(UCDs) residing in the clusters, and find the spatial distributions of UDGs and UCDs appear anti-correlated. Around 15% of UDGs exhibit either compact nuclei or nearby point sources. Taken together, these observations provide additional evidence for a picture where at least some UDGs are destroyed in dense cluster environments and leave behind a residue of UCDs.
author:
- 'Steven R. Janssens, Roberto Abraham, Jean Brodie, Duncan A. Forbes, and Aaron J. Romanowsky'
title: 'The Distribution of Ultra-Diffuse and Ultra-Compact Galaxies in the Frontier Fields'
---

Introduction
============

Large low surface brightness galaxies in galaxy clusters were first reported by [@vcc3] who noted the existence of “very-large-size, low-surface-brightness dwarfs" in the Virgo cluster. They chose not to introduce a new morphological designation for these galaxies, since apart from their large sizes ($\sim$10 kpc in diameter), they resemble otherwise normal dwarfs or dwarf irregulars [@vcc2]. Similarly, [@impey1988] found an additional 27 examples in Virgo, and similar large low surface brightness galaxies were found in Fornax [@ferguson1988; @bothun1991]. Related objects were also found in lower density environments, such as the low surface brightness galaxies described by [@dalcanton1997], and F8D1 in the M81 group [@caldwell1998].

The interest in large low-surface-brightness galaxies has recently been 