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KI V2 Sensitivity and Observing parameters

This page contains KI sensitivity and instrument details for proposal and observation planning for V2 observations. In the V2 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 fringe tracking data and all necessary calibrations.

The V2 mode is open for proposals from all Keck users (UC, Caltech, UH, NASA and NOAO TACs). The sensitivity values below are based on past interferometer performance in good weather. The interferometer performance degrades substantially in poor seeing.

Sensitivity numbers updated: August 3, 2009

New for semester 2010A

In addition to the standard H and K observing, the following modes are available for shared-risk observing in 2010A:
  • L-band
  • Self-phase referencing (V2-SPR)
  • Simultaneous K/L band (split pupil mode results in a 1.2 mag loss in sensitivity for both K and L)

The sensitivity values given below are based on current performance for these modes and while every effort will be made to perform proposed science observations, no guarantees are made for shared-risk observing.

AO (adaptive optics) sensitivity:

Angle tracking

Fringe tracking:

Sky coverage:

Observing efficiency:

For sources where all magnitudes (V,J,K) are > 1 magnitude above the sensitivity limits, KI can achieve 6 scans per hour under good weather and seeing conditions. A scan includes the fringe tracking data and calibrations. A separate scan on a nearby calibrator is required to determine the system visibility. This means that for a source/calibrator pair, there will be 3 integrations on each in an hour.

For sources at the sensitivity limit of one of the sub-systems, the efficiency is generally closer to 4 scans per hour.

The first 30 minutes after the domes open may be necessary for interferometer set-up and no science observations are guaranteed during this time.

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