We present optical and near-infrared (NIR) photometry and spectroscopy of the Type IIb supernova (SN) 2011dh for the first 100 days. We complement our extensive dataset with Swift ultra-violet (UV) and Spitzer mid-infrared (MIR) data to build a UV to MIR bolometric lightcurve using both photometric and spectroscopic data. Hydrodynamical modelling of the SN based on this bolometric lightcurve have been presented in Bersten et al. (2012, ApJ, 757, 31). We find that the absorption minimum for the hydrogen lines is never seen below ∼11 000 km s −1 but approaches this value as the lines get weaker. This suggests that the interface between the helium core and hydrogen rich envelope is located near this velocity in agreement with the Bersten et al. (2012) He4R270 ejecta model. Spectral modelling of the hydrogen lines using this ejecta model supports the conclusion and we find a hydrogen mass of 0.01-0.04 M to be consistent with the observed spectral evolution. We estimate that the photosphere reaches the helium core at 5-7 days whereas the helium lines appear between ∼10 and ∼15 days, close to the photosphere and then move outward in velocity until ∼40 days. This suggests that increasing non-thermal excitation due to decreasing optical depth for the γ-rays is driving the early evolution of these lines. The Spitzer 4.5 µm band shows a significant flux excess, which we attribute to CO fundamental band emission or a thermal dust echo although further work using late time data is needed. The distance and in particular the extinction, where we use spectral modelling to put further constraints, is discussed in some detail as well as the sensitivity of the hydrodynamical modelling to errors in these quantities. We also provide and discuss pre-and post-explosion observations of the SN site which shows a reduction by ∼75 percent in flux at the position of the yellow supergiant coincident with SN 2011dh. The B, V and r band decline rates of 0.0073, 0.0090 and 0.0053 mag day −1 respectively are consistent with the remaining flux being emitted by the SN. Hence we find that the star was indeed the progenitor of SN 2011dh as previously suggested by Maund et al. (2011, ApJ, 739, L37) and which is also consistent with the results from the hydrodynamical modelling.

We present slitless spectra of the Narrow Line Region (NLR) in NGC 4151 from the Space Telescope Imaging Spectrograph (STIS) on HST, and investigate the kinematics and physical conditions of the emission line clouds in this region. Using medium resolution (∼ 0.5Å) slitless spectra at two roll angles and narrow band undispersed images, we have mapped the NLR velocity field from 1.2 kpc to within 13 pc (H • = 75 km s −1 Mpc −1 ) of the nucleus. The inner biconical cloud distribution exhibits recessional velocities relative to the nucleus to the NE and approaching velocities to the SW of the nucleus. We find evidence for at least two kinematic components in the NLR. One kinematic component is characterized by Low Velocities and Low Velocity Dispersions (LVLVD clouds: |v| < 400 km s −1 , and ∆v < 130 km s −1 ). This population extends through the NLR and their observed kinematics may be gravitationally associated with the host galaxy. Another component is characterized by High Velocities and High Velocity Dispersions (HVHVD clouds: 400 < |v| < ∼ 1700 km s −1 , ∆v ≥ 130 km s −1 ). This set of clouds is located within 1.1 ′′ (∼ 70 pc) of the nucleus and has radial velocities which are too high to be gravitational in origin, but show no strong correlation between velocity or velocity dispersion and the position of the radio knots. Outflow scenarios will be discussed as the driving mechanism for these HVHVD clouds. We also find clouds characterized by Low Velocities and High Velocity Dispersions (LVHVD clouds: |v| < 400 km s −1 , ∆v ≥ 130 km s −1 ). These clouds are located within 3.2 ′′ (∼ 200 pc) of the nucleus. It is not clear if the LVHVD clouds are HVHVD clouds whose low velocities are the results of projection effects.Within 3.2 ′′ (∼ 200 pc) of the nucleus, the [OIII]/Hβ ratio declines roughly linearly for both the High Velocity Dispersion (HVD) and LVLVD clouds. Since the ionization parameter is proportional to r −2 n −1 , it appears that the density, n, must decrease as ∼r −1 for the clouds within the inner ∼ 3.2 ′′ . At distances further from the nucleus, the [OIII]/Hβ ratio is roughly constant.

We present measurements of radial velocities for the narrow-line region gas in the Seyfert 2 galaxy Mrk 3 out to D1 kpc from the nucleus. The observations consist of two data sets, both using the Space Telescope Imaging Spectrograph on board the Hubble Space T elescope : (1) an [O III] slitless spectrum with the G430M grating of the inner 3A around the nucleus and (2) a long-slit observation centered on the nucleus (P.A. \ 71¡) by using the G430L grating and the aperture. Our analysis produces 52A ] 0A .1 radial velocity maps of the emission-line gas, which indicate trends in the gas motion. These include blueshifts and redshifts on either side of the nucleus, steep velocity rises from systemic up to about^700 km s~1 taking place in the inner (0.08 kpc) both east and west of the nucleus, gradual velocity 0A .3 descents back to near-systemic values from slightly uneven velocity amplitudes on each side of 0A .3È1A .0, the nucleus, and narrow velocity ranges over the entire observed region. When Ðtted to kinematic models for the NLR gas, the data clearly favor one in which the gas exists in a partially Ðlled bicone, is accelerated radially away from the nucleus, and is followed by a constant deceleration (possibly due to collision with an ambient medium). This geometry and general kinematic model are in agreement with previous work done on the NLR gas of NGC 1068 and NGC 4151. On scales of hundreds of parsecs, we conclude that radial outÑow may be a common feature of Seyfert galaxies.