About

Dee Hibbert Jones is a Professor in the Arts Division at the University of California, Santa Cruz, affiliated with the Digital Arts and New Media, Film and Digital Media Department, and Legal Studies. Her areas of expertise include art, film, digital arts, web-based media, and art/media work. She is based in the Elena Baskin Building, Darc 221, and maintains office hours by appointment. Her work focuses on the intersection of art and digital media, contributing to the fields of film and digital arts through her research and creative projects.

Research topics

• Physics
• Astrophysics
• Astronomy
• Statistics
• Optics
• Mathematical physics

Selected publications

• SNDATA_ROOT for SNANA software

  Zenodo (CERN European Organization for Nuclear Research) · 2026-04-10

  datasetOpen accessSenior author

  Environment for the Supernova Analysis software package (https://github.com/RickKessler/SNANA). This environment Includes public light curve data sets, filter transmissions, primary SEDs, calibration files, models for SNIa & CC, cadence and host-galaxy libraries for simulations, etc ...

  PublisherDOI

• SNDATA_ROOT for SNANA software

  Zenodo (CERN European Organization for Nuclear Research) · 2026-04-10

  datasetOpen accessSenior author

  Environment for the Supernova Analysis software package (https://github.com/RickKessler/SNANA). This environment Includes public light curve data sets, filter transmissions, primary SEDs, calibration files, models for SNIa & CC, cadence and host-galaxy libraries for simulations, etc ...

  PublisherDOI

• Testing for Intrinsic Type Ia Supernova Luminosity Evolution at z > 2 with JWST

  The Astrophysical Journal Letters · 2025-02-24 · 12 citations

  articleOpen access

  Abstract The James Webb Space Telescope (JWST) is opening new frontiers of transient discovery and follow-up at high redshift. Here we present the discovery of a spectroscopically confirmed Type Ia supernova (SN Ia; SN 2023aeax) at z = 2.15 with JWST, including a NIRCam multiband light curve. SN 2023aeax lands at the edge of traditional low- z cosmology cuts because of its blue color (peak rest-frame B − V ∼ −0.3) but with a normal decline rate (Δ m 15 ( B ) ∼ 1.25), and applying a fiducial standardization with the BayeSN model we find the SN 2023aeax luminosity distance is in ∼0.1 σ agreement with ΛCDM. SN 2023aeax is only the second spectroscopically confirmed SN Ia in the dark matter–dominated Universe at z > 2 (the other is SN 2023adsy), giving it rare leverage to constrain any potential evolution in SN Ia standardized luminosities. Similar to SN 2023adsy ( B − V ∼ 0.8), SN 2023aeax has a fairly extreme (but opposite) color, which may be due to the small sample size or a secondary factor, such as host galaxy properties. Nevertheless, the SN 2023aeax spectrum is well represented by normal low- z SN Ia spectra, and we find no definitive evolution in SN Ia standardization with redshift. Still, the first two spectroscopically confirmed z > 2 SNe Ia have peculiar colors and combine for a ∼1 σ distance slope relative to ΛCDM, though in agreement with recent SN Ia cosmological measurements.

  PublisherDOI

• Characterizing the standardization properties of type ia supernovae in the <i>z</i> band with hierarchical Bayesian modelling

  Monthly Notices of the Royal Astronomical Society · 2025-06-29 · 2 citations

  articleOpen access

  ABSTRACT Type Ia supernovae (SNe Ia) are standardizable candles: their peak magnitudes can be corrected for correlations between light-curve properties and their luminosities to precisely estimate distances. Understanding SN Ia standardization across wavelength improves methods for correcting SN Ia magnitudes. Using 150 SNe Ia from the Foundation Supernova Survey and Young Supernova Experiment, we present the first study focusing on SN Ia standardization properties in the z band. Straddling the optical and near-infrared, SN Ia light in the z band is less sensitive to dust extinction and can be collected alongside the optical on CCDs. Pre-standardization, SNe Ia exhibit less residual scatter in z-band peak magnitudes than in the g and r bands. SNe Ia peak z-band magnitudes still exhibit a significant dependence on light-curve shape. Post-standardization, the z-band Hubble diagram has a total scatter of root mean square $=0.195$ mag. We infer a z-band mass step of $\gamma _{z} = -0.105 \pm 0.031$ mag, which is consistent within $1\sigma$ of that estimated from $gri$ data, assuming $R_{V} = 2.61$. When assuming different $R_{V}$ values for high and low mass host galaxies, the z band and optical mass steps remain consistent within $1\sigma$. Based on current statistical precision, these results suggest dust reddening cannot fully explain the mass step. SNe Ia in the z band exhibit complementary standardizability properties to the optical that can improve distance estimates. Understanding these properties is important for the upcoming Vera Rubin Observatory and Nancy G. Roman Space Telescope, which will probe the rest-frame z band to redshifts 0.1 and 1.8.

  PublisherOA PDFDOI

• Spatial Profiles of 3I/ATLAS CN and Ni Outgassing from Keck/KCWI Integral Field Spectroscopy

  ArXiv.org · 2025-10-13 · 4 citations

  preprintOpen access

  Cometary activity from interstellar objects provides a unique window into the environs of other stellar systems. We report blue-sensitive integral field unit spectroscopy of the interstellar object 3I/ATLAS from the Keck-II-mounted Keck Cosmic Web Imager on August 24, 2025 UT. We confirm previously reported CN and Ni outgassing, and present, for the first time, the radial profiles of Ni and CN emission in 3I/ATLAS. We find a characteristic $e$-folding radius of $593.7\pm14.8$ km for Ni and $841.0\pm15.4$ km for CN; this suggests that the Ni emission is more centrally concentrated in the nucleus of the comet and favors hypotheses involving easily dissociated species such as metal carbonyls or metal-polycyclic-aromatic-hydrocarbon molecules. Additional integral field spectroscopy after perihelion will offer a continued opportunity to determine the evolution of the radial distributions of species in interstellar comet 3I/ATLAS.

  PublisherOA PDFDOI

• The <tt>BTSbot-nearby</tt> Discovery of SN 2024jlf: Rapid, Autonomous Follow-up Probes Interaction in an 18.5 Mpc Type IIP Supernova

  The Astrophysical Journal · 2025-05-29 · 8 citations

  articleOpen accessCorresponding

  Abstract We present observations of the Type IIP supernova (SN) SN 2024jlf, including spectroscopy beginning just 0.7 days (∼17 hr) after first light. Rapid follow-up was enabled by the new BTSbot-nearby program, which involves autonomously triggering target-of-opportunity requests for new transients in Zwicky Transient Facility data that are coincident with nearby ( D &lt; 60 Mpc) galaxies and identified by the BTSbot machine learning model. Early photometry and nondetections shortly prior to first light show that SN 2024jlf initially brightened by &gt;4 mag day −1 , quicker than ∼90% of Type II SNe. Early spectra reveal weak flash ionization features: narrow, short-lived (1.3 &lt; τ [days] &lt; 1.8) emission lines of H α , He ii , and C iv . Assuming a wind velocity of v w = 50 km s −1 , these properties indicate that the red supergiant progenitor exhibited enhanced mass loss in the last year before explosion. We constrain the mass-loss rate to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> </mml:msup> <mml:mo>&lt;</mml:mo> <mml:mover accent="true"> <mml:mi>M</mml:mi> <mml:mo>̇</mml:mo> </mml:mover> <mml:mspace width="0.25em"/> <mml:mo stretchy="false">[</mml:mo> <mml:msub> <mml:mi>M</mml:mi> <mml:mo>⊙</mml:mo> </mml:msub> <mml:mspace width="0.25em"/> <mml:msup> <mml:mi>yr</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mo stretchy="false">]</mml:mo> <mml:mo>&lt;</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> by matching observations to model grids from two independent radiative hydrodynamics codes. BTSbot-nearby automation minimizes spectroscopic follow-up latency, enabling the observation of ephemeral early-time phenomena exhibited by transients.

  PublisherDOI

• The Gravity Collective: A Comprehensive Analysis of the Electromagnetic Search for the Binary Neutron Star Merger GW190425

  The Astrophysical Journal · 2025-07-23 · 2 citations

  articleOpen accessCorresponding

  Abstract We present an ultraviolet to infrared search for the electromagnetic (EM) counterpart to GW190425, the second ever binary neutron star merger discovered by the LIGO-Virgo-KAGRA Collaboration. GW190425 was more distant and had a larger localization area than GW170817, so we use a new tool, Teglon , to redistribute the GW190425 localization probability in the context of galaxy catalogs within the final localization volume. We derive a 90th percentile area of 6688 deg 2 , a ∼1.5× improvement relative to the LIGO/Virgo map, and show how Teglon provides an order-of-magnitude boost to the search efficiency of small (≤1 deg 2 ) field-of-view instruments. We combine our data with a large, publicly reported imaging data set, covering 9078.59 deg 2 of unique area and 48.13% of the LIGO/Virgo-assigned localization probability, to calculate the most comprehensive kilonova (KN), short gamma-ray burst (sGRB) afterglow, and model-independent constraints on the EM emission from a hypothetical counterpart to GW190425 to date under the assumption that no counterpart was found in these data. If the counterpart were similar to AT 2017gfo, there would be a 28.4% chance of it being detected in the combined data set. We are relatively insensitive to an on-axis sGRB, and rule out a generic transient with a similar peak luminosity and decline rate as AT 2017gfo to 30% confidence. Finally, across our new imaging and publicly reported data, we find 28 candidate optical counterparts that we cannot rule out as being associated with GW190425, finding that four such counterparts discovered within the localization volume and within 5 days of merger exhibit luminosities consistent with a KN.

  PublisherDOI

• Seeing the Outer Edge of the Infant Type Ia Supernova 2024epr in the Optical and Near Infrared

  The Open Journal of Astrophysics · 2025-08-20 · 10 citations

  articleOpen access

  We present optical-to-near-infrared (NIR) photometry and spectroscopy of the Type Ia supernova (SN~Ia) 2024epr, including NIR spectra observed within two days of first light. The early-time optical spectra show strong, high-velocity Ca and Si features near rarely-observed velocities at $ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>0.1</mml:mn> </mml:math> c$, and the NIR spectra show a “knee.’’ Despite early-time, high-velocity features, SN~2024epr evolves into a normal SN~Ia, albeit with stronger peak-light Ca absorption than other SNe~Ia with the same light curve shape. Although we infer a normal decline rate, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>Δ</mml:mi> <mml:msub> <mml:mi>m</mml:mi> <mml:mn>15</mml:mn> </mml:msub> <mml:mrow> <mml:mo stretchy="true" form="prefix">(</mml:mo> <mml:mi>B</mml:mi> <mml:mo stretchy="true" form="postfix">)</mml:mo> </mml:mrow> <mml:mo>=</mml:mo> <mml:mn>1.09</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.12</mml:mn> </mml:mrow> </mml:math> ~mag, from the light-curve rise, SN~2024epr is a Branch”cool’’ object and has red early-time colors ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mi>g</mml:mi> <mml:mo>−</mml:mo> <mml:mi>r</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>0.15</mml:mn> </mml:mrow> </mml:math> ~mag at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>10</mml:mn> </mml:mrow> </mml:math> ~days). The high velocities point to a density enhancement in the outer layers of the explosion, predicted by some models, but thick-shell He-detonation models do not match the smoothly rising light curve or apparent lack of He in our early-time NIR spectra. No current models (e.g., delayed detonation or thin He shell double detonation) appear to reproduce all observed properties, particularly the unusual early-time colors. Such constraints are only possible for SN~2024epr from the earliest optical and NIR observations, highlighting their importance for constraining SN~Ia models. Finally, we identify several literature SNe~Ia with intermediate mass elements at $ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mn>30</mml:mn> <mml:mspace width="0.167em"/> <mml:mn>000</mml:mn> <mml:mspace width="0.222em"/> <mml:mi>k</mml:mi> <mml:mi>m</mml:mi> <mml:mspace width="0.222em"/> <mml:mi>s</mml:mi> </mml:mrow> </mml:math> ^{-1}$ within days after the explosion that evolve into otherwise normal SNe~Ia at peak light, suggesting the early-time spectra of SNe~Ia may hide a broad diversity of observational characteristics.

  PublisherDOI

• ZTF SN Ia DR2: Improved SN Ia colors through expanded dimensionality with SALT3+

  Astronomy and Astrophysics · 2025-03-25 · 1 citations

  articleOpen access

  Context. Type Ia supernovae (SNe Ia) are a key probe in modern cosmology, as they can be used to measure luminosity distances at gigaparsec scales. Models of their light curves are used to project heterogeneous observed data onto a common basis for analysis. Aims. The SALT model currently used for SN Ia cosmology describes SNe as having two sources of variability, accounted for by a color parameter c , and a “stretch” parameter x 1 . We extend the model to include an additional parameter we label x 2 , to investigate the cosmological impact of currently unaddressed light-curve variability. Methods. We constructed a new SALT model, that we dub “SALT3+”. This model was trained by an improved version of the SALTshaker code, using training data combining a selection of the second data release of cosmological SNe Ia from the Zwicky Transient Facility and the existing SALT3 training compilation. Results. We find additional, coherent variability in supernova light curves beyond SALT3. Most of this variation can be described as phase-dependent variation in g − r and r − i color curves, correlated with a boost in the height of the secondary maximum in i -band. These behaviors correlate with spectral differences, particularly in line velocity. We find that fits with the existing SALT3 model tend to address this excess variation with the color parameter, leading to less informative measurements of supernova color. We find that neglecting the new parameter in light-curve fits leads to a trend in Hubble residuals with x 2 of 0.039 ± 0.005 mag, representing a potential systematic uncertainty. However, we find no evidence of a bias in current cosmological measurements. Conclusions. We conclude that extended SN Ia light-curve models promise mild improvement in the accuracy of color measurements, and corresponding cosmological precision. However, models with more parameters are unlikely to substantially affect current cosmological results.

  PublisherOA PDFDOI

• Final Moments. III. Explosion Properties and Progenitor Constraints of CSM-interacting Type II Supernovae

  The Astrophysical Journal · 2025-10-08 · 6 citations

  articleOpen accessCorresponding

  Abstract We present analysis of the plateau and late-time phase properties of a sample of 39 Type II supernovae (SNe II) that show narrow, transient, high-ionization emission lines (i.e., “IIn-like”) in their early-time spectra from interaction with confined, dense circumstellar material (CSM). Originally presented by W. V. Jacobson-Galán et al., this sample also includes multicolor light curves and spectra extending to late-time phases of 35 SNe with no evidence for IIn-like features at &lt;2 days after first light. We measure photospheric phase light-curve properties for the distance-corrected sample and find that SNe II with IIn-like features have significantly higher luminosities and decline rates at +50 days than the comparison sample, which could be connected to inflated progenitor radii, lower ejecta mass, and/or persistent CSM interaction. However, we find no statistical evidence that the measured plateau durations and 56 Ni masses of SNe II with and without IIn-like features arise from different distributions. We estimate progenitor zero-age main-sequence (ZAMS) masses for all SNe with nebular spectroscopy through spectral model comparisons and find that most objects, both with and without IIn-like features, are consistent with progenitor masses ≤12.5 M ⊙ . Combining progenitor ZAMS masses with CSM densities inferred from early-time spectra suggests multiple channels for enhanced mass loss in the final years before core collapse, such as a convection-driven chromosphere or binary interaction. Finally, we find spectroscopic evidence for ongoing ejecta-CSM interaction at radii &gt;10 16 cm, consistent with substantial progenitor mass-loss rates of ∼10 −4 –10 −5 M ⊙ yr −1 ( v w &lt; 50 km s −1 ) in the final centuries to millennia before explosion.

  PublisherDOI

Frequent coauthors

• A. Rest

  148 shared

• R. J. Foley

  143 shared

• Adam G. Riess

  Space Telescope Science Institute

  107 shared

• Katie Auchettl

  99 shared

• C. D. Kilpatrick

  Northwestern University

  84 shared

• D. Scolnic

  83 shared

• D. A. Coulter

  70 shared

• M. R. Siebert

  Space Telescope Science Institute

  69 shared