While the most common RGB images are slices in energy, any 3 images can be combined into an RGB image.
In this example I create a 3D cube with: SKY X,Y vs. TIME.
download_chandra_obsid 635 evt2
dmcopy "acisf00635N004_evt2.fits.gz[x=2800:6350,y=2890:5820][bin sky=6,time=::#3]" time.cube clob+
cd RGB
dmlist time.cube cols
-------------------------------------------------------------------------------- Columns for Image Block EVENTS_IMAGE -------------------------------------------------------------------------------- ColNo Name Unit Type Range 1 EVENTS_IMAGE[592,489,3] Int2(592x489x3) - -------------------------------------------------------------------------------- Physical Axis Transforms for Image Block EVENTS_IMAGE -------------------------------------------------------------------------------- Group# Axis# 1 1,2 sky(x) = (+2799.50) +(+6.0)* ((#1)-(+0.50)) (y) (+2889.50) (+6.0) ((#2) (+0.50)) 2 3 time = +72039163.853747 [s] +33992.5334 * (#3 -0.50) -------------------------------------------------------------------------------- World Coordinate Axis Transforms for Image Block EVENTS_IMAGE -------------------------------------------------------------------------------- Group# Axis# 1 1,2 EQPOS(RA ) = (+246.8247)[deg] +TAN[(-0.000136667)* (sky(x)-(+4096.50))] (DEC) (-24.5734 ) (+0.000136667) ( (y) (+4096.50))
ds9 -frame delete -scale log -rgbcube time.cube &
[1] 30861
import -window "SAOImage ds9" ds9_05_rgb_04.png
display < ds9_05_rgb_04.png
xpaset -p ds9 quit
[1]+ Done ds9 -frame delete -scale log -rgbcube time.cube