A glint in the eye: Photographic plate archive searches for non-terrestrial artefacts

Villarroel, Beatriz; Mattsson, Lars; Hichem, Guergouri,; Solano, E.; Geier, S.; Onyeuwaoma, Nnaemeka D.; Ward, M. J.

doi:10.1016/j.actaastro.2022.01.039

Cited by 10 publications

(7 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Human satellites at the geostationary orbit could be argued as a possibility to explain the glints found in POSS I images, glints that could be caused by reflections of the Sun. This glints would be bright, have a PSF-like shape and short duration (Villarroel et al 2022). However, we remind the reader that the launch of the first satellite happened in 1957, when most of the POSS I survey was already completed.…”

Section: Discussionmentioning

confidence: 95%

Discovering vanishing objects in POSS I red images using the Virtual Observatory

Solano,

Villarroel,

Rodrigo

2022

Preprint

View full text Add to dashboard Cite

In this paper we report a search for vanishing sources in POSS I red images using Virtual Observatory archives, tools and services. The search, conducted in the framework of the VASCO project, aims at finding POSS I (red) sources not present in recent catalogues like Pan-STARRS DR2 (limiting magnitude 𝑟=21.4) or Gaia EDR3 (limiting magnitude 𝐺=21). We found 298 165 sources visible only in POSS I plates, out of which 288 770 had a crossmatch within 5 arcsec in other archives (mainly in the infrared), 189 were classified as asteroids, 35 as variable objects, 3 592 as artefacts from the comparison to a second digitization (Supercosmos), and 180 as high proper motion objects without information on proper motion in Gaia EDR3. The remaining unidentified transients (5 399) as well as the 172 163 sources not detected in the optical but identified in the infrared regime are available from a Virtual Observatory compliant archive and can be of interest in searches for strong M-dwarf flares, high-redshift supernovae, asteroids, or other categories of unidentified red transients. No point sources were detected by both POSS-I and POSS-II before vanishing, setting the rate of failed supernovae in the Milky Way during 70 years to less than one in one billion.

show abstract

Section: Discussionmentioning

confidence: 95%

Discovering vanishing objects in POSS I red images using the Virtual Observatory

Solano,

Villarroel,

Rodrigo

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…However, another example of technosignatures merits consideration, to wit, the possibility of discovering physical artifacts of extraterrestrial technology within the solar system Bradbury et al 2011;Haqq-Misra & Kopparapu 2012;Lacki 2019;Shostak 2020). This notion was broached by Bracewell (1960) in a well-known publication, after which a handful of searches for artifacts have been conducted in geosynchronous Earth orbits (Villarroel et al 2022a(Villarroel et al , 2022b, at the Earth-Moon Lagrange points (Freitas & Valdes 1980;Valdes & Freitas 1983;Freitas & Valdes 1985), and on the lunar surface (Arkhipov 1995;Lesnikowski et al 2020). Artifact searches could potentially be initiated for objects in proximity to Earth (Steel 1995;Arkhipov 1996;Benford 2021;Loeb & Laukien 2022); co-orbital objects (Benford 2019); or objects located on the surfaces of planets and moons (Carlotto & Stein 1990;Arkhipov et al 1996;Davies & Wagner 2013).…”

Section: Artifact Technosignaturesmentioning

confidence: 99%

Technosignatures: Frameworks for Their Assessment

Lingam

Haqq-Misra

Wright

et al. 2023

ApJ

View full text Add to dashboard Cite

In view of the promising advancements in technosignature science, the question of what constitutes a robust technosignature is rendered crucial. In this paper, we first delineate a Bayesian framework for ascertaining the reliability of potential technosignatures by availing ourselves of recent cognate research in biosignatures. We demonstrate that ideal technosignatures must not only have low risk of stemming from false positives but also evince sufficiently high prior probability of existence. Given the inherent difficulties with estimating the latter, we highlight a few alternative metrics drawn from diagnostic testing such as the Youden index that bypass the requirement of explicitly calculating the prior. We apply the models (Bayesian or otherwise) to a select few technosignature candidates and show that artificial electromagnetic signals, chlorofluorocarbons, and artifacts perform well on this front. While these results may be along expected lines, we suggest that identifying and developing suitable approaches to further evaluate technosignature candidates is of considerable importance.

show abstract

“…No optical pulses were detected. However, Villarroel et al 2020, 2022a, 2022b, and Solano et al (2023 have discovered simultaneous, multiple star-like transients, often in alignment, that appear in single snapshots from the Palomar Sky Survey taken in the 1950's. In one case, nine point sources appeared within half an hour within 10 arcmin on a photographic plate taken in 1950, but the sources are absent on previous and later image (Villarroel et al 2021).…”

Section: Historical Optical Setimentioning

confidence: 99%

“…Detecting unresolved broadband optical pulses must discriminate against false alarms such as glints of sunlight off satellites orbiting the Earth, strobe lights on distant aircraft, laser communication and LIDAR from orbiting satellites, and elementary particles hitting the sensor that mimic a star image (Corbett et al 2021, Nir et al 2021, Richmond et al 2020. Villarroel et al (2020Villarroel et al ( , 2021Villarroel et al ( , 2022aVillarroel et al ( , 2022b and Solano et al (2023) have discovered transients, both in alignment and clumped, in pre-Sputnik images from the Palomar Sky Survey. Work is ongoing to identify these interesting candidates.…”

Section: Introductionmentioning

confidence: 99%

“…Other searches for optical sub-second flashes were performed over a broad band of wavelengths (Horowitz et al 2001, Wright et al 2001Howard et al 2004;Stone et al 2005;Howard et al 2007, Hanna et al 2009, Abeysekara et al 2016, Villarroel et al 2020, 2022a, 2022b, Maire et al 2022, Acharyya et al 2023, Solano et al 2023. Broadband optical searches can detect flashes from both extraterrestrial technology and from the mergers of black holes and neutron stars having a wide range of masses (cf.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A search for transient, monochromatic light from the Galactic plane

Marcy

Tellis²

2023

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

The Galactic Plane was searched for transient, monochromatic light at optical and near-IR wavelengths to detect pulses shorter than 1 sec. An objective-prism Schmidt telescope of 0.28-meter aperture and a CMOS camera were used to observe 973 square degrees, with 8864 exposures of 1-sec each, within a strip 2.1 deg wide along the Galactic Plane, from Galactic longitude -4 deg to +248 deg. All exposures were analyzed for transient, monochromatic sources using a “difference image” algorithm that yielded 11 candidate sources. All 11 sources were found to be associated with either astrophysical emission-line objects or aircraft with sub-second blinking lights. Our survey “rediscovered” many Wolf-Rayet stars, M dwarf flare stars, and planetary nebulae. It also identified an aircraft, of unknown type, that apparently had a nearly monochromatic lamp and a xenon lamp. This survey would have revealed optical and near-IR pulses having a power of ∼180 GW (wavelength dependent) if emitted by a 10-meter aperture laser located 1 kiloparsec away. These non-detections of laser pulses from the Galactic Plane, including a 10-degree region toward the Galactic Centre, add to the non-detections from more than 5000 nearby stars. Indeed, all-sky surveys for emission-line objects (e.g., ionized gas, supernovae remnants, and active galactic nuclei) would have revealed lasers of a wide range of average brightness, wavelength, and cadence. The absence of beacons reveals more of a SETI desert, notably at the intensely surveyed optical and radio wavelengths.

show abstract

A glint in the eye: Photographic plate archive searches for non-terrestrial artefacts

Cited by 10 publications

References 6 publications

Discovering vanishing objects in POSS I red images using the Virtual Observatory

Discovering vanishing objects in POSS I red images using the Virtual Observatory

Technosignatures: Frameworks for Their Assessment

A search for transient, monochromatic light from the Galactic plane

Contact Info

Product

Resources

About