Contents of: VI/111/./abstract/JCLAVEL_SEYFERT2.abs

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SCIENTIFIC ABSTRACT
We propose to study the 2.5 to 12 micron spectrum of about 80% of the
sources in the 46 active galaxies CfA sample with PHOT-S in chopping mode
and ISOCAM with LW filters No. 2(5.0-8.5 mu) and No. 7 (8.5-10.7 mu).
The remaining sources are either too faint (no IRAS detection at 12 micron)
or the subject of a different observing CP program. To the CfA AGN's, we
have added a set of about 20 bright Seyfert galaxies. The CAM broad band
images are necessary to understand the spatial distribution of the flux
and how it may affect the energy distribution observed with PHT-S.
The CfA sample is a well controlled and complete hard X-ray
selected sample  of Seyfert  I  and  Seyfert  II galaxies in sbout
equal proportions.  Hence, the PHOT-S spectra and ISOCAM images
will constitute an  ideal  data-base  for  statistical  studies.
Our  main scientific goals are the  following: (i) disentangle the
various  emission  components  -  thermal  and non-thermal -
which contribute to the observed near and mid-IR  flux  (ii)
search  for  spectral features characteristics of dust (iii)
search for broad (>3000 km/s) spectral lines in  Seyfert  II
galaxies  which  are  thought to be obscured Seyfert Is, and
(iv) search for molecular bands as tracers of  the  putative
molecular  torus which is postulated to surround the core of
AGNs.

This  programme  is  complementary  to  that  by  Rodriguez-
Espinosa  and  collaborators who plan to use PHT-P and PHT-C
to study a similar sample .

Because the list of AOT is longer than 99, the proposal has been split
into two. This is the second part of the proposal.

OBSERVATION SUMMARY


  All sources are observed both with PHT-S and CAM in single
  pointing mode. The PHOT AOT used is PHT-40 in chopping mode.
  With ISOCAM, we use AOT CAM-01 with LW broad band filters No. 2
  (5.0-8.5 micron) and No. 7(8.5-10.7 microns) at a pixel
  magnification of 1.5 arcsec.
  Exposure times have been computed with the simulators on the
  basis of the measured IRAS 12 micron flux and under the assumption
  that the frequency spectral index is -1.2. The background flux used
  in the computation is that measured by IRAS for all sources which
  are at least 15 degrees away from the ecliptic plane. For the
  remaining, ones we multiplied the IRAS-background by 1.5 to be on the
  safe side. The PHT-S exposure times yield an average signal-to-noise
  ratio of at least 10 in the continuum over the 2.5 to 12 micron band.
  For bright sources, the PHT exposure times (and S/N) have been
  increased to 256 sec so as to be larger then the slewing time. The
  same CAM exposure times of 100 s is used for all sources, which
  includes dark current measurements (40 s) and a flat overhead
  of 20 s. Such a time is sufficient to yield a signal-to-noise ratio
  of 80 on a 100 mJy point source.
  The total S/C time is 114,888 s (31.9 hrs) and 115,168 (32.0 hrs)
  for the autumn and spring launch, respectively.

CONCATENATION:
  We request the CAM and PHT-S observations to be concatenated for
  two reasons. First to save slewing time, and second and more important,
  to avoid problems related to variability. AGN's are known to be variable
  in the near IR.


© Université de Strasbourg/CNRS

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