# December 20, 1948 — W of Los Alamos, NM — AESS OP Sighted Green Fireball with Triangulation

**URL:** https://uapdiscovery.discourse.group/t/december-20-1948-w-of-los-alamos-nm-aess-op-sighted-green-fireball-with-triangulation/436
**Category:** Blue Book Unknowns
**Created:** [December 19, 2025, 10:29pm UTC](https://uapdiscovery.discourse.group/t/december-20-1948-w-of-los-alamos-nm-aess-op-sighted-green-fireball-with-triangulation/436 "2025-12-19T22:29:57Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![jeffknox](https://avatars.discourse-cdn.com/v4/letter/j/e47c2d/32.png) [@jeffknox](https://uapdiscovery.discourse.group/u/jeffknox)
#### Post date: [December 19, 2025, 10:29pm UTC](https://uapdiscovery.discourse.group/t/december-20-1948-w-of-los-alamos-nm-aess-op-sighted-green-fireball-with-triangulation/436/1 "2025-12-19T22:29:57Z")

</div>

![12201948-WofLosAlamosNM-NARA-PBB91-410](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/6/64da0312a9e1b337670807b665815e7466c0e278.jpeg)

December 20, 1948 — W of Los Alamos, NM  
8:54 p.m. Shortly after they have packed up their Speed Graphic cameras provided by LaPaz to try to photograph the green fireballs, personnel (William D. Wilson, Buford G. Truett, Clifford E. Strang, and George S. Skipper) at an Atomic Energy Security Service post west of Los Alamos, New Mexico, spot a blue-white fireball moving in a nearly flat trajectory. Two objects separate from the main body and trail behind it. Thanks to an independent observation at another site, LaPaz is able to triangulate its flight path as 7–8 miles, west to east toward Los Alamos. [Eberhart]

NARA-PBB88-745:

 ![12201948-WofLosAlamosNM-NARA-PBB88-745](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/c/ca27be22ca47f2cc63daf17f97dc4a3983bdfad8.jpeg)

MAXW-PBB4-1409:

 ![12201948-WofLosAlamosNM-MAXW-PBB4-1409](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/f/f1430c9359db89e9f5f40533d3e5858c89b0a5a6.jpeg)

Sources:  
Brad Sparks, Blue Books Unknowns Catalogue, Case 155, p. 46;

 ![12201948-WofLosAlamosNM-Sparks-Case155-p46](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/f/f6116f837aba20e781d2750438a93dc877071d33.png)

Jerome Clark, The UFO Encyclopedia, 3rd Ed., p. 540;  
Jerome Clark, The UFO Encyclopedia, 4th Ed., p. 598;

 ![12201948-WofLosAlamosNM-ClarkIII-p540](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/8/8f4e29454278f7708862470173a5c52ced0de062.png)

NICAP, “AFOSI Case 14: AESS OP Sighted Green Fireball with Triangulation”;

> **[Dec 20, 1948; Los Alamos, NM](http://www.nicap.org/alamos481220dir.htm)**

Joel Carpenter, Green Fireball Chronology;

 ![12201948-WofLosAlamosNM-CarpenterChronology](https://canada1.discourse-cdn.com/flex011/uploads/uapdiscovery/original/2X/1/11dc55770354237fffa52b1a275f86f8b2d9a458.png)

> **[PROJECT 1947: Green Fireball Chronology - Joel Carpenter](http://www.project1947.com/gfb/gfbchron.html)**
>
> project 1947, a chronology of green fireball sightings over secret
> New Mexico military installations from 1946 to 1949