A software package consists of an interferometric pattern simulator and characterizer, an optimized tiling generator and a beamforming weights calculator. This document only describes the package from version 1.0.0. Try Mosaic in your web browser here.
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Try Mosaic in your web browser here without installing anything.
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Use Mosaic with Docker:
docker pull ghcr.io/wchenastro/mosaic:stable
- To use Mosaic as a library, install the package via pip:
pip3 install git+https://github.com/wchenastro/mosaic.git
There is a helper script example/maketiling.py to demonstrate the interface of the package. An example of antenna coordinate file is provided here in katpoint format and in geographic coordinates. If the geographic coordinates are used, the parameter --antenna_coordinate_type should be set to geo.
python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 06:02:13.663903 --verbose --subarray 000, 001, 002:0.7, 003:0.5+0.1j \
--size 900 --resolution 40 --psf_plot psf.png --psf_fit psf.fits --weight
with Docker:
docker run -v $PWD:/root --rm -it ghcr.io/wchenastro/mosaic:stable --ants /root/antenna.csv \
--freq 1.284e9 --source 00:24:05.67 -72:04:52.60 --datetime 2020.05.02 06:02:13.663903 \
--verbose --subarray 000, 001, 002:0.7, 003:0.5+0.1j --size 900 --resolution 40 \
--psf_plot /root/psf.png --psf_fit /root/psf.fits --weight
--ants: the file containing the antenna specification.
--freq: the frequency at which the interferometric pattern is simulated (Hz).
--source: the equatorial coordinates of the source in hh:mm:ss.s dd:mm:ss.s format.
--datetime: the date and time of the observation in UTC and in yyyy.mm.dd hh:mm:ss.s format.
--subarray: a list of indexes for selection of antennas in the file specified by --ants. Optional scale or complex weight can be attached after each antenna index separated by a colon.
--resolution: the scale of one single pixel in the pattern in arc seconds; the default is None which means it is determined by the code.
--size: the total number of pixels in the simulation; the default is 400, which corresponds to a pattern of 20x20 in dimension.
--field: the side length of the field of view in sexagesimal units, such as 60s or 20m or 1d, default is None. --resolution, --size and --field can not be used all together; it can be a combination of any two.
--psf_plot: filename of the plot of the pattern; the file format can be anything that matplotlib supports, such as "jpeg" or "pdf".
--psf_fits: filename of the fits file of the pattern
--weight: a switch for individual weight for each antenna; the weight values in --subarray will not be effective without this argument.
--verbose: print logs containing the input parameter and result; the input parameter listed in the log should reproduce the same result.
Example output:
python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 06:02:13.663903 --beamnum 400 --verbose --overlap 0.7 \
--subarray 000, 017, 036, 038, 041, 043, 044 --tiling_method variable_size \
--tiling_shape circle --tiling_plot tiling.png --overlay_source overlay_sources
--beamnum: the requesting beam number in the tiling; the actual number in the generated tiling is less than or equal to this number. The default is 400.
--tiling_method: the method to use for generating the tiling; possible values are:
- "
variable_size": given an overlap ratio, the code decides the size of the tiling - "
variable_ovelap": given a size of the tiling, the code decides the overlap between the beams.
--overlap: The beams in the tiling overlap with each other in their power levels equal to this ratio, only available in the "variable_size" method. The default is 0.5.
--tiling_shape: the shape of the tiling boundaries; possible values are: "circle", "hexagon", "ellipse", "polygon", "annulus". The "variable_size" method only supports the first two shapes.
--tiling_plot: the filename for the plot of the tiling; the file format can be anything that matplotlib supports, such as "jpeg" or "pdf".
--overlay_source: the file containing the point sources to overlay, one per line, in identification RA DEC format. For example: "C 00:23:50.3546 -72:04:31.5048"
Example output:
Generate an elliptical shape tiling, let the code decide a suitable overlap and output the coordinates
python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 06:02:13.663903 --beamnum 400 --verbose --subarray 000, 001, 002, 003 \
--tiling_method variable_overlap --tiling_shape ellipse --tiling_parameter 0.07 0.05 45 \
--tiling_plot tiling.png --tiling_coordinate coordinate.csv
--tiling_coordinate: the filename for the equatorial coordinates in degrees.
--tiling_parameter_coordinate_type: the coordinate type of the parameter; the default is image coordinate.
--tiling_parameter: the parameter of the tiling, for example:
- "
--tiling_shape circle --tiling_parameter 0.05": a circular shape tiling with a radius of 0.05 degree - "
--tiling_shape hexagon --tiling_parameter 0.07 45": a hexagonal shape tiling with its circumradius and orientation in degrees - "
--tiling_shape ellipse --tiling_parameter 0.07 0.05 45": an elliptical shape tiling with its two semi-axes and orientation in degrees - "
--tiling_shape polygon --tiling_parameter 6.1522476, -72.0506681, 5.9448280, -72.0557907, 5.8695621, -72.0879815, 6.0670744, -72.1139826": a polygonal shape tiling with its vertices in "RA1, DEC1, RA2, DEC2, RA3, DEC3" format.
Example output:
Generate a polygon shape tiling using a boundary region file and generate a region file for all the beams
python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 06:02:13.663903 --beamnum 400 --verbose --overlap 0.7 \
--subarray 000, 001, 002, 003 --tiling_method variable_overlap --tiling_shape polygon \
--tiling_parameter_file polygon.reg --tiling_region tiling.reg
--tiling_parameter_file: the filename of the polygon boundary region file from SAOImage DS9
--tiling_region: the filename for the region file of the generated tiling which can be imported into DS9
Example:
| Create a region in DS9 | Create a tiling within the region |
|---|---|
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python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 06:02:13.663903 --beamnum 400 --verbose --subarray 000, 001, 002, 003 \
--tiling_method variable_overlap --tiling_shape annulus --tiling_parameter \
polygon 9.00,-72.5,8.5,-71.2,3,-71.5,2,-73:ellipse 0.4 0.6 100 --tiling_plot tiling.png \
--tiling_coordinate coordinate.csv
--tiling_parameter polygon 9.00,-72.5,8.5,-71.2,3,-71.5,2,-73:ellipse 0.4 0.6 100: an annulus shape with a polygon as the outer boundary and an ellipse as the inner boundary. The parameters of outer and inner boundaries are separated with an ":"; each set of parameters starts with the name of the shape. Currently, only boundaries of polygon and ellipse shapes are supported. If the vectors of the polygon are provided by a file, then it can be specified as --tiling_parameter polygon:ellipse 0.4 0.6 100 --tiling_parameter_file polygon.reg
Example:
python3 ./maketiling.py --ants antenna.csv --freq 1.284e9 --source 00:24:05.67 -72:04:52.60 \
--datetime 2020.05.02 14:02:13.663903 --flag_sidelobe --verbose \
--subarray 000, 062, 063 --psf_plot psf.png
--flag_sidelobe: flag and excludethe sidelobes during the fitting of the beam shape. This option is useful when the presence of the sidelobes is prominent, probabilly due to the number of antennas is rather low or the UV coverage is not even. It masks out sidelobes and preserves only the main beam for fitting.
Example:
| Incorrect fit due to sidelobes | Exclusion of sidelobes |
|---|---|
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