Context. Many applications in transient science, gravitational wave follow-up, and galaxy population studies require all-sky galaxy catalogs with reliable distances, extents, and stellar masses. However, existing catalogs often lack completeness beyond ~100 Mpc, suffer from stellar contamination, or do not provide homogeneous stellar mass estimates and size information. Aims. Our goal is to build a high-purity, high-completeness, all-sky galaxy catalog out to 2000 Mpc, specifically designed to support time-domain and multi-messenger astrophysics. Methods. We combined major galaxy catalogs and deep imaging surveys – including the Legacy Surveys, Pan-STARRS, DELVE, and SDSS – and added spectroscopic, photometric, and redshift-independent distances. We cleaned the sample using the Gaia catalog to remove stars and visually inspected all ambiguous cases below 100 Mpc through a classification platform that gathered 27 000 expert votes. Stellar masses were estimated using optical and mid-infrared profile-fit photometry, and we improved the accuracy of photometric distances by combining multiple independent estimates. Results. The resulting catalog, REGALADE, includes nearly 80 million galaxies with distances under 2000 Mpc. It provides stellar masses for 88% of the sample and ellipse fits for 80%. REGALADE is more than 90% complete for galaxies contributing 50% of the total r-band luminosity out to 360 Mpc. In science tests, it recovers 60% more known supernova hosts, doubles the number of low-luminosity transient hosts, and identifies more reliable hosts for ultraluminous and hyper-luminous X-ray sources. Conclusions. REGALADE is one of the most complete and reliable all-sky galaxy catalog to date for the nearby Universe, built for real-world applications in transient and multi-messenger astrophysics. The full dataset, visual classifications, and code will be released to support broad community use.

Modern astronomical surveys deliver immense volumes of transient detections, yet distinguishing between real astrophysical signals (e.g., explosive events, variable stars) and bogus imaging artifacts remains challenging. Convolutional neural networks (CNNs) are effective for such real-bogus classification in optical imaging data; however, their reliance on latent representations makes it difficult to discern the underlying physical reasoning behind each classification. Here, we show that large language models (LLMs) achieve accuracy comparable to CNNs on three major optical transient survey datasets (Pan-STARRS, MeerLICHT, and ATLAS) while simultaneously providing direct, human-readable descriptions for every transient. Using only 15 examples and a concise set of instructions, Google's LLM, Gemini, achieves a 93\% average accuracy across these datasets which have quite diverse resolution and pixel scales. This is the first demonstration of a successful application of an LLM to imaging data from optical transient surveys and it eliminates the need for extensive and complex labeled sets. Furthermore, we demonstrate that a second LLM can evaluate the coherence of the first LLM classifications, thus guiding iterative improvements by indicating problematic examples. This opens up new possibilities: rather than laboriously training a network from scratch, one can simply define the desired output characteristics and rely on the LLM to deliver them. Furthermore, by generating textual descriptions of observed features, LLMs enable users to query classifications as if navigating an annotated catalog, rather than deciphering abstract latent spaces. As next-generation telescopes and surveys further increase data streams, LLM-based classification could help bridge the gap between automated detection and transparent, human-level understanding.

Context. After the main sequence phase, stars more massive than 2.5 M-circle dot rapidly evolve through the Hertzsprung gap as yellow giants and yellow supergiants (YSGs) before settling into the red giant branch. Identifying Hertzsprung gap stars in nearby galaxies is crucial for pinpointing progenitors of luminous red novae (LRNe) - astrophysical transients attributed to stellar mergers. In the era of extensive transient surveys like the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), this approach offers a new way to predict and select common envelope transients. Aims. This study investigates potential progenitors and precursors of LRNe by analysing Hubble Space Telescope (HST) photometry of stellar populations in galaxies within similar to 20 Mpc to identify YSG candidates. Additionally, we use the Zwicky Transient Facility and MeerLICHT/BlackGEM to identify possible precursors, preparing for future observations by the LSST. Methods. We compiled a sample of 369 galaxies with HST exposures in the F 475W, F 555W, F 606W, and F814W filters. We identified YSG candidates using MESA stellar evolution tracks and statistical analysis of colour-magnitude diagrams. Results. Our sample includes 154 494 YSG candidates with masses between 3 M-circle dot and 20 M-circle dot and is affected by various contaminants, notably foreground stars and extinguished main sequence stars. After excluding foreground stars using Gaia proper motions, contamination is estimated at 1% from foreground stars (based on TRILEGAL simulations) and similar to 20% from extinction affecting main sequence stars. Combining our YSG candidates with time-domain catalogues yielded several interesting candidates. In particular, we identified 12 LRN precursor candidates for which follow-up is encouraged. Conclusions. We highlight the importance of monitoring future transients that match YSG candidates to avoid missing potential LRNe and other rare transients. LSST will be a game changer in the search for LRN progenitors and precursors; it is predicted to discover over 300 000 new YSG candidates and 100 LRN precursors within 20 Mpc.

We present the Near-Ultraviolet eXplorer (NUX), which will consist out of 4 small (36 cm diameter) ground-based telescopes that are optimized for the shortest wavelengths that are detectable from Earth (i.e., the near-UV [NUV] wavelength range of 300-350 nm). Each telescope will have a field-of-view of ~17 square degrees sampled at ~2.6"/pixel, and will reach a NUV magnitude (AB) of 20 in 2.5 minutes exposures (in dark time). The goal of NUX is to improve our understanding of the physical processes that power fast (days) to very fast (hours) hot transients, such as shock-breakout and shock-cooling emission of supernovae and the electromagnetic counterparts of gravitational wave events. Each telescope will be an off-the-shelf 14" Celestron RASA telescope, retrofitted with NUV optics. We have already demonstrated that the normal Schmidt corrector of this telescope can be replaced by a custom made one consisting of NUV transparent glass. Currently, a prototype NUX telescope is being fully assembled to demonstrate the technical and scientific feasibility of the NUX concept. Site tests will be held (in 2025/2026) at La Silla, Chile, to determine the NUV characteristics of the atmosphere at this site.

The discovery of gravitational wave (GW) events and the detection of electromagnetic counterparts from GW170817 has started the era of multimessenger GW astronomy.The field has been developing rapidly and in this paper,we discuss the preparation for detecting these events with the ESA Gaia satellite,during the 4th observing run of the LIGO-Virgo-KAGRA (LVK) collaboration that has started on May 24,2023. Gaia is contributing to the search for GW counterparts by a new transient detection pipeline called GaiaX. In GaiaX, a new source appearing in the field of view of only one of the two telescopes on-board Gaia is sufficient to send out an alert on the possible detection of a new transient. Ahead of O4, an experiment was conducted over a period of about two months. During the two weeks around New Moon in this period of time, the MeerLICHT (ML) telescope located in South Africa tried (weather permitting) to observe the same region of the sky as Gaia within 10 minutes. Any GaiaX detected transient was published publicly. ML and Gaia have similar limiting magnitudes for typical seeing conditions at ML. At the end of the experiment, we had 11861 GaiaX candidate transients and 15806 ML candidate transients, which we further analysed and the results of which are presented in this paper. Finally, we discuss the possibility and capabilities of Gaia contributing to the search for electromagnetic counterparts of gravitational wave events during O4 through the GaiaX detection and alert procedure.

The newest generation of radio telescopes are able to survey large areas with high sensitivity and cadence, producing data volumes that require new methods to better understand the transient sky. Here we describe the results from the first citizen science project dedicated to commensal radio transients, using data from the MeerKAT telescope with weekly cadence. Bursts from Space: MeerKAT was launched late in 2021 and received 89000 classifications from over 1000 volunteers in 3 months. Our volunteers discovered 142 new variable sources which, along with the known transients in our fields, allowed us to estimate that at least 2.1 per cent of radio sources are varying at 1.28 GHz at the sampled cadence and sensitivity, in line with previous work. We provide the full catalogue of these sources, the largest of candidate radio variables to date. Transient sources found with archival counterparts include a pulsar (B1845-01) and an OH maser star (OH 30.1-0.7), in addition to the recovery of known stellar flares and X-ray binary jets in our observations. Data from the MeerLICHT optical telescope, along with estimates of long time-scale variability induced by scintillation, imply that the majority of the new variables are active galactic nuclei. This tells us that citizen scientists can discover phenomena varying on time-scales from weeks to several years. The success both in terms of volunteer engagement and scientific merit warrants the continued development of the project, whilst we use the classifications from volunteers to develop machine learning techniques for finding transients.

The Vera C. Rubin observatory will be performing numerous studies and high cadence surveys. In order to perform the surveys most efficiently, the observations need to be planned in an optimal way, taking into account numerous atmospheric effects such as the current weather conditions and cloud cover. Building on the heritage from the MASCARA station, the DREAM team is developing the cloud & transmission monitoring system. The DREAM station is an upgraded version of the MASCARA station, which has been already been successfully operational on La Palma, Canary Islands, Spain, and La Silla, Chile. Using a set of wide-field cameras, nearly the full local sky is imaged every 6.4 seconds. Using calibrated brightness measurements of all bright stars (V < 8.4) in the field of view, the transmission and extinction is monitored, at a 30-60 seconds cadence. DREAM is currently being assembled and tested in the Netherlands and is expected to be deployed on-site by the end of 2022.

The BlackGEM array Phase I consists of three wide field, optical telescopes, located at the ESO La Silla Observatory, Chile. Each telescope is of a modified Dall-Kirkham design, using an 0.6m primary mirror and a 110 Mpix STA1600 CCD to give a 2.7 square degrees field-of-view sampled at 0.56 ''/pixel. Preliminary commissioning data shows performance on-par with design specifications. Data obtained with the BlackGEM prototype MeerLICHT highlights the capabilities of the design with a 5-sigma limiting magnitude of m(AB)=22.2 in 300s of integration under dark-sky conditions. Extrapolation to the 1 '' seeing-conditions expected at La Silla shows that the main goal of BlackGEM to probe down to m(AB)=23 in 300s can be met. The project suffered a 2-year COVID-19 delay. Commissioning of the array has currently been resumed and science operations are expected to start in Q3/Q4 of 2022. The science programs include the follow-up of gravitational wave alerts from LIGO/Virgo/KAGRA, a six-filter Southern Sky Survey, a Fast Synoptic Survey on selected fields, a Local Universe intra-night monitoring program and a inter-night single-band monitoring for slower transients.

SXP 15.6 is a recently established Be star X-ray binary system (BeXRB) in the Small Magellanic Cloud (SMC). Like many such systems the variable X-ray emission is driven by the underlying behaviour of the mass donor Be star. It is shown here that the neutron star in this system is exceptionally close to spin equilibrium averaged over several years, with the angular momentum gain from mass transfer being almost exactly balanced by radiative losses. This makes SXP 15.6 exceptional compared to all other known members of its class in the SMC, all of whom exhibit much higher spin period changes. In this paper we report on X-ray observations of the brightest known outburst from this system. These observations are supported by contemporaneous optical and radio observations, as well as several years of historical data.

We report on the detection of MKT J174641.0−321404, a new radio transient found in untargeted searches of wide-field MeerKAT radio images centred on the black hole X-ray binary H1743−322. MKT J174641.0−321404 is highly variable at 1.3 GHz and was detected three times during 11 observations of the field in late 2018, reaching a maximum flux density of 590 ± 60 μJy. We associate this radio transient with a high proper motion, M dwarf star SCR 1746−3214 12 pc away from the Sun. Multiwavelength observations of this M dwarf indicate flaring activity across the electromagnetic spectrum, consistent with emission expected from dMe stars, and providing upper limits on quiescent brightness in both the radio and X-ray regimes. TESS photometry reveals a rotational period for SCR 1746−3214 of 0.2292 ± 0.0025 days, which at its estimated radius makes the star a rapid rotator, comparable to other low mass systems. Dedicated spectroscopic follow up confirms the star as a mid-late spectral M dwarf with clear magnetic activity indicated by strong Hα emission. This transient’s serendipitous discovery by MeerKAT, along with multiwavelength characterisation, make it a prime demonstration of both the capabilities of the current generation of radio interferometers and the value of simultaneous observations by optical facilities such as MeerLICHT. Our results build upon the literature of of M dwarfs’ flaring behaviour, particularly relevant to the habitability of their planetary systems.

The wide-field optical telescopes MeerLICHT and BlackGEM feature an atmospheric dispersion corrector (ADC) which is fully integrated in its three-lens field corrector. Atmospheric dispersion is compensated for through lateral displacement of one of the three lenses. In this contribution, we discuss the on-sky calibration and performance of the ADC of the MeerLICHT telescope. We use a novel technique where we determine the optimal position of the ADC lens by minimising colour-dependent offsets on the astrometry of thousands of stars in an image.

Luminous red novae (LRNe) are astrophysical transients associated with the partial ejection of a binary system’s common envelope shortly before its merger. Here we present the results of our photometric and spectroscopic follow-up campaign of AT 2018bwo (DLT 18x), a LRN discovered in NGC 45, and investigate its progenitor system using binary stellar-evolution models. The transient reached a peak magnitude of Mr = −10.97 ± 0.11 and maintained this brightness during its optical plateau of tp = 41 ± 5 days. During this phase, it showed a rather stable photospheric temperature of ∼3300 K and a luminosity of ∼1040 erg s−1. Although the luminosity and duration of AT 2018bwo is comparable to the LRNe V838 Mon and M31-2015LRN, its photosphere at early times appears larger and cooler, likely due to an extended mass-loss episode before the merger. Toward the end of the plateau, optical spectra showed a reddened continuum with strong molecular absorption bands. The IR spectrum at +103 days after discovery was comparable to that of a M8.5 II type star, analogous to an extended AGB star. The reprocessed emission by the cooling dust was also detected in the mid-infrared bands ∼1.5 years after the outburst. Archival Spitzer and Hubble Space Telescope data taken 10−14 yrs before the transient event suggest a progenitor star with Tprog ∼ 6500 K, Rprog ∼ 100 R⊙, and Lprog = 2 × 104 L⊙, and an upper limit for optically thin warm (1000 K) dust mass of Md < 10−6 M⊙. Using stellar binary-evolution models, we determined the properties of binary systems consistent with the progenitor parameter space. For AT 2018bwo, we infer a primary mass of 12–16 M⊙, which is 9–45% larger than the ∼11 M⊙ obtained using single-star evolution models. The system, consistent with a yellow-supergiant primary, was likely in a stable mass-transfer regime with −2.4 ≤ log(Ṁ/M⊙ yr−1) ≤ −1.2 a decade before the main instability occurred. During the dynamical merger, the system would have ejected 0.15–0.5 M⊙ with a velocity of ∼500 km s−1.

ABSTRACT ESO 149-G003 is a close-by, isolated dwarf irregular galaxy. Previous observations with the ATCA indicated the presence of anomalous neutral hydrogen ($\rm{H{\small I}}$) deviating from the kinematics of a regularly rotating disc. We conducted follow-up observations with the MeerKAT radio telescope during the 16-dish Early Science programme as well as with the MeerLICHT optical telescope. Our more sensitive radio observations confirm the presence of anomalous gas in ESO 149-G003, and further confirm the formerly tentative detection of an extraplanar $\rm{H{\small I}}$ component in the galaxy. Employing a simple tilted-ring model, in which the kinematics is determined with only four parameters but including morphological asymmetries, we reproduce the galaxy’s morphology, which shows a high degree of asymmetry. By comparing our model with the observed $\rm{H{\small I}}$, we find that in our model, we cannot account for a significant (but not dominant) fraction of the gas. From the differences between our model and the observed data cube, we estimate that at least 7–8 per cent of the $\rm{H{\small I}}$ in the galaxy exhibits anomalous kinematics, while we estimate a minimum mass fraction of less than 1 per cent for the morphologically confirmed extraplanar component. We investigate a number of global scaling relations and find that, besides being gas-dominated with a neutral gas-to-stellar mass ratio of 1.7, the galaxy does not show any obvious global peculiarities. Given its isolation, as confirmed by optical observations, we conclude that the galaxy is likely currently acquiring neutral gas. It is either re-accreting gas expelled from the galaxy or accreting pristine intergalactic material.

Astronomers require efficient automated detection and classification pipelines when conducting large-scale surveys of the (optical) sky for variable and transient sources. Such pipelines are fundamentally important, as they permit rapid follow-up and analysis of those detections most likely to be of scientific value. We therefore present a deep learning pipeline based on the convolutional neural network architecture called MeerCRAB. It is designed to filter out the so called "bogus" detections from true astrophysical sources in the transient detection pipeline of the MeerLICHT telescope. Optical candidates are described using a variety of 2D images and numerical features extracted from those images. The relationship between the input images and the target classes is unclear, since the ground truth is poorly defined and often the subject of debate. This makes it difficult to determine which source of information should be used to train a classification algorithm. We therefore used two methods for labelling our data (i) thresholding and (ii) latent class model approaches. We deployed variants of MeerCRAB that employed different network architectures trained using different combinations of input images and training set choices, based on classification labels provided by volunteers. The deepest network worked best with an accuracy of 99.5% and Matthews correlation coefficient (MCC) value of 0.989. The best model was integrated to the MeerLICHT transient vetting pipeline, enabling the accurate and efficient classification of detected transients that allows researchers to select the most promising candidates for their research goals.

We present light curves and spectra of the tidal disruption event (TDE) ASASSN-18pg/AT 2018dyb spanning a period of one year. The event shows a plethora of strong emission lines, including the Balmer series, He ii, He i, and metal lines of O iii λ3760 and N iii λλ4100, 4640 (blended with He ii). The latter lines are consistent with originating from the Bowen fluorescence mechanism. By analyzing literature spectra of past events, we conclude that these lines are common in TDEs. The spectral diversity of optical TDEs is thus larger than previously thought and includes N-rich events besides H- and He-rich events. We study how the spectral lines evolve with time, by means of their width, relative strength, and velocity offsets. The velocity width of the lines starts at ∼13,000 km s−1 and decreases with time. The ratio of He ii to N iii increases with time. The same is true for ASASSN-14li, which has a very similar spectrum to AT 2018dyb but its lines are narrower by a factor of >2. We estimate a black hole mass of MBH = 3.3 − 2.0 + 5.0 × 10 6 M⊙ by using the M–σ relation. This is consistent with the black hole mass derived using the MOSFiT transient fitting code. The detection of strong Bowen lines in the optical spectrum is an indirect proof for extreme ultraviolet and (reprocessed) X-ray radiation and favors an accretion origin for the TDE optical luminosity. A model where photons escape after multiple scatterings through a super-Eddington thick disk and its optically thick wind, viewed at an angle close to the disk plane, is consistent with the observations.

The BlackGEM Phase 1 array for optical synoptic surveys consists of three wide-field telescopes providing an 8.1 square degrees field-of-view sampled at 0.56". It will be installed at the ESO La Silla Observatory. Each unit telescope consists of a modified Dall-Kirkham (Wynne-Harmer) configuration with a 65cm parabolic primary mirror, a 23cm spherical secondary and a triplet corrector lens. The third lens in the triplet is motorized to double as an Atmospheric Dispersion Corrector. The 10cm x 10cm flat, achromatic focal plane contains a single STA1600 10.5k x 10.5k chip with 9 micron pixels, providing a 2.7 square degree field-of-view sampled at 0.56"/pix. The telescope is equipped with a 6 slot (u,g,q,r,i,z) filter wheel. Limiting magnitude (5 sigma) in dark conditions is q=23 in 300s integration in 1" seeing. The telescope structure is made from carbon-fibre for maximum stability. The secondary mirror is mounted on a piezo-stage for active control. Each telescope is mounted on the Fornax 200 mount. On La Silla each telescope will be housed in a clamshell dome, and be located on a 7m high double-walled cylinder to lift it above the ground-layer seeing. The outer cylinder will carry the dome and the inner cylinder the telescope. The scientific program of BlackGEM is centered on optical afterglows of gravitational wave mergers, reacting to Advanced LIGO/Virgo triggers. The array will also perform a full southern sky survey (BG-SASS), covering 30000 square degrees (Dec < +30d) down to 22nd magnitude in all six filters at 1" resolution; a fast synoptic survey at 1 minute cadence for characterization of fast transients; bi-weekly all-sky q-band scan; and a twilight survey of the local universe. The BlackGEM consortium consists of the Netherlands Research School for Astronomy (NOVA), Radboud University and KU Leuven as founding members and the University of Manchester, UC Davis, Tel Aviv University, the Weizmann Institute, the University of Canterbury and the Hebrew University Jerusalem as partners. BlackGEM data will be processed on-line for transients and a full-source database using optimal photometry and the ZOGY image subtraction techniques. BlackGEM transients will be announced publically upon detection. All BlackGEM data will be cloud-based, including the 150Tb live database of the full source photometry. BlackGEM Phase 1 is scheduled for installation on La Silla in Q2-Q3 2018 and start of operations of in Q4 2018. In Phase 2 (2019-2022) the array is to be expanded to 15 unit telescopes, providing a 40.5 square degree instantaneous field-of-view. An overview of the array, first results of the prototype and an update of the installation will be given. www.blackgem.org

Here we built up a sample of 22 GRBs at redshifts $z u003e 2$ observed with X-shooter to determine the abundances of hydrogen, metals, dust, and molecular species. This allows us to study the metallicity and dust depletion effects in the neutral ISM at high redshift and to answer the question whether (and why) there might be a lack of H$_2$ in GRB-DLAs. We fit absorption lines and measure the column densities of different metal species as well as atomic and molecular hydrogen. The derived relative abundances are used to fit dust depletion sequences and determine the dust-to-metals ratio and the host-galaxy intrinsic visual extinction. There is no lack of H$_2$-bearing GRB-DLAs. We detect absorption lines from H$_2$ in 6 out of 22 GRB afterglow spectra, with molecular fractions ranging between $fsimeq 5cdot10^{-5}$ and $fsimeq 0.04$, and claim tentative detections in three other cases. The GRB-DLAs in the present sample have on average low metallicities ($mathrm{[X/H]}approx -1.3$), comparable to the rare population of QSO-ESDLAs (log N(HI) $u003e 21.5$). H$_2$-bearing GRB-DLAs are found to be associated with significant dust extinction, $A_V u003e 0.1$ mag, and have dust-to-metals ratios DTM$ u003e 0.4$. All of these systems exhibit column densities of log N(HI) $u003e 21.7$. The overall fraction of H$_2$ detections is $ge 27$% (41% including tentative detections), which is three times larger than in the general population of QSO-DLAs. For $2 21.7$, the H$_2$ detection fraction is 60-80% in GRB-DLAs as well as in extremely strong QSO-DLAs. This is likely a consequence of the fact that both GRB- and QSO-DLAs with high N(HI) probe sight-lines with small impact parameters that indicate that the absorbing gas is associated with the inner regions of the absorbing galaxy, where the gas pressure is higher and the conversion of HI to H$_2$ takes place.

Most Type I superluminous supernovae (SLSNe-I) reported to date have been identified by their high peak luminosities and spectra lacking obvious signs of hydrogen. We demonstrate that these events can be distinguished from normal-luminosity SNe (including Type Ic events) solely from their spectra over a wide range of light-curve phases. We use this distinction to select 19 SLSNe-I and four possible SLSNe-I from the Palomar Transient Factory archive (including seven previously published objects). We present 127 new spectra of these objects and combine these with 39 previously published spectra, and we use these to discuss the average spectral properties of SLSNe-I at different spectral phases. We find that Mn II most probably contributes to the ultraviolet spectral features after maximum light, and we give a detailed study of the O II features that often characterize the early-time optical spectra of SLSNe-I. We discuss the velocity distribution of O II, finding that for some SLSNe-I this can be confined to a narrow range compared to relatively large systematic velocity shifts. Mg II and Fe II favor higher velocities than O II and C II, and we briefly discuss how this may constrain power-source models. We tentatively group objects by how well they match either SN 2011ke or PTF12dam and discuss the possibility that physically distinct events may have been previously grouped together under the SLSN-I label.

Superluminous supernovae (SLSNe) are the most luminous supernovae in the Universe. They are found in extreme star-forming galaxies and are probably connected with the death of massive stars. One hallmark of very massive progenitors would be a tendency to explode in very dense, UV-bright and blue regions. In this paper, we investigate the resolved host galaxy properties of two nearby hydrogen-poor SLSNe, PTF 11hrq and PTF 12dam. For both galaxies Hubble Space Telescope multifilter images were obtained. Additionally, we perform integral field spectroscopy of the host galaxy of PTF 11hrq using the Very Large Telescope Multi Unit Spectroscopic Explorer (VLT/MUSE), and investigate the line strength, metallicity and kinematics. Neither PTF 11hrq nor PTF 12dam occurred in the bluest part of their host galaxies, although both galaxies have overall blue UV-to-optical colours. The MUSE data reveal a bright starbursting region in the host of PTF 11hrq, although far from the SN location. The SN exploded close to a region with disturbed kinematics, bluer colour, stronger [O III] and lower metallicity. The host galaxy is likely interacting with a companion. PTF 12dam occurred in one of the brightest pixels, in a starbursting galaxy with a complex morphology and a tidal tail, where interaction is also very likely. We speculate that SLSN explosions may originate from stars generated during star formation episodes triggered by interaction. High-resolution imaging and integral field spectroscopy are fundamental for a better understanding of SLSNe explosion sites and how star formation varies across their host galaxies.