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IRS: Saturation

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Note : Especially when preparing observations for the IRS, it is very important to read the IRS chapter in the Spitzer Observer's Manual. Information not duplicated on the web pages can be found there!


Saturation levels for the shortest ramp duration available in the IRS AOTs for the medium background level. For flux densities at a given wavelength which exceed these limits, at least one of the samples will be off-scale. Flux densities up to 3 times greater will have at least two unsaturated samples. The observer must decide whether the science can be accomplished if the spectrum is saturated in some spectral or spatial regions, and not in others.

Saturation is not necessarily fatal for an observation as the data processing pipeline will be able to reconstruct the ramp if at least two samples are available (albeit with a larger error than usual). The SSC recommends that the observer designs his/her observations using multiple cycles of short unsaturated ramps.

However, very bright sources may leave latent imprints in the detectors that will compromise further observations until an anneal is performed. The SSC reserves the right to not observe some targets as a result of impacts these bright objects might have on subsequent observations. Observers planning observations of bright objects should discuss the impact of such observations in the proposal.

PUI point source saturation levels (milliJy) for 6/14/30 sec ramp times

filterlow backgroundmedium backgroundhigh background
blue190/90/45190/90/40180/80/35
red430/210/100420/200/90410/190/80

PUI extended source saturation levels (milliJy) for 6/14/30 sec ramp times occurs at 450/190/90 MJy/sr in both fields.

Note : Especially when preparing observations for the IRS, it is very important to read the IRS chapter in the Spitzer Observer's Manual. Information not duplicated on the web pages can be found there!

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This file was last modified on Fri Sep 29 08:42:31 2006.

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