Comet C/2009 P1 (Garradd)

July 2.047, 2011 observation

C11 telescope (D = 0.28)
LISA Spectrograph at R = 700 (35 microns slit)
Atik 314L+ CCD camera (binning 2x2)
Castanet-Tolosan Observatory (France)
Exposure : 11 x 600 s

2D spectrum of C/2009 P1 Garrad (the coloration is artificial). For the essential, the spectrum exibit the Sun signature on dust and a faint gaz emission
except for the the cynogen line in the UV part of the spectrum.


Comparison of a Solar similar star (51 Peg) and Garradd spectrum.

Ratio of comet spectrum and 51 Pegassus spectrum (the latter star produce a spectrum similar to Sun). The ratio elliminate Sun signature (the Fraunhofer
lines and the black body spectral profile). Note the flat aspect of dust reflectance spectrum (red more reflective). CN line is prominent near the UV part
of the spectrum. Faint C2 activity is also visible. Download the ratio file: ratio_20110702.dat

March 26.837, 2012 observation

C11 telescope (D = 0.28)
LISA Spectrograph at R = 1000 (23 microns slit)
Atik 314L+ CCD camera (binning 1x1)
Castanet-Tolosan Observatory (France)
Exposure : 6 x 600 s

Color image taken from suburban Castanet-Tolosan observatory- March 25.87, 2012.FSQ-85E refractor + QSI-582 (3 x (6 x 300 s) exposure).

2D spectrum of comet + sky pollution (stack of 6 x 600 sec. exposure)

2D spectrum of sky pollution only (stack of 6 x 600 sec. exposure). The spectrum is dominated by sodium (hight pressure lamps) and mercury lines.

Substraction of comet + sky spectrum and sky spectrum only. The image shows the spectrum of nuclear region (nearly a Sun spectrum reflected by dust) and the spectrum of coma region (emission bands).
A residual of Earth atmosphere airglow at 6300 A is clearly visible (high temporal variability probably linked to solar activity).

Spectral profile of coma region. Note the detection of ammonia (NH2) line at 6332 A.

Spectral profile of nucleus region (the observed spectrum is divided by the spectrum of a solar like star - HD95128).

Coma spectrum :
Nucleus region :