Daniel Batcheldor

The intrinsic nature of many astronomical objects, such as binary and multiple systems, exoplanets, circumstellar and debris disks, and quasar host galaxies, introduces challenging requirements for observational instrumentation and techniques. In each case, we encounter situations where the light from bright sources hampers our ability to detect surrounding fainter targets. To explore all features of such astronomical scenes, we must perform observations at the maximum possible contrast ratios. Charge-injection devices (CIDs) are capable of potentially exceeding contrast ratios of log 10 ( CR ) > 9 (i.e., 1 part in 1 billion) due to their unique readout architectures and inherent anti-blooming abilities. An on-sky testing of a commercially available CID, SpectraCAM XDR (SXDR), demonstrated raw contrast ratios from sub-optimal ground-based astronomical observations that imposed practical limits on the maximum achievable contrast ratios using CIDs. Here, we demonstrate the extreme contrast ratio imaging capabilities of the SXDR using observations of Sirius with the 1.0 m Jacobus Kapteyn Telescope, La Palma, Spain. Based on wavelet-based analysis and precise photometric and astrometric calibrations, we report a direct contrast ratio of Δm _r = 18.54, log 10 ( CR ) = 7.41 ± 0.08 , or 1 part in 26 million. This is an order of magnitude higher compared to the previous CID results.

The intrinsic nature of many astronomical objects, such as binary systems, exoplanets, circumstellar disks, and quasar host galaxies, introduces challenging requirements on observational instrumentation and techniques. In each case, we encounter situations where the light from bright sources completely outshines the surrounding faint targets. As a result, we are yet to fully understand the processes governing star and galaxy formation and evolution, and there are ongoing attempts to search for habitable worlds around other stars. To explore all features of such astronomical objects, we must perform observations at the maximum possible contrast ratios. Here, we demonstrate the extreme contrast ratio imaging capabilities of the latest generation of commercially available charge injection devices, the SpectraCAM XDR, using Sirius field observations from a world-class observing site. Based on wavelet-based image analysis and precise photometric calibration, we report a direct contrast ratio of 1 part in 100 million.

Considerable uncertainties remain about the nature of warm, AGN-driven outflows and their impact on the evolution of galaxies. This is because the outflows are often unresolved in ground-based observations. As part of a project to study the AGN outflows in some of the most rapidly evolving galaxies in the local Universe, here we present Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) observations of F14394+5332E that resolve the sub-kpc warm outflow for the first time in an ultra-luminous infrared galaxy. The observations reveal a compact, high-ionization outflow region (r_max ∼ 0.9 kpc) set in a more extensive (r_max ∼ 1.4 kpc) halo that is kinematically quiescent and has a lower ionization state. A large line width (600 < FWHM < 1500 km s⁻¹) is measured throughout the outflow region, and the outflowing gas shows a steep velocity gradient with radius, with the magnitude of the blueshifted velocities increasing from ∼500 to 1800 km s⁻¹ from the inner to the outer part of the outflow. We interpret the observations in terms of the local acceleration, and hydrodynamic destruction, of dense clouds as they are swept up in a hot, low-density wind driven by the AGN. We discuss the implications for measuring the mass outflow rates and kinetic powers for the AGN-driven outflows in such objects.

On 2016 June 2 at 10h56m UTC, a -20.4 +/- 0.2 mag superbolide was observed over Arizona. Fragments were located a few days later and the meteorites were given the name Dishchii'bikoh. We present analysis of this event based on three cameras and a multispectral sensor observation by the SkySentinel continuous fireball-monitoring camera network, supplemented by a dash cam footage and a fragmentation model. The bolide began its luminous flight at an altitude of 100.2 +/- 0.4 km at coordinates phi = 34.555 +/- 0.002 degrees N planetographic latitude and lambda = 110.459 +/- 0.002 degrees W longitude, and it had a pre-atmospheric velocity of 17.4 +/- 0.3 km s(-1). The calculated orbital parameters indicate that the meteoroid did not belong to any presently known asteroid family. From our calculations, the impacting object had an initial mass of 14.8 +/- 1.7 metric tonnes with an estimated initial diameter of 2.03 +/- 0.12 m.

The true importance of the warm, AGN-driven outflows for the evolution of galaxies remains uncertain. Measurements of the radial extents of the outflows are key for quantifying their masses and kinetic powers, and also establishing whether the AGN outflows are galaxy-wide. Therefore, as part of a larger project to investigate the significance of warm, AGN-driven outflows in the most rapidly evolving galaxies in the local universe, here we present deep Hubble Space Telescope (HST) narrow-band [O iii] λ5007 observations of a complete sample of eight nearby ULIRGs with optical AGN nuclei. Combined with the complementary information provided by our ground-based spectroscopy, the HST images show that the warm gas outflows are relatively compact for most of the objects in the sample: in three objects, the outflow regions are barely resolved at the resolution of HST (⁠|$0.065 \lt R_{\rm [O\,{\small {III}}]} \lt 0.12$| kpc); in a further four cases, the outflows are spatially resolved but with flux-weighted mean radii in the range |$0.65 \lt R_{\rm [O\,{\small {III}}]} \lt 1.2$| kpc; and in only one object (Mrk273) is there clear evidence for a more extended outflow, with a maximum extent of |$R_{\rm [O\,{\small {III}}]}\sim 5$| kpc. Overall, our observations show little evidence for the galaxy-wide outflows predicted by some models of AGN feedback.

We describe the remote facilities operated by the Southeastern Association for Research in Astronomy (SARA) , a consortium of colleges and universities in the US partnered with Lowell Observatory, the Chilean National Telescope Allocation Committee, and the Instituto de Astrofísica de Canarias. SARA observatories comprise a 0.96 m telescope at Kitt Peak, Arizona; one of 0.6 m aperture on Cerro Tololo, Chile; and the 1 m Jacobus Kapteyn Telescope at the Roque de los Muchachos, La Palma, Spain. All are operated using standard VNC or Radmin protocols communicating with on-site PCs. Remote operation offers considerable flexibility in scheduling, allowing long-term observational cadences difficult to achieve with classical observing at remote facilities, as well as obvious travel savings. Multiple observers at different locations can share a telescope for training, educational use, or collaborative research programs. Each telescope has a CCD system for optical imaging, using thermoelectric cooling to avoid the need for frequent local service, and a second CCD for offset guiding. The Arizona and Chile telescopes also have fiber-fed echelle spectrographs. Switching between imaging and spectroscopy is very rapid, so a night can easily accommodate mixed observing modes. We present some sample observational programs. For the benefit of other groups organizing similar consortia, we describe the operating structure and principles of SARA, as well as some lessons learned from almost 20 years of remote operations.