arXiv subjects

Sara Anderson

Publications and source records attributed to Sara Anderson.

5 recordsLinked to original sources

arXiv2026

The Hubble Advanced Spectral Product (HASP) Program

The Hubble Advanced Spectral Products (HASP) program is designed to robustly coadd Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS) spectra within the Mikulski Archive for Space Telescopes (MAST) in an automated fashion such that coadds are available for new data or archival data with updated calibrations. For each target within a visit or program, HASP employs a meticulous multi-stage filtering process to ensure data quality and creates coadded products for all central wavelengths (CENWAVEs) within specific gratings, as well as combined products using different gratings and instruments. The project also emphasizes making the code accessible to the user community for custom coaddition. As calibrations improve and new data are added to the archive, HASP products are re-created automatically so that they represent the best reduction of a given visit or program. Automated coadditions like those achieved by HASP can significantly enhance the combination of different CENWAVES, increase signal-to-noise ratios, and increase wavelength coverage. These properties make HASP a vital resource for astronomers using archival spectroscopic data from HST.

astro-ph.IM↗

arXiv2026

Overview of the New Hubble Spectroscopic Legacy Archive

The new Hubble Spectroscopic Legacy Archive (HSLA) provides coadded spectra of individual targets that have been observed with the Cosmic Origins Spectrograph (COS) and the Space Telescope Imaging Spectrograph (STIS) over their operating lifetime. HSLA uses data available in the Mikulski Archive for Space Telescopes (MAST). It automatically produces coadds whenever new data become publicly available or when there is newly recalibrated data. HSLA defines individual targets by their associated coordinates, accounting for proper motions, and uses SIMBAD, NED and the Phase II observing proposals to obtain astronomical classifications for each object. Coadded spectra are produced for each observing mode. In the case of COS far-ultraviolet observations there is one coadded spectrum for each lifetime position (LP). Additionally, a spectrum spanning the entire wavelength range covered by the observations is produced by abutting the spectra from a selection of individual modes. For each individual target, HSLA also provides a human-readable metadata file with key information that can be used in searches or for further exploration of the data. The HSLA project also makes the code used for coadding spectra publicly available along with several other tools (using Jupyter notebooks) for custom coaddition required in special cases. In this report we will describe the main components of HSLA and provide a brief description of how the data and metadata can be accessed.

astro-ph.IM↗

arXiv2026

Census Dual Graphs: Properties and Random Graph Models

In the computational study of political redistricting, feasibility necessitates the use of a discretization of regions such as states, counties, and towns. In nearly all cases, researchers use a dual graph, whose vertices represent small geographic units (such as census blocks or voting precincts) with edges for geographic adjacency. A political districting plan is a partition of this graph into connected subgraphs that satisfy certain additional properties, such as connectedness, compactness, and equal population. Though dual graphs underlie nearly all computational studies of political redistricting, little is known about their properties. This is a unique graph class that has been described colloquially as `nearly planar, nearly triangulated,' but thus far there has been a lack of evidence to support this description. In this paper we study dual graphs for counties, census tracts, and census block groups across the United States in order to understand and characterize this graph class. We also consider several random graph models (most based on randomly perturbing grids or Delauney triangulations of random point sets), and determine which most closely resemble dual graphs under key metrics. This work lays an initial foundation for understanding and modeling the properties of dual graphs; this will provide invaluable insight to researchers developing algorithms using them to understand, assess, and quantify the properties of political districting plans.

cs.DM↗

arXiv2024

Disconnected Cliques in Derangement Graphs

We obtain a correspondence between pairs of $N\times N$ orthogonal Latin squares and pairs of disconnected maximal cliques in the derangement graph with $N$ symbols. Motivated by methods in spectral clustering, we also obtain modular conditions on fixed point counts of certain permutation sums for the existence of collections of mutually disconnected maximal cliques. We use these modular obstructions to analyze the structure of maximal cliques in $X_N$ for small values of $N$. We culminate in a short, elementary proof of the nonexistence of a solution to Euler's $36$ Officer Problem.

math.CO↗

arXiv2022

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.

astro-ph.IM↗