Styjun

I am working on a project where I am finding the source matches based on RA and DEC between three sets of astronomical data related to a specific galaxy. I am able to find the source matches and output the matched RA and DEC values for each data set with no problem, but I am having trouble figuring out how to apply the matched sources to the rest of the data in my files (magnitude, flux, etc.) so that I only have data which corresponds to the matched sources. The package I am using is astropy.coordinates and match_coordinates_sky. Is there a way I can take my now matched RA and DEC values and use that to get their corresponding fluxes and magnitudes from my data sets? I was thinking some kind of for loop may be the right approach, but I'm quite new to python.

Currently, I only have matched RA and DEC for each data set, but I would like to end up with a file with those matched RA and DEC values along with their corresponding magnitude and flux values as different columns. This means that in my data, each parameter (RA, DEC, magnitude, flux) is a column and each source corresponds to a row.

My data is in the form of F435W.csv, F550M.csv, and F625W.csv. Where columns 13 and 14 are RA and DEC, respectively. The rest of the columns are variations of magntiude, flux and x and y positions. The data looks similar to this and this is how I need my new matched data to look as well:

1,2017.013,0.01242859,-8.2618,0,51434.12,0.3269918,-11.7781,0,0.01957931,1387.9406,541.916,49.9898514,41.5266996,8.81E+01,1.63E+03,1.44E+02,40.535,8.65,84.72,0.00061,0.00035,62.14
2,84.73392,0.01245409,-4.8201,0.0002,112.9723,0.04012135,-5.1324,0.0004,-0.002142646,150.306,146.7986,49.9942613,41.5444392,4.92E+00,5.60E+00,-2.02E-01,2.379,2.206,-74.69,0.00339,0.0029,88.88
3,215.1939,0.01242859,-5.8321,0.0001,262.2751,0.03840466,-6.0469,0.0002,-0.002961465,3248.686,52.8478,50.003155,41.5019044,4.77E+00,5.05E+00,-1.63E-01,2.263,2.166,-65.29,0.002,0.0019,-66.78
4,0.3796681,0.01240305,1.0515,0.0355,0.5823653,0.05487975,0.587,0.1023,-0.00425157,3760.344,11.113,50.0051049,41.4949256,1.93E+00,1.02E+00,-7.42E-02,1.393,1.007,-4.61,0.05461,0.03818,-6.68
5,0.9584663,0.01249223,0.0461,0.0142,1.043696,0.0175857,-0.0464,0.0183,-0.004156116,4013.2063,9.1225,50.0057256,41.4914444,1.12E+00,9.75E-01,1.09E-01,1.085,0.957,28.34,0.01934,0.01745,44.01
6,2.379565,0.01249223,-0.9412,0.0057,0.231205,0.02710035,1.59,0.1273,-0.004135321,3824.3706,9.0756,50.0052903,41.4940468,7.81E-01,6.99E-02,4.27E-02,0.885,0.26,3.42,0.01265,0.00622,15.52
7,0.3171223,0.01250492,1.2469,0.0428,0.5233852,0.05406558,0.7029,0.1122,-0.00399635,4097.3604,7.0301,50.0059585,41.4902884,9.61E-01,1.63E+00,-3.94E-01,1.346,0.883,-65.16,0.06171,0.04005,-65.05
8,0.289245,0.0125176,1.3468,0.047,0.2744479,0.02238134,1.4039,0.0886,-0.004173243,3904.7402,7.3912,50.0055069,41.4929422,7.90E-01,2.38E-01,7.13E-02,0.894,0.479,7.24,0.04501,0.02071,8.29
9,0.3543034,0.01247953,1.1266,0.0383,0.7666836,0.06376094,0.2885,0.0903,-0.004009248,4107.0684,3.259,50.0060503,41.4901611,3.53E+00,1.28E+00,-4.60E-01,1.903,1.09,-11.12,0.06873,0.03955,-11.22
10,1.308331,0.01250492,-0.2918,0.0104,-0.005209296,0.004877397,99,99,-0.004193406,3933.9834,6,50.0056001,41.4925416,5.78E-01,8.33E-02,0.00E+00,0.76,0.289,0,0.01272,0.00424,0

In my code, idx are indices into catalog that are the closest objects to each of the coordinates in c, sep2d are the on-sky distances between them. catalog_matches and c_matches prints out RA and DEC as columns where each row corresponds to a source. I am using a separation constraint because I know that no matches will be exact matches.

import numpy as np

my_csv1 = np.loadtxt(open("F435W.csv"), delimiter=",") #reading in first data set
my_csv2 = np.loadtxt(open("F550M.csv"), delimiter=",") #reading in second data set

from astropy.coordinates import SkyCoord
from astropy import units as u
from astropy.coordinates import match_coordinates_sky

c = SkyCoord(my_csv1[:, 12], my_csv1[:, 13], frame='icrs', unit='deg') 
catalog = SkyCoord(my_csv2[:, 12], my_csv2[:, 13], frame='icrs', unit='deg')

max_sep = 1.0*u.arcsec #maximum separation between values to be considered a match
idx, sep2d, _ = c.match_to_catalog_sky(catalog) #matching
sep_constraint = sep2d < max_sep
c_matches = c[sep_constraint] #matched RA and DEC values for F435W.csv
catalog_matches = catalog[idx[sep_constraint]] #matched RA and DEC values for F550M.csv

print (len(c_matches), len(catalog_matches)) #print lengths of the arrays containing the matched values
#lengths should be the same, and they are, so this works. How do I apply this to the rest of the data?