2.015. To date, it is the most extensively observed high-redshift core-collapse SN and…

GRB 260310A/SN 2026fgk: Photometric and Spectroscopic Evolution of a Nearby GRB-Supernova and an Exceptionally Bright Afterglow at z=0.153

Brendan O'Connor, Malte Busmann, Xander J. Hall +24

The association of broad-lined Type Ic supernovae with long-duration gamma-ray bursts (GRBs) has been known for 28 years. However, only about seventy gamma-ray burst supernovae (GR…

EP260321a/SN 2026gzf: The Faintest Shock Breakout Associated with a Broad-Lined Supernova

Brendan O'Connor, Xander J. Hall, Malte Busmann +33

The explosion of a star is first marked by the shock wave breaking out of the stellar surface, producing a burst of ultraviolet and X-ray radiation. These events are observationall…

astro-ph.GA2026

Discovery of an extremely narrow trail-like feature crossing the Veil Supernova Remnant in deep amateur observations

David Martinez-Delgado, Jan-Niklas Pippert, Miguel A. Perez-Torres +9

We report the discovery of an extremely narrow and highly collimated gaseous trail-like structure crossing the eastern region of the Veil Nebula (Cygnus Loop). The feature was firs…

Discovery of a Supernova Following the Einstein Probe Transient EP250302a at z = 1.131

Brendan O'Connor, Malte Busmann, James Freeburn +7

We present a multi-wavelength analysis of the Einstein Probe (EP) fast X-ray transient (FXT) EP250302a located at redshift $z = 1.131$ . Despite its luminous prompt X-ray emission, th…

astro-ph.EP2026

TOI-2147 b and TOI-6019 b: Two eccentric warm Jupiters detected and characterized with TESS and MaHPS

Luis Thomas, Louise D. Nielsen, Hanna Kellermann +36

The population of Jupiter-sized exoplanets with orbital periods between 10 and 200 days (WJs) exhibits a broad range of orbital eccentricities and system architectures, suggesting…

An extremely bright slow-rising afterglow from an off-axis jet in GRB 260310A

Yu-Han Yang, Roberto Ricci, Eleonora Troja +31

We present a multi-wavelength study of GRB 260310A, a nearby long-duration gamma-ray burst at $z ≃ 0.153$ associated with a broad-lined Type Ic supernova. Despite its modest pro…

Electromagnetic Follow-up of the Sub-Solar Mass Gravitational Wave Candidate S251112cm: Kilonova Constraints and a Coincident IIb Supernova

Xander J. Hall, Tomas Ahumada, Julius Gassert +25

On November 12th, 2025 the LIGO--Virgo--KAGRA (LVK) collaboration reported gravitational waves (GWs) from a compact object merger candidate (S251112cm) with at least one sub-solar…

A Natural $≳ 100 \times$ Telescope: Discovery of the Strongly Lensed Type II SN 2025mkn at $z = 1.37$

Cameron Lemon, Ariel Goobar, Joel Johansson +90

We present the discovery of SN 2025mkn, a gravitationally lensed Type II supernova. First detected as a blue transient in ZTF, 0.83 $^{''}$ from a $z = 0.42$ elliptical gala…

Long GRB 250916A: an Off-axis Powerlaw Jet with Thermal Cocoon

Utkarsh Pathak, Sameer K. Patil, Hitesh Tanenia +22

Some gamma-ray bursts (GRBs) exhibit precursor emission episodes preceding the main emission, with a quiescent period in between. The properties of the precursor emission and the d…

astro-ph.HE2026★ 1 cited

TDE 2025abcr: A Tidal Disruption Event in the Outskirts of a Massive Galaxy

Robert Stein, Jonathan Carney, Charlotte Ward +27

Tidal disruption events (TDEs) have traditionally been discovered in optical sky surveys through targeted searches of nuclear transients. However, it is expected that some TDEs wil…

EP250827b/SN 2025wkm: An X-ray Flash-Supernova Powered by a Central Engine and Circumstellar Interaction

Gokul P. Srinivasaragavan, Dongyue Li, Xander J. Hall +100

We present the discovery of EP250827b/SN 2025wkm, an X-ray Flash (XRF) discovered by the Einstein Probe (EP), accompanied by a broad-line Type Ic supernova (SN Ic-BL) at $z = 0.119…

ZTF25abjmnps (AT2025ulz) and S250818k: A Candidate Superkilonova from a Sub-threshold Sub-Solar Gravitational Wave Trigger

Mansi M. Kasliwal, Tomas Ahumada, Robert Stein +61

On August 18, 2025, the LIGO-Virgo-KAGRA collaboration reported gravitational waves from a sub-threshold binary neutron star merger. If astrophysical, this event would have a surpr…

AT2025ulz and S250818k: Deep X-ray and radio limits on off-axis afterglow emission and prospects for future discovery

Brendan O'Connor, Roberto Ricci, Eleonora Troja +15

The first joint electromagentic (EM) and gravitational wave (GW) detection, known as GW170817, marked a critical juncture in our collective understanding of compact object mergers.…

AT2025ulz and S250818k: Investigating early time observations of a subsolar mass gravitational-wave binary neutron star merger candidate

Xander J. Hall, Malte Busmann, Hauke Koehn +32

Over the past LIGO--Virgo--KAGRA (LVK) observing runs, it has become increasingly clear that identifying the next electromagnetic counterparts to gravitational-wave (GW) neutron st…

AT2025ulz and S250818k: Leveraging DESI spectroscopy in the hunt for a kilonova associated with a sub-solar mass gravitational wave candidate

Xander J. Hall, Antonella Palmese, Brendan O'Connor +47

On August 18th, 2025, the LIGO--Virgo--KAGRA collaboration reported a sub-threshold gravitational wave candidate detection consistent with a sub-solar-mass neutron star merger, den…

Comprehensive X-ray Observations of the Exceptional Ultra-long X-ray and Gamma-ray Transient GRB 250702B with Swift, NuSTAR, and Chandra: Insights from the X-ray Afterglow Properties

Brendan O'Connor, Ramandeep Gill, James DeLaunay +22

GRB 250702B is an exceptional transient that produced multiple episodes of luminous gamma-ray radiation lasting for $> 25$ ks, placing it among the class of ultra-long gamma-ray bur…

The redshift distribution of Einstein Probe transients supports their relation to gamma-ray bursts

Brendan O'Connor, Paz Beniamini, Eleonora Troja +9

The launch of the \textit{Einstein Probe} unleashed a new era of high-energy transient discovery in the largely unexplored soft X-ray band. The \textit{Einstein Probe} has detected…

astro-ph.HE2025★ 1 cited

GRB 250704B: An Off-axis Short GRB with a Long-Lived Afterglow Plateau

Vishwajeet Swain, Tomás Ahumada, Sameer K. Patil +27

We present a detailed multi-wavelength afterglow study of the short GRB 250704B, extensively monitored in optical and near-infrared bands. Its afterglow displays an unusually long-…

Optical/infrared observations of the extraordinary GRB 250702B: a highly obscured afterglow in a massive galaxy consistent with multiple possible progenitors

Jonathan Carney, Igor Andreoni, Brendan O'Connor +31

GRB 250702B was the longest gamma-ray burst ever detected, with a duration that challenges standard collapsar models and suggests an exotic progenitor. We collected a rich set of o…