Chandra X-ray Center, MIT group

(For the primary CXC web site, go to


The CXC Group at MIT is dedicated to the support of transmission grating spectroscopy with the Chandra X-Ray Observatory through an active research program, instrument calibration, software development, and observer support.

The MIT/CXC team is primarily responsible for:

  • Scientific Research Maintaining an active research program, both with Chandra and other observatories, or in theoretical investigations.
  • Spectroscopic Expertise Development and maintenance of resources necessary for scientific interpretation of Chandra transmission grating spectra.
  • Analysis Software Emphasis is on the spectroscopic content in support of grating observations.
  • Calibration Measurement and analyses necessary to determine and describe the in-flight performance of the HETG and its primary read-out detector (ACIS-S).
  • Expert Support Provide technical support for HETG, LETG, or ACIS.
  • Planning Support guest observers and mission planning for HETG observations.
  • ACIS Operation Provide support for ACIS uplink and flight software.


Our group works on a range of topics. High-resolution spectroscopy with the HETG is our most important tool, but we perform observations with many different ground-based and space-based telescopes as well as numerical simulations to learn more about how the universe works.

          image of AGN

Active Galactic Nuclei and Jets

Chandra guaranteed time observations of AGN with the HETG continue at a high pace, and over past few years we have been busy analyzing new data sets, and performing more sophisticated in depth analysis and modeling of previous observations.

Several point sources in a stellar cluster


Stars are the main actors in creating variety in the universe. Their fusion “burning” of primordial H and He creates the elements we are made of and illuminates the universe. In studying stars we consider two general categories: “Cool stars” which include stellar coronae, active binaries, and low-mass pre-main sequence stars; and “Hot” stars which consist of massive stars, associated winds and shocks, and stars in young star clusters.

Artist impression of X-ray binary

X-ray binaries

X-ray binaries, as the name implies, consist of two objects: a compact object – a neutron star (NS) or black hole (BH) - and a companion star. Mass is transferred from the companion and falls toward the compact object often creating an accretion disk (AD) around it. X-ray heating and emission occur in the accretion disk and as mass leaves the accretion disk and lands on (NS) or falls into (BH) the compact object.


We provide a range of information about pipeline processing, the CXC Data Analysis System, Grating related analysis issues, and general scientific analysis algorithms.

Introduction to X-Ray Data Analysis

``Introduction to X-Ray Data Analysis'', David Huenemoerder (MIT) and Randall Smith (CfA); Presentation for the CXC/CIAO Workshops, November 2001.

ABC Guide to Pileup

A Chandra-ACIS specific overview of pileup - i.e., the phenomena of two or more photon events overlapping in a single detector frame and being read as a single event. We discuss who pile-up happens, how it can be avoided, and what to to if pile-up is found in your data.

Memos and specifications

Our group defines and specifies many of the tasks and calibration products for ACIS data reduction and the gratings. This includes e.g. the specification for acis_process_events, or the LSFPARM files in CALDB.

Proposal guides

Guided examples for writing Chandra/HETG proposals.


Our group contributes to the development CIAO, the Chandra data reduction and analysis system. In addition, we maintain several other software packages for X-ray analysis.


Marx simulats the on-orbit performance of the Chandra X-ray Observatory. It provides a detailed ray-trace simulation of how Chandra responds to a variety of astrophysical sources and can generate standard FITS event files and images as output.


ISIS, the Interactive Spectral Interpretation System, is designed to facilitate the interpretation and analysis of high resolution X-ray spectra.

S-Lang Modules

Modules/Packages for the S-Lang Scripting Language.

S-Lang packages

S-Lang programs (possibly depending on ISIS or modules above).

Suzaku Software

S-lang/ISIS scripts for attitude correction and pileup estimation of Suzaku data.


Claude Canizares

CXC Associate Director, HETG Principala Investigator


Moritz Günther

Grating simulations, ray tracing; star formation and stellar activity


David Huenemoerder

Grating Pipelines, Management; low-mass stellar activity and high-mass stars


Herman Marshall

HETG Calibration, AGN, X-ray polarimetry lab


Melania Nynka

HETG data analysis, ACIS pipeline processing, neutron stars


David Principe

ACIS pipeline processing, HETG data analysis, star formation and stellar activity


Norbert Schulz

ACIS/HETG calibration, star formation, ISM, X-ray Binaries containing neutron stars, X-ray optics