<p>Say I have 2 records, in horizontal coordinates of the azimuth ($A_z,A_z^{'}$) and altitude ($\alpha,\alpha^{'}$) of the moon at the same time in two different places that are $\theta$ degrees apart (taking the angle from the centre of the earth and assuming the earth is a perfect sphere). Is it possible to calculate the parallax angle of the moon between these two points with only the values above? if so how and if not what other values would I need?</p>

CC BY-SA 3.0
2018-01-04T23:55:43.860Z
My intuition is that you need the latitude and longitude of the two places, not the angle between them. With that information, you can construct vectors from each observer to the Moon, from which you can calculate where they intersect (or more likely where they are closest to each other).
JohnHoltz
CC BY-SA 3.0
2018-01-05T13:15:47.213Z
Seems like a geometry problem. Try to make a sketch of the situation: Earth, two positions at different latitudes connecting their lines of sight with the moon. Mark the angles represented by  the coordinates you know, and the solution should become clear.
AtmosphericPrisonEscape
CC BY-SA 3.0
2018-01-09T01:44:36.153Z
Assuming the Earth is a sphere, you could easily calculate the baseline from $\theta$, and you have your two vector angles.
Mick
<the-moon><coordinate><parallax>
calculating paralax angle from observations
cal
# calculating paralax angle from observations

(Asked by: username_0 on 2018-01-04)

Say I have 2 records, in horizontal coordinates of the azimuth ($A\_z,A\_z^{'}$) and altitude ($\alpha,\alpha^{'}$) of the moon at the same time in two different places that are $\theta$ degrees apart (taking the angle from the centre of the earth and assuming the earth is a perfect sphere). Is it possible to username_0culate the parallax angle of the moon between these two points with only the values above? if so how and if not what other values would I need?

**Tags:** the-moon, coordinate, parallax

> **Comments:**
> **username_1**: My intuition is that you need the latitude and longitude of the two places, not the angle between them. With that information, you can construct vectors from each observer to the Moon, from which you can username_0culate where they intersect (or more likely where they are closest to each other).  
> **username_2**: Seems like a geometry problem. Try to make a sketch of the situation: Earth, two positions at different latitudes connecting their lines of sight with the moon. Mark the angles represented by  the coordinates you know, and the solution should become clear.  
> **username_3**: Assuming the Earth is a sphere, you could easily username_0culate the baseline from $\theta$, and you have your two vector angles.  

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