Arcetri Solar Physics Group

IBIS First Light - June 2003
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In June 2003, IBIS was successfully installed at the Dunn Solar Telescope (DST) at the National Solar Observatory in Sunspot, NM, USA. The instrument is fed by the adaptive optics system available at the DST, which allows it to achieve diffraction limited imaging in a broader range of atmospheric conditions. IBIS will remain at the National Solar Observatory for two years where it will be made available to all users of the telescope.

IBIS Installation Team
IBIS Installation Team (from L to R):
Kevin Reardon, Tito Grisendi, Fabio Cavallini (PI), Gilberto Falcini, Sergio Paloschi

Click image to enlarge

Below we display an example of the data obtained with IBIS, a scan of a region near sun-center including a small pore. The scan shows the change in structures as we look at different heights in the solar atmosphere (both within a single spectral line and between lines). The small inset image shows that IBIS is able to resolve structures at the resolution allowed by the DST, while providing full spectral information on those structures.

IBIS Spectral Scan Movie
Click to start movie or Select format below
Available as an
MPEG-1 movie (2.2 MB)
Quicktime movie (2.3 MB)
Animated GIF (3.3 MB)

This movie shows an example of an IBIS sequence made up of scans through three different spectral lines in the solar atmosphere. The round image at the top shows the full field of view of IBIS, which has a diameter of 80 arcseconds. The smaller rectangle to the side is an enlargement of the 5 x 8 arcsec2 central area outlined by the blue box on the full image. Tick marks on the smaller box are at 1 arcsecond spacing. The details in this enlarged imaged have been enhanced through the use of Sobel edge-enhancement techniques.

The three spectral ranges are shown underneath, with a plot of the average profile measured from these data, normalized to the the level of the local continuum. The three spectral lines observed include:

  • Fe II, 7224.5 Å, deep photosphere;
  • Fe I, 7090.4 Å, upper photosphere; and
  • Ca II 8542.1 Å, chromosphere.

    As the movie progresses, the blue line indicates the relative position of the spectral passband at the center of each image. The spectral passband has a FWHM of 30-40 mÅ for these spectral ranges (widening at longer wavelengths). The spectral passband is progressively blueshifted when moving radially away from the center of the field. This blueshift reaches a peak of approximately 80 mÅ at the edge of the field. This slight wavelength shift is responsible for the change in appearance and contrast seen at times within the single images. The entire scan included a total of 50 different spectral positions.

    The images shown have been corrected only for the dark current of the CCD used to acquire the data. No flat field corrections have been applied to the data. The intensity of each image has been individually scaled to best show the features in each image. The edge-enhancement applied to the small rectangular insets introduces additional random noise that is not present in the original data.

  • Last Updated: 23 August, 2003