The Slitless Simulation package aXeSIM

Introduction

As part of the ST-ECF support for the spectroscopic modes of Wide Field Camera 3 (WFC3), the slitless spectroscopy group of the ST-ECF has developed a dedicated simulation package applicable to WFC3. Whilst the package was initiated for exploitation of WFC3 slitless grism modes, it is equally applicable to other slitless spectroscopy modes of HST, such as ACS and NICMOS.

aXeSIM as web application for WFC3

In addition to the software package, aXeSIM can be run as a web application for the WFC3 slitless modes. The web application offers a subset of all options available in aXeSIM. Without any registration the user can select a WFC3 slitless mode, choose or adjust additional parameters and start the simulation. Once ready, the simulation images and data can then be downloaded from the web. The web interface targets new, less experienced or occasional users and offers a subset of all options existing in aXeSIM.

The following link allows to simulate WFC3 slitless images via a Web application:

Disclaimer

The WFC3 slitless image simulator was developed independently of the STScI Exposure Time Calculator (ETC). While every effort has been made to ensure that the imaging simulator provides similar estimates of detected counts to the ETC, differences are bound to result. The STScI ETC is to be taken as the official tool and should be used to determine exposure times for the purposes of critical time justification in Phase I and II. The WFC3 ETC can be found here.

What is New?

15-Jul-2009: aXeSIM version 1.4 released.
26-Jun-2008: The sensitivity files of WFC3 grism modes which are used in aXeSIM were updated to reflect the status of Thermal Vac 3 (TV3) calibrations. While the UV channel sensitivity remained largely unchanged since TV2, there are relative sensitivity gains ranging from 25 to 70% for the IR grisms due to the installation of the new IR detector (IR4; FPA165).
14-Feb-2008: Release of aXeSIM version 1.1. The changes with respect to version 1.0 are an improvement of the computational speed and a small change in the definition of the simulated beams, which corrects a problem for the simulations of large objects with WFC3/G280.

Installation and Download

aXeSIM is distributed to be installed and used as the external IRAF/PyRAF package taxesim14, and as a sub-package of STSDAS (from version 3.10 on).

The current situation (as of July. 15th, 2010) is that aXeSIM-1.4, the latest aXeSIM version, was released as the external package taxesim14. The latest STSDAS version 3.12 (released in June 2010) also contains aXeSIM-1.4

aXeSIM version 1.4

Starting with aXeSIM version 1.4 and aXe version 2.1, the two packages have been united on the code level. As a consequence, the package taxesim14 automatically contains taxe21 and vice versa.

To install aXeSIM, please consult the README or the Section 2 of the manual.

Statically linked binaries for the aXeSIM-1.4 and aXe-2.1 C code are available for download for the following platforms:

aXeSIM Documentation

The aXeSIM User Manual gives a detailed description on how aXeSIM is working and how to perform simulations with aXeSIM. It is available for browsing as well as for download in various formats:

aXeSIM test packages

To verify the aXeSIM installation and to help users making their first steps with aXeSIM, we have composed test packages for some HST instruments with slitles spectroscopic observing modes.

WFC3 UVIS and IR ACS WFC, HRC and SBC

Please download the tarball, unpack it and follow the instructions in the README.

Help and more information

For further help and more information concerning aXeSIM and its use, drop an email to stdesk@eso.org. Please include "aXeSIM" in the subject line to differentiate your request from SPAM.

Maintained by Martin Kümmel <mkuemmel@eso.org>