EMIR Optimized Slits Positioner ( OSP) is an aplication written in java, using the JSkyCat library and implementing algorithms to search and validate optimized project masks. The Multi-Object Spectroscopic (MOS) system of EMIR is composed of a robotic reconfigurable multi-slit mask or Cold Slit Unit ( CSU). It can be able to obtain 55 spectra simultaneously and this tool is needed to optimize the science targets in our field, simulate the final characteristics of the 2D spectra on the detector, and allow the user to perform the configuration of all the slits though a Graphical User Interface.

Download and Install

The EMIR OSP can de downloaded here.

To install unpack the tar.gz file using (for example) the command:

     $ tar -zxvf EMIR-OSP-v<version>.tar.gz

To run the OSP simply use the commands:

     $ cd OSP-v<version>/
     $ ./osp.sh

Please make sure that the osp.sh file is executable to run the final command (by default it should be).


The EMIR OSP documentation is currently being improved. The EMIR-OSP-cookbook is a guide on how to use the OSP and contains some helpful tips and tricks.

EMIR OSP overview and Usage

Briefly, the OSP takes as input an image of the region of interest as well as a catalogue, either user defined or using one of the available catalogue tools, and allows the user to allocate slitlets to targets in an optimised way. The result is then taken as input for the GTC to create the appropriate masks at the telescope.

To use the EMIR OSP one must have two input files:

  1. A user input catalogue
  2. An image covering the field of view

A template input catalogue can be found here. The input image must be in the correct orientation (North up, East left) and contain no distortions.


The output is an XML file describing the complete shape of the mask. Individual slits are specified by their central position on the field, their length, and their width. These values have to be specified for each slit, together with the position of the center and the orientation of the field. The OSP will be mainly used during the preparation phases of an observation (Phase II of GTC).

To send comments or bug detection please, do not hesitate to send an email to: lpatrick [at] iac.es and osp-support(at)ast(dot)obs-mip(dot)fr