Program: SLICE Purpose: Make a slice through a set Category: MANIPULATION, COORDINATES, HEADER, PLOTTING File: slice.c Author: M.G.R. Vogelaar Keywords: INSET= Give set, subsets: Maximum number of subsets is 4096. Dimension of the subsets must be 2. POSITION= Give central position: [0,0] ANGLE= Give angle (deg), w.r.t North towards the East: GRIDOUT= New grid spacing of [spacing in longitude] rotated axis: POINTS= Give number of pixels on rotated axis: [Number of pixels on longitude axis] SLICES= Number of slices above and below slice [0,0] through new projection centre. Total number of slices cannot exceed 256. SPACE= Spacing between slices: [grid spacing in latitude] OUTSET= Give output set: PLOT= Create plot of slice? Y/[N] If you want to now how the slices are orientated in your box, select PLOT=Y. A box is plotted and labeled and the slices in the first subset are displayed. The following keywords can be specified now: PGPLOT keywords: GRDEVICE= Plot device: [List of devices] Destination of plot, Screen or Hardcopy. PGMOSAIC= View surface sub divisions in x,y: [1,1] View surface can contain a number of plots in in X and Y direction (mosaic). Default is 1 plot in both X- and Y direction. PGPAPER= Give width(cm), aspect ratio: [calc, calc] Aspect ratio is height/width. PGBOX= Corners of box Xl,Yl,Xh,Yh: [default by application] It is possible to overrule the calculated PGPLOT box size with PGBOX=. The coordinates (x,y) of the lower point are given first. ** PGCOLOR= Give color 1..15: [1] See description for the available colors. ** PGWIDTH= Give line width 1..21: [2] ** PGHEIGHT= Give character height: [1.0] ** PGFONT= Give font 1..4: [2] ** PGSYMBOL= Give symbol number 0..127: [1] Description: The program SLICE allows you to extract a plane from a data set (INSET=) under an arbitrary angle. The extracted plane is stored in an output set (OUTSET=) that has the same axis structure as the input set. The subsets you define in the input must be two dimensional and must have two spatial axes. The number of subsets determine the length of the third axis in the output (usually the spectral axis) and must be less than 4096. You can think of the output as a set where the longitude axis originates from a rotated and/or shifted axis in the input set. The number of pixels in the latitude direction depends on the number of parallel slices you want to extract. In order to view for example a LV plane in GIDS you specify something like: VIEW INSET=M8320SLICE d 0 The central position (POSITION=) is used to determine the position of the rotation centre. The positions can be prefixed (according to the documentation of dcdpos.dc3). For example, if you want the new central position in input pixel coordinates (-10.680130, -8.700096) and position (0,0) in your input corresponds to the physical coordinates 198.468100, 46.002610 deg. you specify: POSITION=-10.680130 -8.700096 (pixels) or: POSITION= U 198.493667 U 45.983306 (deg, deg) or: POSITION= * 13 13 58.48 * 45 58 59.90 (hms, dms) The position angle of the major axis of a galaxy is defined as the angle taken in anti-clockwise direction between the north direction in the sky and the major axis of the receding half of that galaxy (Rots 1975) astron, astrophys 45, 43. If you want a slice through this galaxy specify ANGLE= The program takes care of the fact that your original latitude axis perhaps does not align with the north. POINTS= gives the number of pixels on the rotated axis and the value in GRIDOUT= determines which pixels of the input are taken into account. If your new spacing exceeds a certain value, it will be possible that pixels are examined outside the input frame. The program substitudes blanks for these positions. Parallel slices (in real space) can be constructed if you specify SLICES= The default is no extra slices. If SLICES=n, m you get slices n pixels below and m output pixels above the central slice. The grid spacing of these output pixels are given in SPACE= Color indices: 0 Background 1 Default (Black if background is white) 2 Red 3 Green 4 Blue 5 Cyan 6 Magenta 7 Yellow 8 Orange 7 Yellow 8 Orange 9 Green + Yellow 10 Green + Cyan 11 Blue + Cyan 12 Blue + Magenta 13 Red + Magenta 14 Dark Gray 15 Light Gray 16-255 Undefined Available fonts: 1 single stroke "normal" font 2 roman font 3 italic font 4 script font Notes: If Hermes is in TEST MODE, there is extra output to the screen about properties of all axes in the input set. Example: Updates: Sep 12, 1991: VOG, Document created. Apr 12, 1995: VOG, removed extra 'PGLAB' code. Apr 09, 2009: VOG, Added offsets to grids from proco. Finally all plots show slices through the selected origin, even for CRPIX values that end on 0.5