Not Humanity’s Last View …

This is being described as “humanity’s last view of the JWST.”

6:50 AM CST, Christmas Morning

I expect imaging, and even direct viewing, of the James Webb Space Telescope from terrestrial telescopes to become a popular amateur astronomical activity in the summer of 2022. Here is why:

A full Moon has apparent magnitude -12.7. This is the result of its distance of ≈380,000 kilometers, its effective area (a circle of radius ≈1,700 kilometers) of ≈9.1 million km², and its albedo of ≈0.12.

The JWST will be at ~4 LD, the effective area of its sunshield will be ≈830 m², and its albedo will be very close to 1.

Its distance makes it 16 times as faint, its effective area makes it 11 billion times as faint, and its albedo makes it 8.3 times as bright. Multiplying all these together yields a factor of 21 billion.

The magnitude scale is measured in increments of ⁵√100 ≈ 2.5, such that each 5 steps downward is 100 times brighter. Venus, which can reach an apparent magnitude of -4.7, is nearly 100 times brighter than Arcturus (α Boötis), at -0.05. The stars in the Big Dipper and in Orion’s Belt are around magnitude +2.

The limits of my experience are the Sun, apparent magnitude -26.7, and some of the fainter Pleiades, magnitude +6.5 or even fainter—note that this takes not only very clear, dark, moonless skies, but also an hour and a half or more of no artificial light whatsoever for excellent dark adaptation, and probably eyes younger than mine are now (I am recalling an incident from my 30s). That’s a factor of almost 20 trillion.

Anyway, doing the math, something 21 billion times fainter than a full Moon has an apparent magnitude of +13.1.

Every amateur astronomer reading this just went huh. Easy.

Taking the usual limiting magnitude of the unaided eye to be exactly +6 and the effective aperture of the human pupil to be 7mm, less than 200mm of primary lens or mirror diameter would be enough. In the real world, it’s going to be harder than that … but I found Pluto in my 333mm f/4.5 Newtonian at magnitude +13.8 or thereabouts during a Texas Star Party in the 1990s.

The challenge will be figuring out which thirteenth-magnitude speck in the field of view is actually the JWST, but one thing’s going to make it a lot easier: it won’t be moving with the starry background. Its motion will essentially be at the solar rate, ~1°/day. That’s 2½ arc-minutes per hour, or 2½ arc-seconds per minute. A pair of images taken even a few minutes apart will pop it out, much like the discovery images of Pluto in 1930.

 

UPDATE (12/31): en route

Afghanalysis

There is no shortage of facile commentary about this disaster. It grabs attention like a bad car wreck, but attention and insight are two very different things. This post will mostly be a list of “dont’s,” gaps in our current knowledge, admonitions about epistemic humility, and reminders of stupefying incompetence exhibited by the ostensibly qualified. And I know about some of them because I’ve made the same mistakes as many of those reacting to events now.

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Pwosesis Ayiti A

No reward for resistance; no assistance, no applause.

— Neil Peart, “Lock and Key

 

For none of us lives to himself, and none of us dies to himself.

— Paul of Tarsus, Epistle to the Romans

La merde a frappé le ventilateur; my earlier post became abruptly more topical on Wednesday the 7th, when we woke to the news of the assassination of Haitian President Jovenel Moïse. This follow-up will consider the implications of developments since late June and will specifically respond to commenters on Dilèm Aksyon Kolektif nan Matisan. Most of the structure of this post will follow the Deming process-workbench model, because history is, to a great extent, a series of contingent events, and because I am a giant process nerd.

Follow along, kids, as I summon the shade of W. Edwards Deming (1900-1993) to analyze the biggest mess I’ve ever been in!

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Dilèm Aksyon Kolektif nan Matisan

Generatim discite cultus

(Learn the culture proper to each after its kind)

— Virgil, Georgics II

Stephen Biddle, Nonstate Warfare: the Military Methods of Guerrillas, Warlords, and Militias (Princeton: Princeton University Press, 2021)

one-to-many entity-relationship symbol superposed over map of Martissant, Haiti

By way of making this more than a merely armchair review, I will be discussing the developing situation of state failure in Haiti, which is providing a personally harrowing example of the phenomena theorized and studied in this book. NB: additional situation reports like the one I quote from below will appear at this OCHA webpage.

I. Increasingly Scale-Free Military Activity in the 21st Century

In this follow-up to 2004’s Military Power: Explaining Victory and Defeat in Modern Battle (also from Princeton), Stephen Biddle continues to elucidate the many ramifications of the one-to-many relationship which came to dominate the battlefield between the Napoleonic Wars and World War I. Over that century and in the decades that followed, individual-service weapons increased in rate of fire from a (very) few rounds per minute to ~10 rounds per second, in effective range from ~100 to >300 meters, and in accuracy from (optimistically) 10 to 1.5 milliradians. Say 2½ orders of magnitude improvement in RoF, half an order of magnitude in range, and one order of magnitude in accuracy; multiplying these together to create a sort of index of effectiveness, I get an overall change of 4 orders of magnitude, with stark implications for battlefield environments.

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Tiananmen OSINT

“Either write something worth reading or do something worth writing.” — Benjamin Franklin

[Readers are directed to the end of this post for an explanation of my timing and motivation.

UPDATE 6/5, 11 AM CDT: videos embedded!]

I. Anniversary Reconnoiter

At around nine in the morning local time on the thirtieth anniversary of the “June Fourth Incident,” I began a reconnoiter of Tiananmen Square in central Beijing to observe security measures and, if possible, witness any attempt at commemorating the massacre. I accompanied Dr. Andrew R. Cline, professor of media, journalism, and film at Missouri State University in Springfield. We were part of group of eleven people—four students, two faculty, and five others including me—comprising a “Study Away” program from MSU which had spent the previous twelve days in China, flying into Beijing and taking high-speed trains to Xi’an and Xining, then on via the Qinghai–Tibet railway to Lhasa before flying back to Beijing. Of all days, Tuesday 4 June 2019 was designated a free day for the group: no itinerary—and no guide. The remaining nine group members, as it turned out, had other ideas about what to do that day.

Andy’s motivation was broadly journalistic, garnished with a specific interest in whether any actual Marxists would show up. I went along out of a feeling that I had something of a reputation to uphold, and quickly decided during our approach that I would evaluate the security measures and write up a more quantitative report, although I will also pass along some thoughts about the organizational behaviors involved.

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