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Spectroscopy

Low-moderate resolution spectroscopy can be obtained either at f/6 through each of the 1-5μm windows or at f/32 (the latter usually with adaptive optics) at JHK only. A variety of slit widths are available. The properties of the slits, grisms, and blocking filters are decribed in the section. The f/6 and f/32 pixel scales in spectroscopy mode are the same as those in imaging mode.

References

Below are papers describing aspects of Michelle's design, fabrication and testing.

Data Format and Reduction

The Gemini IRAF MIDIR package has been released, consisting of scripts allowing basic reduction of imaging and spectroscopy data. Given the similarities in the reduction of data from T-ReCS and Michelle, this topic is covered in the mid-IR data reduction pages. The basic format of all Gemini data is explained in the Data section of the Gemini website.

OT Details

This page guides you through the main steps and considerations for configuring Michelle observations in the Observing Tool (OT).

Observation Preparation

This section contains instructions for configuring Michelle at phase II. It is organised as follows:


Guiding Options

Guiding with Michelle (and T-ReCS) can currently only be performed on one side of the chop. The reasons for and implications of this are discussed in more detail in the Mid-IR Resources section.

Observing Overheads

Mid-IR observing overheads can be significant and must be taken into account when proposing for time on Michelle. The following table summarises the overheads and efficiency, but please be sure to read the detailed notes below.

Sensitivity and Overheads

This section contains information on the sensitivity and performance of Michelle in its various observing modes. Go directly to:


Entrance Window

Michelle uses an entrance window made of Potassium Bromide (KBr). KBr has a transmission of ~90% across the mid-infrared. Since KBr is hygroscopic, all contact between water with the window must be minimized. This includes dew that may form on the window while observing under high humidity conditions. The humidity limit for observing with Michelle at Gemini is a relative humidity of 80%. During its use at UKIRT, a protective "sacrificial window" system was implemented to help prevent damage to the cryostat window that serves as the vacuum seal between the dewar and the atmosphere.