NIRI SV observation 8

Status: in preparation
Data link: not yet available
Assessment: not yet available
Mode: Low-background imaging
Additional instrument verification: Pipeline reduction; ability to subtract adjacent continuum from dithered images and detect faint emission lines
Telescope verification: Standard dithering techniques, communications between TCS and instrument control.
Proposed observing sequence: Narrow-band images centered on the strongest near-IR emission lines (as observed in previously obtained spectra) : [FeII] 1.644 microns, Pa beta (1.2818 microns), H_2 (2.122 microns), Br gamma (2.1655 microns) and adjacent continuum, in order to subtract the contribution of the latter.
OT program file: not yet available
Science background: Narrow-band IR Imaging of Nearby AGN

Narrow-band imaging is a powerful tool for investigating the structure, excitation and collimation mechanisms of the nuclear regions of nearby Seyfert galaxies. Three Seyfert galaxies with high fluxes in the IR emission-lines Pa beta, [FeII]1.644, H_2 2.122 and Br gamma have been selected from previous spectroscopic studies in order to obtain narrow-band images through filters centered on these lines. The selected galaxies, in addition, show extended anisotropic high excitation optical emission, and well mapped radio structures approximately cospatial with the high excitation gas.

Our scientific goals are: (1) Search for the presence of a molecular torus, which, if present, should extend perpendicular to the radio axis; (2) map the excited gas along the cone, expected to be traced by the [FeII] emission, to investigate the known correlation between the IR [FeII] emission and radio emission in Seyferts; (3) investigate the distribution of different gas excitation mechanisms and reddening through line-ratio maps.

Target(s):
Object approx. RA (2000) approx. dec (2000) redshift
NGC 3227 10:23:30 19:51:54 0.0039
NGC 4151 12:10:33 39:24:21 0.0033
NGC 5506 14:13:15 -03:12:27 0.006
Observing condition constraints: image quality: 20%-ile
sky transparency (clouds): 50%-ile
sky transparency (water vapour): Any
sky background: 80%-ile
max air mass: 2.0
Observing time requirements: FeII, PaBeta, H2, BrGamma, continuum: 30 minutes on-source in each filter
Broadband filters ~3 minutes on-source per filter.
Total ~4 hours for each galaxy, including overhead
SV team member(s) responsible for assessment: Thaisa Storchi Bergmann

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Last update October 29, 1999; Joe Jensen