S. Kaspi
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View article: A high geometric albedo and small size for the Haumea cluster member (24835) 1995 SM <sub>55</sub> determined from a stellar occultation and photometric observations
A high geometric albedo and small size for the Haumea cluster member (24835) 1995 SM <sub>55</sub> determined from a stellar occultation and photometric observations Open
Context . Trans-Neptunian objects (TNOs) are thought to be some of the most ancient and primitive bodies in our Solar System. Understanding their basic physical properties is crucial to unraveling their origin and the evolution of the oute…
View article: Echo mapping of the black hole accretion flow in NGC 7469
Echo mapping of the black hole accretion flow in NGC 7469 Open
Reverberation mapping (RM) can measure black hole accretion disc sizes and radial structure through observable light travel time lags that should increase with wavelength as $\tau \propto \lambda ^{4/3}$ due to the disc’s $T\propto r^{-3/4…
View article: Size and shape of the trans-Neptunian object (470316) 2007 OC10: Comparison with thermal data
Size and shape of the trans-Neptunian object (470316) 2007 OC10: Comparison with thermal data Open
Context. The shapes of only 12 trans-Neptunian objects have been directly measured, offering crucial insights into their internal structure. These properties are strongly connected to the processes that shaped the early Solar System, and p…
View article: Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593
Double-peaked Ca II traces a relativistic broad-line region disk in NGC 4593 Open
Context. Double-peaked emission lines are observed in a small percentage of active galactic nuclei (AGN). These lines allow the determination of fundamental properties of the line-emitting region, known as the broad-line region (BLR). Aims…
View article: Size and shape of the trans-Neptunian object (470316) 2007 OC10: Comparison with thermal data
Size and shape of the trans-Neptunian object (470316) 2007 OC10: Comparison with thermal data Open
The shapes of only 12 trans-Neptunian objects have been directly measured, offering crucial insights into their internal structure. These properties are strongly connected to the processes that shaped the early Solar System, and provide im…
View article: Stellar Occultation Observations of (38628) Huya and Its Satellite: A Detailed Look into the System
Stellar Occultation Observations of (38628) Huya and Its Satellite: A Detailed Look into the System Open
The physical and orbital parameters of trans-Neptunian objects provide valuable information about the solar system’s formation and evolution. In particular, the characterization of binaries provides insights into the formation mechanisms t…
View article: Broad-line Region Characterization in Dozens of Active Galactic Nuclei Using Small-aperture Telescopes
Broad-line Region Characterization in Dozens of Active Galactic Nuclei Using Small-aperture Telescopes Open
We present the results of a nearly decade-long photometric reverberation mapping (PRM) survey of the H α emission line in nearby (0.01 ≲ z ≲ 0.05) Seyfert galaxies using small (15–40 cm) telescopes. Broadband filters were used to trace the…
View article: Multiwavelength monitoring and reverberation mapping of NGC 2617 at deepest minimum with a sharp upward turn during 2021–2024
Multiwavelength monitoring and reverberation mapping of NGC 2617 at deepest minimum with a sharp upward turn during 2021–2024 Open
We present the results of a new X-ray to near-IR photometric and spectroscopic monitoring of the changing look active galactic nucleus NGC 2617 carried out from March 2022 to March 2024. We found significant variability at all wavelengths …
View article: Broad-Line Region Characterization in Dozens of Active Galactic Nuclei Using Small-Aperture Telescopes
Broad-Line Region Characterization in Dozens of Active Galactic Nuclei Using Small-Aperture Telescopes Open
We present the results of a nearly decade-long photometric reverberation mapping (PRM) survey of the H$α$ emission line in nearby ($0.01\lesssim z \lesssim0.05$) Seyfert-Galaxies using small ($15\,\mathrm{cm}-40\,\mathrm{cm}$) telescopes. …
View article: AGN STORM 2. X. The Origin of the Interband Continuum Delays in Mrk 817*
AGN STORM 2. X. The Origin of the Interband Continuum Delays in Mrk 817* Open
The local ( z = 0.0315) active galactic nucleus (AGN) Mrk 817 was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign, AGN STORM 2. Here, we present a comprehensive anal…
View article: Reverberation Mapping of High-mass and High-redshift Quasars Using Gravitational Time Delays
Reverberation Mapping of High-mass and High-redshift Quasars Using Gravitational Time Delays Open
Mass estimates of black holes (BHs) in the centers of active galactic nuclei (AGNs) often rely on the radius–luminosity relation. However, this relation, usually probed by reverberation mapping (RM), is poorly constrained in the high-lumin…
View article: AGN STORM 2: X. The origin of the interband continuum delays in Mrk 817
AGN STORM 2: X. The origin of the interband continuum delays in Mrk 817 Open
The local (z=0.0315) AGN Mrk 817, was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign AGN STORM 2. Here, we present a comprehensive analysis of the broad-band contin…
View article: AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-Ray Reverberation and UVOIR Disk Reprocessing Time Lags
AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-Ray Reverberation and UVOIR Disk Reprocessing Time Lags Open
X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad…
View article: AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy
AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy Open
We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multiwavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AGN…
View article: AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-ray Reverberation and UVOIR Disk Reprocessing Time Lags
AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-ray Reverberation and UVOIR Disk Reprocessing Time Lags Open
X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad…
View article: AGN STORM 2. VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations*
AGN STORM 2. VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations* Open
We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in the Hubble Space Telescope/Cosmic Origins Spectr…
View article: First Direct Evidence for Keplerian Rotation in Quasar Inner Broad-line Regions
First Direct Evidence for Keplerian Rotation in Quasar Inner Broad-line Regions Open
We introduce a novel method to derive rotation curves with light-day spatial resolution of the inner regions of lensed quasars. We aim to probe the kinematics of the inner part of the broad-line region by resolving the microlensing respons…
View article: Reverberation mapping of high-mass and high-redshift quasars using gravitational time delays
Reverberation mapping of high-mass and high-redshift quasars using gravitational time delays Open
Mass estimates of black holes (BHs) in the centers of Active Galactic Nuclei (AGN) often rely on the radius-luminosity relation. However, this relation, usually probed by reverberation mapping (RM), is poorly constrained in the high-lumino…
View article: First Direct Evidence for Keplerian Rotation in Quasar Inner Broad Line Regions
First Direct Evidence for Keplerian Rotation in Quasar Inner Broad Line Regions Open
We introduce a novel method to derive rotation curves with light-day spatial resolution of the inner regions of lensed quasars. We aim to probe the kinematics of the inner part of the broad-line region (BLR) by resolving the microlensing r…
View article: Revealing the inner workings of the lensed quasar SDSS J1339+1310: Insights from microlensing analysis
Revealing the inner workings of the lensed quasar SDSS J1339+1310: Insights from microlensing analysis Open
Aims. We aim to unveil the structure of the continuum and broad-emission line (BEL) emitting regions in the gravitationally lensed quasar SDSS J1339+1310 by examining the distinct signatures of microlensing present in this system. Our stud…
View article: Revealing the inner workings of the lensed quasar SDSS J1339+1310: Insights from microlensing analysis
Revealing the inner workings of the lensed quasar SDSS J1339+1310: Insights from microlensing analysis Open
We aim to unveil the structure of the continuum and broad-emission line (BEL) emitting regions in the gravitationally lensed quasar SDSS J1339+1310 by examining the distinct signatures of microlensing present in this system. Our study invo…
View article: AGN STORM 2: VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations
AGN STORM 2: VIII. Investigating the Narrow Absorption Lines in Mrk 817 Using HST-COS Observations Open
We observed the Seyfert 1 galaxy Mrk817 during an intensive multi-wavelength reverberation mapping campaign for 16 months. Here, we examine the behavior of narrow UV absorption lines seen in HST/COS spectra, both during the campaign and in…
View article: The small size and high geometric albedo of the Haumea cluster member 1995 SM55 from a stellar occultation and ground based photometry
The small size and high geometric albedo of the Haumea cluster member 1995 SM55 from a stellar occultation and ground based photometry Open
The Trans-Neptunian Object with provisional designation 1995SM55 is one of the few members of the Haumea orbital cluster and therefore it is a very relevant body to study through the occultation technique in order to accurately determine s…
View article: Comet C/2012 S1 (ISON) crossing the Jupiter orbit
Comet C/2012 S1 (ISON) crossing the Jupiter orbit Open
We report results of intensive time-resolved imaging photometry and synoptic deep imaging of the comet C/2012 S1 (ISON) performed in February 2013. The data were obtained at the Wise Observatory in Israel (WO), at the Himalayan Chandra Tel…
View article: AGN STORM 2: IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-ray Spectroscopy
AGN STORM 2: IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-ray Spectroscopy Open
We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multi-wavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AG…
View article: AGN STORM 2. V. Anomalous Behavior of the C <scp>iv</scp> Light Curve of Mrk 817*
AGN STORM 2. V. Anomalous Behavior of the C <span>iv</span> Light Curve of Mrk 817* Open
An intensive reverberation mapping campaign of the Seyfert 1 galaxy Mrk 817 using the Cosmic Origins Spectrograph on the Hubble Space Telescope revealed significant variations in the response of broad UV emission lines to fluctuations in t…
View article: The transient event in NGC 1566 from 2017 to 2019
The transient event in NGC 1566 from 2017 to 2019 Open
Context. NGC 1566 is a local face-on Seyfert galaxy and is known for exhibiting recurrent outbursts that are accompanied by changes in spectral type. The most recent transient event occurred from 2017 to 2019 and was reported to be accompa…
View article: AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817
AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817 Open
We fit the UV/optical lightcurves of the Seyfert 1 galaxy Mrk 817 to produce maps of the accretion disk temperature fluctuations δ T resolved in time and radius. The δ T maps are dominated by coherent radial structures that move slowly ( v…
View article: AGN STORM 2. IV. Swift X-Ray and Ultraviolet/Optical Monitoring of Mrk 817
AGN STORM 2. IV. Swift X-Ray and Ultraviolet/Optical Monitoring of Mrk 817 Open
The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from the inner accretion disk to the broad emission line region and out to the dusty torus. As part of this c…
View article: Probing the structure of the lensed quasar SDSS J1004+4112 through microlensing analysis of spectroscopic data
Probing the structure of the lensed quasar SDSS J1004+4112 through microlensing analysis of spectroscopic data Open
We aim to reveal the sizes of the continuum and broad emission line (BEL) emitting regions in the gravitationally lensed quasar SDSS J1004+4112 by analyzing the unique signatures of microlensing in this system. Through a comprehensive anal…