astro-ph.IM Archives

Intelligence & Language, Interstellar, SETI & Technosignatures, Status Report

The Eschatian Hypothesis

by Keith CowingDecember 15, 2025December 15, 2025

The history of astronomical discovery shows that many of the most detectable phenomena, especially detection firsts, are not typical members of their broader class, but rather rare, extreme cases with […]

Comet Interceptor Spacecraft And Instruments (ESA)

Comets and Asteroids, Interstellar, Missions & Hardware, Status Report

Intercepting Interstellar Objects

by Keith CowingDecember 11, 2025December 10, 2025

We describe how the ESA Comet Interceptor mission, which is due to launch in 2028/29 to a yet-to-be-discovered target, can provide a conceptual basis for a future mission to visit […]

Illustration of calibration levels from measured centroid in pixel space to angular relative astrometry. -- astro-ph.IM

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

System Analysis For A high-precision High-accuracy Astrometric Instrument For HWO

by Keith CowingDecember 8, 2025December 8, 2025

This study presents a comprehensive system analysis for an instrument onboard the Habitable Worlds Observatory (HWO), designed for high-precision, high-accuracy differential astrometry, with the primary scientific goal to determine the […]

Hertzsprung–Russell diagram comparing the BGM-simulated stellar population (background) with the subset of Gaia sources (superimposed in red) for which reliable effective temperatures and absolute magnitudes are available. The Gaia sample is restricted to within 1 kpc due to parallax accuracy, and most white dwarfs lack reliable temperature estimates. Utilising the BGM enables consideration of the complete breadth of stellar types captured within the bycatch population, including bright Main Sequence stars and minimal confusion between faint Main Sequence and white dwarfs. -- astro-ph.IM

Astronomy & Telescopes, SETI & Technosignatures, Status Report

Simulating The Stellar Bycatch: Constraining The Prevalence Of Extraterrestrial Transmitters Within Radio SETI Surveys

by Keith CowingNovember 26, 2025November 26, 2025

Searches for radio technosignatures place constraints on the prevalence of extraterrestrial transmitters in our Galaxy and beyond. It is important to account for the complete stellar population captured within a […]

Suppression in logarithmic units (diffraction intensity at the telescope aperture ∥f ∥ P ∥ 2 ) is shown for the HWO 60 m starshade with 16 petals at a wavelength of 500 nm, with a spatial sampling of ∆P = 2 cm, NP = 6000. The central dark shadow is masked by the telescope and produces the on-axis stellar PSF. The dark shadow must therefore be as large as the aperture. To maintain the dark shadow (contrast), the Fresnel number should remain constant f = R2 ss λz ∼ 10 − 20. This can be maintained at wavelengths outside of the band by changing the lateral flight distance of the starshade z. The dark shadow is approximately the size of the starshade in diameter (60m). -- astro-ph.IM

Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Efficient Exoplanet Imaging Simulations of the Habitable Worlds Observatory

by Keith CowingNovember 20, 2025November 20, 2025

Direct imaging simulations of starshades and other proposed mission concepts are needed to characterize planet detection performance and inform mission design trades.

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Ice Giant, Missions & Hardware, Neptune, Status Report, Uranus

Ice Giants Pre-Decadal Survey Mission Study Report

by Keith CowingNovember 20, 2025November 19, 2025

The Ice Giants Study was commissioned by NASA to take a fresh look (as of 2017) at science priorities and concepts for missions to the Uranus and Neptune systems in […]

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Intelligence & Language, Magnetic Fields, Electromagnetism, bioelectricity,, Radiation, Space Weather & Heliophysics, Status Report

The Exospace Weather Frontier

by Keith CowingNovember 17, 2025

Space weather is among the most powerful and least understood forces shaping planetary atmospheres. In our Solar System, we observe its effects directly: atmospheric escape, chemical disruption, and spectacular auroral […]

The extracted time-series stellar spectra for the +1 (left) and −1 (right) spectral orders for the transit of HAT-P-41b. The color bar denotes time from mid-transit, with the median spectrum of the time-series shown in black. --astro-ph.IM

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Analyzing Exoplanet Transits Observed with the WFC3/UVIS G280 Grism

by Keith CowingNovember 16, 2025November 15, 2025

Here we describe a Jupyter notebook demonstrating methods for the reduction and analysis of exoplanet transit observations taken with the WFC3/UVIS G280 grism.

Intelligence & Language, Interstellar, SETI & Technosignatures, Status Report

A Firefly-inspired Model For Deciphering The Alien

by Keith CowingNovember 11, 2025November 11, 2025

The Search for Extraterrestrial Intelligence (ETI) is, historically, a search for aliens like us, inspired by human centric ideas of intelligence and technology.

The four giant planets as seen by Hubble WFC3/UVIS at different near-UV wavelengths, and processed by Judy Schmidt (note - these images are not shown to scale). The Jupiter and Saturn images are constructed from F343N (red), F275W (green), and F225 (blue), whereas a lack of observations for Uranus and Neptune required us to shift to redder wavelengths: F547M (red), F467M (green), and F336W (blue) for the Ice Giants. Jupiter and Ganymede were observed 2017-02-02 at 12:16UT, Saturn was observed at 2018-06-07 at 00:06UT, Uranus on 2015-08-30 at 10:08UT, and Neptune on 2015-09-02 at 07:58UT. Strong UV absorption is visible at the poles of Jupiter and Saturn due to the nature of highaltitude aerosols and the potential link to auroral chemistry. Red vortices, such as Jupiter’s Great Red Spot and Oval BA (lower left), appear dark due to the blue-absorbing chromophore responsible for their red colours. Uranus’ bright north polar cap of aerosols, and its narrow rings, are just visible in this image. Neptune’s banding, and some bright high clouds (appearing in pink) can be seen in both northern and southern hemispheres. In addition, Saturn’s rings appear reddish due to UV absorption. Credit: NASA/ESA/CSA/Hubble/Judy Schmidt.

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Imaging & Spectroscopy, Jupiter, Neptune, Saturn, Status Report, Uranus

Exploring Giant Planet Atmospheres with Habitable Worlds Observatory

by Keith CowingOctober 22, 2025October 22, 2025

Visible and ultraviolet imaging and spectroscopy of Solar System giant planets can set the paradigm for the atmospheric, ionospheric, and magnetospheric processes shaping the diversity of giant exoplanets, brown dwarfs, […]