The animated gif below is a combination of
200 images taken with the Slit-viewing camera on NIRSPEC
on Keck II. The images were taken before, during and
after the impact. The dark band seen in some images is
the entrance slit to the spectrograph. Most of the
light from the comet goes down the slit so that we can
take spectra of the comet. A spectrum is the light
from an object divided up by its wavelength. Using
spectra, we can identify the elements and molecules
present in the comet.
Each image is a zoomed in view of the slit-viewing camera. The image
is 17.8 arcseconds on a side. At the comet's distance
from Earth, each pixel is about 115 km (72 miles). The slit is aligned
north-south with north pointing to the right. All
images are in the infrared K-band (2.2 microns), 4
seconds in length, and background subtracted.