WIRCam Press Release Images
Credit line: "Canada-France-Hawaii Telescope / 2006"
Copyright © 2006 Canada-France-Hawaii Telescope Corporation

The Orion Nebula
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Color composite made by TERAPIX (Courtesy C. Marmo/Terapix)
The Orion Nebula, at a distance of merely 1300 light-years from Earth, is the closest star nursery and one of the most prolific found in the Milky Way. Most stars in the Orion Nebula are only a few millions years old, a thousand times younger than the Sun and Earth. Many are still actively forming and are embedded in their natal opaque dust clouds. Contrarily to ordinary visible light, infrared light can penetrate dust and allows astronomers to study star formation. Most of the red stars in this image suffer high dust extinction and were only first observed with the advent of infrared cameras. WIRCam, with its wide field of view, allows astronomers to observe all of the Orion stars in a snapshot. This color image is a composite of 3 monochromatic images taken through the Y, H and H2 filters and totals about 30 minutes of observation. Several red fingers of molecular hydrogen gas are seen near the core of the Nebula. They are associated with newly-formed stars escaping from that region at high velocity.  

The Orion Nebula seen with MegaCam and WIRCam
 Medium  (1000 x 500) 
WIRCam color composite made by TERAPIX (Courtesy C. Marmo/Terapix)
Differences between the optical (left - MegaCam) and infrared (right - WIRCam) views of the same object (Orion Nebulae) are striking. The pink and white hues seen on the MegaCam image come from heated hydrogen atoms which only shine in the optical colors. Clouds of dust are more transparent in the infrared and stars, usually hidden by dust, are now visible. For example, stars pop up around the red clouds at the very bottom of the infrared image. See the caption above for more information on the the WIRCam image.

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Color composite made by TERAPIX (Courtesy C. Marmo/Terapix)
This galaxy is an excellent example of what a spiral galaxy like our Milky Way looks like seen edge-on. The central galaxy bulge is a collection of billions of old stars formed early in history. The black lane sourrounding the bulge is made of gas and fine dust particles forming complex clouds. In this image, the filamentary structure of these giant molecular clouds can be seen by superposition onto the whitish stellar light background. An important property of infrared light is its ability to penetrate through this dust and reveal the galaxy bulge. To envision the scale of a galaxy like NGC 891, one has to realize that each filament may eventually contract under gravity, form thousand of stars and produce a nebula ressembling the Orion Nebula (see the Orion Nebula image). This color composite is made from 10-minute observations through the Y, J and Ks filters.

The Ring Nebula (Messier 57)
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The Ring Nebula is what astronomers refer to as a planetary nebula. But contrarily to what its name suggests, it does not harbour planets. Instead, it represents the final outcome of stellar evolution when a star dies and expells most of its gas in a catastrophic event. The Sun will go through this phase when it dies in about 5 billion years. While most of the star's enveloppe is ejected in space, what was the core of the star is left behind, and is called a white dwarf. It is faintly visible here in the center of the image. The Ring Nebula takes a different aspect when seen through infrared light. Signature of this cold molecular hydrogen gas forming the outer ringlets and arcs is only found in the infrared light, not in the visible light. This 10-minute false-color image was taken through an H2 filter. It is a simple stack of short exposures slightly offset with respect to each other to fill the gaps of the mosaic. The different distortion experienced by stars in the field from exposure to exposure, not corrected for in this stacking process, is visible on stars in the lower part of the images, unlike on the other WIRCam images shown on this page above and below, where this effect has been carefully corrected at TERAPIX.

MegaCam and WIRCam field of view comparison
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Color composite made by TERAPIX (Courtesy C. Marmo/Terapix)

Here is one of the four deep fields (D2) as observed by MegaCam for the CFHT Legacy Survey. The image size is 1degree x 1degree on the sky: 4 full moons could be viewed in two rows of two side by side in such an image!  The white square  shows the size of the field of  view of WIRCam. Though it is only 1/9th of the field of MegaCam, it is still very large for an infrared camera! See below for the first composite using both MegaCam and WIRCam.

MegaCam and WIRCam imaging the same field...
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Color composite made by TERAPIX (Courtesy C. Marmo/Terapix)
This image covers the square illustrated in the image above. The composite is made of  two colors from MegaCam in the visible, g' and i',  with the addition of one color from WIRCam, Ks, in the infrared centered at 2.15 microns. Field of view is  20' x 20'.

The CFHT dome on top of Mauna Kea - Hawai`i
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The observatories on Mauna Kea benefit from the high altitude of the site (about 14,000 feet or 4,200 meters), resulting in a clearer and dryer atmosphere, a darker sky, more clear nights per year and most importantly, sharper images, thanks to the low turbulence of the atmosphere at the summit. As the tourists prepare to leave the summit after viewing the wonderful sunset offered at that altitude, the CFHT dome opens and is prepared for a night of observations.  These ordinarily last 10 hours, with little variation from summer to winter, since Hawaii stands at a latitude of 20 degrees north.

WIRCam being installed on top of the telescope
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Under the close watch of the operator in the crane cab, the WIRCam Upper End is slowly lowered on the top ring of the telescope. WIRCam is actually housed in the black tall structure called the prime focus cage.  In the early days of the telescope, photographic plates were the detectors of choice. The astronomer used to sit there for hours, one eye on an eyepiece and one hand on a paddle used to keep the telescope pointed on the target while the plate was being exposed...  Now, all the observations are carried out from the comfort of a warm control room one floor below the dome observing floor!

A close-up on the infrared detector array being populated
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The first of the four infrared detectors was just installed on the mechanical support of the mosaic. It is an array of 2048 x 2048 pixels especially developed by Rockwell Scientific. Nicknamed Hawaii-2RG,  this array is very sensitive to infrared light and at the same time exhibits a low "noise": an ideal combination for observing faint astronomical objects.



The infrared mosaic with its four detectors
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The four detectors are now installed in a two by two mosaic, for a total of 4096 x 4096 pixels.
The mosaic can be read in a few seconds and exposure times are limited by the brightness of the sky itself, typically up to 30 seconds to one minute for broad band filters.


The mosaic on the camera
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With is back ready to be connected to the cables carrying its signals to the electronics, the mosaic is now installed on the back of the cryostat. Though the heart of WIRCam, it is only a tiny part of the whole system...


The mosaic is now connected...
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The cryostat is ready to be closed. The next step will be to pump the air out of the camera. The vacuum inside will have to be good enough to cool down the components of the camera down to around 80 Kelvin (-193 Celsius). The whole process will take a few days, so we better make sure that everything is in order inside the camera before starting the process!


Copyright policy and credits related to all press release materials

All images on this page are to be used exclusively for the purpose of media announcements related to WIRCam.
For any other use, please seek authorization from CFHT's PR officer .
Any images used should be credited as follow: "Canada-France-Hawaii Telescope / 2006"