Other Than Mars Thread

Quote:

Astronomers discovered a quasar, which is the "brightest of its kind" and the "most luminous object ever observed," using the European Southern Observatory's (ESO) Very Large Telescope (VLT), a statement said.

This record-breaking quasar is also growing rapidly, as is typical with the brightest quasars in the galaxy. The new study detailing the find, published in Nature Astronomy, reports that it is growing by the size of one sun per day and is over 500 trillion times brighter than the sun. It has been dubbed J0529-4351.

at one time, they really didn't know what these things are. Quasi-stellar became quasar

maybe you can still say that, except it seems to fit the theory that black holes can have [always have?] the poles emitting beams, so it's probably what they are

I just downloaded the good stuff for the year 1992.

It's 157 MB in pdf.

I went here, then downloaded in pdf:
https://archive.org/details/131123ExplanatorySupplementAstronomicalAlmanac/page/n7/mode/2up

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EXPLANATORY SUPPLEMENT TO THE ASTRONOMICAL ALMANAC
A Revision to the EXPLANATORY SUPPLEMENT TO THE ASTRONOMICAL EPHEMERIS
and THE AMERICAN EPHEMERIS AND NAUTICAL ALMANAC

Prepared by THE NAUTICAL ALMANAC OFFICE, U.S. NAVAL OBSERVATORY WITH CONTRIBUTIONS FROM
H.M. NAUTICAL ALMANAC OFFICE, BOYAL GREENWICH OBSERVATORY, JET PROPULSION LABORATORY,
BUREAU DES LONGITUDES, and THE TIME SERVICE AND ASTROMETRY DEPARTMENTS. U.S, NAVAL OBSERVATORY

Edited by
P Kenneth Seidelmann
UNIVERSITY SCIENCE BOOKS
MillValley, Califomia
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Foreword

The Explanatory Supplement to the Astronomical Ephemeris and the Americen
Ephemeris and Nautical Almanac was first published in 1961 "to provide the user
of these publications with fuller explanations of these publications themselves."
This supplement was reprinted with amendments in 1972, 1974, and 1977. It was
allowed to go out of print because the International Astronomical Union decided to
introduce new astronomical constants, a new standard epoch and equinox, new time
arguments, a new astronomical reference frame, and new fundamental ephemerides,
all of which required major revisions to the supplement. In addition, The
Astronornical Ephemeris and The American Ephemeris and Nautical Almanac series were
continued from 1981 with a new title, The Astronomical Almanac, which contains a
revised content and arrangement and is printed only in the United States, The work
of computation, preparation, proofreading, and production of reproducible material
is still shared between the United Kingdom and the United States of America.
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.
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So the privately owned moon lander tipped over on its side?

Oops.

File that under "shift happens."

Good one!

Good info:

"As Earth loses energy and slows down, the Moon gains this energy and its orbital period and distance from Earth increase."

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DELTA T (ΔT) AND UNIVERSAL TIME
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For many centuries, the fundamental unit of time was the rotational period of the Earth with respect to the Sun. Universal Time or UT (colloquially called Greenwich Mean Time or GMT) is based on mean solar time from Greenwich, England. Unfortunately, Universal Time is not a uniform time scale because Earth's rotational period is gradually increasing.

As Earth rotates on its axis, tidal friction is imposed on it through the gravitational attraction with the Moon and, to a lesser extent, the Sun. This secular acceleration gradually transfers angular momentum from Earth to the Moon. As Earth loses energy and slows down, the Moon gains this energy and its orbital period and distance from Earth increase.

The secular acceleration of the Moon is very poorly known and may not be constant. Careful records for its derivation only go back as far as 100 years or so. Before then, spurious and often incomplete eclipse and occultation observations from medieval and ancient manuscripts comprise the data base. In any case, the current value implies an increase in the length of the day by about 0.002 seconds per day per century. Such a trivially small amount may seem insignificant, but it has very measurable cummulative effects. If we compare the rotation of the actual Earth with a fictional Earth turning at a constant rate, we would find that solar time on the real Earth would fall about one minute behind the fictional Earth after just one century.

Earth's rotation on its axis is also subject to short term fluctuations for periods of up to several decades. It is believed that these fluctuations may be due to fluid motions in Earth's core which interact with and disturb the rotation of the mantle. However, climatological changes and variations in sea-level may also play significant roles since they should alter Earth's moment of inertia. Whatever the mechanism is, it is clear that its effects cannot be predicted with the current state of knowledge. When combined, the long term secular changes and rapid multi-decade fluctuations can put Earth an hour or more "behind schedule" in the course of one millennium.

Terrestrial Dynamical Time (TDT) is an atomic time scale. It can be thought of as the time that would be kept by an ideal clock. Most astronomical calculations (including eclipses) use Terrestrial Dynamical Time since the orbits of all the planets can be accurately described with it.

Although solar eclipse predictions are based on Terrestrial Dynamical Time, the position of the central eclipse path still depends on Universal Time. To convert TDT predictions to UT, one must know the difference between Terrestrial Dynamical Time and Universal Time. This parameter is known as delta-T or ΔT (ΔT = TDT - UT).
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https://eclipse.gsfc.nasa.gov/SEhelp/deltaT.html

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Quote: missedhervee

So the privately owned moon lander tipped over on its side?

Oops.

File that under "shift happens."

Last message. "I've fallen and I can't get up."

Voyager 1 starts making sense again after months of babble

Quote:

On March 1, the Voyager team sent a command, dubbed a "poke," to get the probe's Flight Data System (FDS) to try some other sequences in its software in the hope of circumventing whatever had become corrupted.

Readers of a certain vintage will doubtless have memories of poke sheets for various 1980s games

Quote:

The availability of skills is an issue. Many of the engineers who worked on the project - Voyager 1 launched in 1977 - are no longer around, and the team that remains is faced with trawling through reams of decades-old documents to deal with unanticipated issues arising today.

https://www.msn.com/en-us/news/technology/voyager-1-starts-making-sense-again-after-months-of-babble/ar-BB1jSZxL?ocid=msedgntp&pc=HCTS&cvid=b847c41a5a1340818a4e9daae8888488&ei=20

Mind candy:

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Think'st thou existence doth depend on time?

It doth; but actions are our epochs: mine

Have made my days and nights imperishable

Endless, and all alike, as sands on the shore

Innumerable atoms; and one desert

Barren and cold, on which the wild waves break,

But nothing rests, save carcases and wrecks,

Rocks, and the salt-surf weeds of bitterness.

-- Lord Byron

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Quote: rxwine

The availability of skills is an issue. Many of the engineers who worked on the project - Voyager 1 launched in 1977 - are no longer around, and the team that remains is faced with trawling through reams of decades-old documents to deal with unanticipated issues arising today.

That sounds like a dream job to me.