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.

For python 3.8.5+

• numpy
• scipy
• matplotlib
• astropy
• nvector
• geographiclib
• katpoint

For python 2.7, A docker instance is recommended, the content of Dockerfile list below:

FROM ubuntu:16.04

MAINTAINER Weiwei Chen [email protected]

RUN apt-get update && \
    apt-get --no-install-recommends -y install \
    wget python-pip python-setuptools python-wheel \
    build-essential python-dev python-scipy python-numpy \
    python-matplotlib python-astropy

RUN pip install 'nvector==0.7.0' 'pillow==4.0.0' WCSAxes geographiclib katpoint

Try Mosaic in your web browser here without installing anything.

To use offline, you can download the package, and import it in your code.

There is a helper script example/maketiling.py to demonstrate the interface of the package

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 30 --psf_plot psf.png --psf_fit 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 index 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 seconds, default is None which means it is determined by the code.

--size: the total number of pixels in the simulation, default is 400 which corresponds to a pattern of 20x20 in dimension.

--psf_plot: filename of the plot of the pattern, the file format can be anything that matplotlib supports, such as "jpeg, 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.

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_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 decide the size of the tiling
• "variable_ovelap": given a size of the tiling, the code decide 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, pdf".

--overlay_source: the file containing the point sources to overlay, one per line, in identification RA DEC format. for example: "A 13:26:39.670 -47:30:11.64"

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, 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 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-axis 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.

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 ds9

--tiling_region: the filename for the region file of the generated tiling which can be imported into ds9

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