Explanipedia

The very high energy view of gamma-ray bursts with the MAGIC telescopes Open

A. Berti, Ž. Bošnjak, A. J. Castro‐Tirado, S. Covino, Susumu Inoue , et al. · 2025

Gamma-ray bursts (GRBs) are one of the main targets for the observations of the MAGIC telescopes. As a result of the effort in improving the sensitivity of the instrument and the automatic follow-up strategy, MAGIC detected two GRBs in the…

Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations Open

Sara Capecchiacci, Ioannis Liodakis, R. Middei, Dawoon E. Kim, Laura Di Gesu , et al. · 2025

Polarimetric properties of blazars allow us to put constraints on the acceleration mechanisms that fuel their powerful jets. By studying the multiwavelength polarimetric behaviour of high synchrotron peaked (HSP) and low synchrotron peaked…

OGLE-2015-BLG-1609Lb: A sub-Jovian planet orbiting a low-mass stellar or brown dwarf host Open

Mateusz J. Mroz, R. Poleski, A. Udalski, T. Sumi, Y. Tsapras , et al. · 2025

We present a comprehensive analysis of the planetary microlensing event OGLE-2015-BLG-1609. The planetary anomaly was detected by two survey telescopes, OGLE and MOA. Both surveys collected enough data over the planetary anomaly to enable …

Spectropolarimetry of SN 2023ixf Reveals Both Circumstellar Material and an Aspherical Helium Core Open

Manisha Shrestha, Sabrina DeSoto, David J. Sand, G. G. Williams, Jennifer L. Hoffman , et al. · 2025

We present multi-epoch optical spectropolarimetric and imaging polarimetric observations of the nearby Type II supernova (SN) 2023ixf discovered in M101 at a distance of 6.85 Mpc. The first imaging polarimetric observations were taken +2.3…

Astronomical Seeing Prediction with Machine Learning Open

Fernando Abárzuza, I. A. Steele, Helen Jermak, Joao Bento, David Copley , et al. · 2025

We investigate the use of supervised machine learning models to predict current atmospheric seeing at the Observatorio del Roque de Los Muchachos, La Palma. The prediction is made from current, local meteorological conditions as measured b…

The polarisation behaviour of OJ 287 viewed through radio, millimetre, and optical observations between 2015 and 2017 Open

Jenni Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, Wara Chamani , et al. · 2025

OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300–58000) contains several interesting events …

The polarisation behaviour of OJ 287 viewed through radio, millimetre and optical observations between 2015 and 2017 Open

Jenni Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, Wara Chamani , et al. · 2025

OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300-58000) contains several interesting events …

A Two-Week $IXPE$ Monitoring Campaign on Mrk 421 Open

W. Peter Maksym, Ioannis Liodakis, M. Lynne Saade, Dawoon E. Kim, R. Middei , et al. · 2024

X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blaza…

Spectropolarimetry of SN 2023ixf reveals both circumstellar material and helium core to be aspherical Open

Manisha Shrestha, Sabrina DeSoto, David J. Sand, G. G. Williams, Jennifer L. Hoffman , et al. · 2024

We present multi-epoch optical spectropolarimetric and imaging polarimetric observations of the nearby Type II supernova (SN) 2023ixf discovered in M101 at a distance of 6.85 Mpc. The first imaging polarimetric observations were taken +2.3…

Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations Open

Ioannis Liodakis, S. Kiehlmann, Alan P. Marscher, Haocheng Zhang, D. Blinov , et al. · 2024

Variability can be the pathway to understanding the physical processes in astrophysical jets. However, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to pr…

Distinguishing radiation mechanisms and particle populations in blazar jets through long-term multiband monitoring with RINGO3 and <i>Fermi</i> Open

Callum McCall, Helen Jermak, I. A. Steele, I. Agudo, U. Barres de Almeida , et al. · 2024

We present the results of seven years of multicolour photometric monitoring of a sample of 31 $\gamma$-ray bright blazars using the RINGO3 polarimeter on the Liverpool Telescope from 2013–2020. We explore the relationships between simultan…

Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations Open

Ioannis Liodakis, S. Kiehlmann, Alan P. Marscher, Haocheng Zhang, D. Blinov , et al. · 2024

Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to pr…

IXPE observation of PKS 2155-304 reveals the most highly polarized blazar Open

Pouya M. Kouch, Ioannis Liodakis, R. Middei, Dawoon E. Kim, F. Tavecchio , et al. · 2024

We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also…

Fires in the deep: The luminosity distribution of early-time gamma-ray-burst afterglows in light of the Gamow Explorer sensitivity requirements Open

Д. А. Канн, N. E. White, G. Ghirlanda, S. R. Oates, A. Melandri , et al. · 2024

\nContext. Gamma-ray bursts (GRBs) are ideal probes of the Universe at high redshift (ɀ), pinpointing the locations of the earliest star-forming galaxies and providing bright backlights with simple featureless power-law spectra that can be…

The extreme coronal line emitter AT 2022fpx: Varying optical polarization properties and late-time X-ray flare Open

K. I. I. Koljonen, Ioannis Liodakis, E. Lindfors, K. Nilsson, T. Reynolds , et al. · 2024

Supermassive black holes disrupt passing stars, producing outbursts called tidal disruption events (TDEs). TDEs have recently gained attention due to their unique dynamics and emission processes, which are still not fully understood. Espec…

A study of Be stars in the time domain. I. Spectral data and polarimetry Open

Adrián Castañón Esteban, I. A. Steele, Helen Jermak · 2024

We present the first part of a spectroscopic and polarimetric study on a sample of 58 Be stars that have been measured since 1998. The aim of the study is to understand the timescales of disk variability, formation and dissipation as a fun…

Detection of an intranight optical hard-lag with colour variability in blazar PKS 0735+178 Open

Callum McCall, Helen Jermak, I. A. Steele, S. Kobayashi, J. H. Knapen , et al. · 2024

Blazars are a highly variable subclass of active galactic nuclei that have been observed to vary significantly during a single night. This intranight variability remains a debated phenomenon, with various mechanisms proposed to explain the…

Automated SpectroPhotometric Image REDuction (ASPIRED) Open

Marco C. Lam, Richard J. Smith, I. A. Steele · 2023

We aim to provide a suite of publicly available spectral data reduction software to facilitate rapid scientific outcomes from time-domain observations. For time resolved observations, an automated pipeline frees astronomers from performanc…

GRB 210619B: First Gamma-Ray Burst Detection by the Novel Polarimeter MOPTOP Open

Manisha Shrestha, I. A. Steele, S. Kobayashi, R. J. Smith, Helen Jermak , et al. · 2023

GRB 210619B was a bright long gamma-ray burst (GRB) which was optically followed up by the novel polarimeter MOPTOP on the Liverpool Telescope. This was the first GRB detection by the instrument since it began science observations. MOPTOP …

GRB 210619B: first gamma-ray burst detection by the novel polarimeter MOPTOP Open

Manisha Shrestha, I. A. Steele, S. Kobayashi, R. J. Smith, Helen Jermak , et al. · 2023

GRB~210619B was a bright long gamma-ray burst (GRB) which was optically followed up by the novel polarimeter MOPTOP on the Liverpool Telescope (LT). This was the first GRB detection by the instrument since it began science observations. MO…

Optimizing the observation of optical kilonovae with medium-size telescopes Open

A. E. Camisasca, I. A. Steele, Mattia Bulla, C. Guidorzi, Manisha Shrestha · 2023

We consider the optimization of the observing strategy (cadence, exposure time, and filter choice) using medium-size (2-m-class) optical telescopes in the follow-up of kilonovae localized with arcminute accuracy to be able to distinguish a…

The role of the magnetic fields in GRB outflows Open

N. Jordana-Mitjans, C. G. Mundell, S. Kobayashi, R. J. Smith, C. Guidorzi , et al. · 2023

Gamma-ray bursts (GRBs) are bright extragalactic flashes of gamma-ray radiation and briefly the most energetic explosions in the Universe. Their catastrophic origin —the merger of compact objects or the collapse of massive stars— drives th…

A Short Gamma-Ray Burst from a Protomagnetar Remnant Open

N. Jordana-Mitjans, C. G. Mundell, C. Guidorzi, R. J. Smith, E. Ramirez‐Ruiz , et al. · 2022

The contemporaneous detection of gravitational waves and gamma rays from GW170817/GRB 170817A, followed by kilonova emission a day after, confirmed compact binary neutron star mergers as progenitors of short-duration gamma-ray bursts (GRBs…

Short timescale imaging polarimetry of geostationary satellite Thor-6: The nature of micro-glints Open

K. Wiersema, P. Chote, Jonathan M. Marchant, S. Covino, J. R. Maund , et al. · 2022

An isolated stellar-mass black hole detected through astrometric microlensing Open

K. C. Sahu, Jay Anderson, Stefano Casertano, Howard E. Bond, A. Udalski , et al. · 2022

We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (tE ≃ 270 days), h…

Laboratory and On-sky Testing of an InGaAs Detector for Infrared Imaging Open

Kristoffor Batty, I. A. Steele, C. M. Copperwheat · 2022

We describe the results of testing a shortwave infrared CMOS camera using an indium gallium arsenide (InGaAs) detector. The new generation of InGaAs detectors offers a cost-effective alternative to mercury cadmium telluride (HgCdTe) for as…

GRB 191016A: A highly collimated gamma-ray burst jet with magnetised energy injection Open

Manisha Shrestha, I. A. Steele, S. Kobayashi, N. Jordana-Mitjans, R. J. Smith , et al. · 2021

Long gamma-ray burst GRB 191016A was a bright and slow rising burst that was detected by the \textit{Swift} satellite and followed up by ground based Liverpool Telescope (LT). LT follow-up started $2411$-s after the \textit{Swift} Burst Al…

Automated SpectroPhotometric Image REDuction (ASPIRED) -- A Python-based spectral data reduction toolkit Open

Marco C. Lam, R. J. Smith, I. Arcavi, I. A. Steele, Josh Veitch-Michaelis , et al. · 2021

We provide a suite of publicly available spectral data reduction software to facilitate rapid scientific products from time-domain observations. The Automated SpectroPhotometric REDuction (ASPIRED) toolkit is aimed to be as general as poss…

THE 4 M NEW ROBOTIC TELESCOPE PROJECT: AN UPDATED REPORT Open

C. M. Gutiérrez, M.E. Torres, A.J. Oria, J. J. Fernández-Valdivia, Donald M. Arnold , et al. · 2021

The New Robotic Telescope (NRT) is an international collaboration to build and operate a 4m diameter fully robotic telescope. The telescope will take advantage of the superb atmospheric conditions at the Observatory of the Roque de los Muc…

Gaia Data Release 2. The astrometric solution Open

L. Lindegren, J. Hernández, A. Bombrun, S. Klioner, U. Bastian , et al. · 2021

Gaia Data Release 2 (Gaia DR2) contains results for 1693 million sources in the magnitude range 3 to 21 based on observations collected by the European Space Agency Gaia satellite during the first 22 months of its operational phase. We des…

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