New North & East Arrow Script in PI Pleiades Astrophoto PixInsight · Dale Penkala · ... · 31 · 1229 · 2

jayhov 7.30
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Hi Jay, the arrows are in fact correct.
The source of confusion is that we are dealing with two systems of coordinates: 1. the celestial equatorial for the sky, and 2. the local horizon (geographical, terrestrial) for earth orientation.

When you are talking about directions in the sky, you use celestial equatorial coordinates, not the terrestrial geographical.
In the sky you have by definition the north arrow pointing to the North Celestial Pole (not the Zenith!) and the east arrow points 90° left of north, wherever you are in the sky.

If you happen look in direction of the geographical north, you have the celestial east arrow pointing to the terrestrial west, but you are talking two different things.

Hope this helps.
Ciao, Mau


Thanks @Mau_Bard  et al ... but I have tried to picture this (in my head AND in the sky).  If  I look at the NCP, all celestial movement is coming from the east, which is to the right in the sky, and moving to the west, which is to the left in the sky.  Of course, it is not my intention to be argumentative or controversial.  Perhaps I just need a few more (dozen) clear nights to clear my head ??  Jay
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Mau_Bard 4.06
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Jay Hovnanian:
Hi Jay, the arrows are in fact correct.
The source of confusion is that we are dealing with two systems of coordinates: 1. the celestial equatorial for the sky, and 2. the local horizon (geographical, terrestrial) for earth orientation.

When you are talking about directions in the sky, you use celestial equatorial coordinates, not the terrestrial geographical.
In the sky you have by definition the north arrow pointing to the North Celestial Pole (not the Zenith!) and the east arrow points 90° left of north, wherever you are in the sky.

If you happen look in direction of the geographical north, you have the celestial east arrow pointing to the terrestrial west, but you are talking two different things.

Hope this helps.
Ciao, Mau


Thanks @Mau_Bard  et al ... but I have tried to picture this (in my head AND in the sky).  If  I look at the NCP, all celestial movement is coming from the east, which is to the right in the sky, and moving to the west, which is to the left in the sky.  Of course, it is not my intention to be argumentative or controversial.  Perhaps I just need a few more (dozen) clear nights to clear my head ??  Jay

To have a simple reference, I suggest you look straight south (technically you look the meridian) and the celestial sphere rotates from left to right, i.e. from east to west.
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jayhov 7.30
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To have a simple reference, I suggest you look straight south (technically you look the meridian) and the celestial sphere rotates from left to right, i.e. from east to west.


@Mau_Bard   Yes, I get that.  If we look due south, east is to the left ... but if we look to the north, east is to the right ....  Let's just leave it here.  If I don't get it, that's okay.  There's a lot of things in life I just don't get ....  Thanks
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Kanadalainen 6.10
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Thanks @Dale Penkala for pointing us to this script.  I used it for the first time yesterday night, and its really nice.

Ian
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nico1038 0.00
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Jay Hovnanian:
To have a simple reference, I suggest you look straight south (technically you look the meridian) and the celestial sphere rotates from left to right, i.e. from east to west.


@Mau_Bard   Yes, I get that.  If we look due south, east is to the left ... but if we look to the north, east is to the right ....  Let's just leave it here.  If I don't get it, that's okay.  There's a lot of things in life I just don't get ....  Thanks

Now that you are looking south, imagine that you raise your head and look at the zenith. Then draw the arrows from the zenith: North is towards your back and East is to your left.
Edited ...
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Mau_Bard 4.06
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Jay Hovnanian:
To have a simple reference, I suggest you look straight south (technically you look the meridian) and the celestial sphere rotates from left to right, i.e. from east to west.


@Mau_Bard   Yes, I get that.  If we look due south, east is to the left ... but if we look to the north, east is to the right ....  Let's just leave it here.  If I don't get it, that's okay.  There's a lot of things in life I just don't get ....  Thanks

Mh, let me try to represent this in a different way: if you look at a picture of the sky, that is oriented with celestial north at the top, then the celestial east is always on the left side. This is valid for any picture of the sky, and independently where the point was when the picture was taken.
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DalePenkala 19.38
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Ian Dixon:
Thanks @Dale Penkala for pointing us to this script.  I used it for the first time yesterday night, and it’s ourreally nice.

Ian

You’re very welcome Ian, I’m glad you find it useful. I sure did!

Dale
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