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Abstract We present results from a high-cadence multiwavelength observational campaign of the enigmatic changing-look active galactic nucleus 1ES 1927+654 from 2022 May to 2024 April, coincident with an unprecedented radio flare (an increase in flux by a factor of ∼60 over a few months) and the emergence of a spatially resolved jet at 0.1–0.3 pc scales. Companion work has also detected a recurrent quasi-periodic oscillation (QPO) in the 2–10 keV band with an increasing frequency (1–2 mHz) over the same period. During this time, the soft X-rays (0.3–2 keV) monotonically increased by a factor of ∼8, while the UV emission remained nearly steady with <30% variation and the 2–10 keV flux showed variation by a factor ≲2. The weak variation of the 2–10 keV X-ray emission and the stability of the UV emission suggest that the magnetic energy density and accretion rate are relatively unchanged and that the jet could be launched owing to a reconfiguration of the magnetic field (toroidal to poloidal) close to the black hole. Advecting poloidal flux onto the event horizon would trigger the Blandford–Znajek mechanism, leading to the onset of the jet. The concurrent softening of the coronal slope (from Γ = 2.70 ± 0.04 to Γ = 3.27 ± 0.04), the appearance of a QPO, and the low coronal temperature ( $k{T}_e=8_{-3}^{+8}\mathrm{keV}$) during the radio outburst suggest that the poloidal field reconfiguration can significantly impact coronal properties and thus influence jet dynamics. These extraordinary findings in real time are crucial for coronal and jet plasma studies, particularly as our results are independent of coronal geometry. 

ABSTRACT We have re-observed $$\rm \sim$$40 low-inclination, star-forming galaxies from the MaNGA survey (σ ∼ 65 km s−1) at ∼6.5 times higher spectral resolution (σ ∼ 10 km s−1) using the HexPak integral field unit on the WIYN 3.5-m telescope. The aim of these observations is to calibrate MaNGA’s instrumental resolution and to characterize turbulence in the warm interstellar medium and ionized galactic outflows. Here we report the results for the Hα region observations as they pertain to the calibration of MaNGA’s spectral resolution. Remarkably, we find that the previously reported MaNGA line-spread-function (LSF) Gaussian width is systematically underestimated by only 1 per cent. The LSF increase modestly reduces the characteristic dispersion of H ii regions-dominated spectra sampled at 1–2 kpc spatial scales from 23 to 20 km s−1 in our sample, or a 25 per cent decrease in the random-motion kinetic energy. This commensurately lowers the dispersion zeropoint in the relation between line-width and star-formation rate surface-density in galaxies sampled on the same spatial scale. This modest zero-point shift does not appear to alter the power-law slope in the relation between line-width and star-formation rate surface-density. We also show that adopting a scheme whereby corrected line-widths are computed as the square root of the median of the difference in the squared measured line width and the squared LSF Gaussian avoids biases and allows for lower signal-to-noise data to be used reliably. 

We describe the optimum telescope focal ratio for a two-element, three-surface, telecentric image-transfer microlens-to-fiber coupled integral field unit within the constraints imposed by microoptics fabrication and optical aberrations. We create a generalized analytical description of the microoptics optical parameters from first principles. We find that the optical performance, including all aberrations, of a design constrained by an analytic model considering only spherical aberration and diffraction matches within ± 4 % of a design optimized by ray-tracing software such as Zemax. The analytical model does not require any compromise on the available clear aperture; about 90% mechanical aperture of hexagonal microlens is available for light collection. The optimum telescope f-ratio for a 200-μm core fiber-fed at f / 3.5 is between f / 7 and f / 12. We find the optimum telescope focal ratio changes as a function of fiber core diameter and fiber input beam speed. A telescope focal ratio of f / 8 would support the largest range of fiber diameters (100 to 500 μm) and fiber injection speeds (between f / 3 and f / 5). The optimization of the telescope and lenslet-coupled fibers is relevant for the design of high-efficiency dedicated survey telescopes, and for retrofitting existing facilities via introducing focal macro-optics to match the instrument input requirements. 

The optical fiber integral field unit (IFU) built to feed the near infrared (NIR) spectrograph for the 11-meter Southern African Large Telescope (SALT) has undergone prototyping and rigorous performance testing at Wash- burn Astronomical Laboratories of the University of Wisconsin-Madison Astronomy Department. The 43 m length of 256 fibers which make up the object and sky arrays and spares are routed from the SALT payload down into the spectrograph room in four separate cables. The IFU covers 344 arcsec2 on the sky, with the object array spanning a 552 arcsec2 near-rectangular area at roughly 56% fill-factor. Companion papers describe the mechanical design of the fiber cable that mitigates potential sources of mechanical strain on the optical fiber (Smith et al.) and details of the spectrograph (Wolf et al.). Here we present the results of the performance testing of various test cables as well as performance testing and end-to-end mapping of the fully-assembled science cable. The fiber optics experience an extreme temperature gradient at the ingress to the instrument enclosure held at -40 ◦C during operation. We find an increase in focal ratio degradation (FRD) when holding progressively longer lengths of test fiber at reduced temperature. However, we confirm that this temperature dependent FRD is negligible for our designed length of cold fiber. We also find negligible contributions to FRD from the rubber seal that breaches the room temperature strain relief box and the cold instrument enclosure. Our measure- ments characterize performance including the effects of internal fiber inhomogeneities, stress induced from fiber handling and termination, as well as any imperfections from end-polishing. We present the room-temperature laboratory performance measurements of the fully-assembled science cable; the effective total throughput the fiber cable delivers to the spectrograph collimator is 81±2.5% across all fibers accounting for all losses.