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Papers by Jonathan Grindlay

Symposium - International Astronomical Union, 2005

We present VLA and MERLIN monitoring data of the JVAS gravitational lens system B1030+074. The sy... more We present VLA and MERLIN monitoring data of the JVAS gravitational lens system B1030+074. The system was monitored with the VLA from February 1998 to October 1998 at 8.4-GHz during which the VLA was at its A, BnA and B configuration. The 47 epochs of observations have an average spacing of approximately 5 days. Ten MERLIN snapshots were obtained in the L-band (1.7 GHz) during the months of April, May and June 1998. Preliminary light curves of the two components of the lens system obtained from the VLA data indicate that during the period of the monitoring the A flux density showed a steady decrease. No changes are observed in the B light curve.

The Astrophysical Journal Supplement Series

The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 ... more The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 has opened the era of gravitational-wave multimessenger astronomy. Rapid identification of the optical/infrared kilonova enabled a precise localization of the source, which paved the way to deep multiwavelength follow-up and its myriad of related science results. Fully exploiting this new territory of exploration requires the acquisition of electromagnetic data from samples of NS mergers and other gravitational-wave sources. After GW170817, the frontier is now to map the diversity of kilonova properties and provide more stringent constraints on the Hubble constant, and enable new tests of fundamental physics. The Vera C. Rubin Observatory’s Legacy Survey of Space and Time can play a key role in this field in the 2020s, when an improved network of gravitational-wave detectors is expected to reach a sensitivity that will enable the discovery of a high rate of merger events involving NSs (∼...

The Astrophysical Journal, 2015

We present optical observations of supernova SN 2014C, which underwent an unprecedented slow meta... more We present optical observations of supernova SN 2014C, which underwent an unprecedented slow metamorphosis from H-poor type Ib to H-rich type IIn over the course of one year. The observed spectroscopic evolution is consistent with the supernova having exploded in a cavity before encountering a massive shell of the progenitor star's stripped hydrogen envelope. Possible origins for the circumstellar shell include a brief Wolf-Rayet fast wind phase that overtook a slower red supergiant wind, eruptive ejection, or confinement of circumstellar material by external influences of neighboring stars. An extended high velocity Hα absorption feature seen in near-maximum light spectra implies that the progenitor star was not completely stripped of hydrogen at the time of core collapse. Archival pre-explosion Subaru Telescope Suprime-Cam and Hubble Space Telescope Wide Field Planetary Camera 2 images of the region obtained in 2009 show a coincident source that is most likely a compact massive star cluster in NGC 7331 that hosted the progenitor system. By comparing the emission properties of the source with stellar population models that incorporate interacting binary stars we estimate the age of the host cluster to be 30−300 Myr, and favor ages closer to 30 Myr in light of relatively strong Hα emission. SN 2014C is the best-observed member of a class of core-collapse supernovae that fill the gap between events that interact strongly with dense, nearby environments immediately after explosion and those that never show signs of interaction. Better understanding of the frequency and nature of this intermediate population can contribute valuable information about the poorly understood final stages of stellar evolution.

AIP Conference Proceedings, 2000

We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal a... more We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal array of seven 10 m aperture imaging Cherenkov telescopes. The selected site is Montosa Canyon (1390 m a.s.l.) at the Whipple Observatory, Arizona. Each telescope, of 12 m focal length, will initially be equipped with a 499 element photomultiplier camera covering a 3.5 degree field of view. A central station will initiate the readout of 500 MHz FADCs upon receipt of multiple telescope triggers. The minimum detectable flux sensitivity will be 0.5% of the Crab Nebula flux at 200 GeV. Detailed simulations of the array's performance are presented elsewhere at this meeting. VERITAS will operate primarily as a γ-ray observatory in the 50 GeV to 50 TeV range for the study of active galaxies, supernova remnants, pulsars and gamma ray bursts.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

We have constructed a moderately large area (32 cm 2), fine pixel (2.5 mm pixel, 5 mm thick) CZT ... more We have constructed a moderately large area (32 cm 2), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256 cm 2) developed for a balloon-borne wide-field hard X-ray telescope, ProtoEXIST1. ProtoEXIST1 is a prototype for the High Energy Telescope (HET) in the Energetic X-ray imaging Survey Telescope (EXIST), a next generation space-borne multi-wavelength telescope. We have constructed a large (nearly gapless) detector plane through a modularization scheme by tiling of a large number of 2 cm × 2 cm CZT crystals. Our innovative packaging method is ideal for many applications such as coded-aperture imaging, where a large, continuous detector plane is desirable for the optimal performance. Currently we have been able to achieve an energy resolution of 3.2 keV (FWHM) at 59.6 keV on average, which is exceptional considering the moderate pixel size and the number of detectors in simultaneous operation. We expect to complete two modules (512 cm 2) within the next few months as more CZT becomes available. We plan to test the performance of these detectors in a near space environment in a series of high altitude balloon flights, the first of which is scheduled for Fall 2009. These detector modules are the first in a series of progressively more sophisticated detector units and packaging schemes planned for ProtoEXIST2 & 3, which will demonstrate the technology required for the advanced CZT imaging detectors (0.6 mm pixel, 4.5 m 2 area) required in EXIST/HET.

New Astronomy Reviews, 2004

We describe the energetic X-ray imaging survey telescope EXIST, designed to carry out a sensitive... more We describe the energetic X-ray imaging survey telescope EXIST, designed to carry out a sensitive all-sky survey in the 10-600 keV band. The primary goal of EXIST is to find black holes in the local and distant universe. EXIST also traces cosmic star formation via gamma-ray bursts and gamma-ray lines from radioactivity ejected by supernovae and novae.

The development of a survey that exploits the event-by-event data capture ca-pabilities of the Sw... more The development of a survey that exploits the event-by-event data capture ca-pabilities of the Swift-BAT during periods of spacecraft slewing is instrumental in expanding the overall capabilities of the Swift mission by expanding its spa-tial and time coverage without affecting any of its conventional pointing-mode operations. We hereby demonstrate both the importance and the feasibility of a BAT Slew Survey (BATSS), by first showing that the imaging method em-ployed not only extends coverage but also deepens the instrument sensitivity when compared to pointing observations of equivalent source exposure time and coding fraction. An imaging and detection algorithm for slew-mode data has been devised and implemented for real-time data taking, and the automated pipeline has been shown to handle the required data rates and is capable of reporting positions of candidate GRBs in as short as 2.5 hours for the fastest speeds of spacecraft telemetry downlink. The BATSS system is also equippe...

The BAT instrument on Swift is the large area, wide-field hard X-ray imager for discovering GRBs ... more The BAT instrument on Swift is the large area, wide-field hard X-ray imager for discovering GRBs (and transient as well as persistent sources) to conduct the primary mission science. Its 1.4sr (50% coded fraction) field of view covers 60-70% of the full sky on a typical day of pointings on 10 targets (previous GRBs under study as well as targeted sources) while waiting for the next GRB to then initiate a rapid slew of the narrow-field telescopes (XRT and UVOT) for precise GRB location and spectral studies. A typical Swift day then includes 60 such rapid ( 60-100sec) slews which combined cover 80-90% of the sky with typically any given point covered 6-10 times. As of now (July, 2006) BAT data has not been telemetered down during slews except for those initiated by a GRB trigger ( 2 per week). We report extensive simulations and analysis of existing GRB slews, which include "event mode" time-tagged BAT photon data, on the prospects for a BAT Slew Survey (BATSS) which would i...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

ABSTRACT Motivated by the proposed EXIST mission, a “medium-class” space observatory to survey bl... more ABSTRACT Motivated by the proposed EXIST mission, a “medium-class” space observatory to survey black holes and the Early Universe proposed to the 2010 NAS/NRC Astronomy and Astrophysics Decadal Survey, we have developed the first “large” area 256cm2 close-tiled (0.6mm gaps) hard X-ray (20–600keV) imaging detector employing pixelated (2.5mm) CdZnTe (CZT) detectors, each 2×2×0.5cm3. We summarize the design, development and operation of this detector array (8×8 CZTs) and its performance as the imager for a coded aperture telescope on a high altitude (40km) balloon flight in October, 2009, as the ProtoEXIST1 payload. We then outline our current development of a second-generation imager, ProtoEXIST2, with 0.6mm pixels on a 32×32 array on each CZT, and how it will lead to the ultimate imaging system needed for EXIST. Other applications of this technology will also be mentioned.

ABSTRACT We describe the full X-ray source catalog from the Chandra Multi-wavelength Plane Survey... more ABSTRACT We describe the full X-ray source catalog from the Chandra Multi-wavelength Plane Survey (ChaMPlane). Taking advantage of the high sensitivity and superb spatial resolution of the Chandra X-ray Observatory, ChaMPlane constrains the distribution and nature of the faint Galactic X-ray sources. ChaMPlane uses the archival data of Chandra observations within 12 deg of the Galactic plane and not centered on bright sources or clusters. ChaMPlane also includes our own targeted observations such as the deep Bulge Window Survey and the shallow Bulge Latitude Survey. We have processed about 180 individual Chandra pointings for 74 separate fields from the Galactic Bulge to Anti-Galactic center region under a custom developed X-ray analysis pipeline. More than 15000 discrete X-ray sources have been found, with luminosity down to 1030-31 erg/sec (for D=8.5 kpc) in the deep exposure of Galactic center region fields. The catalog includes the astrometric and photometric results of each X-ray source along with energy quantiles, which allows a simple classification of faint X-ray sources with diverse spectral types. This catalog will be a legacy database for future study of Galactic X-ray sources, and it will complement the relatively bright source list in the Chandra Source Catalog and the XMM-Newton Galactic Plane Survey.

Symposium - International Astronomical Union, 2005

We present VLA and MERLIN monitoring data of the JVAS gravitational lens system B1030+074. The sy... more We present VLA and MERLIN monitoring data of the JVAS gravitational lens system B1030+074. The system was monitored with the VLA from February 1998 to October 1998 at 8.4-GHz during which the VLA was at its A, BnA and B configuration. The 47 epochs of observations have an average spacing of approximately 5 days. Ten MERLIN snapshots were obtained in the L-band (1.7 GHz) during the months of April, May and June 1998. Preliminary light curves of the two components of the lens system obtained from the VLA data indicate that during the period of the monitoring the A flux density showed a steady decrease. No changes are observed in the B light curve.

The Astrophysical Journal Supplement Series

The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 ... more The discovery of the electromagnetic counterpart to the binary neutron star (NS) merger GW170817 has opened the era of gravitational-wave multimessenger astronomy. Rapid identification of the optical/infrared kilonova enabled a precise localization of the source, which paved the way to deep multiwavelength follow-up and its myriad of related science results. Fully exploiting this new territory of exploration requires the acquisition of electromagnetic data from samples of NS mergers and other gravitational-wave sources. After GW170817, the frontier is now to map the diversity of kilonova properties and provide more stringent constraints on the Hubble constant, and enable new tests of fundamental physics. The Vera C. Rubin Observatory’s Legacy Survey of Space and Time can play a key role in this field in the 2020s, when an improved network of gravitational-wave detectors is expected to reach a sensitivity that will enable the discovery of a high rate of merger events involving NSs (∼...

The Astrophysical Journal, 2015

We present optical observations of supernova SN 2014C, which underwent an unprecedented slow meta... more We present optical observations of supernova SN 2014C, which underwent an unprecedented slow metamorphosis from H-poor type Ib to H-rich type IIn over the course of one year. The observed spectroscopic evolution is consistent with the supernova having exploded in a cavity before encountering a massive shell of the progenitor star's stripped hydrogen envelope. Possible origins for the circumstellar shell include a brief Wolf-Rayet fast wind phase that overtook a slower red supergiant wind, eruptive ejection, or confinement of circumstellar material by external influences of neighboring stars. An extended high velocity Hα absorption feature seen in near-maximum light spectra implies that the progenitor star was not completely stripped of hydrogen at the time of core collapse. Archival pre-explosion Subaru Telescope Suprime-Cam and Hubble Space Telescope Wide Field Planetary Camera 2 images of the region obtained in 2009 show a coincident source that is most likely a compact massive star cluster in NGC 7331 that hosted the progenitor system. By comparing the emission properties of the source with stellar population models that incorporate interacting binary stars we estimate the age of the host cluster to be 30−300 Myr, and favor ages closer to 30 Myr in light of relatively strong Hα emission. SN 2014C is the best-observed member of a class of core-collapse supernovae that fill the gap between events that interact strongly with dense, nearby environments immediately after explosion and those that never show signs of interaction. Better understanding of the frequency and nature of this intermediate population can contribute valuable information about the poorly understood final stages of stellar evolution.

AIP Conference Proceedings, 2000

We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal a... more We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal array of seven 10 m aperture imaging Cherenkov telescopes. The selected site is Montosa Canyon (1390 m a.s.l.) at the Whipple Observatory, Arizona. Each telescope, of 12 m focal length, will initially be equipped with a 499 element photomultiplier camera covering a 3.5 degree field of view. A central station will initiate the readout of 500 MHz FADCs upon receipt of multiple telescope triggers. The minimum detectable flux sensitivity will be 0.5% of the Crab Nebula flux at 200 GeV. Detailed simulations of the array's performance are presented elsewhere at this meeting. VERITAS will operate primarily as a γ-ray observatory in the 50 GeV to 50 TeV range for the study of active galaxies, supernova remnants, pulsars and gamma ray bursts.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

We have constructed a moderately large area (32 cm 2), fine pixel (2.5 mm pixel, 5 mm thick) CZT ... more We have constructed a moderately large area (32 cm 2), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256 cm 2) developed for a balloon-borne wide-field hard X-ray telescope, ProtoEXIST1. ProtoEXIST1 is a prototype for the High Energy Telescope (HET) in the Energetic X-ray imaging Survey Telescope (EXIST), a next generation space-borne multi-wavelength telescope. We have constructed a large (nearly gapless) detector plane through a modularization scheme by tiling of a large number of 2 cm × 2 cm CZT crystals. Our innovative packaging method is ideal for many applications such as coded-aperture imaging, where a large, continuous detector plane is desirable for the optimal performance. Currently we have been able to achieve an energy resolution of 3.2 keV (FWHM) at 59.6 keV on average, which is exceptional considering the moderate pixel size and the number of detectors in simultaneous operation. We expect to complete two modules (512 cm 2) within the next few months as more CZT becomes available. We plan to test the performance of these detectors in a near space environment in a series of high altitude balloon flights, the first of which is scheduled for Fall 2009. These detector modules are the first in a series of progressively more sophisticated detector units and packaging schemes planned for ProtoEXIST2 & 3, which will demonstrate the technology required for the advanced CZT imaging detectors (0.6 mm pixel, 4.5 m 2 area) required in EXIST/HET.

New Astronomy Reviews, 2004

We describe the energetic X-ray imaging survey telescope EXIST, designed to carry out a sensitive... more We describe the energetic X-ray imaging survey telescope EXIST, designed to carry out a sensitive all-sky survey in the 10-600 keV band. The primary goal of EXIST is to find black holes in the local and distant universe. EXIST also traces cosmic star formation via gamma-ray bursts and gamma-ray lines from radioactivity ejected by supernovae and novae.

The development of a survey that exploits the event-by-event data capture ca-pabilities of the Sw... more The development of a survey that exploits the event-by-event data capture ca-pabilities of the Swift-BAT during periods of spacecraft slewing is instrumental in expanding the overall capabilities of the Swift mission by expanding its spa-tial and time coverage without affecting any of its conventional pointing-mode operations. We hereby demonstrate both the importance and the feasibility of a BAT Slew Survey (BATSS), by first showing that the imaging method em-ployed not only extends coverage but also deepens the instrument sensitivity when compared to pointing observations of equivalent source exposure time and coding fraction. An imaging and detection algorithm for slew-mode data has been devised and implemented for real-time data taking, and the automated pipeline has been shown to handle the required data rates and is capable of reporting positions of candidate GRBs in as short as 2.5 hours for the fastest speeds of spacecraft telemetry downlink. The BATSS system is also equippe...

The BAT instrument on Swift is the large area, wide-field hard X-ray imager for discovering GRBs ... more The BAT instrument on Swift is the large area, wide-field hard X-ray imager for discovering GRBs (and transient as well as persistent sources) to conduct the primary mission science. Its 1.4sr (50% coded fraction) field of view covers 60-70% of the full sky on a typical day of pointings on 10 targets (previous GRBs under study as well as targeted sources) while waiting for the next GRB to then initiate a rapid slew of the narrow-field telescopes (XRT and UVOT) for precise GRB location and spectral studies. A typical Swift day then includes 60 such rapid ( 60-100sec) slews which combined cover 80-90% of the sky with typically any given point covered 6-10 times. As of now (July, 2006) BAT data has not been telemetered down during slews except for those initiated by a GRB trigger ( 2 per week). We report extensive simulations and analysis of existing GRB slews, which include "event mode" time-tagged BAT photon data, on the prospects for a BAT Slew Survey (BATSS) which would i...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

ABSTRACT Motivated by the proposed EXIST mission, a “medium-class” space observatory to survey bl... more ABSTRACT Motivated by the proposed EXIST mission, a “medium-class” space observatory to survey black holes and the Early Universe proposed to the 2010 NAS/NRC Astronomy and Astrophysics Decadal Survey, we have developed the first “large” area 256cm2 close-tiled (0.6mm gaps) hard X-ray (20–600keV) imaging detector employing pixelated (2.5mm) CdZnTe (CZT) detectors, each 2×2×0.5cm3. We summarize the design, development and operation of this detector array (8×8 CZTs) and its performance as the imager for a coded aperture telescope on a high altitude (40km) balloon flight in October, 2009, as the ProtoEXIST1 payload. We then outline our current development of a second-generation imager, ProtoEXIST2, with 0.6mm pixels on a 32×32 array on each CZT, and how it will lead to the ultimate imaging system needed for EXIST. Other applications of this technology will also be mentioned.

ABSTRACT We describe the full X-ray source catalog from the Chandra Multi-wavelength Plane Survey... more ABSTRACT We describe the full X-ray source catalog from the Chandra Multi-wavelength Plane Survey (ChaMPlane). Taking advantage of the high sensitivity and superb spatial resolution of the Chandra X-ray Observatory, ChaMPlane constrains the distribution and nature of the faint Galactic X-ray sources. ChaMPlane uses the archival data of Chandra observations within 12 deg of the Galactic plane and not centered on bright sources or clusters. ChaMPlane also includes our own targeted observations such as the deep Bulge Window Survey and the shallow Bulge Latitude Survey. We have processed about 180 individual Chandra pointings for 74 separate fields from the Galactic Bulge to Anti-Galactic center region under a custom developed X-ray analysis pipeline. More than 15000 discrete X-ray sources have been found, with luminosity down to 1030-31 erg/sec (for D=8.5 kpc) in the deep exposure of Galactic center region fields. The catalog includes the astrometric and photometric results of each X-ray source along with energy quantiles, which allows a simple classification of faint X-ray sources with diverse spectral types. This catalog will be a legacy database for future study of Galactic X-ray sources, and it will complement the relatively bright source list in the Chandra Source Catalog and the XMM-Newton Galactic Plane Survey.