The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a “Missing Star”

Abstract

In this paper we report the current status of a new research program. The primary goal of the "Vanishing & Appearing Sources during a Century of Observations" (VASCO) project is to search for vanishing and appearing sources using existing survey data to find examples of exceptional astrophysical transients. The implications of finding such objects extend from traditional astrophysics fields to the more exotic searches for evidence of technologically advanced civilizations. In this first paper we present new, deeper observations of the tentative candidate discovered by Villarroel et al. (2016). We then perform the first searches for vanishing objects throughout the sky by comparing 600 million objects from the US Naval Observatory Catalogue (USNO) B1.0 down to a limiting magnitude of ∼ 20 − 21 with the recent Pan-STARRS Data Release-1 (DR1) with a limiting magnitude of ∼ 23.4. We find about 150,000 preliminary candidates that do not have any Pan-STARRS counterpart within a 30 arcsec radius. We show that these objects are redder and have larger proper motions than typical USNO objects. We visually examine the images for a subset of about 24,000 candidates, superseding the 2016 study with a sample ten times larger. We find about ∼ 100 point sources visible in only one epoch in the red band of the USNO which may be of interest in searches for strong M dwarf flares, high-redshift supernovae or other catagories of unidentified red transients.

A Search for Analogs of KIC 8462852 (Boyajian’s Star): A Proof of Concept and the First Candidates

“…If this is actually possible, it could lead to a clump of stars with inhabited planets over an extended region of space. Villarroel et al (2020), in describing a search for stars exhibiting unusual photometric behavior, remarked "if a region of the sky has a tendency to produce an unexpectedly large fraction of candidates relative to the background, this region or "hot spot" may deserve some extra attention [with regard to SETI]". In a subsequent paper, Villarroel et al (2021) discussed a group of nine apparent transcients scattered over a region about ten arc minutes across on a plate from the Palomar Observatory Sky Survey.…”

SETI: the argument for artefact searches

“…Perhaps the most general artefact search to date has been a comparison of imagery compiled in early sky surveys (the US Naval Observatory Catalog B1.0) with more recent Pan-STARRS observations, looking for objects that either appear or disappear (Villarroel et al, 2019). While many candidates for such objects were found, it is not yet clear whether any of these can be ascribed to the workings of advanced intelligence.…”

Ukrvo Spectral Photographic Archive of Variable Stars

“…The stars of R CrB type were deeply studied in various observational programs of the MAO NASU, see, for example, the monograph by Zhiliaev et al (1978) and papers by Začs et al (2007), Yakovina et al (2013). The R CrB stars as the longterm variables are of particular interest for the modern projects such as the VASCO (Villarroel et al 2020). 1, 24 spectral astronegatives, Gaia DR2 379224622732758528).…”