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Last modified: 2 September 2010

Science Threads


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.


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.


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.


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.


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.


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.




Data Used in Threads


How to Download Chandra Data from the Archive
ObsID Object Instrument Threads
3 Trapezium Cluster HETG/ACIS-S Grating Spectra for Multiple Sources - ACIS

29 Alpha Cen LETG/HRC-S Grating Spectra for Multiple Sources - HRC

133 PSR B0540-69 ACIS-I Apply Barycenter Correction
Phase-binning a Spectrum

144 G21.5-0.9 HRC-I HRC-I Exposure Map and Fluxed Image
Setting the Observation-specific Bad Pixel Files

198 Cas A ACIS-S True Color Images in ds9

313 M31 ACIS-S Compute Net Counts, Rate, or Flux for Point Sources

315 NGC 4038/NGC 4039 ACIS-S An Image of Diffuse Emission
Calculate the Flux for a Position

441 Chandra Deep Field South ACIS-I Correcting Absolute Astrometry with reproject_aspect

459 3C 273 HETG/ACIS-S Remove the acis_detect_afterglow Correction
New ACIS Bad Pixel File: Identify ACIS Hot Pixels and Cosmic Ray Afterglows
Creating ACIS Spectra, ARFs, & RMFs for Pointlike Sources
Examining Grating Spectra and Regions: PHA2 files
HETG/ACIS-S Grating Spectra
ACIS-S Grating RMFs
HETG/ACIS-S Grating ARFs
Grouping a Grating Spectrum
PHA Background File for XSPEC
Add Grating Spectra and Average ARFs
Extract Coadded and Grouped Nth-Order Spectra and ARFs

460 3C 273 LETG/HRC-S Examining Grating Spectra and Regions: PHA2 files
LETG/HRC-S Grating Spectra
HRC Grating RMFs
LETG/HRC-S Grating ARFs
Grouping a Grating Spectrum

461 3C 273 HRC-I Basic Lightcurves
Improving the Astrometry of your Data: Correct for a Known Processing Offset

578 3C 295 ACIS-S Running wavdetect
Running vtpdetect
Running celldetect
A Note on Processing Versions

581 Chandra Deep Field South ACIS-I Correcting Absolute Astrometry with reproject_aspect

650 GK Persei ACIS-S Creating Source and Background Files

884 0235+164 ACIS-S Clean ACIS Background in VFAINT Mode

953 3C 273 HRC-I Basic Lightcurves

990 Vega HRC-S HRC-S Exposure Map and Fluxed Image
Calculate the Flux for a Position

1198 3C 273 LETG/ACIS-S LETG/ACIS Grating Spectra
LETG/ACIS-S Grating ARFs
Examining Grating Spectra and Regions: PHA2 files

1451 II Peg HETG/ACIS-S Create a Color Spectrum

1463 Jupiter ACIS-S Reprojecting Coordinates of a Solar System Object

1522 Trapezium Cluster ACIS-I Running celldetect

1557 G21.5-0.9 HRC-S Setting the Observation-specific Bad Pixel Files

1703 PKS 2149-306 LETG/ACIS-S Correcting a Misplaced Zero-order Source Position

1712 3C 273 ACIS-S Using SAOImage ds9
The ACIS "Blank-Sky" Background Files
Using CIAO Region Files
Filtering Lightcurves
Remove the ACIS Readout Streak

1800 PKS 2155-304 LETG/HRC-I Examining Grating Spectra and Regions: PHA2 files

1801 PKS 2155-304 LETG/HRC-I LETG/HRC-I Grating Spectra
LETG/HRC-I Grating ARFs

1838 G21.5-0.9 ACIS-S The ACIS "Blank-Sky" Background Files
Estimate Source Counts in an Image
True Color Images
Match the Binning of an Image
Multiple Chip ACIS Exposure Map and Fluxed Image Step-by-Step
Single Chip ACIS Exposure Map and Fluxed Image Step-by-Step
Obtain and Fit a Radial Profile
Create a PSF

1842 G21.5-0.9 ACIS-I Using merge_all to Compute ACIS Exposure Maps and Fluxed Images
Merging Data from Multiple Imaging Observations

1843 G21.5-0.9 ACIS-I Introductory Threads
A Note on Processing Versions
Setting the Observation-specific Bad Pixel Files
Using merge_all to Compute ACIS Exposure Maps and Fluxed Images
Merging Data from Multiple Imaging Observations

2463 3C 273 HETG/ACIS-S Add Grating Spectra and Average ARFs

3207 3C 294 ACIS-S Weighting ARFs and RMFs: multiple sources

3726 Jupiter ACIS-S Object-centered Aspect Solution and Exposure Map

5969 Vega HRC-S Computing Average HRC Dead Time Corrections

6476 HZ 43 HRC-I New Observation-Specific HRC Bad Pixel File

9100 SNR 0104-72.3 ACIS-S Coadding Spectra and Weighted Responses

9810 SNR 0104-72.3 ACIS-S Coadding Spectra and Weighted Responses

Last modified: 2 September 2010