C/2001 Q4 (NEAT)
spectrography + polarization


Comet Q4 NEAT, the 13.8 May, 2004
Canon EOS 10D + Canon 100 mm f2.8 macro - stack of 6 x 60 seconds exposure - Toulouse (suburban)




May 14.879 UT 2004 Observation


Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: Takahashi FS-128 refractor (5-inch aperture) -
MERIS spectrograph (bin. 2x2 - sampling of 5.75 A/pixel) + Audine KAF-0401E CCD
Cumulative exposure time of 12 minutes (stack of 6 two minutes frame)

The comet through a large slit (order 0 image - pointing phase)

The comet through a more narrow slit (order 0 image )

The 2-D spectrum of Q4 NEAT + the spectrum of background sky (high pressure lamp spectral signature - click here)
(artificial colour, but representative)

The 2-D spectrum of Q4 NEAT after sky removal
Band heads of diatomic C2 are clearly shown.
(artificial colour, but representative)

The spectral profile (nuclear region).


Note: the spectrum is corrected for the instrumental spectral response.
Download 140504.dat


May 15.867 UT 2004 Observation


Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: Takahashi FS-128 refractor (5-inch aperture) -
MERIS spectrograph (bin. 2x2 - sampling of 5.50 A/pixel) + Audine KAF-0402ME CCD
Cumulative exposure time of 32 minutes (stack of 16 two minutes frame)

 
Bleue region of NEAT (note the usage of a KAF-402ME CCD  for its bleue sensitivity). CN band at 3880 A is visible at left.


The spectral profile (nuclear region) . Note the presence of CN  band (cyanogen) at 3883 angstroms.


Note: the spectrum is corrected for the instrumental spectral response.
Download 150504.dat 


May 16.9 UT 2004 Observation
Polarization analysis


Observatory: Castanet Tolosan (France) - IAU959
Observer: Christian Buil
Instrument: Takahashi FS-128 refractor (5-inch aperture) -
Canon EOS 10D - Linear polarizing filter
Three position filter: 0 (stack of 24 x 30 seconds exposure) - 60 (stack of 24 x 30 seconds exposure) - 120 (stack of 24 x 30 seconds exposure)

   
From left to right:
(1) gray representation of central region (stack of the 72 x 30 seconds available exposures),
(2) false-colors + isophotes from a logarithm intensity scale
(3) radial gradient of -4 pixels (note the jet in front the nucleus).
The scale of this images is 1.47 arcsec/pixel. A median composite of the individual frames permit to eliminate the field star trails.
 

   
From left to right:
(1) 0 orientation of the polarization filter (relative to the declinaison great circles)
(2) 60 orientation of the polarization filter (relative to the declinaison great circles)
(1) 120 orientation of the polarization filter (relative to the declinaison great circles)
 


Polarization map superimposed to a false-colors image. The orientation of the vectors indicate the direction of the local polarization plane. The length of the vectors indicates the degree of polarization. The polarisation level measured in the immediate vicinity of the nucleus of 21%. The polarization degree front to the nucleus (jet) is 15%. The mean polarization of the external part is typically of 7%.


Back to the comets page