Station-supplied geometry loads with the measurement.
DERIVED / BASELINE ÷ WAVELENGTH
Local Fourier plane
u, v / λ
Zenith-referenced ENU projection. Mirrored points are mathematical conjugates, not additional measurements. This is not equatorial UV coverage for a tracked celestial target.
HOW WE OBSERVE / ELECTROMAGNETICLong wavelength → short · conceptual scale
FOLLOW THE MEASUREMENT / TAP A STAGE
02 / Inspect the measurement
SELECTION → VISIBILITY → FOURIER CONTRIBUTION
Select an antenna or pair
Tap an element to illuminate its measured connections. Tap a second to inspect their complex visibility.
One measured baseline's Fourier contribution. Independently scaled, uncalibrated; this fringe pattern is not an identified source.
CHOOSE A DIRECTION IN THE SKY
Observe an object
WAITING
Select Orion, the Sun, or another target to inspect the measured array response in its predicted direction. TART observes the whole sky; selecting a target steers the software analysis, not the hardware.
Positions load with the observation, using the telescope's location.
Orion Nebula · M42
Waiting for station location and observation time.
A new point is recorded for each distinct observation timestamp.
Response is a normalized, signed correlation sum (−1 to +1), not brightness in Jy or a detection probability. Other objects, satellites, sidelobes, and interference can contribute. Below-horizon targets have no directional measurement. Traces stay in this tab until exported.
03 / Data & provenance
DERIVED VIEW → MEASUREMENT → ORIGINAL SOURCE
Visibility matrix
Raw antenna pair correlations
Hover or tap a pair for values. Use antenna selectors for accessible pair selection.
Snapshots retain the original upstream products and processing context. The observation package adds the normalized instrument, geometry, product, and provenance model. Target traces can be exported in the object inspector.
What am I looking at? · Method & limitations
A visibility is a complex correlation between two antennas, not a photograph or an audio stream. START fetches the latest visibility record, antenna positions, station information, and available gain metadata through a read-only relay. Requests are shared for 30 seconds; the desk refreshes every 60 seconds while visible.
The preview uses equal-weight direct Fourier synthesis, Re Σ Vᵢⱼ exp[−2πi (rᵢ − rⱼ)·s / λ], with station antenna positions interpreted in TART's East/North/Up convention. Zenith is the center; north is up and east is right. The inverse phase sign is checked against TART's simulated-visibility convention. Array alignment still depends on the station's supplied position calibration.
When enabled and available, gain/phase correction follows TART: V′ᵢⱼ = Vᵢⱼ gᵢ gⱼ exp[−i(φᵢ−φⱼ)]. Zero-gain antennas and flagged baselines are excluded. Missing or invalid gain metadata produces an explicitly labeled raw preview. This does not establish the age or quality of the upstream calibration. No primary-beam correction, deconvolution, flux calibration, or automatic detection is applied. The matrix continues to show raw measured correlations.
Common-object positions use SIMBAD ICRS coordinates and Astropy's built-in solar-system ephemeris at the observation timestamp and telescope location, with offline Earth-rotation data and no refraction. Satellite predictions come from the TART catalogue for that same time. Markers indicate where to examine data, not what has been detected. Orion is the Orion Nebula (M42), not the full constellation. Catalogue flux/range placeholders are not presented as measured values.
“Fresh” means the observation timestamp is within five minutes of Sol's retrieval time. An API can respond successfully with old data. Failed refreshes retain the previous observation with an explicit warning. Networked TART stations are separate arrays; this page does not coherently combine their signals into a planet-sized interferometer.
05 / A different way to see
SIGNAL → CORRELATION → IMAGE
↘ ↙
Many small antennas.
TART uses an array of radio receivers to sample the same sky. At the GPS L1 band, satellites and local radio interference are prominent parts of the observing environment.
∿ × ∿
One shared measurement.
A correlator compares each antenna pair. A 24-element array provides 276 unique cross-correlations, carrying information about the spatial structure of incoming signals.
⊙
An image made in software.
Antenna geometry and complex correlations let software reconstruct a sky response. Reliable interpretation also needs calibration, interference checks, and the array's response pattern.
Choose a telescope above, compare visibility amplitudes and phases, and download a timestamped JSON snapshot. No receiver or account is needed to read these public observations.
Use an SDR, suitable antenna, filtered low-noise amplifier, and computer. A 21 cm hydrogen-line experiment operates near 1420 MHz, distinct from TART's L1 band. Results depend on the antenna, receiver sensitivity, interference, and integration time.
Compare two or more receivers with a coherent reference and measured delays. A shared 1 PPS alone does not guarantee phase-coherent sampling. Establish clock, local-oscillator, and cable-delay stability before interpreting fringes.
Study current TART hardware, correlator, installation, and calibration designs. Confirm kit availability and a complete bill of materials with the project. Geographic networking enables shared observations; coherent long-baseline imaging needs additional timing, signal, and calibration infrastructure.
Explore larger facilities through their archives. Public metadata, account registration, and permission to retrieve a particular observation are separate things. These links open the provider's own services.
Facility
Without an account
When to register
Get started
TARTPublic observations
Read live public API data.
Authentication is required for protected configuration changes.
Access guidance checked 3 October 2026 UTC against the linked provider and client documentation. ALMA account and proprietary-data access can be separate from NRAO; consult the ALMA Science Archive. No provider accounts or credentials are stored by START.