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Can any one tell how to check whether the dispersion axis is along line or along column ?

If this is an IRAF-reduced image you can check the image header for the DISPAXIS keyword (1=along lines, 2=along columns). For unreduced data you would simply display the image to see which way the data run, and then set the 'dispaxis' package parameter for the APEXTRACT or LONGSLIT package you will be using. If the DISPAXIS keyword is set in the image header it will be used when processing.

No for example , in my raw spectroscopic image if slit is along x axis of ds9 so dispersion axis is weather along line or column and if slit is along y-axis of ds9 ,so in which direction is it? With slit i mean if we open image in ds9 it is showing a horizontal or vertical line (along x or y axis respectively). So looking those horizontal or vertical lines in ds9 can we get an idea of dispersion axis of being along line or column???

If you display the image and the lines run left-to-right, the dispersion is on the X-axis, i.e. dispaxis=1.