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Data from the Colorado State University (CSU) CHILL radar located near Greeley, Colorado during the Pre-CIP_2021 (Preparatory Rockies Experiment for the Campaign In the Pacific 2021) campaign in July and August 2021. CHILL is a dual wavelength S- and X-band, dual-polarization radar that conducted RHI and surveillance scans. 

Data from the Colorado State University (CSU) CHIVO radar located near Fort Collins, Colorado during the Pre-CIP_2021 (Preparatory Rockies Experiment for the Campaign In the Pacific 2021) campaign from May-August 2021. CHIVO is a C-band, dual-polarization radar that conducted RHI and surveillance scans. 

Data from the Colorado State University radiosonde systems that were deployed at Hsinchu, Taiwan and Yonaguni, Japan for the PRECIP campaign. Measurements include vertical profiles of temperature, moisture and winds. 

Data from the Colorado State University (CSU) Sea-Going Polarimetric (SEA-POL) radar that was deployed on Yonaguni (a Japanese island to the east of Taiwan) for the PRECIP (Prediction of Rainfall Extremes Campaign in the Pacific) campaign from June to August 2022. SEA-POL is a deployable C-band dual-polarization radar that conducted RHI and surveillance scans on 12-minute cycles. 

ABSTRACT We present a low-frequency (170–200 MHz) search for prompt radio emission associated with the long GRB 210419A using the rapid-response mode of the Murchison Widefield Array (MWA), triggering observations with the Voltage Capture System for the first time. The MWA began observing GRB 210419A within 89 s of its detection by Swift, enabling us to capture any dispersion delayed signal emitted by this gamma-ray burst (GRB) for a typical range of redshifts. We conducted a standard single pulse search with a temporal and spectral resolution of $$100\, \mu$$s and 10 kHz over a broad range of dispersion measures from 1 to $$5000\, \text{pc}\, \text{cm}^{-3}$$, but none were detected. However, fluence upper limits of 77–224 Jy ms derived over a pulse width of 0.5–10 ms and a redshift of 0.6 < z < 4 are some of the most stringent at low radio frequencies. We compared these fluence limits to the GRB jet–interstellar medium interaction model, placing constraints on the fraction of magnetic energy (ϵB ≲ [0.05–0.1]). We also searched for signals during the X-ray flaring activity of GRB 210419A on minute time-scales in the image domain and found no emission, resulting in an intensity upper limit of $$0.57\, \text{Jy}\, \text{beam}^{-1}$$, corresponding to a constraint of ϵB ≲ 10−3. Our non-detection could imply that GRB 210419A was at a high redshift, there was not enough magnetic energy for low-frequency emission, or the radio waves did not escape from the GRB environment. 

Abstract Many short gamma-ray bursts (GRBs) originate from binary neutron star mergers, and there are several theories that predict the production of coherent, prompt radio signals either prior, during, or shortly following the merger, as well as persistent pulsar-like emission from the spin-down of a magnetar remnant. Here we present a low frequency (170–200 MHz) search for coherent radio emission associated with nine short GRBs detected by the Swift and/or Fermi satellites using the Murchison Widefield Array (MWA) rapid-response observing mode. The MWA began observing these events within 30–60 s of their high-energy detection, enabling us to capture any dispersion delayed signals emitted by short GRBs for a typical range of redshifts. We conducted transient searches at the GRB positions on timescales of 5 s, 30 s, and 2 min, resulting in the most constraining flux density limits on any associated transient of 0.42, 0.29, and 0.084 Jy, respectively. We also searched for dispersed signals at a temporal and spectral resolution of 0.5 s and 1.28 MHz, but none were detected. However, the fluence limit of 80–100 Jy ms derived for GRB 190627A is the most stringent to date for a short GRB. Assuming the formation of a stable magnetar for this GRB, we compared the fluence and persistent emission limits to short GRB coherent emission models, placing constraints on key parameters including the radio emission efficiency of the nearly merged neutron stars ( $$\epsilon_r\lesssim10^{-4}$$ ), the fraction of magnetic energy in the GRB jet ( $$\epsilon_B\lesssim2\times10^{-4}$$ ), and the radio emission efficiency of the magnetar remnant ( $$\epsilon_r\lesssim10^{-3}$$ ). Comparing the limits derived for our full GRB sample (along with those in the literature) to the same emission models, we demonstrate that our fluence limits only place weak constraints on the prompt emission predicted from the interaction between the relativistic GRB jet and the interstellar medium for a subset of magnetar parameters. However, the 30-min flux density limits were sensitive enough to theoretically detect the persistent radio emission from magnetar remnants up to a redshift of $$z\sim0.6$$ . Our non-detection of this emission could imply that some GRBs in the sample were not genuinely short or did not result from a binary neutron star merger, the GRBs were at high redshifts, these mergers formed atypical magnetars, the radiation beams of the magnetar remnants were pointing away from Earth, or the majority did not form magnetars but rather collapse directly into black holes. 

Abstract We present the most sensitive and detailed view of the neutral hydrogen ( $${\rm H\small I}$$ ) emission associated with the Small Magellanic Cloud (SMC), through the combination of data from the Australian Square Kilometre Array Pathfinder (ASKAP) and Parkes (Murriyang), as part of the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) pilot survey. These GASKAP-HI pilot observations, for the first time, reveal $${\rm H\small I}$$ in the SMC on similar physical scales as other important tracers of the interstellar medium, such as molecular gas and dust. The resultant image cube possesses an rms noise level of 1.1 K ( $$1.6\,\mathrm{mJy\ beam}^{-1}$$ ) $$\mathrm{per}\ 0.98\,\mathrm{km\ s}^{-1}$$ spectral channel with an angular resolution of $$30^{\prime\prime}$$ ( $${\sim}10\,\mathrm{pc}$$ ). We discuss the calibration scheme and the custom imaging pipeline that utilises a joint deconvolution approach, efficiently distributed across a computing cluster, to accurately recover the emission extending across the entire $${\sim}25\,\mathrm{deg}^2$$ field-of-view. We provide an overview of the data products and characterise several aspects including the noise properties as a function of angular resolution and the represented spatial scales by deriving the global transfer function over the full spectral range. A preliminary spatial power spectrum analysis on individual spectral channels reveals that the power law nature of the density distribution extends down to scales of 10 pc. We highlight the scientific potential of these data by comparing the properties of an outflowing high-velocity cloud with previous ASKAP+Parkes $${\rm H\small I}$$ test observations.