OSIRIS Hieroglyph The OSIRIS User's Manual

System Overview

OSIRIS is a general-purpose 1-2.5 micron imager and moderate-resolution spectrometer built by the Imaging Sciences Laboratory at Ohio State University. The instrument was designed to fully illuminate a 256x256 array with 27 micron pixels back when this was a big array. However, the current array is a 1024x1024 HgCdTe device with 18.5 micron pixels. Because the current detector is larger than the original design specifications, some vignetting does occur. Here is an image of the useful area of the array.

OSIRIS can be used at either the CTIO 4-m Blanco telescop (with the f/14.5 secondary) or at the CTIO 1.5-m telescope (with the f/13.5 secondary). The instrument contains two reimaging cameras, f/2.8 and f/7, which provide two different plate scales. See the section on Imaging for information on the plate scales. There is also a pupil viewing camera (a silicon lens) for aligning the pupil plane mask, which is designed to block thermal emission from the telescope secondary.

The spectroscopic mode has three different configurations. There are low-resolution (R ~ 1200) and high-resolution (R ~ 3000) modes with a long slit and a low-resolution (R ~ 1200) cross-dispersed mode with a short slit. Configuring the spectoscopic mode is discussed in detail in the Spectroscopy Overview section.

All of these configurations of the instrument are under direct user control and can be changed rapidly (i.e. within a few minutes) so that many different observational programs can be accommodated during a single night.

The population of the instrument filter, slit, and camera wheels changes occasionally, but generally includes standard broad band imaging filters (i.e. JHK), a narrowband filter set, a cross-dispersed grism, and several slits, in addition to the grating for spectroscopic mode.

Instrument Views:

The control interface for OSIRIS is the Prospero package written at OSU. More information on Prospero can be found at:


Please note that Prospero is not an image processing package, but an interactive instrument control system. Simple commands for inspecting images are included in the Prospero command suite, but the observer is expected to use their favorite package to fully reduce and analyze their data. A useful summary of the Prospero commands pertinent to OSIRIS is provided in the form of a 2-page quick-reference card, copies of which may be obtained from:

This PostScript file: osiris quick reference

Or from


Or via our anonymous ftp server:

ftp.astronomy.ohio-state.edu in the directory pub/prospero/instcards

A separate document (the Prospero Observer's Guide) describes how to use the Prospero package, and is available online.

We will also track any problems with OSIRIS on this page, along with potential fixes.

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Updated: 1999 December 22