CEMGA stands for Charge Transfer Inefficiency Effects Models for Gaia, it is a platform that hosts models to simulate the operation of non-irradiated and irradiated CCDs. The different charge transfer inefficiency (CTI) models hosted by the platform have been developed within the Gaia framework. The platform aims to offer a rigorous environment for testing, verifying and comparing the hosted models. It also comes with a set of pre-configured experiments such as FPR and EPER (First Pixel Response, Extended Pixel Edge Response) and various tools to analyse the simulations (e.g., I/O management methods, image location and minimization algorithms, visualizing routines) and compare them to experimental test data. Although developed in ESA's Gaia mission context, the platform and its models can be used to simulate CTI in any CCD and for any kind of measurements, e.g. it is currently used for ESA's dark matter/energy mission Euclid and ESA's earth observation mission Sentinel 4.

CEMGA is developed by Thibaut Prod'homme (ESA/ESTEC, The Netherlands) and benefits from the contributions of several other astronomy institutes in Europe, in particular Leiden (The Netherlands), Lund Observatory (Sweden), the Institute of Astronomy in Cambridge (United-Kingdom), and l'Observatoire de Paris-Meudon (France).

CEMGA is developed in JAVA and is available as a JAVA package (or project directly usable under Eclipse for instance) without any restriction to all the scientists of the Gaia Data Processing and Analysis Consortium DPAC under the usual svn repository.

For all other users, a lighter version of the platform is available for download here >> CEMGA_lite_v1.tar. It contains the key elements of the CCD operation simulation and 3 different CTI effect models. Documentation about the code itself is provided here >> JAVA DOC.

In both cases, we recommend any potential user to directly contact Thibaut Prod'homme (thibaut.prodhomme _at_ esa.int) for guidance and extra information.

The main purpose of this software is to evaluate the effects of CTI on any potential space based measurements carried with CCDs and to characterize the optimal CCD operating conditions to support the CCD design phase taking into account the effects of radiation damage. However we do not take any responsability in the results obtained using CEMGA, and we strongly advised any potential user to get in contact with us if you are using the software.

As CEMGA uses libraries under the GNU Lesser General Public License it inherits from those the same license.

If you publish results that have been entirely or partly obtained using CEMGA, please acknowledge us, and include the proper references (Prod'homme et al MNRAS 2011, and CEMGA).

CEMGA has been used to performed a detailed assesment of the impact of CTI on Gaia astrometry (Prod'homme et al 2012, Holl et al 2012), it is now used to verificy the CDM (Charge Distortion Model) candidates (fast analytical CTI effects model candidates essential to achieving the Gaia mission requirements) (Short et al MNRAS 2013 accepted), and to study the Gaia CCD pixel architecture (Seabroke et al. MNRAS 2013 accepeted). It is also used to assess the impact of CTI on the weak lensing measurements of Euclid, the future dark matter mission of ESA.

It currently hosts a variety of macroscopic and microscopic models, which includes the present CDM candidate, the analytical model used by the Gaia Instrument and Basic Image Simulator (GIBIS). CEMGA also hosts the most advanced and detailed Monte-Carlo model developed within the Gaia community that simulates the trapping processes at the level of each individual trap and the charge transfer at the pixel electrode level. The linked video gives an example of a CEMGA simulation using such a model.