The Spitzer Local Volume Legacy (LVL) Global Optical Photometry

TL;DR

This paper provides comprehensive optical photometry for 246 nearby galaxies in the LVL survey, enabling detailed panchromatic studies of galaxy properties across different types and sizes.

Contribution

It offers a new, extensive optical dataset for LVL galaxies, combining multiple imaging sources and defining apertures that better capture extended galaxy emission.

Findings

Later-type galaxies are bluer in color-color relationships.

Optical apertures often underestimate galaxy extent compared to IR apertures.

The dataset fills a gap for constructing full UV-optical-IR spectral energy distributions.

Abstract

We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D < 11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < M_B < -20.7 mag. A composite optical (UBVR) data set is constructed from observed UBVR and SDSS ugriz imaging, where the ugriz magnitudes are transformed into UBVR. We present photometry within three galaxy apertures defined at UV, optical, and IR wavelengths. Flux comparisons between these apertures reveal that the traditional optical R25 galaxy apertures do not fully encompass extended sources. Using the larger IR apertures we find color-color relationships where later-type spiral and irregular galaxies tend to be bluer than earlier-type galaxies. These data provide the missing optical emission from which future LVL studies can construct the full panchromatic (UV-optical-IR) spectral energy distributions.