Transients in the Palomar Observatory Sky Survey

[HoaxEye]

Interesting, it seems @Brian Dunning is saying the study/paper showing a positive correlation between detected transients and nuclear testing was based on just 9 transients?!:

The Skeptoid episode is not accurate about the publication history and misattributed the origin of the nine transients.

The nine transients were actually introduced in a June 2021 paper, "Exploring nine simultaneously occurring transients on April 12th 1950" (Villarroel et al.). The Hambly and Blair rebuttal paper (2024) was written specifically to analyze and refute the nine transients from that 2021 paper, not the later 2025 ones.

Edit: this nine-transient issue does not invalidate the podcast conclusions. We cannot rule out plate defects without physical microscopic validation of the original glass plates.

Btw, the nine transients were apparently dropped silently from the candidate list. Before 2025 papers, they introduced "triple transients" in MNRAS 2024 (https://doi.org/10.1093/mnras/stad3422) by Solano et al. At this point they used the automated software pipeline (Solano et. al. 2022), and the published list of 5,399 candidates. The current "107K" candidate list originating from the same software pipeline was selected as the primary list in later papers. It's currently the most referenced and discussed candidate list, but it has never been published.

 

[NorCal Dave]

The Skeptoid episode is not accurate about the publication history and misattributed the origin of the nine transients.

Yeah, when I first heard it, it seemed to say the 9 were used to argue the nuclear testing correlations. But in reading the transcript, I think it just gets jumbled up.

As you noted, there's multiple papers, with multiple changing lists and multiple claims, but the most important data, the actual transients date, time and location, are never shared.

The details and intricacies are to complicated for the Skeptoid short form, so the main claims are highlighted as well as the major problems.

 

[HoaxEye]

Update on my "Vasco60" work. I have been working on a slightly different version of the pipeline for some time. Code is not yet public.
Also testing whether a looser, more permissive version can approach the third-party ~107K-scale candidate list.

Checked so far:
- Raw source detection recovers ~99% of the third-party list's rows. Detection sensitivity is not the issue. I've identified a more suitable sextractor parameter set using only one-pass call, without PSFex step. However, this doesn't matter as much as the "naive" tessellation method where plates are downloaded fully, including the edge areas that were excluded earlier
- Most of the gap between "strict pipeline" and "third-party list scale" comes from two places: how much sky area gets covered, and the Gaia/PanSTARRS/USNO-B cross-match veto stage. The veto stage is working correctly
- Testing suggests the strict pipeline, once matched for the same sky coverage, lands roughly in the right ballpark of scale. Early result, not fully validated yet

Unexpected finding (also early result, not fully validated yet):
- The third-party list's plate identifiers appear to have real errors on some plates. A meaningful fraction of rows are tagged with the wrong originating plate. Observation dates could be therefore partly wrong, too

Current status:
- Moved from single-plate pilots to processing plates one at a time across the sky, with checks at every stage
- I'll share more once there's a broader, more solid full-sky picture.