# Montage Cookbook: Symbols

mViewer symbols are drawn using the same infrastructure that is used for coordinate grids and other sky drawing. So they can be of any scale and "track" the coordinate system they are drawn in. When drawn in pixel coordinates the look like basic 2D graphics (click on the command text to display the resultant image): mViewer \ -ct 0 \ -color gray \ -grid equatorial \ -color yellow \ -symbol 7. polygon 3 -mark 100p 100p \ -symbol 7. starred 3 -mark 200p 100p \ -symbol 7. skeletal 3 -mark 300p 100p \ -symbol 7. polygon 4 -mark 100p 200p \ -symbol 7. starred 4 -mark 200p 200p \ -symbol 7. skeletal 4 -mark 300p 200p \ -symbol 7. polygon 5 -mark 100p 300p \ -symbol 7. starred 5 -mark 200p 300p \ -symbol 7. skeletal 5 -mark 300p 300p \ -symbol 7. polygon 6 -mark 100p 400p \ -symbol 7. starred 6 -mark 200p 400p \ -symbol 7. skeletal 6 -mark 300p 400p \ -symbol 7. polygon 7 -mark 100p 500p \ -symbol 7. starred 7 -mark 200p 500p \ -symbol 7. skeletal 7 -mark 300p 500p \ -symbol 7. polygon 8 -mark 100p 600p \ -symbol 7. starred 8 -mark 200p 600p \ -symbol 7. skeletal 8 -mark 300p 600p \ -symbol 7. polygon 9 -mark 100p 700p \ -symbol 7. starred 9 -mark 200p 700p \ -symbol 7. skeletal 9 -mark 300p 700p \ -symbol 17. compass -mark 200p 900p \ -symbol 7. box -mark 300p 900p \ -color ff9090 \ -symbol 0.25 circle -mark 1000p 1000p \ -symbol 0.50 circle -mark 1000p 987p \ -symbol 1.00 circle -mark 1000p 975p \ -symbol 2.00 circle -mark 1000p 950p \ -symbol 4.00 circle -mark 1000p 900p \ -symbol 8.00 circle -mark 1000p 825p \ -symbol 16.00 circle -mark 1000p 700p \ -symbol 32.00 circle -mark 1000p 500p \ -gray SDSS_r.fits -1s max gaussian-log \ -png symbolsSDSS.png But when the same symbols are drawn on the sky, they become part of it: mViewer \ -ct 0 \ -color c08080 \ -grid galactic \ -csys galactic \ -color yellow \ -symbol 3. polygon 3 -mark 210 -45 \ -symbol 3. starred 3 -mark 240 -45 \ -symbol 3. skeletal 3 -mark 270 -45 \ -symbol 3. polygon 4 -mark 210 -30 \ -symbol 3. starred 4 -mark 240 -30 \ -symbol 3. skeletal 4 -mark 270 -30 \ -symbol 3. polygon 5 -mark 210 -15 \ -symbol 3. starred 5 -mark 240 -15 \ -symbol 3. skeletal 5 -mark 270 -15 \ -symbol 3. polygon 6 -mark 210 00 \ -symbol 3. starred 6 -mark 240 00 \ -symbol 3. skeletal 6 -mark 270 00 \ -symbol 3. polygon 7 -mark 210 15 \ -symbol 3. starred 7 -mark 240 15 \ -symbol 3. skeletal 7 -mark 270 15 \ -symbol 3. polygon 8 -mark 210 30 \ -symbol 3. starred 8 -mark 240 30 \ -symbol 3. skeletal 8 -mark 270 30 \ -symbol 3. polygon 9 -mark 210 45 \ -symbol 3. starred 9 -mark 240 45 \ -symbol 3. skeletal 9 -mark 270 45 \ -symbol 15. compass -mark 240 60 \ -symbol 3. box -mark 270 60 \ -color green \ -symbol 30. starred 5 -mark 0 0 \ -gray equatorial.fits -1s max gaussian-log \ -png symbolsAllsky.png Pulling coordinates from a catalog, we can display any of the above symbols at each location: mViewer \ -ct 0 \ -color yellow \ -symbol 3. circle \ -catalog tbl/fp_2mass.tbl \ -gray fits/SDSS_r.fits -1s max gaussian-log \ -png circleSymbol.png But this gives an inaccurate view of the sky, overemphasizing the large number of dim sources. It is better to scale the symbols by the brightness of the source (here computed from one of the magnitude columns (2MASS J): mViewer \ -ct 0 \ -color yellow \ -symbol 1. circle \ -scalecol j_m 17 mag \ -catalog tbl/fp_2mass.tbl \ -gray fits/SDSS_r.fits -1s max gaussian-log \ -png scaledSymbol.png Another take on the data shows some other parameter as the color of the symbol. Here, the J-K 2MASS astronomical color has been converted into an RGB color. The transform could use any of the 16-million colors available; we have opted for the 512 colors on the B->G->R primary lines (points with J magnitude but no J-K color are shown in white): mViewer \ -ct 0 \ -color yellow \ -symbol 3. circle \ -colorcol color \ -catalog tbl/fp_2mass.tbl \ -gray fits/SDSS_r.fits -1s max gaussian-log \ -png colorSymbol.png Of course, there nothing preventing us from combining the size and color information: mViewer \ -ct 0 \ -color yellow \ -symbol 1. circle \ -scalecol j_m 17 mag \ -colorcol color \ -catalog tbl/fp_2mass.tbl \ -gray fits/SDSS_r.fits -1s max gaussian-log \ -png scaledColorSymbol.png This could be taken further, with shape representing some other parameter. This would make sense if there were a relatively small set to choose from (like galaxies vs. stars) but otherwise gets too busy. | Data: SDSS_r.fits, allsky.fits, fp_2mass.tbl