We present the widest-field resolved stellar map to date of the closest (D ∼ 3.8 Mpc) massive elliptical galaxy NGC 5128 (Centaurus A; Cen A), extending out to a projected galactocentric radius of ∼ 150 kpc. The dataset is part of our ongoing Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) utilizing the Magellan/Megacam imager. We resolve a population of old red giant branch stars down to ∼ 1.5 mag below the tip of the red giant branch, reaching surface brightness limits as low as µ V,0 ∼ 32 mag arcsec −2 . The resulting spatial stellar density map highlights a plethora of previously unknown streams, shells, and satellites, including the first tidally disrupting dwarf around Cen A (CenA-MM-Dw3), which underline its active accretion history. We report 13 previously unknown dwarf satellite candidates, of which 9 are confirmed to be at the distance of Cen A (the remaining 4 are not resolved into stars), with magnitudes in the range M V = −7.2 to −13.0, central surface brightness values of µ V,0 = 25.4−26.9 mag arcsec −2 , and half-light radii of r h = 0.22−2.92 kpc. These values are in line with Local Group dwarfs but also lie at the faint/diffuse end of their distribution; interestingly, CenA-MM-Dw3 has similar properties to the recently discovered ultra-diffuse galaxies in Virgo and Coma. Most of the new dwarfs are fainter than the previously known Cen A satellites. The newly discovered dwarfs and halo substructures are discussed in light of their stellar populations, and they are compared to those discovered by the PAndAS survey of M31.

We present deep imaging of the most distant dwarf discovered by the Dark Energy Survey, Eridanus II (Eri II). Our Magellan/Megacam stellar photometry reaches ∼3 mag deeper than previous work and allows us to confirm the presence of a stellar cluster whose position is consistent with Eri II's center. This makes Eri II, at = -M 7.1 V , the least luminous galaxy known to host a (possibly central) cluster. The cluster is partially resolved, and at = -M 3.5V it accounts for ∼4% of Eri II's luminosity. We derive updated structural parameters for Eri II, which has a half-light radius of ∼280 pc and is elongated (ò ∼ 0.48) at a measured distance of D ∼ 370 kpc. The colormagnitude diagram displays a blue, extended horizontal branch, as well as a less populated red horizontal branch. A central concentration of stars brighter than the old main-sequence turnoff hints at a possible intermediate-age (∼3 Gyr) population; alternatively, these sources could be blue straggler stars. A deep Green Bank Telescope observation of Eri II reveals no associated atomic gas.

We present a comprehensive analysis of the structural properties and luminosities of the 23 dwarf spheroidal galaxies that fall within the footprint of the Pan-Andromeda Archaeological Survey (PAndAS). These dwarf galaxies represent the large majority of Andromeda's known satellite dwarf galaxies and cover a wide range in luminosity (−11.6 ∼ < M V ∼ < −5.8 or 10 4.2 ∼ < L ∼ < 10 6.5 L ⊙ ) and surface brightness (25.1 ∼ < µ 0 ∼ < 29.3 mag/arcsec 2 ). We confirm most previous measurements, but find And XIX to be significantly larger than before (r h = 3065 +1065 −935 pc, M V = −10.1 +0.8 −0.4 ) and cannot derive parameters for And XXVII as it is likely not a bound stellar system. We also significantly revise downward the luminosities of And XV and And XVI, which are now M V ∼ −7.5 or L ∼ 10 5 L ⊙ . Finally, we provide the first detailed analysis of Cas II/And XXX, a fairly faint system (M V = −8.03 ) of typical size (r h = 270 ± 50 pc), located in close proximity to the two bright elliptical dwarf galaxies NGC 147 & 185. Combined with the set of homogeneous distances published in an earlier contribution, our analysis dutifully tracks all relevant sources of uncertainty in the determination of the properties of the dwarf galaxies from the PAndAS photometric catalogue. We further publish the posterior probability distribution functions of all the parameters we fit for in the form of MCMC chains available online; these inputs should be used in any analysis that aims to remain truthful to the data and properly account for covariance between parameters.

The Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) is constructing a wide-field map of the resolved stellar populations in the extended halos of these two nearby, prominent galaxies. We present new Magellan/Megacam imaging of a ∼ 3 deg 2 area around Centaurus A (Cen A), which filled in much of our coverage to its south, leaving a nearly complete halo map out to a projected radius of ∼150 kpc and allowing us to identify two new resolved dwarf galaxies. We have additionally obtained deep Hubble Space Telescope (HST) optical imaging of eleven out of the thirteen candidate dwarf galaxies identified around Cen A and presented in Crnojević et al. (2016b): seven are confirmed to be satellites of Cen A, while four are found to be background galaxies. We derive accurate distances, structural parameters, luminosities and photometric metallicities for the seven candidates confirmed by our HST/ACS imaging. We further study the stellar population along the ∼60 kpc long (in projection) stream associated with Dw3, which likely had an initial brightness of M V ∼−15 and shows evidence for a metallicity gradient along its length. Using the total sample of eleven dwarf satellites discovered by the PISCeS survey, as well as thirteen brighter previously known satellites of Cen A, we present a revised galaxy luminosity function for the Cen A group down to a limiting magnitude of M V ∼ −8, which has a slope of −1.14 ± 0.17, comparable to that seen in the Local Group and in other nearby groups of galaxies.