Víctor Gómez-Rivera

In 2026, the Event Horizon Telescope (EHT) carried out the first time-lapse monitoring campaign comprising a series of 18 observations of the 6.1 6 − 0.57 + 0.71 × 1 0 9 M ⊙ black hole at the center of M87 with a cadence of approximately twice per week over a few months, matched to the expected dynamical timescale. Here we present a first-look image from the campaign, reconstructed from a single four-minute scan obtained on 2026 April 3. The resulting image displays the now-familiar asymmetric ring morphology first revealed by the 2017 EHT observations and subsequently confirmed by observations obtained in 2018 and 2021. While representing only a very small subset of the full program, this image demonstrates a significant advance in the operational capabilities of the EHT. Through improvements in array operations, data transport and processing, the collaboration has reduced the interval between observation and imaging to only a few months, establishing the EHT as a facility capable of routinely undertaking time-domain studies of the dynamic universe at extremely high resolutions of ∼20 μ as.

Context. The L1157 outflow is a prototype of chemically active outflows in which to look for molecular species linked to complex chemistry. Aims. With the aim of imaging the large (parsec) scale structure of key prebiotic molecules, we aim to map the whole blue lobe of the L1157 outflow with the Large Millimeter Telescope (LMT), proving the potential of this facility to detect weak and extended molecular emission. Methods. Isocyanic acid (HNCO), an important precursor of complex chemistry, was chosen to be observed in its (4 _0,4 –3 _0,3 ) transition at 87.925 GHz with the SEQUOIA focal-plane array, covering an area of 3×3 arcmin ² centered at the position of the main shock L1157-B1, which included a large portion of the vicinity of the protostellar region. Results. The HNCO emission was detected not only from the outflow, it was also found tracing a structure of about 0.3 pc in length, corresponding to the filament from which the protostellar system was born. Conclusions. The HNCO molecule was found to be a tracer of the densest part of filaments in molecular clouds, and given its importance in the formation of more complex molecules, its presence in the cold, quiescent filamentary gas indicates that the building blocks of complex chemistry are already well established in stages prior to protostellar warming or shocks. By allowing the detection of structures related to the filament, these observations proved the LMT’s potential to map weak and extended components in molecular clouds.

We report on the results of the on-sky test and science demonstration conducted with the 2 mm receiver system, B4R, on the 50 m Large Millimeter Telescope (LMT), located at an altitude of 4600 m in Mexico. The B4R receiver was developed based on the dual-polarization sideband-separating mixer technology of the Atacama Large Millimeter/submillimeter Array and is equipped with a fast Fourier transform digital spectrometer, XFFTS. The primary science objective is the spectroscopic redshift identification of high-redshift dusty star-forming galaxies, complementing the existing 3 mm Redshift Search Receiver by enabling the detection of multiple carbon monoxide lines. Additionally, the B4R receiver broadens the range of science cases possible with the LMT, including astrochemistry, as the 2 mm band encompasses unique molecular lines such as deuterated molecules and shock tracers. During on-site commissioning in 2018 and 2019, we successfully demonstrated on-the-fly mapping and position-switching observations toward the Orion Molecular Cloud 1 and bright high-redshift dusty star-forming galaxies, respectively. We confirmed that the installed B4R system largely met its basic performance specifications. Furthermore, we measured the LMT’s aperture efficiencies across the entire B4R frequency range (130–160 GHz), finding them to be roughly consistent with expectations based on a surface accuracy of 100 μ m and the receiver optics design. These results with the B4R will enable the most sensitive single-dish spectroscopic observations at 2 mm using the LMT.

We present emission maps ( 1 .′ 5 × 1 .′ 5 scale, corresponding to 0.18 pc) of the DCN (J = 2 − 1) and DCO⁺ (J = 2 − 1) lines in the 2 mm band toward the Orion KL region obtained with the 2 mm receiver system named B4R installed on the Large Millimeter Telescope. The DCN emission shows a peak at the Orion KL hot core position, whereas no DCO⁺ emission has been detected there. The DCO⁺ emission shows enhancement at the west side of the hot core, which is well shielded from the UV radiation from OB massive stars in the Trapezium cluster. We have derived the abundance ratio of DCN/DCO⁺ at three representative positions where both species have been detected. The gas components with V _LSR ≈ 7.5–8.7 km s⁻¹ are associated with low abundance ratios of ∼4–6, whereas much higher abundance ratios (∼22–30) are derived for the gas components with V _LSR ≈ 9.2–11.6 km s⁻¹. We have compared the observed abundance ratio to our chemical models and found that the observed differences in the DCN/DCO⁺ abundance ratios are explained by different densities.