... 6951

Based on observations made with the 4.2m William Herschel Telescope operated by the Isaac Newton Group, and the 2.6m Nordic Optical Telescope operated jointly by Denmark, Finland, Iceland, Norway, and Sweden, on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

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...

Also based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the ESA Space Telescope European Coordinating Facility.

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...1

Visiting astronomer, German-Spanish Astronomical Centre, Calar Alto, operated by the Max-Planck-Institute for Astronomy, Heidelberg, jointly with the Spanish National Comission for Astronomy.

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...4

On sabbatical at Queen Mary and Westfield College, Astronomy Unit, London, UK

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... IRAF

The authors acknowledge the data analysis software FIGARO provided by the Starlink Project which is run by CCLRC on behalf of PPARC. IRAF is the Image Analysis and Reduction Facility made available to the astronomical community by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy (AURA), Inc., under contract with the U.S. National Science Foundation.

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... same

If this circumnuclear region is a decoupled gaseous disk, it could have a different inclination to the line of sight that the main galaxy disk, but we will assume here that this is not the case and that the inclination is the same.

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... 6951

Based on observations made with the 4.2m William Herschel Telescope operated by the Isaac Newton Group, and the 2.6m Nordic Optical Telescope operated jointly by Denmark, Finland, Iceland, Norway, and Sweden, on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

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...

Also based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the ESA Space Telescope European Coordinating Facility.

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...1

Visiting astronomer, German-Spanish Astronomical Centre, Calar Alto, operated by the Max-Planck-Institute for Astronomy, Heidelberg, jointly with the Spanish National Comission for Astronomy.

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...4

On sabbatical at Queen Mary and Westfield College, Astronomy Unit, London, UK

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... IRAF

The authors acknowledge the data analysis software FIGARO provided by the Starlink Project which is run by CCLRC on behalf of PPARC. IRAF is the Image Analysis and Reduction Facility made available to the astronomical community by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy (AURA), Inc., under contract with the U.S. National Science Foundation.

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... same

If this circumnuclear region is a decoupled gaseous disk, it could have a different inclination to the line of sight that the main galaxy disk, but we will assume here that this is not the case and that the inclination is the same.

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...)

Computing the intersection between the bar pattern speed and the curve 40#40 (were 41#41 is the angular velocity and 42#42 the epicyclic frequency) directly from the data points in the velocity curve is hampered by the dependence of 42#42 on the derivative of the velocity, which implies that small errors and structure in the velocity as a function of radius translate into large fluctuations in 42#42. In the case of NGC 6951 this problem is further exacerbated by the scarcity of data points in the region outside the circumnuclear ring, between 10 arcsec and 30 arcsec.

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... ILR)

The shallow radial dependence of 41#41 at this distance from the nucleus, and the steeper dependence closer to the nucleus, implies that a 10% or 20% uncertainty in the position of CR does not affect significantly the location of the ILRs.

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... divided

This process of enhancement consists in dividing the original image by a median filtered version, so as to enhance sharp features.

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