405 citations · 1.3k across the 30 of their papers we have counts for
31 papers
No Small Scale Radio Jets Here: Multi-Epoch Observations of Radio Continuum Structures in NGC 1068 with the VLBA
Travis C. Fischer, Megan C. Johnson, Nathan J. Secrest +2
We present recent Very Long Baseline Array (VLBA) 5 GHz radio observations of the nearby, luminous Seyfert 2 galaxy NGC 1068 for comparison to similar VLBA observations made on 199…
Radio-Optical Reference Catalog, version 1
Valeri V. Makarov, Megan C. Johnson, Nathan J. Secrest
The fundamental celestial reference frame (CRF) is based on two catalogs of astrometric positions, the third realization of the International Celestial Reference Frame (ICRF3), and…
The Importance of Co-located VLBI Intensive Stations and GNSS Receivers: A case study of the Maunakea VLBI and GNSS stations during the 2018 Hawai`i earthquake
Christopher Dieck, Megan C. Johnson, Daniel S. MacMillan
Frequent, low-latency measurements of the Earth's rotation phase, UT1UTC, critically support the current estimate and short-term prediction of this highly variable Earth Orienta…
Fundamental Reference AGN Monitoring Experiment (FRAMEx) III: Radio Emission in the Immediate Vicinity of Radio Quiet AGNs
Onic I. Shuvo, Megan C. Johnson, Nathan J. Secrest +5
We present follow-up results from the first Fundamental Reference AGN Monitoring Experiment (FRAMEx) X-ray/radio snapshot program of a volume-complete sample of local hard X-ray-se…
Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution
Andrew J. Sargent, Megan C. Johnson, Amy E. Reines +5
Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are ``wandering" in the outskirts of their host…
The U.S. Naval Observatory VLBI Spectroscopic Catalog
Remington O. Sexton, Nathan J. Secrest, Megan C. Johnson +1
Despite their importance for astrometry and navigation, the active galactic nuclei (AGNs) that comprise the International Celestial Reference Frame (ICRF) are relatively poorly und…
FRAMEx II: Simultaneous X-ray and Radio Variability in Active Galactic Nuclei The Case of NGC 2992
Luis C. Fernandez, Nathan J. Secrest, Megan C. Johnson +4
Using simultaneous Very Long Baseline Array and Neil Gehrels Swift Observatory X-ray Telescope observations of the active galactic nucleus (AGN) in NGC 2992 over a six-month observ…
Imaging Sources in the Third Realization of the International Celestial Reference Frame
Lucas R. Hunt, Megan C. Johnson, Phillip J. Cigan +2
The third iteration of the International Celestial Reference Frame (ICRF3) is made up of 4536 quasars observed at S/X bands using Very Long baseline Interferometry (VLBI). These so…
Tully-Fisher Distances and Dynamical Mass Constraints for 24 Host Galaxies of Reverberation-Mapped AGN
Justin H. Robinson, Misty C. Bentz, Hélène M. Courtois +6
We present Tully-Fisher distances for 24 AGN host galaxies with black hole mass () measurements from reverberation mapping, as well as the first calibration of the $…
Fundamental Reference AGN Monitoring Experiment (FRAMEx) I: Jumping Out of the Plane with the VLBA
Travis C. Fischer, Nathan J. Secrest, Megan C. Johnson +7
We present the first results from the Fundamental Reference AGN Monitoring Experiment (FRAMEx), an observational campaign dedicated to understanding the physical processes that aff…
Detection of a Radio Bubble around the Ultraluminous X-ray Source Holmberg IX X-1
Ciprian T. Berghea, Megan C. Johnson, Nathan J. Secrest +3
We present C and X-band radio observations of the famous utraluminous X-ray source (ULX) Holmberg IX X-1, previously discovered to be associated with an optical emission line nebul…
HI Spectroscopy of Reverberation-Mapped Active Galactic Nuclei
Justin H. Robinson, Misty C. Bentz, Megan C. Johnson +2
We present HI 21 cm spectroscopy from the GBT for the host galaxies of 31 nearby AGNs with direct M measurements from reverberation mapping. These are the first pub…
CHANG-ES XX. High Resolution Radio Continuum Images of Edge-on Galaxies and their AGNs -- Data Release 3
Judith Irwin, Theresa Wiegert, Alison Merritt +17
The CHANG-ES galaxy sample consists of 35 nearby edge-on galaxies that have been observed using the VLA at 1.6 GHz and 6.0 GHz. Here we present the 3rd data release of our sample,…
The Next Generation Celestial Reference Frame
Megan Johnson, Frank Schinzel, Jeremy Darling +10
Astrometry, the measurement of positions and motions of the stars, is one of the oldest disciplines in Astronomy, extending back at least as far as Hipparchus' discovery of the pre…
Relationship between the Line Width of the Atomic and Molecular ISM in M33
Eric W. Koch, Erik W. Rosolowsky, Andreas Schruba +5
We investigate how the spectral properties of atomic (HI) and molecular (H) gas, traced by CO(2-1), are related in M33 on pc scales. We find the HI and CO(2-1) velocity at…
Kinematics of the Atomic ISM in M33 on 80 pc scales
Eric W. Koch, Erik W. Rosolowsky, Felix J. Lockman +7
We present new L-band ($1\mbox{--}2$ GHz) observations of the nearby spiral galaxy M33 with 80 pc resolution obtained with the Karl G. Jansky Very Large Array. The HI observations,…
Towards the ICRF3: astrometric comparison of the USNO 2016A VLBI solution with ICRF2 and Gaia DR1
Julien Frouard, Megan C. Johnson, Alan Fey +2
The VLBI USNO 2016A (U16A) solution is part of a work-in-progress effort by USNO towards the preparation of the ICRF3. Most of the astrometric improvement with respect to the ICRF2…
Detection of an OH 1665-MHz Maser in M33
Eric Koch, Erik Rosolowsky, Megan C. Johnson +2
We report one OH 1665-MHz detection in new observations with the NSF's Karl G. Jansky Very Large Array. To the authors' knowledge, this is the first OH maser detection in M33. The…
The HI Chronicles of LITTLE THINGS BCDS III: Gas Clouds in and around Mrk 178, VII Zw 403, AND NGC 3738
Trisha Ashley, Caroline E. Simpson, Bruce G. Elmegreen +2
In most blue compact dwarf (BCD) galaxies, it remains unclear what triggers their bursts of star formation. We study the HI of three relatively isolated BCDs, Mrk 178, VII Zw 403,…
CHANG-ES VI: Probing Supernova Energy Deposition in Spiral Galaxies Through Multi-Wavelength Relationships
Jiang-Tao Li, Rainer Beck, Ralf-Jurgen Dettmar +13
How a galaxy regulates its SNe energy into different interstellar/circumgalactic medium components strongly affects galaxy evolution. Based on the JVLA D-configuration C- (6 GHz) a…
CHANG-ES IV: Radio continuum emission of 35 edge-on galaxies observed with the Karl G. Jansky Very Large Array in D-configuration, Data Release 1
Theresa Wiegert, Judith Irwin, Arpad Miskolczi +21
We present the first part of the observations made for the Continuum Halos in Nearby Galaxies, an EVLA Survey (CHANG-ES) project. The aim of the CHANG-ES project is to study and ch…
Blasting away a dwarf galaxy: The "tail" of ESO 324-G024
Megan C. Johnson, Peter Kamphuis, Baerbel S. Koribalski +6
We present Australia Telescope Compact Array radio data of the dwarf irregular galaxy ESO 324-G024 which is seen in projection against the giant, northern lobe of the radio galaxy…
The Shape of LITTLE THINGS Dwarf Galaxies DDO 46 and DDO 168: Understanding the stellar and gas kinematics
Megan C. Johnson, Deidre A. Hunter, Sarah Wood +4
We present the stellar and gas kinematics of DDO 46 and DDO 168 from the LITTLE THINGS survey and determine their respective Vmax/sigma_z,0 values. We used the KPNO's 4-meter teles…
High-resolution mass models of dwarf galaxies from LITTLE THINGS
Se-Heon Oh, Deidre A. Hunter, Elias Brinks +13
We present high-resolution rotation curves and mass models of 26 dwarf galaxies from LITTLE THINGS. LITTLE THINGS is a high-resolution Very Large Array HI survey for nearby dwarf g…