vlbisim

vlbisim is a Python package for simulating Very Long Baseline Interferometry (VLBI) observations. It allows users to define telescope arrays, simulate uv-coverage for astronomical sources, visualize baseline distributions, and create synthetic dirty images. The package supports major VLBI arrays such as VLBA, EHT, ngVLA, EVN, and user-defined custom arrays.

Features

• Define and configure telescopes with latitude, longitude, elevation, and visibility limits.
• Calculate uv-coverage for arbitrary telescope arrays and sources.
• Simulate interferometric observations with customizable observation times and scan durations.
• Plot uv-coverage with baseline highlighting options.
• Generate synthetic dirty images from uv-coverage.
• Visualize telescope locations on world maps and globes.
• Supports major VLBI arrays, including VLBA, EHT, ngVLA, GMVA, EVN, MeerKAT, SKA, and others.

Installation

pip install vlbisim

Note: Some features require additional dependencies such as numpy, matplotlib, astropy, basemap, and numba.

Usage

Importing the package

from vlbisim import Telescope, getArray, simulateUV, plotUVdata, plotMap

Define telescopes

# Create a single telescope
t1 = Telescope(lat=50.524778, lon=6.883972, name="Effelsberg", elev_lim=15)

# Load a pre-defined array
vlba = getArray("VLBA")

Simulate uv-coverage

# Define source coordinates [RA, Dec] in degrees
source = [180.0, 45.0]

# Simulate uv-coverage
uv_coverage = simulateUV(vlba, source, n_iter=100, obsstart=0, obsend=24, make_plot=True)

Plot uv-coverage

plotUVdata(uv_coverage, highlight_baselines=[0, 1, 2])

Plot telescope array on a world map

plotMap(vlba, llcrnrlat=-90, urcrnrlat=90, llcrnrlon=-180, urcrnrlon=180)

Additional Utilities

• SplitScans: Split long observations into shorter scans.
• combine_telescopes: Merge multiple arrays.
• getHighlightBaselines: Highlight specific baselines in plots.
• plotGlobe: Visualize telescope arrays on a 3D globe.
• get_elevation: Fetch telescope elevation using Open-Meteo API.

Examples

# Combine two arrays
full_array = combine_telescopes([getArray("VLBA"), getArray("EVN")])

# Split observation into scans
uv_scans = SplitScans(full_array, source=[180,45], obstart=0, obsend=24, scan_time=2, n_scans=12)

# Animate uv-coverage and save as mp4
simulateUV(full_array, source, make_movie=True, output_name="uvout.mp4")

Dependencies

• numpy
• matplotlib
• astropy
• basemap
• numba
• requests

License

This project is licensed under the MIT License.