January 4-8, 2026 (Phoenix, AZ)

Town Hall: Nancy Grace Roman Space Telescope Town Hall

• Nancy Grace Roman Space Telescope Town Hall

  (Monday, January 5, 7:30–9:30 p.m. MT; Phoenix Convention Center, 224A)

  The Nancy Grace Roman Space Telescope is a NASA flagship mission planned for launch no earlier than September 2026. The Roman Space Telescope will perform breakthrough science in dark energy cosmology, exoplanet microlensing, and NIR sky surveys with its Wide Field Instrument. Roman will also feature the Coronagraph Instrument (CGI), a technology demonstration that will directly image and take spectra of exoplanetary systems using several novel technologies together for the first time in space. This session will cover the status of the project and upcoming opportunities for community involvement in planning and executing the science and technology demonstration aspects of Roman.

 

Workshops

• Roman Galactic Bulge Time Domain Survey Data Challenge

(Sunday, January 4, 9:00–5:00 p.m. MT; Phoenix Convention Center, 224A)

The Nancy Grace Roman Space Telescope (Roman) is the next NASA Astrophysics flagship mission and is currently planned for launch in fall 2026. As one of the core community surveys to be carried out during its prime mission, the Roman Galactic Bulge Time Domain Survey (RGBTDS) will monitor approximately 1.4 square degrees toward the Galactic bulge with a cadence of about 12 minutes during six 72-day seasons spread over the five-year prime mission. One of the primary goals of the RGBTDS is to complete the census of exoplanets initiated by Kepler and TESS by using the microlensing technique to characterize the population of cold exoplanets beyond the snow line. Roman is expected to detect over 20,000 microlensing events, including thousands of bound and free-floating planets. While an automated pipeline will provide a uniform analysis of most detections, many events will benefit from—or even require—more detailed, customized analyses. These events offer an unprecedented opportunity for the community to extract unique and transformational exoplanet science from the Roman survey. Although the theoretical foundations of the microlensing technique are well understood, the method is often perceived as more conceptually challenging than other exoplanet detection techniques. Moreover, the exoplanet microlensing community has historically been small, and as a result, the field lacks the extensive infrastructure (e.g., publicly available data reduction and analysis codes, statistical tools, etc.) that supports other methods. Consequently, there exist significant barriers to entry for new researchers in the microlensing field. This workshop aims to introduce the broader astronomical community to microlensing and encourage researchers to take advantage of the scientific opportunities provided by the RGBTDS, and in turn infuse the field with new perspectives, ideas, analysis techniques and methodologies. We will do this by lowering the barrier to entry through a well-curated data analysis challenge. Specifically, the workshop will include: • A brief introduction to microlensing by exoplanets, including hands-on tutorials using Python notebooks; • A review of relevant publicly available analysis tools for microlensing data; • An overview of the data challenge structure, levels, submission process, and timeline; • A moderated hack session with expert tutors, where participants can familiarize themselves with simulated data products and available tools. The target audience includes astronomers and scientists at all career stages who are interested in learning how to analyze microlensing events through participation in the data challenge. A basic understanding of astronomical concepts—particularly data analysis and reduction—is required, along with basic proficiency in Python. Registration is required. Participants must bring their own laptops and install necessary software prior to the workshop.

• Preparing for the Nancy Grace Roman Space Telescope: Working in the Roman Research Nexus

(Sunday, January 4, 9:00–5:00 p.m. MT; Phoenix Convention Center, 221 C)

The Nancy Grace Roman Space Telescope is anticipated to generate close to 30 petabytes of data during its five-year primary mission, heralding a new era of big data in astronomy. As data sets grow too large for personal computers, virtual science platforms offer a solution by providing cloud-based data processing and analysis capabilities. The Roman Research Nexus is a science platform being developed to provide the astronomical community with a cloud-based computing environment for Roman data. It combines data-code proximity with a pre-configured software setup and real-time collaboration tools, making it easier for users to work with data and collaborate in teams. The platform includes pre-loaded notebook tutorials and scientific workflows tailored to specific astronomical use cases. Built on the JupyterLab environment, it allows users to create Jupyter Notebooks that integrate code, analysis results, data visualizations, and tools for working with astronomical images, spectra, and catalogs. Users will also be able to customize their environments and install their own software as needed. This one-day workshop will provide the scientific community with an introductory overview of the Roman Research Nexus. In addition to offering hands-on training, we aim to gather feedback to understand the needs of the user community. The workshop will include both directed training and independent exploration. The training will feature presentations and short tutorials, alternating with hands-on practical exercises focused on exploring several high-level workflows. Examples include an introduction to Roman data reduction tools, learning how to work with the ASDF file format, and using visualization and simulation tools such as Jdaviz (image visualization), Pandeia (Exposure Time Calculator), RIST (Roman Interactive Sensitivity Tool), Roman I-sim (Roman Image simulator), STIPS (Space Telescope Image Product Simulator), and WebbPSF for Roman (PSFs simulator). Attendees will also learn how to access and analyze state-of-the-art Roman simulations, as well as how to simulate their own data using the Roman simulation tools. This course is aimed at astronomers and scientists at all stages of their education and careers. A basic knowledge of Python and familiarity with astronomical data concepts (e.g., data reduction, photometry) is expected. Prior experience with science platforms, Jupyter Notebooks, or the Roman mission is not required. This workshop requires registration. Participants will need personal computers and should set up Roman Research Nexus accounts in advance with help from the workshop organizers.

 

Oral Splinter Sessions

• Roman Slitless Spectroscopy Data Challenge

  (Monday, January 5, 10:00 a.m.–12:00 p.m. MT; Phoenix Convention Center, 131 A)

  This is the third of planned data challenge workshops on Roman slitless spectroscopy. We look forward to welcoming both returning and new participants. In this session, we will first recap the basic spectroscopic capabilities of Roman (both grism and prism). We will then introduce a simulated data set, consisting of a complex scene “observed” with Roman slitless spectroscopy, and including a variety of source classes. We will then demonstrate the extraction of multiple sources from the simulated data set, building on the pedagogical Jupyter notebooks presented in earlier sessions. Finally, we will provide the guidelines of the data challenge for participants who wish to analyze the simulated data sets to identify and characterize objects of interest.

• Roman Space Telescope Proposal and Science Planning

  (Tuesday, January 6, 10:00 a.m.–12:00 p.m. MT; Phoenix Convention Center, 121 B)

  NASA’s Nancy Grace Roman Space Telescope is currently scheduled to launch no later than May 2027, and as early as September 2026. The recently released Call for Proposals includes support for analyzing the archival data as well as the opportunity to propose for new surveys. This splinter meeting will equip attendees with the knowledge and resources needed to prepare competitive Roman proposals. Representatives from the Roman project and the Roman Science Centers at IPAC and STScI will provide updates on the implementation of community-defined surveys, available simulations, forthcoming data products, and the proposal process itself. The session will also highlight essential tools that support understanding the community-defined surveys as well as proposal preparation and science planning. These include the Roman Telescope Proposal System (RTPS), the Astronomer’s Proposal Tool (APT), the Exposure Time Calculator (ETC), the Roman Image Simulator (Roman I-Sim), and the Roman Research Nexus, a powerful platform for collaborative research, data analysis, and community engagement.

• Resources for the Roman Cosmology, Exoplanet, and Time Domain Communities

  (Tuesday, January 6, 3:00 p.m.–5:00 p.m. MT; Phoenix Convention Center, 126 C)

  The Nancy Grace Roman Space Telescope is NASA's next flagship mission. It will conduct several large, ambitious surveys to address fundamental questions in Cosmology, Exoplanets, and Astrophysics. The mission is on track to launch in September 2026. The Roman Project Infrastructure Teams (PITs) are responsible for developing and maintaining the infrastructural tools and capabilities needed to achieve the mission objectives and support community science collaborations. The PITs work closely with the Roman Project Science Office and mission partners at the IPAC and STScI Roman Science Centers. With just over nine months remaining before launch, this session presents detailed work and deliverables of the PITs. The talks will inform the community about the tools developed by the PITs for Roman science and will allow the teams to benefit from community feedback. The Roman PITs, competitively selected by NASA, are: "Cosmology with the Roman High Latitude Imaging Survey," "Project Infrastructure for the Roman Galaxy Redshift Survey," "A Roman Project Infrastructure Team to Support Cosmological Measurements with Type Ia Supernovae," "The Roman Galactic Exoplanet Survey Project Infrastructure Team," and "RAPID: Roman Alerts Promptly from Image Differencing".

 

Oral Special Sessions

• Preparing for Time Domain Science with the Roman Space Telescope

  (Thursday, January 8, 10:00–11:30 a.m. MT; Phoenix Convention Center, 226 C)

  The Nancy Grace Roman Space Telescope is set to revolutionize time-domain astrophysics (TDA) with its combination of wide-field imaging coverage and infrared sensitivity (~27.5 mag AB). Roman will be capable of discovering Galactic and Extragalactic transients and variables such as the electromagnetic counterparts of neutron star mergers (kilonovae), stellar mergers, tidal disruption events (TDEs), and supernovae. With its launch no later than May 2027, now is the ideal time for the community to prepare for time-domain science with Roman. In order to enable time-domain science for the Roman astronomical community, the Roman Alerts Promptly from Image Differencing (RAPID) Project Infrastructure Team will provide the following four services: - Rapid image-differencing of every new Roman Wide Field Instrument science image; - A public alert stream of transient and variable candidates from Roman difference images; - Photometry for every Roman transient source observed more than once in same filter (light curves); - Forced photometry service at any sky location in available Roman data. The highest priority of RAPID is to generate and disseminate low-latency alerts from image differencing for every Roman imaging observation to enable timely multi-wavelength follow-up. In this session, we will showcase prototypes of the RAPID services and products and engage with the AAS attendees to prepare for time-domain science with Roman. We will also seek community feedback to encourage a wide representation of science interests to utilize RAPID services. The session will include talks and demos from the RAPID team and invited speakers followed by a panel discussion.

 

Oral Session Talks

• sGRB Orphan Afterglows in the Roman Space Telescope Era - Tzvetelina Dimitrova, Nathaniel Butler (ASU).

  (Monday, January 5, 10:20–10:30 a.m. MT; Phoenix Convention Center, 221 A)

  There is strong tension between the rate of short-duration Gamma-ray Bursts (sGRBs) detected by Swift and Fermi, and rate estimates for their likely progenitors - binary neutron star (BNS) events. In Dimitrova et al. 2023, we find these numbers strongly depend on sGRB beaming. Estimates are thus fundamentally limited by a scarcity of jetting angle constraints. The lack of BNS events and joint sGRB observations in aLIGO O4 further emphasizes beaming as a key factor in understanding sGRB-BNS/GW association. To tighten sGRB jetting effects, measurements or limits of orphan afterglow (OA) rates are needed from the upcoming Nancy Grace Roman Space Telescope and Rubin Observatory. We predict these next generation surveys will significantly improve OA detections, enough to potentially constrain sGRB beaming and energetics - with an optimistic rate of 95 all-sky all-z per year with Roman. In these upcoming facilities, we look forward to updating estimates of off-axis sGRB rates as we investigate implications for future aLIGO observational runs and probe multi-messenger significance.

• The TRExS Photometry Pipeline for the Roman GBTDS - Jorge Martinez-Palomera (UMBC/NASA GSFC), Robert Wilson (UMD/NASA GSFC)

  (Monday, January 5, 2:10–2:20 p.m. MT; Phoenix Convention Center, 228 B)

  The Nancy Grace Roman Space Telescope's Galactic Bulge Time-Domain Survey (GBTDS) is estimated to discover tens of thousands of transiting exoplanets. A primary challenge for this endeavor is achieving the high-precision photometry required for transit detection in the densest stellar fields of our Galaxy. To address this, the Transits in the Roman Exoplanet Survey (TRExS) working group has developed an end-to-end pipeline that simulate Roman GBTDS imagery, extract photometric time series, search and vet transiting exoplanet candidates. We utilize the Roman IMage and TIMe-series SIMulator to generate realistic data products that mirror the GBTDS observing strategy. Our initial simulation of a single 70-day season using the main filter F146 and the two secondary filters F087 and F213 produced a 1.8 TB dataset containing nearly five million sources. This includes 53,000 systems with transiting planets, 15,000 eclipsing binaries, and 128,000 other variables. To manage this data volume, we developed a stack of Python packages that extract time series from small cutouts of the original images. The photometric extraction implements the Linearized Field Photometry (LFD) method (Figure 1). This technique models the effective Point Spread Function (PSF) and performs a simultaneous linear fit to the fluxes of all sources and the sky background, making it exceptionally well-suited for de-blending light in crowded fields. We have successfully applied this pipeline to the first realization of our simulations, extracting high-quality light curves and quantifying the photometric precision as a function of magnitude. We demonstrate significant improvement in performance over successive versions of the extraction algorithm, with our latest results approaching the theoretical photometric precision limits of the simulation. We also evaluated the computational efficiency of our pipeline and estimated the computing power necessary to run the light curve extraction on the GBTDS season data. The software packages developed by the TRExS team are publicly documented and available, providing a critical resource for community preparedness. This work represents a key development step of the data analysis strategies that will be essential for realizing the full potential of Roman's exoplanet transit survey.

• Twinkle Twinkle Little Star, Roman Sees Where You Are: Predicting Exoplanet Transit Yields with the Nancy Grace Roman Space Telescope in the Rosette Nebula - Ritvik Sai Narayan (U. Wisconsin-Madison) et al.

  (Monday, January 5, 2:20–2:30 p.m. MT; Phoenix Convention Center, 228 B)

  Star-forming regions (SFRs) are dynamic environments where stars, planets, and moons take shape, yet the early evolution of these celestial bodies remains poorly understood. The Nancy Grace Roman Space Telescope (Roman) presents an unprecedented opportunity to study these young systems by detecting transiting exoplanets and faint stellar companions that are otherwise obscured by interstellar dust. We present predicted exoplanet transit yields for a month-long survey of the Rosette Nebula, a 10 Myr SFR with a dense and diverse stellar population. With Gaia DR3 astrometry, we use clustering algorithms and comoving searches to determine memberships and constrain the (sub)stellar population across the Roman/WFI footprint. Synthetic photometry from evolutionary models is propagated through the Roman Exposure Time Calculator to estimate signal-to-noise in the F146 broadband filter. Finally, we couple these estimates to analytic transit models, requiring a 7-sigma detection threshold for companions, and evaluate yields through Monte Carlo injection-recovery simulations. These detections would substantially expand the current sample of exoplanets younger than 20 Myr, probing an age regime where planetary radii remain inflated and the stability of close-in orbits is uncertain. This survey offers a path to constrain early planetary evolution and establish prime targets for the James Webb Space Telescope, Vera Rubin Observatory, and the Habitable Worlds Observatory.

• Observing the Alpha Cen Ab Planet Candidate Using the Roman Space Telescope Coronagraph - Eduardo Bendek (NASA Ames Research Center) et al.

  (Monday, January 5, 2:30–2:40 p.m. MT; Phoenix Convention Center, 228 B)

  The Roman Space Telescope Coronagraph offers a unique opportunity to observe our nearest solar twin, Alpha Centauri A, and characterize the habitable-zone gas giant candidate, Alpha Cen Ab. The candidate uniquely stands out among all imaged exoplanets to date as the one most similar in temperature, age and location to the planets in our own Solar System. Roman CGI offers the tantalizing opportunity to observe the candidate—determining its radius, temperature, and albedo—and to constrain its orbit. Observing Alpha Cen Ab with Roman would make it the first exoplanet to be imaged in both thermal emission and reflected light and would motivate an exciting search for habitable exomoons with the upcoming ELTs and HWO. In addition, this candidate will inform the planet formation history and current dynamics of the Alpha Centauri AB system, including potentially habitable planets around both stars. In this talk, we describe our plan to observe this target using the Roman CGI, including the timing strategy to minimize contrast and avoid background objects. We also describe the key technical insights about coronagraph performance that we aim to gain, such as measuring companion leakage intensity, evaluating the impact of the large stellar diameter, and assessing CGI performance on very bright targets. In subsequent observations, we aim to demonstrate Multi-Star Wavefront Control (MSWC) on-sky, observing Alpha Cen A using the Wide FoV Shaped Pupil MSWC contributed mode in the Roman CGI. The insights from these technology demonstrations are crucial preparation for the planned HWO mission.

• Roman Space Telescope Sonifications: Building Excitement for the Future of Time-Domain Astrophysics - Brandon Lawton (STScI) et al.

  (Monday, January 5, 3:00–3:10 p.m. MT; Phoenix Convention Center, 227 B)

  On behalf of NASA, the Office of Public Outreach at the Space Telescope Science Institute works with our Roman Space Telescope partners to develop media and public outreach products that share the science that will be enabled by Roman’s Wide Field Instrument (WFI) surveys. In this talk, we present how we are using visualizations paired with sonifications to excite the media and public about the future of Roman’s time-domain astrophysics studies. We will share examples from recent Roman science articles and cover the best practices we follow, lessons learned, and initial evaluation results. NASA’s Nancy Grace Roman Space Telescope is NASA’s next flagship astrophysics observatory and is scheduled to launch by May 2027. Roman will advance our understanding of the cosmos through large surveys of the universe with its WFI and provide a technology demonstration of a next-generation coronagraph. Via Roman’s WFI, the observatory is designed to survey the sky 1,000 times faster than Hubble with comparable image resolution in the near-infrared. Roman’s stability and speed will enable opportunities to explore the dynamic universe from our nearby solar system to the edge of the observable universe. The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA's Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems, Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.

• Taming the Roman data deluge: an adaptive HEALPix strategy for galactic and extragalactic stellar surveys - Adrien Thob (U. Pennsylvania) et al.

  (Tuesday, January 6, 11:00–11:10 a.m. MT; Phoenix Convention Center, 228 B)

  The Nancy Grace Roman Space Telescope will revolutionize resolved stellar astrophysics through both the upcoming Galactic Plane Survey (GPS) and the anticipated Roman Infrared Nearby Galaxy Survey (RINGS). These ambitious programs face a common challenge: managing billions of stellar sources with highly non-uniform spatial distributions. Managing and analyzing this data requires a move beyond simple, fixed-resolution sky tessellations. In this talk, we demonstrate how the Multi-Order Coverage (MOC) map scheme - a hierarchical HEALPix-based structure - of the IVOA (International Virtual Observatory Alliance) provides an elegant and efficient solution. This approach dynamically adapts the HEALPix tessellation level to the underlying stellar density, creating a sparse, hierarchical data structure. We have integrated the MOC standard into our py-ananke pipeline, a framework for generating synthetic star catalogs from cosmological simulations. By creating realistic mock data, we demonstrate its efficacy across both major survey domains. For RINGS targets (M83, M51, Cen A), the MOC map uses high-resolution pixels in dense bulges and spiral arms, medium-resolution pixels to resolve halo structures like streams and satellites, and large pixels in the diffuse stellar halo background. For the Roman Galactic Plane Survey (GPS), which will for the first time penetrate the deep, highly extincted layers of the Galactic disk, the scheme automatically adapts to the extreme and variable crowding, enabling efficient data structuring in regions previously inaccessible to detailed stellar studies. This strategy offers critical advantages over fixed-resolution tessellations, leading to significant reductions in file counts and enabling highly efficient, targeted spatial queries. This approach allows an analyst to seamlessly navigate from a full-galaxy overview to the intricate details of a single stellar stream. We showcase how this adaptive structure streamlines analysis workflows and discuss its readiness for integration with cloud-based platforms like the Roman Research Nexus. By providing a scalable, efficient data structure for Roman's diverse stellar surveys, this work prepares the community to maximize the scientific return from its upcoming data deluge.

• Weak lensing with The Nancy Grace Roman Space Telescope: Challenges and wavelength-dependent systematics - Federico Berlfein (Carnegie Mellon U.)

  (Thursday, January 8, 10:50–11:00 a.m. MT; Phoenix Convention Center, 228 B)

  The Nancy Grace Roman Space Telescope High-Latitude Imaging Survey will deliver unprecedented wide-field, high-resolution, near-infrared imaging of roughly a billion galaxies that will transform our understanding of dark energy, dark matter, and the growth of cosmic structure. Among its core science goals is the precise measurement of weak gravitational lensing to probe the distribution of matter across cosmic time. These measurements manifest as the correlated distortions, or shear, of the shapes of distant galaxies. As we become dominated by systematics rather than statistics, control and understanding of sources of systematic errors will be key for accurate shear measurement. In particular, accurate estimation of the Point Spread Function (PSF) is crucial for shear measurement and poses one of the biggest challenges for Roman weak lensing. One important source of systematic error will come from the wavelength dependence of the PSF, which can introduce non-negligible biases that impact shear inference. Differences between the spectral energy distributions (SEDs) of stars, used to model the PSF, and galaxies, used to measure shear, can lead to chromatic biases that systematically distort inferred lensing signals. We quantify these effects for Roman using image simulations, and find that these biases exceed the mission’s tolerance limits. In response, we develop a novel mitigation scheme to directly correct for such biases at the PSF-level and demonstrate that first-order corrections to the PSF reduce biases to within survey requirements. We then test our methods under more realistic survey conditions and evaluate the dependence of our results to different survey configurations. Although developed in the context of Roman, these techniques are broadly applicable to other current and future surveys—such as Euclid and LSST—where wavelength-dependent PSF effects can limit cosmological precision. This work demonstrates a practical path toward meeting Roman’s stringent weak-lensing requirements and enabling its full cosmological potential.

• A Precursor Survey of the Roman Galactic Bulge Time Domain Fields - Sean Terry (U. Maryland) et al.

  (Thursday, January 8, 10:50–11:10 a.m. MT; Phoenix Convention Center, 232 A)

  I will present a coordinated parallel HST imaging survey of the upcoming Roman Galactic Bulge Time Domain Survey (RGBTDS) field. Precursor imaging of this area with HST several years before the start of the Roman Galactic Exoplanet Survey (RGES) will greatly strengthen Roman's ability to characterize a majority of detected exoplanet systems, as well as provide a rich and wide-field archive for use as a Legacy dataset toward the Galactic bulge for the broader community. The campaign here will secure HST's lasting impact on the high-precision study of stellar populations, dynamics, exoplanet systems, interstellar extinction, metallicities, cluster associations, and many more toward the center of the Galaxy. This HST survey will complement what will effectively be one of the deepest exposures ever taken of the sky; the RGBTDS.

• Simulating Luminous Red Giants for the Roman GBTDS - Trevor Weiss (CSU Long Beach) et al.

  (Thursday, January 8, 2:30–2:40 p.m. MT; Phoenix Convention Center, 228 B)

  The Nancy Grace Roman Space Telescope is anticipated to take infrared images of unprecedented quality that will improve our understanding of exoplanet populations and of extragalactic astronomy. In addition to its core microlensing and cosmology goals, Roman’s Galactic Bulge Time-Domain Survey (GBTDS) will open new opportunities for asteroseismology in the Galactic bulge, which will play a central role in understanding the formation of the bulge and characterizing the stellar populations near the Galactic center. Recent work has predicted ~310,000 red clump and red giant asteroseismic detections during the high-cadence season of Roman’s 5-year mission plan. We expand that work here by considering the impact of the full GBTDS observing strategy, including low-cadence seasons, and also by simulating the most luminous red giants (𝞶max < 3) available to Roman. The impact of the variable observing cadence, including seasonal gaps, on the spectral window function can be mitigated, with the resulting detections increasing expected yields compared to prior forecasts by ~10%. Including luminous red giants with 𝞶max < 3 also introduces a younger stellar population in our stellar population model and extends the reach of Roman far beyond the Galactic center. We show that Roman will therefore populate stellar distances for the Galactic plane region behind the bulge, which has been so far inaccessible to time-series analysis.

 

iPoster Sessions

• Count Rate Dependent Nonlinearity Calibration for the Roman Space Telescope - Lindsay Koo (Columbia U.) et al.

  (Monday, January 5, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  Through observations of Type Ia supernovae and weak gravitational lensing, the Nancy Grace Roman Space Telescope will help us explore the exact nature of dark energy. Roman’s science goals depend on precise corrections of various systematics exhibited by the 18 H4RG-10 detectors that constitute its Wide Field Instrument (WFI). One effect, count rate dependent nonlinearity (CRNL), is especially important to constrain for measuring these cosmological probes, particularly supernovae. CRNL is a flux-dependent systematic that results in the underestimation of signals from faint sources. By modeling the Lamp On Lamp Off (LOLO) testing procedure that the WFI’s Relative Calibration System (RCS) will conduct in space, we are combining simulations with ground test data to characterize the impact of CRNL, design a commissioning plan for when Roman is in orbit, and thus aid in mitigating systematic biases throughout its mission.

• Detecting exoplanetary rings with Roman CGI reflected light phase curve observations - Elizabeth Lane (U. Michigan) et al.

  (Monday, January 5, 5:30–6:30 p.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The Nancy Grace Roman Space Telescope’s Coronagraphic Instrument (CGI) will provide the first opportunity to directly detect mature giant exoplanets in reflected light. However, such detections are expected to be challenging, as most known radial velocity planets lie near the limit of CGI’s sensitivity. In contrast, exorings of these planets, analogous to Saturn’s ring system, are likely to be much more accessible. Our modeling shows that rings can outshine their host planets by one to two orders of magnitude or more in many cases, making them easier to detect than the planets themselves. These signals, however, complicate the interpretation of reflected-light measurements, since the contributions from the planet and rings will be blended and the presence of rings will not be known a priori. As a potential method to disentangle these signals, we model reflected-light phase curves of ringed and unringed planets. Ring systems produce a distinctive signature, with four extrema per orbital phase curve instead of the two expected for unringed planets, enabling robust confirmation of rings with multi-epoch CGI observations. As a demonstration, we simulated CGI observations of Eps Eri b (3.5 AU, 1 Mjup) with a Saturn-like ring system, showing that such a configuration would be detectable with CGI. These results suggest that the brightness of rings may expand the pool of viable CGI targets to include planets previously thought to be beyond its reach. We conclude that CGI is poised to provide the first observational constraints on the prevalence of Saturn-like rings around giant exoplanets.

• Vetting Reference Stars for the Roman Space Telescope - Isabel Lockhart (DePaul U.) et al.

  (Monday, January 5, 5:30–6:30 p.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The Nancy Grace Roman Space Telescope (RST) Coronagraph Instrument will be the first space-based instrument to demonstrate technologies that could enable the direct imaging of habitable exoplanets. The coronagraph creates destructive interference with the light of a star, suppressing its starlight and forming a high-contrast region—‘digging a dark hole’. This suppression could allow light reflected by a planet to be distinguished from the light of the host star. During observations, the coronagraph must be continually calibrated to maintain the dark hole by alternating observations between science targets and bright reference stars. Reference stars must meet several stringent criteria: they must have a visual magnitude brighter than 3, have a resolved diameter less than 2 mas, have a sun pitch angle that is within a few degrees of the science target, and they must not be part of a binary system. These constraints result in a limited sample of roughly 40 potential reference targets. To further validate their suitability, archival observations of each star are examined. I investigate a subset of these candidate stars, examining whether a star is part of a binary system. Candidate star data is retrieved through the Gemini Observatory Archive at NSF NOIRLab, specifically selecting images captured by the Near Infrared Imager (NIRI) at the Gemini North telescope. Using both DRAGONS (Data Reduction for Astronomy from Gemini Observatory North and South) and pyKLIP, data reduction and analysis techniques are applied to assess whether a potential reference star may be part of a binary system. We quantify our dataset’s sensitivity to binary stellar companions by generating contrast curves to characterize how detection limits vary with separation from each star. If a star appears suitable following the analysis of Gemini Observatory archival data, it remains under consideration as a potential reference star for the Roman Space Telescope. This vetting process supports the preparatory efforts required for accurate coronagraph calibration, helping to ensure successful observations by the RST.

• The Nancy Grace Roman Space Telescope Wide Field Instrument Bright Star Saturation Test - Dana Louie (CUA/NASA GSFC) et al.

  (Wednesday, January 7, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The Wide Field Instrument (WFI) is the primary science instrument for the Nancy Grace Roman Space Telescope (Roman), NASA’s next Astrophysics Flagship mission. The WFI focal plane array is comprised of 18 Teledyne H4RG-10 Sensor Chip Assemblies (SCAs), which together produce a field of view ~100 times that of Hubble’s WFC3 IR camera, while offering better sensitivity and similar spatial resolution. Roman will conduct 3 Core Community Surveys (CCSs) to investigate outstanding questions regarding the expansion history of the universe and growth of structure, as well as exoplanet demographics. Additionally, the community-designed General Astrophysics Survey of the Galactic Plane was approved for Early Definition. Further surveys will be pursued through a General Astrophysics program. The Roman Cycle 1 Call for Proposals will be released in Fall 2025, and will fund investigators to propose both archival research and new observations. During WFI’s second Thermal Vacuum test campaign (TVAC2) in Spring 2024, we conducted a test program to examine the effects of observing bright stars during Roman’s CCSs. The Galactic Bulge Time Domain Survey (GBTDS) field is expected to contain ~1500 stars brighter than 10th mag and ~40 stars brighter than 7th mag. The High Latitude Wide Area Survey (HLWAS) will include sources as bright as 3rd or 4th mag. These stars will go into deep saturation in typical exposures. Our Saturated Star Test program simulated 9 stellar PSFs ranging from approximately 4th to 18th mag at 9 well separated locations in a 3 x 3 grid on two SCAs in the focal plane. We collected data for typical exposure sequences planned for the GBTDS survey to quantify and characterize the effects of saturation. We also performed sequences of dark exposures after illumination to measure persistence. Here, we present the details of the test program and our analysis of the saturated PSF data and highlight our key findings regarding saturation and persistence.

• DeepDISC: Deep Learning-Driven Deblending Using Overlapping Roman and Rubin LSST Data - Yaswant Sai Ejjagiri (U. Illinois Urbana-Champaign) et al.

  (Wednesday, January 7, 5:30–6:30 p.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will revolutionize cosmology through remarkable statistical power, yet unrecognized blends in ground-based surveys introduce a major source of systematic errors. DeepDISC, our deep learning source detector/deblender/classifier, addresses this critical challenge by synergizing LSST data with high-resolution imaging from the Nancy Grace Roman Space Telescope (Roman). With Roman's capability to survey the sky 1000 times faster than Hubble, while maintaining similar sensitivity and resolution, it presents a unique opportunity to enhance our understanding of galaxy structures and distributions. By leveraging Roman's higher resolution space-based imaging in combination with LSST data, we aim to significantly improve the recognition of blended sources compared to traditional detection algorithms. Our model will be trained on simulated Rubin images and input catalogs as a baseline, with the addition of Roman imaging data during training and testing phases. This approach will allow us to quantify the impact of Roman's higher resolution on blend recognition, source classification accuracy, and overall catalog completeness and purity. By comparing DeepDISC's performance against truth catalogs and science pipeline results from both Roman and LSST, we will demonstrate how this synergy between space-based and ground-based observations can optimize scientific output and directly address systematic uncertainties that impact dark energy constraints from LSST, particularly through probes like weak lensing. Preliminary tests show a 10% improvement in detection completeness-achieved exclusively through joint Roman-LSST training-leading to a better mapping of the universe that will be crucial for downstream cosmological analyses. This work highlights a paradigm for Rubin-era discovery: integrating multi-survey data with machine learning driven analysis to overcome fundamental limits in ground-based observations.

• Probing Matter Scaling Beyond ΛCDM with Roman Simulations - Hussain Ahmed Khan, Benjamin Rose, (Baylor U.)

  (Wednesday, January 7, 5:30–6:30 p.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The ΛCDM model has had remarkable success in explaining large scale cosmological observations. But the phenomenological nature of our assumptions about the dark sector motivates us to investigate any possible discrepancies with them. For instance, the standard ΛCDM model assumes that the matter density scales as the inverse cubic power of the scale factor, that is, ρm(a) ∼ a−3 or equivalently ρm(z) ∼ (1 + z)3. We will investigate a potential deviation from cubic behavior, such as ρm(z) ∼ (1 + z)3+ϵ. The parameter ϵ will encode the said deviation. These deviations are enhanced and noticeable at higher redshifts, making the Nancy Grace Roman Space Telescope (z ∼ 2) the ideal probe to help us investigate them. Using SNANA, we simulate Roman-like SN Ia observations, treating ΛCDM (ϵ = 0) as our baseline model, and testing a few alternative scenarios (ϵ ≠ 0). Through these simulations, we will obtain a better constraint on ϵ, and any departure from the cubic nature of matter scaling will hint at a beyond ΛCDM universe.

• The Roman Research Nexus: Enabling Low-Barrier Access and Collaboration in the Cloud - Tyler Desjardins (STScI) et al.

  (Thursday, January 8, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  Science platforms offer a unified user experience for discovering, exploring, accessing, and analyzing data. As astronomy enters an era of petabyte-scale data, cloud-based science platforms will become essential interfaces between researchers and observational data. The Nancy Grace Roman Space Telescope (Roman) is NASA's next flagship astrophysics mission, and with its wide field of view and unprecedented survey speed, it is anticipated to generate an estimated 30 petabytes (PB) of data during its five-year primary mission. The Space Telescope Science Institute (Roman Science Operations Center) has developed the Roman Research Nexus, a user-friendly science platform focused on low-barrier access and collaboration to help the community prepare for Roman’s scientific discoveries. In this poster, we present an overview of the Roman Research Nexus platform, including simulated datasets, Jupyter notebook tutorials, science workflows, and other tools for the community to prepare for and engage with Roman. These resources demonstrate the Nexus's capabilities and ease of use, helping to prepare users for a new era in observational astronomy.

• Simulating Roman Galactic Bulge Time Domain Survey Microlensing Data - Alina Hussain (Illinois Inst. Technology) et al.

  (Thursday, January 8, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  With the launch of the Nancy Grace Roman Space Telescope (Roman) in May of 2027, the Galactic Bulge Time Domain Survey (GBTDS) will begin observations of the Milky Way’s galactic bulge. Given the parameters of the survey (which include regular observations in the wide F146 filter and occasional observations in the narrower F087 and F213 filters), we expect to see increased observations of microlensing events. To get a better idea of what microlensing events will look like through Roman, we simulate the data of a Milky Way microlensing survey using PopSyCLE (Population Synthesis for Compact-Object Lensing Events) to plot lightcurves and astrometric data. The Roman data is simulated by considering noise, error, and when Roman will be actively observing the bulge using microlensing models generated by BAGLE (Bayesian Analysis of Gravitational Lensing Events). Analysis is done on the population to determine what types of events and how many events will be visible using Roman. By performing straight-line chi-squared metrics and general outlier calculations, we determine events that are photometrically and/or astrometrically significant and will be theoretically visible to Roman. Future work includes characterizing source and lens masses using the simulated lightcurves. We are especially interested in simulated microlensing events involving black hole lenses.

• Realistic Grism Simulations for the Nancy Grace Roman Space Telescope - Keith Buckholz (Yale U.) et al.

  (Thursday, January 8, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  I will describe the current state of Grism Simulations for the Nancy Grace Roman Space Telescope Galaxy Redshift Survey Project Infrastructure Team (Roman GRS PIT), as well as active efforts to further improve them. The GRS PIT's grism simulation software adapts the "grizli" python package, and aims to add in realistic instrumental effects and noise (e.g. wavelength-dependent PSF and Poisson Noise), realistic galaxy distributions (e.g. varying morphology, line fluxes, and magnitudes), and realistic star distributions (e.g. stellar type and magnitude). Users running their own simulations write a single yaml file and call the pipeline script, which generates and saves grism images, direct/references images, and other helper files. The pipeline is designed to be flexible to allow for testing of a range of parameters, e.g. different roll angles and dithers, variations in grism dispersion solutions, inclusion of various levels of instrumental effects/noise, etc. This code is in active development on the Roman GRS PIT Github and will be released at a future date.

• An Update from the Roman Space Telescope’s Science Operations Center <1 Year from Launch - William Schultz (STScI) et al.

  (Thursday, January 8, 9:00–10:00 a.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  The Nancy Grace Roman Space Telescope, NASA’s next flagship astrophysics mission, is scheduled for launch in fall 2026. Roman’s Wide Field Instrument (WFI) will deliver Hubble-like resolution across a 0.28 deg² field of view, featuring eight imaging filters spanning 0.48–2.3 μm and wide-field slitless spectroscopy via a grism and prism. The mission also includes a Coronagraph technology demonstration to achieve high-contrast imaging of Jupiter-like exoplanets around Sun-like stars. The Science Operations Center (SOC) at the Space Telescope Science Institute in Baltimore, MD, will manage the planning and scheduling of both WFI and Coronagraph observations and perform low-level calibration of all WFI data. The SOC will also perform high-level processing of most WFI imaging data and archive all the WFI and Coronagraph data, in collaboration with the Science Support Center at IPAC, which will perform all additional processing (high-level WFI spectroscopic data, a subset of WFI imaging data, and the Coronagraph data). As a resource to the community, the SOC will host a cloud-based science platform, the Roman Research Nexus, offering a computing environment for interactive data analysis, proposal development tools, and simulation capabilities for the community. We present an overview of SOC services and highlight recent progress, updates, and key milestones in preparation for the Cycle 1 Call for Proposals and the Roman launch.

• Lens flux analysis of microlensing events with Roman space telescope - Himanshu Verma (LSU) et al.

  (Thursday, January 8, 1:00–2:00 p.m. MT; Phoenix Convention Center, Exhibit Hall B/C/D)

  This study aims to constrain the lens flux contribution and relative proper motion using 2D imaging of the source-lens system that will be obtained by the Roman Space Telescope at a later/earlier epoch following the microlensing event. Building upon the pioneering work of Bennet, Anderson, and Gaudi 2007, we develop a rigorous 2D Fisher information matrix analysis that extends beyond their 1D approximation and incorporates realistic observational effects including background noise, oversampling factor, and finite image cutout size. Our methodology combines two complementary techniques: Image Elongation, where the unresolved source-lens system exhibits PSF elongation proportional to their angular separation, and Color-Dependent Centroid Shift, where differential source-lens colors produce wavelength-dependent astrometric shifts. Using realistic Roman PSFs simulation, we characterize systematic uncertainties and derive mission-specific fudge factors. We then apply this framework to simulated Roman planetary microlensing events, which enables Einstein angular radius measurements of the host star across planetary masses from 0.1 to $10^4$ M$_\oplus$.