Wide-Field Imaging and Spectral Index Correction
Posted: Tue Nov 27, 2012 9:43 am
Hi All,
I have been reading over the forum and found a few interesting posts regarding the correction for the spectral index and primary beam over the 2GHz band.
Just to sum up and make sure I understand:
When creating a wide-field image with the 2GHz band one would follow these steps:
(0) Data has been cleaned and self-calibrated across the full band if required.
(1) Split your band up into subbands, i.e. make the data narrow band instead of wide band.
(2) Image the subbands separately and correct for the different resolution (convolving or using different robust parameter value) across the band.
(4) Use the task MFSPIN to determine the spectral index in each subband.
(5) Correct each subband image for the spectral index, i.e. adjust the flux to the centre of the subband.
(6) Put all subband images into LINMOS and correct for the primary beam.
Does this look reasonable?
Condon+ (2012) (http://adsabs.harvard.edu/abs/2012ApJ...758...23C) do something similar with EVLA data. They have one pointing in the 2 - 4 GHz band. Using equations 8 and 9 they correct for the spectral index and primary beam across the field of view. They use an average spectral index of -0.7 instead of using a result like what MIRIAD gives for MFCLEAN and MFSPIN.
Anyone have any thoughts or additional comments on wide-band wide-field imaging with CABB?
Cheers,
Julie
I have been reading over the forum and found a few interesting posts regarding the correction for the spectral index and primary beam over the 2GHz band.
Just to sum up and make sure I understand:
When creating a wide-field image with the 2GHz band one would follow these steps:
(0) Data has been cleaned and self-calibrated across the full band if required.
(1) Split your band up into subbands, i.e. make the data narrow band instead of wide band.
(2) Image the subbands separately and correct for the different resolution (convolving or using different robust parameter value) across the band.
(4) Use the task MFSPIN to determine the spectral index in each subband.
(5) Correct each subband image for the spectral index, i.e. adjust the flux to the centre of the subband.
(6) Put all subband images into LINMOS and correct for the primary beam.
Does this look reasonable?
Condon+ (2012) (http://adsabs.harvard.edu/abs/2012ApJ...758...23C) do something similar with EVLA data. They have one pointing in the 2 - 4 GHz band. Using equations 8 and 9 they correct for the spectral index and primary beam across the field of view. They use an average spectral index of -0.7 instead of using a result like what MIRIAD gives for MFCLEAN and MFSPIN.
Anyone have any thoughts or additional comments on wide-band wide-field imaging with CABB?
Cheers,
Julie