Deep Impact at ESO

... Observations After the Impact

The following images are a sample representative of the unique data collected by the observers at the ESO La Silla Paranal Observatory on the night of July 4-5 (except for the NACO image which was taken the following night), i.e. after the impact of part of the Deep Impact spacecraft with Comet Tempel 1. These data show the various instruments used and their complementarity. Read more about the first results in ESO Press Release 19/05. Note that for all images the orientations is North up and East to the left. Click on the images to see a larger version.


Image of Comet Tempel 1 observed with FORS2 on the VLT.
The image shows the solar light reflected on the cometary dust particles.
It is a combination of three images taken with broadband filters selecting different colours in visible light.
The image covers about 40,000 km at the distance of the comet.

UVES: (Left) Slit viewer image showing the UVES slit place on an off-nucleus position in the cometary coma. (Right) Part of a two-dimensional spectrum showing some molecular lines - mainly from the C2 molecule - in the red part of the spectrum of comet Tempel 1.


WFI: Image through the R broadband filter (the full image has a 600 x 600 arcsec field of view). The image shows the large extension of the cometary dust coma. The vertical dark strips seen on the full-size image are unexposed interchip areas between the eight WFI CCDs.


EMMI: Image through the C2 gas filter (field of view: 300 x 300 arcsec). The image shows the combined dust reflected sunlight and the emission of the C2 gas in the coma of the comet. The vertical strip in the images results from the interchip area of the instrument detector array.


FORS1: the image shows the spectrum image of the inner coma in two perpendicular polarization direction. These images are used to evaluate the linear polarization degree of the dust in the coma, a measure for the size distribution and material of the grains therein. The bright horizontal strip shows the cometary spectrum along with a diffuse weaker halo from the dust. Diffuse vertical bands indicate emission bands from the coma gas. The sharp and bright vertical lines are emission lines from the Earth atmosphere.


SOFI: Image of Comet Tempel 1 though a J filter (field of view: 150 x 150 arcsec). The image shows mostly sunlight reflected by the dust grains of the comet.

NACO: Image in the K-band using the adaptive optics instrument. In this wavelength region the comet shines in dust reflected sunlight and thermal emission from the heated dust grains. The field of view is 11 x 11 arcsec.
TIMMI2: (Left) Image through the N filter (9.8 micron). The field of view is 15 x 15 arcsec. The image has a scale of 0.2arcsec per pixel (or 130km at the distance of the comet).The exposure shows the thermal emission of the heated dust grains in the coma. (Middle) N band spectrum of the comet. (Right) Flux distribution of the N band spectrum shown in the middle. This is one spectrum of a sample of about 20 similar spectra and further data-processing of the entire data sets will substantially improve the quality. From these spectra, the chemical composition of the dust can be assessed.


VISIR: Image through the Q band filter (17.65 micron). The field of view is 4.5 x 4.5 arcsec. The exposure shows the thermal emission of the heated dust grains in the coma. This image, in combination with the quasi-instantaneous TIMMI2 image allows for a precise determination of dust-grain temperatures.