Verification of optical flashes among ~8,000 candidate features on POSS1-E plate E0070

Ascertain whether any of the approximately 8,000 morphologically spurious features identified on Palomar Observatory Sky Survey first-epoch (POSS1-E) plate E0070 represent true optical flashes rather than artifacts or misclassified objects.

Background

Hambly and Blair (2024) analyzed POSS1-E plate E0070 and identified about 8,000 spurious objects that are statistically and morphologically distinct from stars and galaxies.

The authors note that none of these features has been independently validated as a true optical transient, leaving unresolved whether any are authentic optical flashes.

References

The following questions remain unanswered after N. Hambly & A. Blair (2024): (i) whether optical flashes exhibit smaller FWHM on POSS1 plates; (ii) whether any of the 8,000 features selected on plate E0070 by N. Hambly & A. Blair (2024) represent an optical flash; and (iii) whether some categories of plate artifacts exhibit a smaller FWHM when compared to stars, on average.

— Critical Evaluation of Studies Alleging Evidence for Technosignatures in the POSS1-E Photographic Plates  (2601.21946 - Watters et al., 29 Jan 2026) in Section 2