NQ2 or NQ3 or NGQ3

[acdw]

On 2020-09-04 (Friday) at 11:47, Luke Emmet <luke at marmaladefoo.com> wrote:

> Hi All
> 
> I've been growing in affection for the term NQ2 (I think originally 
> coined by acdw) as another way to refer to the virtual space that is the 
> gemisphere/gemspace/geminispace/geminiverse/etc. And the wikipedia page 
> for Gemini, says it is in NQ2.

Hey! I think it was me --- I'm glad others have found it a useful shorthand :)
> 
> https://en.wikipedia.org/wiki/Gemini_(constellation)
> 
> I was then curious to see what is the definition of a galactic quadrant 
> which led me to the wikipedia page about those. And on that page, it 
> shows Gemini being in NGQ3 (NGQ3 - North Galactic Quadrant 3), together 
> with a diagram which seems to indicate it clearly.
> 
> https://en.wikipedia.org/wiki/Galactic_quadrant
> 
> https://en.wikipedia.org/wiki/Galactic_quadrant#/media/File:Galactic_quadrants.png
> 
> Could it be the shocking truth one of these pages on wikipedia is wrong? 
> Also its not unknown for my understanding to be deeply flawed. I'm 
> inclined to go with the page about galactic quadrants as it has a 
> diagram, but to be honest if anyone has expertise in this area, it would 
> be great to clear this up, so normal service can continue.

I had no idea about this, and lo and behold you're right -- though, with more research, I *think* (the astonomical writings I'll put below are hard to figure out) that it's due to a difference in frames of reference.

Apparently, most astronomical observations are made from the "equatorial coordinates" -- which are extensions of the terrestrial equator out into space. I'm guessing "NQ2" refers to Gemini with that system.

However, "galactic coordinates" use the plane of the galaxy (mostly) as the equator, which means that from that perspective, things are in different quadrants -- I think in this system, Gemini is in NGQ3.

I personally like NQ2, since it's a character shorter. But if everyone starts calling it the NGQ3 (or NQ3), I'll hop on the bandwagon!

REFERENCES

https://www.astro.rug.nl/~sctrager/teaching/OA/PositionalAstronomy.pdf
^ a presentation that walks through the different coordinate systems

https://www.daviddarling.info/encyclopedia/C/coordinate.html
^ a webpage that explains the differences

https://heasarc.gsfc.nasa.gov/cgi-bin/Tools/convcoord/convcoord.pl?CoordVal=gemini&CoordType=J2000&Resolver=GRB%2FSIMBAD%2BSesame%2FNED&NoCache=on&Epoch=
^ a NASA tool that ... does something? This just looked cool. I have no idea how to read it.

https://en.wikipedia.org/wiki/Celestial_coordinate_system
^ Wikipedia page on celestial coordinate systems.

-- 
~ acdw
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