Convolution Kernels

Spitzer IRAC/MIPS and Herschel SPIRE/PACS

!!!To Lower Resolution Only!!!

Karl D. Gordon (kgordon@stsci.edu)


Updates:

These kernels are available for use by anyone for anything, but no guaranty as to their accuracy is given. Use at your own risk! Comments are welcome and appreciated.

I have written an IDL program (conv_image, also need change_image_scale and ensure_psf_centered) which I use to do the convolutions. This code handles different pixel sizes and tries to keep the header updated. Feedback is appreciated. Use at your own risk.


Convolution kernels which convert a higher resolution Spitzer(IRAC/MIPS) or Herschel(PACS/SPIRE) PSF to lower resolution PSF are given here. There kernels were created using a Fourier technique which requires a certain fiddling to get good results. While these kernels are approximate as a result, they should give quite good results. Not all of them have been extensively tested. Feedback to Karl Gordon (kgordon@stsci.edu) is appreciated. If you use these kernels in a paper, please reference Gordon et al. (2008, ApJ, 682, 336).

Spitzer IRAC/MIPS

The MIPS PSFs were generated from STinyTim and show variation with assumed blackbody temperature. In general, the MIPS PSFs generated for 100K seem to work well. The IRAC PSFs are from observations (see Spitzer website) and so don't vary with temperature.

Herschel PACS/SPIRE

The PACS/SPIRE PSF should probably be considered somewhat preliminary and will likely be updated at least once more (after additional work comparing observations to models). Currently the PACS PSFs are generated from models and downloaded from the NASA/Herschel website (slope-1 used). The SPIRE PSFs are the theoretical versions and are downloaded from here.

Kernels

IRAC/MIPS kernels for other MIPS temperatures:

Images of Kernels to Spitzer IRAC/MIPS PSFs

The sizes of the displayed images of the PSFs/kernels below is based on the FOV of the to and from PSF. The number given with the band is the FWHM of the PSF.

To PSF
From PSF IRAC 4.5
1.7"
IRAC 5.8
1.7"
IRAC 8.0
1.9"
MIPS 24
6"
MIPS 70
18"
MIPS 160
38"
IRAC 3.6
1.7"
IRAC 4.5
1.7"
IRAC 5.8
1.9"
IRAC 8.0
2.0"
MIPS 24
6"
MIPS 70
18"

Images of Kernels to Herschel SPIRE/PACs PSFs

The sizes of the displayed images of the PSFs/kernels below is based on the FOV of the to and from PSF. The number given with the band is the FWHM of the PSF. For cases where the to PSF FWHM is much larger (i.e. around 10x) than the from PSF FWHM, then the to PSF can be used as the convolution kernel.

To PSF
From PSF PACS 70
5.2"
PACS 100
7.7"
PACS 160
12"
MIPS 70
18"
SPIRE 250
18"
SPIRE 350
25"
SPIRE 500
37"
MIPS 160
38"
IRAC 3.6
1.7"
IRAC 4.5
1.7"
IRAC 5.8
1.9"
IRAC 8.0
2.0"
MIPS 24
6"
PACS 70
5.2"
MIPS 70
18"
PACS 100
7.7"
PACS 160
12"
SPIRE 250
18"
SPIRE 350
25"

Karl D. Gordon