Wide-band, wide-field imaging
Posted: Tue Feb 12, 2013 12:23 pm
Hi,
I have been thinking about how best to image some wide-band CABB data. I am using 800-MHz of data, from 1350 to 2150 MHz. I have many pointings which I need to combine to form a mosaic. To improve the accuracy of the primary beam correction, I have decided to split the band into 4 sub-bands so that a different primary beam model can be used for each sub-band.
One disadvantage with this is that it is harder to clean the individual sub-bands because of the poorer sensitivity and uv-coverage. I thought a better strategy would be to image the entire 800-MHz band and generate a model using mfclean, then somehow use that model to produce images of the separate sub-bands. I am not sure whether it is possible to this in Miriad.
One thing I tried is this: I imaged the whole 800-GHz band and generated a model using mfclean. I then imaged the sub-bands separately using the model I obtained for the whole band as an initial model of the deconvolved image. I wasn't able to do this as Miriad complained that the reference pixel values differ. I am guessing that this is because the reference frequency of the model differs from that of the dirty map and beam. I didn't think this would matter because I thought that Miriad would be able to generate the model for the required frequency range from the model of the 800-GHz band.
I was wondering what your thoughts are on this and if there is a better way of proceeding rather than just imaging and cleaning each sub-band separately.
Thanks
Tom
I have been thinking about how best to image some wide-band CABB data. I am using 800-MHz of data, from 1350 to 2150 MHz. I have many pointings which I need to combine to form a mosaic. To improve the accuracy of the primary beam correction, I have decided to split the band into 4 sub-bands so that a different primary beam model can be used for each sub-band.
One disadvantage with this is that it is harder to clean the individual sub-bands because of the poorer sensitivity and uv-coverage. I thought a better strategy would be to image the entire 800-MHz band and generate a model using mfclean, then somehow use that model to produce images of the separate sub-bands. I am not sure whether it is possible to this in Miriad.
One thing I tried is this: I imaged the whole 800-GHz band and generated a model using mfclean. I then imaged the sub-bands separately using the model I obtained for the whole band as an initial model of the deconvolved image. I wasn't able to do this as Miriad complained that the reference pixel values differ. I am guessing that this is because the reference frequency of the model differs from that of the dirty map and beam. I didn't think this would matter because I thought that Miriad would be able to generate the model for the required frequency range from the model of the 800-GHz band.
I was wondering what your thoughts are on this and if there is a better way of proceeding rather than just imaging and cleaning each sub-band separately.
Thanks
Tom