= Interactive Data Reduction and Analysis for CanariCam



iDealCam is an IDL GUI application developed for processing raw FITS data produced by CanariCam (CC), one of the first-light instruments of GTC. It provides astronomers with an efficient tool to view, reduce, and analyze multi-extension FITS files. Although iDealCam is optimized for CC imaging and polarimetry data, it can also work with other types of data produced by CanariCam, T-ReCS (facility mid-IR camera of Gemini South), and Michelle (facility mid-IR camera of Gemini North).

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In order to get rid of the strong (and fast varying) thermal background coming from the atmosphere and the telescope itself (a good way to think about this is to imagine that you are observing a star with naked eyes during daytime), nearly all state-of-the-art mid-IR cameras operate with a special technique called “chop and nod” (Gemini website has a very nice and detailed explanation of it). Meanwhile, due to the strong background and finite well depth of the detector, the mid-IR arrays need to be read out with a very short frame time (typically around 10 ms). Consequently, a raw mid-IR FITS files is in fact more like a short movie rather than a single image, consisting of a large number of chop and nod frames. To see the final product of the observation (i.e., the science image of your selected object), those frames need to be properly combined. The FITS structure might be complex, and different cameras use different formats to save the chop/nod frames in their raw FITS files.

In this context, iDealCam is a very handy app to check those mid-IR “movies”, and to stack frames. Compared with other existing IRAF or IDL packages and procedures, using iDealCam requires little programming skill. You do not have to be an expert of the mid-IR data structure either. Once the program is installed and compiled, everything can be done interactively with the graphical user interface.

iDealCam is not merely a FITS viewer, it also provides a variety of analyzing tools, such as aperture photometry, signal-to-noise measurement, etc. As a polarimetry reduction tool, iDealCam is able to calculate the Stokes parameters and visualize the polarizations.

Current release of iDealCam (v1.4) does NOT have the capability to reduce CC spectroscopic data. However, one can still use it to check and stack the mid-IR spectroscopic FITS files.

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Restrictions & known bugs

HOW to install & USE


update history


Available in the current release:

  1. -Graphical user interface

  2. -Support multiple instruments and data types:

       CanariCam - imaging, spectroscopy, polarimetry

       T-ReCS - imaging, spectroscopy

       Michelle - imaging, spectroscopy

  1. -Bad frame(s) removal and frame registration

  2. -Quick access to each single chop or nod frame

  3. -Display a collection of FITS header keywords that are most relevant to image reduction and analyses

  4. -Zoom in to show a portion of the image in detail

  5. -Save a single frame into a new FITS file with a proper header

  6. -Display images with different color scheme and scale (similar to DS9)

  7. -Aperture photometry and profile fitting on either a stacked image or a single frame

  8. -Sky background, noise level, and Signal-to-noise measurements

  9. -Image centroid, FWHM, and jitter

  10. -Built-in database of Cohen standards and in-band fluxes for CC fitlers

  11. -Polarimetry reductio and publication-quality visualization

Will be available in the next release:

  1. -Calculate the sensitivity when an image of Cohen star is given

  2. -Bad pixel correction

Planned to be added in the future releases:

  1. -Strehl ratio measurement

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You can download the newest version of iCealCam using this link

iDealCam is free to use for everyone. However, please let me know if you want to make any modification on the original version, unless you restrict the modified version to you own use. Thank you!

If you want to be added to a mailing list for future messages regarding the update of iDealCam, please send me an email (no content is needed)

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iDealCam makes use of a few routines from the IDL Astronomy Library that can be downloaded from here. You also need to download Frank Varosi’s library from here. Make sure both libraries are in your IDL paths.

To compile and start iDealCam from the IDL command line, type in:

IDL> .compile idealcam

IDL> idealcam

Or use the “Compile” and “Run” buttons in the IDL Development Environment.

A manual is available for download. If you have any questions regarding iDealCam, please feel free to send me an email.

When using iDealCam, you can find some hints from the status bar at the bottom of the GUI

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iDealCam is developed in IDL 8.0. It has been tested in both IDL 8.0/8.2. The compatibility with IDL versions earlier than 8.0 is not guaranteed.

There is a bug in the build-in routine CW_BGROUP in IDL 8.1, so iDealCam cannot run in this version of IDL (has been fixed in IDL 8.2)

The compatibility between iDealCam and Windows OS has not been tested throughout yet.

If you try to open a FITS file that is damaged or not finished properly, iDealCam may halt (not crash). In this case, you can either restart the program, or type in the IDL command line:

IDL> retall

This will allow you to stop the running of module for opening the file, and hopefully the remaining part of the GUI is still running and you can then select another file to open.

If you find any other bugs or actions that may cause a crash, please send me a message by email. Thank you very much!

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  1. -V 2.0 (Jun 22, 2014)

    Improved polarimetric data reduction

  1. -V 1.5 (Feb 17, 2013)

    Bugs in aperture polarimetry fixed.

  1. -V 1.4 (Sept 28, 2012. With minor update/bug-fix on Dec 30, 2012)

    Add a separated routine (dl_cc_poloplot) into the packge for plotting the     reduced CanariCam polarimetry data in EPS format

  1. -V 1.2 (Nov 8 2011)

    Aperture polarimery

  1. -V 1.1 (Nov 1 2011)

    Polarimetry Reduction

  1. -V 1.0 (July 20 2011)

    Add frame registration (using centroids of the frames)

  1. -V 0.9 (July 16 2011)

    Add a built-in data base of Cohen standard stars and their fluxes

  1. -V 0.8 (July 6 2011)

    Add the module to read Michelle FITS files

  1. -V 0.7 (June 25 2011)

    First published version

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