All Threads - CIAO 4.0

Introduction

Beginners should start here. The Introductory threads provide an overview of the main components (GUI applications, parameter files) and concepts (the Data Model, filtering) in the CIAO data analysis software.

Getting Started:
- Installing CIAO 4.0
- Patching CIAO 4.0 to CIAO 4.0.1
- Patching CIAO 4.0 or 4.0.1 to CIAO 4.0.2
- Introduction to CIAO
- Starting CIAO
  (10 Apr 2008)
Chandra Data:
General:
GUIs:
A Complete List of CIAO tools can be found at the Introduction to Tools page.
If you are looking for a general topic, try the CXC Search at the top of the page.

Data Preparation

When Chandra data goes through Standard Data Processing (SDP), the most recently available calibration is applied to it. Since this calibration is continuously being improved, one should check whether there are newer files available. Similarly, some science decisions are made during SDP; every user has the option to reprocess the data with different parameters.

See the current Calibration Status Report
Analysis Guides:
- ACIS Data Preparation
- HRC Data Preparation
General:
- Setting the Observation-specific Bad Pixel Files
  Uses: the acis_set_ardlib script
- Filtering Data
- Filtering Lightcurves
  Uses: the analyze_ltcrv.sl S-Lang script
Coordinates, Astrometry, & Spatial Filtering:
ACIS:
- Check the ACIS Data Caveats
- Removing Cosmic-Ray Afterglows:
- acis_process_events:
  - Reprocessing Data to Create a New Level=2 Event File thread: apply the newest calibration (CTI, TGAIN); includes CC mode times of arrival calculation.
  - Clean ACIS Background in VFAINT Mode
- The ACIS "Blank-Sky" Background Files
  Uses: the acis_bkgrnd_lookup script; the lc_clean.sl S-Lang script
- Remove the ACIS Readout Streak
HRC:
- New Observation-Specific HRC Bad Pixel File
- Reprocessing Data to Create a New Level=2 Event File thread: applies the newest calibration (degap, AMP_SF/tapringing).
- Computing Average HRC Dead Time Corrections
Deprecated Threads:
- The following threads have been deprecated and will be removed in the next CIAO release. The information in these threads is available in the Reprocessing Data to Create a New Level=2 Event File thread, as well as the CIAO Why Topics.
- Apply the Time-Dependent ACIS Gain Correction
- Apply the ACIS CTI Correction
- Apply an ACIS Gain Map
- Remove ACIS Pixel Randomization
- Apply/Remove ACIS PHA Randomization
- Calculate CC-mode Times of Arrival
- Destreak the ACIS-S4 Chip
- HRC AMP_SF Correction and Reducing Tap-Ringing Distortions
- HRC-I Degap Correction
- HRC-S Degap Correction

Timing Analysis

In order to perform absolute timing analysis on a dataset, a barycenter correction must first be applied to the data. One may then create lightcurves and phase-binned spectra to look for variability in the source. These threads also provide information on working with data taken in the ACIS continuous clocking (CC) mode.

General:
- Why topic: Continuous Clocking Mode
- Apply Barycenter Correction
- Phase-binning a Spectrum
Analyzing Lightcurves:
- Why topic: Timing Analysis with Lightcurves
- Basic Lightcurves
- Filtering Lightcurves
  Uses: the analyze_ltcrv.sl S-Lang script
See the S-lang/ISIS Timing Analysis Routines (SITAR) package which provides a set of functions and subroutines for timing analysis within ISIS.

Imaging

The Imaging threads cover a wide range of topics that include source detection, creating exposure maps and normalized images, and calculating image statistics. How to create color images for publication is addressed, as well as merging data from multiple observations.

Analysis Guides:
- HRC Imaging
- Extended Sources
General:
- The ACIS "Blank-Sky" Background Files
  Uses: the acis_bkgrnd_lookup script; the lc_clean.sl S-Lang script
- Match the Binning of an Image
  Uses: the get_sky_limits script
- True Color Images
- True Color Images in ds9
- An Image of Diffuse Emission
  Uses: the mkBgReg.pl script; the mkSubBgReg.pl script
- Using Data Cubes
Reprojecting Data:
Coordinates, Astrometry, & Spatial Filtering:
Source Counts & Surface Brightness:
- Estimate Source Counts in an Image
- Obtain and Fit a Radial Profile
PSFs:
- ChaRT: the Chandra Ray Tracer
- Create a PSF
Detect:
Exposure Maps:
- Using merge_all to Compute ACIS Exposure Maps and Fluxed Images
  Uses: the merge_all script
- Single Chip ACIS Exposure Map and Fluxed Image Step-by-Step
  Uses: the get_sky_limits script
- Multiple Chip ACIS Exposure Map and Fluxed Image Step-by-Step
  Uses: the get_sky_limits script
- HRC-I Exposure Map and Fluxed Image
  Uses: the get_sky_limits script
- HRC-S Exposure Map and Fluxed Image
  Uses: the get_sky_limits script
- Match the Binning of an Image
  Uses: the get_sky_limits script

Imaging Spectroscopy

After extracting source and background PI or PHA spectra from an imaging observation, the appropriate response files (ARF, RMF) are created so that the data may be modeled and fit. In the case of multiple or extended sources, a weighted ARF and RMF are built for the spectral analysis.

Extracting Spectra and Creating Response Files:

specextract should be used for the analysis of extended sources only. Users working with point sources should instead use the psextract script. The mkwarf tool, which is used for ARF generation by specextract, may not produce accurate results for point sources. The mkarf tool, used by psextract, is preferred for point source extraction.

In certain cases, the mkacisrmf tool will need to be run separately to create the best possible RMFs for ACIS observations; see the thread for details.
- The ACIS "Blank-Sky" Background Files
  Uses: the acis_bkgrnd_lookup script; the lc_clean.sl S-Lang script
- Using specextract to Extract ACIS Spectra and Response Files
- Using psextract to Extract ACIS Spectra and Response Files for Pointlike Sources
  Uses: the psextract script; the acis_fef_lookup script
  (30 May 2008)
- Coadding Spectra and Weighted Responses
  Uses: the acisspec script
- Creating ACIS RMFs with mkacisrmf
Step-by-step Analyses:

These threads give step-by-step instructions for creating spectra and response files. Note that all of the tasks described here are executed automatically by the specextract script.
- The ACIS "Blank-Sky" Background Files
  Uses: the acis_bkgrnd_lookup script; the lc_clean.sl S-Lang script
- Weighting ARFs and RMFs: multiple sources
- Step-by-Step Guide to Creating ACIS Spectra for Pointlike Sources
  Uses: the acis_fef_lookup script
General:
- A Note on HRC Spectra

Grating Spectroscopy

If new calibration has been applied to the event file, the grating spectrum should be re-extracted as well. It is then possible to build grating response files (gARF, gRMF) in order to model and fit the data.

Chandra Grating Analysis Page
WebGUIDE: Interactive GUIDE for ATOMDB version 1.3
General:
- Examining Grating Spectra and Regions: PHA2 files
- Create a Color Spectrum
Problems with the Zero Order:
- Correcting a Misplaced Zero-order Source Position
- Source Position for Grating Data with a Piled or Blocked Zero Order
HETG/ACIS:
- HETG/ACIS-S Grating Spectra
- Grating Spectra for Multiple Sources - ACIS
- ACIS-S Grating RMFs
- HETG/ACIS-S Grating ARFs
  Uses: the fullgarf script
  (30 May 2008)
- Grouping a Grating Spectrum
LETG/ACIS:
- LETG/ACIS Grating Spectra
- Grating Spectra for Multiple Sources - ACIS
- ACIS-S Grating RMFs
- LETG/ACIS-S Grating ARFs
  Uses: the fullgarf script
  (30 May 2008)
- Grouping a Grating Spectrum
LETG/HRC-S:
LETG/HRC-I:
Combining Spectra & Fitting:
- Extract Coadded and Grouped Nth-Order Source & Background Spectra and ARFs
  Uses: the add_grating_orders script
  (6 Jun 2008)
- Add Grating Spectra and Average ARFs
  Uses: the add_grating_spectra script
  (6 Jun 2008)
- PHA Background File for XSPEC
  Uses: the tg_bkg script

S-Lang

A list of threads that use S-Lang, the CIAO Scripting Language, to automate a variety of tasks.

Threads using S-Lang:
- Filtering Lightcurves
  Uses: the analyze_ltcrv.sl S-Lang script
- The ACIS "Blank-Sky" Background Files
  Uses: the acis_bkgrnd_lookup script; the lc_clean.sl S-Lang script

Analysis Notes

Matching CIAO and CALDB Versions

Source Detection and Cosmic-Ray Afterglows

News

Science Threads for CIAO 4.0

Introduction

Getting Started:

Chandra Data:

General:

GUIs:

Data Preparation

Analysis Guides:

General:

Coordinates, Astrometry, & Spatial Filtering:

ACIS:

Removing Cosmic-Ray Afterglows:

acis_process_events:

HRC:

Deprecated Threads:

Timing Analysis

General:

Analyzing Lightcurves:

Imaging

Analysis Guides:

General:

Reprojecting Data:

Coordinates, Astrometry, & Spatial Filtering:

Source Counts & Surface Brightness:

PSFs:

Detect:

Exposure Maps:

Imaging Spectroscopy

Extracting Spectra and Creating Response Files:

Step-by-step Analyses:

General:

Grating Spectroscopy

General:

Problems with the Zero Order:

HETG/ACIS:

LETG/ACIS:

LETG/HRC-S:

LETG/HRC-I:

Combining Spectra & Fitting:

S-Lang

Threads using S-Lang:

Data Used in Threads