I have a set of close of 10,000 points on the sky. They are plotted using the RA (right ascension) and DEC (declination) on the sky. When plotted, they take the shape of a circle.
What I would like to do is to slice the circle into 8 equal parts and remove each part one at a time and do some calculations using the remaining parts.
To do so I came up with this illustration in mind, i.e. slicing them using the arcs.
I know that the equation of the arc is given by:
S = r * theta
where
r --> radius
theta --> angle (in our case 45 degrees)
I would somehow like to do this like:
slice1 = []
for a,b in zip(ra,dec):if a>some value and a<some value and b>some value and b<some value:slice1.append(a,b)
If they were a square, it becomes really easy, and the above equation can immediately be applied.
So once I have my slice, I can then do a numpy.where()
to find out the rest of my circle.
I can easily slice it into four slices by just mentioning the min(RA),max(RA),min(DEC) and max(DEC)
. One such example when I do it for the first quadrant will give me this:
RA>0.0 and RA<max(RA) DEC>0.0 and DEC<max(DEC)
I don't know how to go about doing this in my case (i.e. into 8 quadrants!!), wherein I only have the x,y coordinates of my data points!!