astro: Astronomy Functions, Tools and Routines for R

sls = function(n, alpha = 1){
    
    # source: http://soliton.vm.bytemark.co.uk/pub/cpt-city/ds9/
    # red
    vred = c(0, 0.04314, 0.08627, 0.12941, 0.17255, 0.21569, 0.25882, 0.30588, 0.34902, 0.39216, 0.43529, 0.47843, 0.52157, 0.50588, 0.49412, 0.47843, 0.46275, 0.44706, 0.43529, 0.41961, 0.40392, 0.39216, 0.37647, 0.36078, 0.3451, 0.31765, 0.2902, 0.25882, 0.23137, 0.20392, 0.17255, 0.1451, 0.11373, 0.08627, 0.05882, 0.02745, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.03137, 0.06667, 0.09804, 0.13333, 0.16471, 0.2, 0.23137, 0.26667, 0.29804, 0.33333, 0.36471, 0.39608, 0.43137, 0.46275, 0.49804, 0.52941, 0.56471, 0.59608, 0.62745, 0.66275, 0.69412, 0.72941, 0.76078, 0.79216, 0.81176, 0.82745, 0.84314, 0.86275, 0.87843, 0.89804, 0.91373, 0.92941, 0.94902, 0.96471, 0.98431, 1, 0.99608, 0.99216, 0.98824, 0.98431, 0.98039, 0.97255, 0.96863, 0.96471, 0.96078, 0.95686, 0.95294, 0.94902, 0.95294, 0.95686, 0.96078, 0.96471, 0.96863, 0.97255, 0.98039, 0.98431, 0.98824, 0.99216, 0.99608, 1, 1, 0.99608, 0.99608, 0.99216, 0.99216, 0.98824, 0.98824, 0.98824, 0.98431, 0.98431, 0.98039, 0.98039, 0.95686, 0.93333, 0.90588, 0.88235, 0.85882, 0.83529, 0.81176, 0.78824, 0.76078, 0.73725, 0.71373, 0.6902, 0.71765, 0.74118, 0.76863, 0.79216, 0.81961, 0.84314, 0.87059, 0.89804, 0.92157, 0.94902, 0.97255, 1, 1, 1, 1, 1, 1, 1, 1)
    # green
    vgreen = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.01961, 0.03922, 0.05882, 0.07843, 0.09804, 0.11765, 0.13725, 0.15686, 0.17647, 0.2, 0.21961, 0.23922, 0.26667, 0.29804, 0.32941, 0.36078, 0.39216, 0.42353, 0.45098, 0.48235, 0.51373, 0.5451, 0.57647, 0.60784, 0.63137, 0.65882, 0.68235, 0.70588, 0.73333, 0.75686, 0.78431, 0.80784, 0.83137, 0.85882, 0.88235, 0.9098, 0.90196, 0.89412, 0.8902, 0.88235, 0.87843, 0.87059, 0.86275, 0.85882, 0.85098, 0.84706, 0.83922, 0.83137, 0.83137, 0.83137, 0.83137, 0.83137, 0.83137, 0.83137, 0.83137, 0.83137, 0.82745, 0.82745, 0.82745, 0.82745, 0.83529, 0.83922, 0.84706, 0.85098, 0.85882, 0.86667, 0.87059, 0.87843, 0.88235, 0.8902, 0.89412, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.90196, 0.89804, 0.89412, 0.88627, 0.88235, 0.87843, 0.87451, 0.86667, 0.86275, 0.85882, 0.8549, 0.84706, 0.84314, 0.82353, 0.80784, 0.78824, 0.76863, 0.74902, 0.72941, 0.71373, 0.69412, 0.67451, 0.6549, 0.63922, 0.61961, 0.6, 0.58039, 0.56471, 0.5451, 0.52549, 0.50588, 0.4902, 0.47059, 0.45098, 0.43137, 0.41176, 0.39608, 0.36078, 0.32941, 0.29804, 0.26275, 0.23137, 0.19608, 0.16471, 0.13333, 0.09804, 0.06667, 0.03137, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.08235, 0.16863, 0.25098, 0.33333, 0.41569, 0.50196, 0.58431, 0.66667, 0.74902, 0.83137, 0.91765, 1, 1, 1, 1, 1, 1, 1, 1)
    # blue
    vblue = c(0, 0.05098, 0.10588, 0.15686, 0.21176, 0.26275, 0.31765, 0.36863, 0.42353, 0.47451, 0.52941, 0.58039, 0.63529, 0.63922, 0.64706, 0.65098, 0.65882, 0.66275, 0.66667, 0.67451, 0.67843, 0.68627, 0.6902, 0.69804, 0.70196, 0.71373, 0.72157, 0.73333, 0.74118, 0.75294, 0.76471, 0.77255, 0.78431, 0.79216, 0.80392, 0.81569, 0.82353, 0.83922, 0.8549, 0.86667, 0.88235, 0.89804, 0.91373, 0.92549, 0.94118, 0.95686, 0.97255, 0.98431, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0.97647, 0.94902, 0.92549, 0.90196, 0.87843, 0.85098, 0.82745, 0.80392, 0.77647, 0.75294, 0.72941, 0.70196, 0.67843, 0.65098, 0.62353, 0.59608, 0.56863, 0.54118, 0.51373, 0.48627, 0.46275, 0.43529, 0.40784, 0.38039, 0.35294, 0.32941, 0.30196, 0.27843, 0.25098, 0.22745, 0.2, 0.17647, 0.14902, 0.12549, 0.09804, 0.07451, 0.06667, 0.05882, 0.0549, 0.04706, 0.04314, 0.03529, 0.03137, 0.02353, 0.01961, 0.01176, 0.00784, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.00392, 0.00784, 0.01176, 0.01569, 0.01961, 0.02353, 0.02745, 0.03137, 0.03529, 0.03922, 0.04314, 0.04706, 0.05098, 0.0549, 0.05882, 0.06275, 0.06667, 0.07059, 0.07451, 0.07843, 0.08235, 0.08627, 0.0902, 0.09412, 0.08627, 0.07843, 0.07059, 0.06275, 0.0549, 0.04706, 0.03922, 0.03137, 0.02353, 0.01569, 0.00784, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0.08235, 0.16863, 0.25098, 0.33333, 0.41569, 0.50196, 0.58431, 0.66667, 0.74902, 0.83137, 0.91765, 1, 1, 1, 1, 1, 1, 1, 1)
    
    # create color palette
    cp = colorRampPalette(rgb(vred,vgreen,vblue))
    
    # create colours
    slscol = rgb(t(rbind(col2rgb(cp(n))/255)), alpha=alpha)
    return(slscol)
    
}