NAME:
wfc3model
PURPOSE: (one line)
Generate synthetic PSF images for the HST WFC3 UVIS Camera.
DESCRIPTION:
A generated PSF is added to the output array. If the array is not
defined, it is created with dimensions 4096 by 2048. Successive calls
will add objects (PSF's) to the array.
CATEGORY:
CCD data processing
CALLING SEQUENCE:
wfc3model, chip, xsrc, ysrc, inten, filter, bmvnum, back, image
INPUTS:
chip : CCD number (1 or 2) for UVIS1 or UVIS2, use 3 for IR channel
xsrc, ysrc : Position of the PSF in the output array.
inten : Intensity of PSF relative to TinyTim output PSF
filter : Filter name in the form Fxxx(W,LP,M,N).
bmvnum : B-V list value (TinyTim V7.0 values):
BMVNUM TYPE B-V
1 O5 -0.34
2 O8F -0.32
3 O6 -0.31
4 B1V -0.27
5 B3V -0.21
6 B6V -0.12
7 A0V -0.04
8 A5V 0.12
9 F6V 0.37
10 F8V 0.48
11 G2V 0.56
12 G5V 0.66
13 G8V 0.75
14 K4V 0.92
15 K7V 1.28
16 M1.5V 1.45
17 M3V 1.44
This can be a scalar to be applied to all objects or it can
be a vector but the length must match xsrc,ysrc,inten
back : Background to be added.
KEYWORD PARAMETERS:
; DISTORT : If set the input x,y are taken to be in an undistorted reference
; plane. They will be converted to the instrumental (distorted)
; frame before generating the psf's for the model image, which is
; in distorted space as always.
GRID : Grid spacing for psf files.
HSTPATH : Alternate path for HST PSF's.
JITTER : If set contains the gaussian smearing to apply to the image.
This number set the 1/e half width of the jitter in pixels.
If not set, no smearing is applied. This calculation is done
in double precision or float according to the type of image.
The values passed to the exp function
( e - (((x/j)^2 + y/j)^2/2) )
are restricted to a maximum based on the computational
precision to avoid floating point underflow.
Another option is to provide a jitter kernel externally. This
allows being a bit more creative and handling something like
a smearing funciton.
NEW : If set, clears the output array to zeros before building the
PSF image(s).
OBJRAD : Radius of object in pixels. If not set, assumed to be a point
source. If set and radius is greater than 0.5, then PSF is
convolved with a circular function of this radius. This models
the object as a Lambert disk, crude but useful for barely
resolved objects. Keep in mind that this is absolutely wrong
for objects that are clearly resolved.
PSFSIZE : Size of requested PSF, in arcseconds (default: 5).
VERBOSE : If set, prints informational message.
XSIZE : size of output array to generate, default full image
YSIZE : size of output array to generate, default full image
XOFFSET : X offset to apply to input coordinates to convert to absolute
chip values (used if you only want to compute a sub-array)
YOFFSET : Y offset to apply to input coordinates to convert to absolute
chip values (used if you only want to compute a sub-array)
Z4 : setting for fourth (focus) Zernicke coefficient (default=0).
OUTPUTS:
image : The image array into which the PSF is placed.
COMMON BLOCKS:
SIDE EFFECTS:
RESTRICTIONS:
PROCEDURE:
The Tiny Tim programs are used, via the procedure HSTPSF, to generate
a distorted PSF at the nearest grid location to the
requested position. (This grid and default spacing are defined in hstpsf).
MODIFICATION HISTORY:
Cloned from pc2model.pro,
Written by Marc W. Buie, Southwest Research Institute, 2009/09/01
2011/03/22, MWB, added IR camera support, added XSIZE/YSIZE keywords
2014/07/08, MWB, added new option for input jitter/smearing kernel
2014/09/23, MWB, reversed jitter kernel for true convolution
2017/05/26, MWB, added a kludge to prevent pasting kernel out of bounds