Produce simulated time series data from a regrided ACSIS data cube
The output time series detector samples are created by interpolating the supplied input sky cubes at the position of the reference time series sample centre. Various interpolation methods can be used (see parameter INTERP).
The output time series cubes inherit all meta-data from the corresponding input reference
time series. The only thing modified is the values in the NDF "
Data"
array.
"
Linear"
– The output sample values are calculated by bi-linear interpolation among the four nearest
pixels values in the input sky cube. Produces smoother output NDFs than the nearest-neighbour
scheme, but is marginally slower.
"
Nearest"
– The output sample values are assigned the value of the single nearest input pixel. A very
fast method.
"
Sinc"
– Uses the sinc(pi$\ast $x)
kernel, where x is the pixel offset from the interpolation point and sinc(z)=sin(z)/z. Use of this scheme
is not recommended.
"
SincSinc"
– Uses the sinc(pi$\ast $x)sinc(k$\ast $pi$\ast $x)
kernel. A valuable general-purpose scheme, intermediate in its visual effect on NDFs between the
bi-linear and nearest-neighbour schemes.
"
SincCos"
– Uses the sinc(pi$\ast $x)cos(k$\ast $pi$\ast $x)
kernel. Gives similar results to the "
Sincsinc"
scheme.
"
SincGauss"
– Uses the sinc(pi$\ast $x)exp(-k$\ast $x$\ast $x)
kernel. Good results can be obtained by matching the FWHM of the envelope function to the
point-spread function of the input data (see parameter PARAMS).
"
Somb"
– Uses the somb(pi$\ast $x)
kernel, where x is the pixel offset from the interpolation point and
somb(z)=2$\ast $J1(z)/z
(J1 is the first-order Bessel function of the first kind). This scheme is similar to the "
Sinc"
scheme.
"
SombCos"
– Uses the somb(pi$\ast $x)cos(k$\ast $pi$\ast $x)
kernel. This scheme is similar to the "
SincCos"
scheme.
[current value]
PARAMS( 1 ) is required by all the above schemes. It is used to specify how many pixels are to contribute to the interpolated result on either side of the interpolation point in each dimension. Typically, a value of 2 is appropriate and the minimum allowed value is 1 (i.e. one pixel on each side). A value of zero or fewer indicates that a suitable number of pixels should be calculated automatically. [0]
PARAMS( 2 ) is required only by the SombCos, SincSinc, SincCos, and SincGauss schemes. For the SombCos, SincSinc, and SincCos schemes, it specifies the number of pixels at which the envelope of the function goes to zero. The minimum value is 1.0, and the run-time default value is 2.0. For the SincGauss scheme, it specifies the full-width at half-maximum (FWHM) of the Gaussian envelope. The minimum value is 0.1, and the run-time default is 1.0. Good results are often obtained by approximately matching the FWHM of the envelope function, given by PARAMS(2), to the point-spread function of the input data. []