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Optically Identified Supernova Remnants in the Nearby Spiral Galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101
We present the results of an optical search for supernova remnants (SNRs) in the spiral galaxies NGC 5204, NGC 5585, NGC 6946, M81, and M101. Using the criterion that emission nebulae with [S II]/HαExpand
Optical emission-line properties of evolved galactic supernova remnants
New optical spectrophotometric data are presented for the supernova remnants CTB 1, OA 184, VRO 42.05.01, S147, the Monoceros Loop, G206.9 + 2.3, and G65.3 + 5.7. These data are combined withExpand
The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant
HST images of the young supernova remnant Cas A are used to explore the expansion and spatial distribution of its highest velocity debris. ACS WFC images taken in 2004 March and December with SloanExpand
Recent Developments Concerning the Crab Nebula
On presente les informations essentielles relatives a la nebuleuse du Crabe. On passe en revue les determinations spectroscopiques de la masse et de la composition chimique de la nebuleuse. OnExpand
The Expansion Center and Dynamical Age of the Galactic Supernova Remnant Cassiopeia A
We present proper motions for 21 bright main shell and 17 faint, higher velocity, outer ejecta knots in the Cas A supernova remnant and use them to derive new estimates for the remnant's expansionExpand
The nature of the filaments northeast of the supernova remnant IC 443.
New optical spectrophotometry of the faint filaments northeast of the bright supernova remnant IC 443 show emission-line ratios very similar to those seen in the bright filaments of IC 443 and otherExpand
An Optical Study of the Circumstellar Environment Around the Crab Nebula
Long-slit spectra of two peripheral regions around the Crab Nebula show no H(alpha) emission down to a flux level of 1.5 x 10(exp -7)erg/sq cm s sr (0.63 Rayleigh), corresponding to an emissionExpand
The quadruple gravitational lens PG 1115+080: Time delays and models
Optical photometry is presented for the quadruple gravitational lens PG 1115+080. A preliminary reduction of data taken from 1995 November to 1996 June gives component C leading component B by 23.7 ?Expand
Dust and the Type II-Plateau Supernova 2004et
We present mid-infrared (MIR) observations of the Type II-plateau supernova (SN) 2004et, obtained with the Spitzer Space Telescope between 64 and 1406 days past explosion. Late-time optical spectraExpand
Supernova remnants (SNRs) have long been assumed to be the source of cosmic rays (CRs) up to the knee of the CR spectrum at 1015 eV, accelerating particles to relativistic energies in their blastExpand