In 1952, Palomar Observatory captured a strange astronomical phenomenon. Three luminous sources, shining almost like ordinary stars, were observed, only to disappear within an hour. In a recent pre-publication article submitted to the MNRAS (Monthly Notices of the Royal Astronomical Society), an international team of astronomers delves into this mystery.
On a summer night on July 19, 1952, astronomers at Palomar Observatory, nestled in the California mountains, identified three luminous sources with a magnitude of approximately 15, located within 10 arc seconds of each other. These sources, absent from previous sky mappings, vanished in less than an hour. The study, led by Enrique Solano, aims to unravel this mystery by utilizing recent measurements and analyzing historical data.
Archival Investigation
The team began by exploring Palomar Observatory’s archives, where the anomalies were initially recorded. Using the first Palomar sky survey (POSS I), they were able to recover the original images taken in 1952. These images were particularly valuable as they were free from light pollution caused by satellites, making their analysis clearer and less cluttered. They also used data from several projects, including Pan-STARRS1, SuperCOSMOS Science Archive, and the NASA/IPAC Infrared Science Archive.
Eliminating Common Sources of Error
The researchers also took care to eliminate other potential explanations. They compared the light profiles with those of nearby stars to ensure they were not the result of artifacts such as cosmic rays, sensor defects, asteroids, or other moving objects.
One aspect of the analysis involved determining the shape and structure of the three luminous sources. At first glance, they appeared to have a typical circular shape, but the team wanted to be certain. They compared the profile of one of these sources to that of a nearby star to see if they were similar. The results are conclusive: the profiles closely resemble those of the surrounding stars, suggesting, as the article indicates, that they are genuine sources of light and not artifacts or errors.
“In summary, we find no evidence that the transient is anything other than a bona fide unresolved, point source of light. In particular, the profiles show no evidence of a moving source such as an aircraft, asteroid, or elementary particle, nor of a defect in the photographic plate.”
Recent observations
The researchers used the Optical System for Imaging and Low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) camera of the 10.4-meter Gran Telescopio Canarias (GTC). Using image processing techniques, they obtained images of the region where the phenomenon had been observed. The GTC is capable of detecting objects with a brightness ten times fainter than those observed in 1952.
By comparing the new images with those from the past, the team was unable to rediscover the three luminous sources. Furthermore, while a few very faint stars are visible near the expected locations, they do not appear to be related to the original luminous sources.
By combining all of these methods, the team was able to confirm the transient nature of the three luminous sources and rule out several possible explanations, such as airplanes or asteroids.
Sources
Another intriguing question is whether these three sources could be related to Fast Radio Bursts (FRBs), which are still mysterious cosmic phenomena.
Another proposed theory is that these are not three distinct objects but three images produced by a gravitational lensing effect. This occurs when the light from a distant object is bent by the gravity of a massive object located between it and the observer, creating multiple or amplified images of the distant object.
Similar events, where luminous sources appear and disappear rapidly, have been reported in other studies, notably by Dr. Beatriz Villarroel and the VASCO project (Vanishing & Appearing Sources during a Century of Observations), whose aim is precisely to study these phenomena as Dr Villaroel describes here:
“The VASCO citizen science project has now launched, and together with schools and amateur associations, we are orchestrating a community effort to search for anomalies in astronomical images separated by 70 years.”
The exact nature of these phenomena, if indeed they are related, remains to be discovered. One avenue to explore is that of a technosignature:
“Technosignatures represent any sign of technology that we can use to infer the
existence of intelligent life elsewhere in the universe, including familiar objects of
searches for extraterrestrial intelligence such as narrow-band radio signals or pulsed lasers.”
If you wish to participate in the VASCO project, please visit: VASCO Project Link.
Main picture: Image by Lumina Obscura from Pixabay