#constellation of the day

[thevalleysbelow]

Constellation of the day: the IAU designated constellations and their names

The IAU’s first General Assembly was held in Rome in 1922, and there the Commission on Notations and Units agreed on a list of 88 constellations covering the entire sky, with three-letter abbreviations of their Latin names, for everyone to have a common reference despite the existence of a number of different sky cultures. These are the 88 IAU constellations that are still recognised today.

In 1925, at the Second IAU General Assembly held in Cambridge, Eugène Delporte of the Royal Observatory in Brussels presented a clearly defined system of constellation boundaries drawn along lines of right ascension and declination (right a-what? I’ll explain in the next post. It’s the equivalent of longitude and latitude on Earth anyway).

Delporte was appointed to prepare some official boundaries for constellations, made in such a way that the variable stars remained in the constellation to which they were originally assigned.

So, nowadays constellations are indeed scientifically defined areas of sky. When saying a star or a cluster of stars or any celestial object is “in a certain constellation”, one means that the star can be found within certain boundaries on a sky map. It’s like saying that if we tell someone a certain town is in a certain state, we are implicitly stating that the town falls somehow under the jurisdiction of the capital of that state, even if it’s clearly separated from it. Still, it is enclosed in an imaginary closed line we call border, that is by convention associated to a city that is designated capital. Only, in our constellations cinematic universe every “state” takes the name of its “capital” (the actual dots-and-lines-constellation).

Now. Each IAU constellation name is in Latin and has two forms, nominative and genitive. Whoever is familiar with Latin or any other language that includes a case system probably knows what I’m talking about. For those who don’t, the nominative denotes a case of noun, pronoun, and adjectives used as a subject; the geinitive is another grammatical case that marks usually a noun, indicating its attributive relationship to another word. You could either masochistically learn to decline nouns in Latin up to the genitive for the sole purpose of having something to brag of to your friends, or know that the nominative is used to talk about the constellation itself, the genitive (the one that usually ends in -ae, -i, -is) to talk about something within the constellation. For example: in Latin “Centaur” is “Centaurus”, and Centaurus is the nominative. The genitive of Centaurus is Centauri (word that could be roughly translated as “belonging to the Centaur”). Hence we have the constellation Centaurus, and then the objects α Centauri, β Centauri, and so on.

You just need to type on the research bar of your favourite research engine “IAU constellations” to find some nice table of said constellations in alphabetical order with nominative and related genitive and three-letters abbreviation. As always, the IAU site surely is the best source.

This post ends here. Next time I’ll probably talk about celestial coordinates and related concepts. See ya!

~Ad Astra~

[lalage]

miss mona megistus

dress is sarah burton for alexander mcqueen 2016 with mona specific alterations

[tinybunbunn]

Based on a scene from The Constellations Within Us! I read this part and immediately knew I wanted to sketch it out 🥺 I highly recommend reading it! I’m constantly rotating the series around in my brain lmao

@cloud-somersault

[mugwot]

funnyjokespunperson

[aliensfuckmeup]

DROPS THIS ON THE TABLE AND COLLAPSES DEAD ON THE GROUND.

Illustration for chapter 10 of In Blood And Stars by @actingwithportals.

[forgetful-river]

Aradia August Day 9: Aries ♈

[theofficialastronomy101]

1200 Megapixel

⚠️Remember to click on photo to view in full hd quality

[northernfireart]

can we have some domestic tentoorose? i love your art!

ohh this request. i love u. spent a whole week sketching stuff because of how many separate ideas i had

so may i offer you today all of these

[wyvernity]

sss day my favorite national holiday WOOOOHHHH

bonus

[thevalleysbelow]

Constellation of the day: a couple words on catalogues and the “naming stars” thing

The number of stars bright enough to be visible to the naked eye from any (any) point on the surface of Earth is around 3000. So it might prove a bit difficult to keep track of whatever’s happening in the sky without the help of a reliable catalogue, that can, e.g., prove essential to identify transient phenomena (like comets, or novae) as such.

In fact, two of the historically most important catalogues (by Hipparchus of Nicea and Tycho Brahe respectively) have as their raison d’être the explosion of a star somewhere near enough to be both visible and a quite strong antithesis to the popular assumption of an immutable cosmos. For more information on historical catalogues, you can start looking here. Or well, on Wikipedia. Paying some attention to the sources.

A number of modern catalogues are available in electronic format and can be freely downloaded from space agencies' databases. The largest is being compiled from the spacecraft Gaia, and has over a billion stars. You can freely download the latest version from the Gaia Archive, just have to find 10TB of space to store it.

Particularly important is the catalogue by Johann Bayer (1572-1625), the Uranometria, first atlas representing the whole sky. Its importance resides in the fact that Bayer, in every constellation, defined the stars of crescent magnitude (let’s say, “apparent brightness”, I’ll come to that too) with Greek letters, switching to Latin letters if the Greek alphabet happened to be insufficient. This practice is now a consolidated one. For example, α Orionis (aka Betelgeuse), brightest star in the Orion constellation. Followed by β Orionis (aka Rigel) and soooo on.

Another special mention goes to the Messier Catalog. Check out the Hubble version.

There are of course a number of conventions now approved by the IAU for naming planets, stars, and any celestial object. Can find everything here, if you’re curious.

Here’s a summary for the “occasional readers”.

The IAU Working Group on Designations & Nomenclature provides guidelines on creating new alphanumeric designations for astronomical objects outside the solar system.

The designations of astronomical source should consist of three parts, that is:

Acronym ^ Sequence ^ (Specifier)

Where ^ denotes a blank. The only optional part is the specifier, that’s to be enclosed in parentheses if present. The acronym is an alphanumerical string of characters that specifies the catalog or collection of sources. It may be constructed from catalog names (NGC, BD, etc.), names of authors (Caswell, WT, RGH…), instruments, observatories, etc. (there are guidelines, dictionaries and hints for that also).

The sequence (numbering) is another alphanumeric string of characters (more often than not only numerical) that uniquely determines the source within a catalog or collection. It may be a sequence number within a catalog, or based on fields or coordinates. The way the sequence is constructed is called the format of the sequence. Also for that, there’s an Inventory of the Formats. And more rules for the usage of coordinates as sequences. Obviously I can’t summarise all that in a post- but I suggest looking that up, if you’d like to make more sense of the names. The the post I hope will come after the next one might prove useful to make sense of the coordinates themselves, and I’ll return to the “use of coordinates in names” matter there.

Now obsolete, the specifier was optional and allowed one to indicate other source parameters. Syntax not required.

Concerning special characters:

• The blanks [ ] are used as separators

• Underscores [_] are used in place of blanks, in case the latter cause problems

• [-] should only be used as a minus sign, for example in coordinates. Other usages are discouraged.

• [.] should be reserved for a decimal point

• [/] should be used for concatenation of the source quoted. Example (same as in the main page of the naming guidelines): “DR 21/23” meaning “DR 21 and DR 23”.

• [:] should be reserved to indicate a subdivision. More rules and practices to be found on the subject.

Now I’ll almost quote the IAU site (I don’t think there’s a better summary and of course the examples are all perfectly fitting):

Stars in binary or multiple systems are labelled by capital letters from the Latin alphabet if the star has a common colloquial name; by Bayer name; by Flamsteed designation; or by a catalogue number. For example, the brightest star in the sky, Sirius (Canis Major), has a white dwarf companion that is catalogued as each of the following: Sirius B, Alpha Canis Majoris B, and HD 48915 B.

Variable stars are nowadays catalogued according to their order of discovery. The first variable to be discovered in each constellation was assigned the letter R and the Latin genitive of the constellation name (I’ll come to that in the next post), such as R Andromedae. The second discovered variable is dubbed S, an then one goes all the way up to Z, beyond which two-letter names are introduced, from RR to RZ, to SS to SZ, up to ZZ. As more variable stars are discovered, the scheme returns to AA to AZ, BB to BZ, and up to QQ to QZ. The letter J is omitted not to be confused with the letter I. So we have 334 possible unique designations for variable stars in a constellation. If even more are discovered, the catalogue turns to designations whereby the constellation name is preceded by the letter V and a number (e.g., V1500 Cygni). The exceptions are those variable stars already assigned a Bayer name, which are not given a new name according to this scheme (for example, Delta Cephei, Beta Lyrae, Beta Persei, or Omicron Ceti).

Stellar explosions called novae and supernovae are transient brightening events. These stellar explosions employ a slightly different alphanumeric system than variable stars. Novae are assigned designations according to their constellation, together with the year their superlumination event occurred (e.g. Nova Cygni 1975), and are later given variable star designations. Indeed, Nova Cygni 1975 refers to the same object as V1500 Cygni, mentioned above, but V1500 Cyg designates the variable stellar system, a cataclysmic binary, and Nova Cygni 1975 refers to its 1975 eruption. Supernovae are also named for their year of occurrence, along with the letters SN and an additional uppercase letter, as in the supernova SN 1987A. A double-lowercase designation is used (e.g., SN 1997bs) if a single year is particularly flush with supernova events. When double-lowercase designations are exhausted, triple-lowercase (e.g. SN 2022hrs) and even quadruple-lowercase designations (e.g. SN 2021afsj) are used.

And that’s everything for now. See ya with the next (shorter) post about constellation names!

~Ad Astra~

[egophiliac]

Wait, is Lilia canonically 700? I thought he was thousands of years old. Did I miss something in Chapter 7....

I thought so too! the stuff about his real birthday being lost to time, the way he talks about the planetary alignment thing that only happens every 100 years, and other things like that made me think he was waaaay older than he is. but nope, in 7-26 he says he's just shy of turning 700! (so he's actually like. 699.) his particular type of fae can live to around 1000, but he's running down early because he pushed himself too much when he was younger (and also he plays too many online games) (he was probably not serious about that but c'mon, man, at least use a blue-light filter or something).

meanwhile, Mal is from a much longer-lived race that doesn't even reach adulthood until 1000 (500 is young adult, and 200 is still a little fledgeling dragon baby). Lilia doesn't say exactly how old he is, except that he's developmentally a "little" older than the third-years (so like about 20 in dragon years? ...can Leona sense this. is this part of why he sees Malleus as his Eternal Rival.) which means he's probably somewhere around or just under 500.

...I just realized that, depending on when it happened, this means Lilia might've been, like, mentally a teenager during the flashback of The Time Baby Malleus Almost Killed Everybody. he's just had Dad Instincts his entire life, I guess.

[azure-bluet]

hbg sketches

[leawesomesloth]

BIRB BOYS BIRB BOYS BIRB BOYS

[a-star-that-burns-brightly]

I'm going to sound like such a smartass but I'm glad I'm seeing more people express that "Huh, maybe this girl who has an entire song repeating to herself over and over again that her murder was not her fault meanwhile she-

portrays herself as a giant grotesque bug in her headspace with her victim, who she clearly still holds a high opinion of, being the only human in said headspace looking at her with visible disgust and fear,

Making this expression upon realizing what she just did

These being the lyrics that follow right after, having a moment of reconsideration

Before jumping back to trying to convince herself that she was in the right, because she put her trust in us to tell her if what she did was right or not, and the answer that came out was yes... That maybe, just maybe. She thinks that what she did...

Might have been her fault."

[kcrabb88]

It's Talk Like a Pirate Day, so I would be remiss not to plug my recently-completed trilogy! Not that I don't talk about it a lot, but today feels like a free pass :D I like to call it a Les Mis meets Black Sails meets Robin Hood story about stories, historical narratives, and the power they hold. It's got queer pirates of all different stripes, complicated antagonists, ruminations on empire and colonialism, found family, messy blood family, and a whole lot of ships and swords. You can check it out here, and I'll drop the summary of book 1 below! Thank you to everyone around here who has supported me for years while I got this out! <3

In the 18th century West Indies, stories hold the ultimate power. Sailors spin yarns about pirates. Newspapers tell tales full of half-truths. Myths spread like whispered wildfire. East India Company sailor Nicholas Jerome has no patience for pirates, determined to leave his father’s thieving past behind. After a convict and an enslaved woman escape his grasp with the aid of an aristocrat’s mysterious wife, he faces one last chance to save his career. Finding an unexpected home with a new crew, he gains a chosen younger brother in René Delacroix, the son of his wealthy captain and the grandson of Jamaica’s cruel governor. But there’s a storm brewing in the Delacroix household. For René and his best friend Frantz, the Robin Hood tales about legendary pirate Ajani Danso and his famed female quartermaster are a lifeline amidst the governor’s abuse. Danso robs greedy merchants, frees slaves, and shelters queer sailors, inspiring the downtrodden across the New World. When death and betrayal shatter the lives they knew, René and Jerome each face a obey, or rebel. A war for history’s favor begins, and as an uprising against colonialism erupts on the ocean, everyone must choose a story to believe in

[galaxostars]

presque vu (almost seen): the intense feeling of being on the very brink of a powerful epiphany, insight, or revelation, without actually achieving the revelation

Sirius Black is born.

Sirius Black dies.

Everything in between is the unknown.

—from the fic Presque Vu by @starsworth