A Cepheid-based Distance to the Seyfert Galaxy NGC 6814

Abstract

We present a Cepheid-based distance to the nearby Seyfert galaxy NGC 6814 from Hubble Space Telescope observations. We obtained F555W and F814W imaging over the course of 12 visits with logarithmic time spacing in 2013 August−October. We detected and made photometric measurements for 16,469 unique sources across all images in both filters, from which we identify 90 excellent Cepheid candidates spanning a range of periods of 13–84 days. We find evidence for incompleteness in the detection of candidates at periods <21 days. Based on the analysis of Cepheid candidates above the incompleteness limit, we determine a distance modulus for NGC 6814 relative to the LMC of ${\mu }_{\mathrm{rel}\mathrm{LMC}}={13.200}_{-0.031}^{+0.031}$ mag. Adopting the recent constraint of the distance modulus to the LMC determined by Pietrzyński et al., we find $m-M={31.677}_{-0.041}^{+0.041}$ which gives a distance of 21.65 ± 0.41 Mpc to NGC 6814