The astronomers were unable to recover either of the candidates at Sloan r < 23 magnitude and, after careful analysis of both visibility and detectability issues, this null result is interpreted as evidence that either both candidates are actually much fainter than predicted, or that they are false positives.
Null results can be important, and finding nothing at all when something was expected or predicted can lead to improved algorithms and software. This is particularly important when the current technology is being pushed to its limits.
The data from the mini-survey performed using PF-QHY were processed and analysed using the automatic software pipeline UMBRELLA, and the results visualised using the web-based WEBRELLA application developed for EURONEAR by Malin Stănescu, with both software applications running on the EURONEAR server at the University of Craiova, Romania. The computer-generated results were validated by independent, manual analyses. The negative detections were checked using the Astrometrica software tool, and were also confirmed by eye. Both machine- and human-powered data processing and analyses produced fully consistent results.
A null result was not completely unexpected as Rice and Laughlin had warned that some of their candidate detections could originate in unmodelled systematic errors. Successes and failures in recovering candidates using ground-based telescopes can therefore be used to improve the "shift-stacking" algorithm and produce better automated software that may lead to robust detections when the entire TESS dataset is processed.
About the William Herschel Telescope
Based on observations made with the Willliam Herschel Telescope (WHT) operated on the island of La Palma by the Isaac Newton Group of Telescopes (ING) in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC). The ING is funded by the Science and Technology Facilities Council (STFC-UKRI) of the United Kingdom, the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) of the Netherlands, and the IAC in Spain. IAC's contribution to ING is funded by the Spanish Ministry of Science, Innovation and Universities.
Carlos de la Fuente Marcos, Raúl de la Fuente Marcos, Ovidiu Vaduvescu & Malin Stănescu, 2022,"Distant trans-Neptunian object candidates from NASA's TESS mission scrutinized: fainter than predicted or false positives?", MNRAS, 513, L78. Paper: DOI.
Malena Rice & Gregory Laughlin, 2020,
"Exploring Trans-Neptunian Space with TESS: A Targeted Shift-stacking Search for Planet Nine and Distant TNOs in the Galactic Plane", PSJ, 1, 81. Paper: DOI.
Discovery of 2018 VG18: MPEC 2018-Y14, 17 December 2018.
Discovery of 2018 AG37: MPEC 2021-C187, 10 February 2021.
Carlos de la Fuente Marcos (Universidad Complutense de Madrid, Spain)
Javier Méndez (ING PR Officer)
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