Hi,
I'm having a problem with the Gaia isosurface widget and wondered if
anyone had any insights.
The problem actually relates to trying to overlay more than one
cube. Either cube can be loaded and viewed with the widget without any
obvious problems. However, when I try to overlay one upon the other I
cannot get the cubes to line up. At first I thought this was due to
the fact that the z-axis in one was velocity, while in the other it
was frequency. This should be easy enough for Gaia to deal with but to
eliminate this as a cause I converted the frequency cube to velocity.
The region of interest in the cube is at around -40 km/s, the first
cube I load up displays my ROI at this velocity. However, the second
gets placed far from here in the z-axis.
To try and counter this, I rewrote the fits headers so that the peak
of each cube was defined as being at 0 km/s. Now I can get the
isosurfaces to coincide in the z-direction but they are not aligned
well in RA and Dec.
Might this be due to differing pixel sizes in the two cubes? I made
them the same in the z-direction but it now appears that they don't
match in RA and Dec. I can overlay the cubes perfectly well in contour
images so don't think this is a mis-calibration or positional issue.
Is there a way of getting the two cubes to match so that they can be
displayed correctly.
I expect that this is to do with the way that the widget is handling
the cubes but just for reference, I'm running the development version
of gaia (4.4.1) on Snow Leopard 64 bit (10.6).
Cheers
Larry
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