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dear all,
i am faced with an important question about extracting 1D-spectum. i extracted several spectra from different parts of a galaxy in one slit. Except the core area, the continuum from other part of a galaxy is too weak to be traced, so when tracing, the RMS must be too large. i don't know what to do. Select "not tracing"? or else?
i think spetra in those parts shouldn't be traced but follow the tracing of spectrum from core area.
But what can i do?

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Center for Astrophysics University of Science and Technology of China Hefei, Anhui 230026, China

Hi,The approach you should take is to edit the apertures using the core tracing as the reference. In this mode you can shift the center by some amount or set the lower and upper edges (:lower, :upper or 'l' and 'u' keys (I think)) to something else. Then extract while turning the tracing off. For example is the aperture position and edges at the reference line/colum are something like256 324.3 -5 5You would change it to something like256 324.3 -35 -25 Yours,
Frank Valdes