Cross-identify TGSS and NVSS catalogues with positional matching about blobmatch

[chengsoonong]

I wonder whether it is worth pre-filtering with a Euclidean nearest neighbour?
https://docs.scipy.org/doc/scipy/reference/generated/scipy.spatial.cKDTree.html#scipy.spatial.cKDTree

[daccordeon]

Not quite sure what that would be Cheng, is it just for computational speed?

[MatthewJA]

Yes! KDTrees are super fast ways to do spatial look-ups. There's a few reasons you wouldn't want one for this particular cross-matching problem (I'll leave you to think about what those might be) but they'd make a great first-pass.

[daccordeon]

(1) Obtain the TGSS and NVSS catalogues
done! must be called CATALOG.FIT and TGSSADR1_7sigma_catalog.tsv
(2) Following the paper, match TGSS and NVSS
done! see catalogue.csv
(3)Plot a histogram of the angular separation between matches
done! see hist_angle.png
(4)Using Equation 3 of the above paper, compute the spectral index ɑ and reproduce Figure 2.
done! see hist_alpha.png