Pickett N-500-ES and N600-ES

The N-500 family was produced in the United States from 1958 to 1975. Fabricated with aluminum, the scales were photo printed on a yellow (ES- Eye Saver) or white (T- Traditional White) paint coat. Cursor lenses were all plastic and were screwed to also plastics ends. 

The first N-500 model produced was labeled N-500-ES Log-Log Duplex and had 20 scales:  LL0, LL00, A [ B, ST, T, S, C ] D, K  on the front face, and  L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 on the back face. In 1962 this model evolved to the N-500-ES HI-Log-Log Duplex, now with 22 scales: +LL1, -LL1, A [ B, T Cot, ST, S Cos, C ] D, DI, K on the front face, and +LL2, -LL2, DF [ CF, CIF, L, CI, C ] D, +LL3, -LL3 on the back face. This last model had an extra reverse scale DI and an extra Log-Log scale. The N-500-ES HI-Log-Log Duplex has the same scale set as the N-800 family, with the difference that scales on N-500 are all separated.

The N-600 family was produced in the United States also from 1958 to 1975. Again an all aluminum rule with plastic cursor, it has the same scales set as the N-500-ES-HI-Log-Log, plus an additional natural logarithmic Ln paired to the  scale L. There is also design difference between these models, the scales at the edges of the rule: +LL1, -LL1, and DI, K on the front face, and +LL2, -LL2, and+LL3, -LL3 on the back face, separated on the N-500-ES-Hi-Log-Log, are drawn on the same line in the N-600.

According to the logos drawn on the N-500 and N-600 rules in this collection, I conclude that these were fabricated in the period 1963-1965:

Next are links to simulators of the N600 slide rule:

http://www.antiquark.com/sliderule/sim/virtual-slide-rule.html 

https://www.sliderules.org/react/pickett_n600.html 

The N-500 and N-600 families were designed for high end Science and Engineering applications. Their aluminum body and the photo printed scales gave them light and a high precision rules. This is the reason why Pickett slide rules were chosen to be used by the Apollo astronauts on their mission to the moon, as they were lighter than their wood core counter parts. 

Picket publicized the N-600 as the rule carried aboard five Apollo missions. Next is a famous picture of Buzz Aldrin using a N-600 in the Apollo 11. It is known that when the Gemini XII computer docking system failed, Buzz Aldrin calculated the docking trajectory using a sextant and a slide rule. In an interesting paper written by Col. Michael Gibson: The Great Pickett Slide Rule Apollo Conundrum, you can find the full story of what slide rule models were used in the Apollo Mission.  

By the way, the rule used by By Buzz  Aldrin was auctioned by Heritage Auctions on September 20 , 2007  for $77,675.00 USD. This is the description used for this auction:

Buzz Aldrin's Apollo 11 Slide Rule - Flown to the Moon. A Pickett Model N600-ES (Eye Saver) Log Log Speed Rule, a six-inch pocket rule with 22 five-inch scales. Most of today's cell phones have much more computing power than the Apollo 11 mission carried on board. Though they seem archaic to many of this present generation, the slide rule was (and is) a powerful computational tool and would certainly come in very handy on a space flight in the event of a computer malfunction. The rule offered here was flown to the moon aboard Apollo 11 by Dr. Aldrin. The Pickett Company, founded in 1943, was proud of the fact that NASA selected this slide rule model of theirs to fly on five of the Apollo missions; they used that fact in their advertising of the period. Research shows that the N600-ES would have sold for $10.95 at retail in 1969 (one wonders what NASA paid). Very fine condition. From the personal collection of Dr. Buzz Aldrin and accompanied by a signed Letter of Authenticity from him. 

References: 

• Gibson, Michael: The Great Pickett Slide Rule Apollo Conundrum. www.rfcafe.com July 20, 2016     https://www.rfcafe.com/miscellany/smorgasbord/Great-Pickett-Slide-Rule-Apollo-Conundrum.htm

• Kramer, Peter D:  Moon landing: No small step, no giant leap without NJ slide rules. July 19,2019, North Jersey. USA Today Network. https://www.northjersey.com/story/news/2019/07/19/apollo-11-slide-rules/1742820001/?fbclid=IwAR3WRNGAx95LsiaOjmr4wQb1HUbT2NciwGbc2117kwBaNbrrknKOmsYljuM