A note on generating tutorial outputs

All the tutorial outputs along with the entire documentation can be generated locally from the source code as shown below:

$ git clone https://github.com/iniyannatarajan/Anime.jl.git
$ cd Anime.jl
$ julia --project=docs/
(docs) pkg> instantiate
(docs) pkg> dev .
julia> include("docs/make.jl")

The outputs are generated in the docs/build directory.

Creating data sets

Anime uses the CASA Measurement Set (MS) data format as on-disk storage format from which data are read and written back to. Conversion to and from the more traditional uvfits format is also supported. While there is no standard modern data format yet for storing VLBI data, support for a handful of commonly used data formats will be made available.

Assuming Anime is installed and the necessary dependencies are met, the following code snippets demonstrate how to create an MS from scratch and from an existing uvfits file. We load Anime first.

using Anime

The python casatasks and casatools modules can sometimes refuse to load, raising a segmentation fault. These modules are necessary for synthetic data generation from scratch. In such cases, an alternative approach is to include the module directly by typing include("path/to/Anime.jl/src/Anime.jl") in the REPL. This will load the module without the need to call using Anime.

In manual mode

In manual mode, the function createmsfromconfig is used to create an MS from scratch, with the observation and site parameters passed as arguments. The casatools python library is used under the hood. In the following, replace relativepath with the path to the source code of Anime.jl which contains sample input files under inputs/.

obsconfig = Dict()
obsconfig["msname"] = "eht.ms"
obsconfig["mode"] = "manual"
obsconfig["stations"] = joinpath(relativepath, "inputs", "eht_2017.stations")
obsconfig["casaanttemplate"] = joinpath(relativepath, "inputs", "antenna_table.template")
obsconfig["spw"] = Dict()
obsconfig["spw"]["centrefreq"] = [229.0e9]
obsconfig["spw"]["bandwidth"] = [2.0e9]
obsconfig["spw"]["channels"] = [32]
obsconfig["source"] = Dict{String, Any}("M87" => Dict{String, String}("RA"=>"12h30m49.42", "Dec"=>"+12.23.28.04", "epoch"=>"J2000"))
obsconfig["starttime"] = "UTC,2021/04/28/00:00:00.00"
obsconfig["exposure"] = 1.0
obsconfig["scans"] = 2
obsconfig["scanlengths"] = [900.0, 600.0]
obsconfig["scanlag"] = 300.0
obsconfig["autocorr"] = false
obsconfig["telescopename"] = "VLBA"
obsconfig["feed"] = "perfect R L"
obsconfig["shadowlimit"] = 1e-6
obsconfig["elevationlimit"] = "10deg"
obsconfig["stokes"] = "RR RL LR LL"

delim = ","
ignorerepeated = false

stationinfo = readstationinfo(obsconfig["stations"], delim=",", ignorerepeated=false) # read station info file

createmsfromconfig(obsconfig, stationinfo)

Python: True

The above step creates a fully functional MS that can be used for further processing.

In uvfits mode

This method accepts an existing uvfits file (e.g. output by eht-imaging) and uses CASA to convert between the two formats. This is done via createmsfromuvfits. As before, replace relativepath with the path to the source code of Anime.jl which contains sample input files under inputs/:

uvfits = joinpath(relativepath, "inputs", "uvfitsfiles", "hops_lo_3601_M87+zbl-dtcal_selfcal.uvfits")
msname = "eht.ms"
mode = "uvfits"

createmsfromuvfits(uvfits, msname, mode)

Python: True

It is the responsibility of the user to ensure that the input uvfits file contains all the necessary information that CASA would need to create an MS. eht-imaging output files are consistent with these specifications.

A helper function to convert an MS back to uvfits format is also provided:

msname = "eht.ms" # the MS we just created above
uvfits = "eht.uvfits"
datacolumn = "data"

createuvfitsfromms(msname, uvfits, datacolumn)

[ Info: Creating eht.uvfits from eht.ms...

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