PTI Visibility Overview

This document briefly describes the capabilities and current sensitivities of the visibility amplitude mode at PTI. A complete instrument description is available here.

In the V 2 mode the main data product is the normalized visibility amplitude squared for a given source. Integrations on the target source and calibrators are interleaved in time, where each integration comprises 120 seconds of fringe tracked data and all necessary calibrations. See the data overview for more details on the data.

Acquisition and star tracking

Stars are acquired and tracked in the visible with a sensitivity limit of V < 11.

Fringe tracking

PTI runs with active fringe tracking in the near-infrared. The tracking rate used depends on the source brightness and weather conditions; the available rates are 100, 50 and 20 Hz. The brightness limits are:

  • H < 5.2
  • K < 6

Spectral resolution

  • H band: 4 channels
  • K band: 5 or 9 channels

Observing efficiency

Observations at PTI are highly automated. In good observing conditions, PTI averages 8 integrations per hour.

Field of view

The field of view for the fiber-filtered spectrometer data is 1 arcsec (FHWM).

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