A Census of Nearby Galaxies


Mansi Kasliwal


Spectroscopic observations of nearby galaxies identified in Palomar Transient Factory (PTF) imaging, taken with the goal of completing a census of the local universe

Finding Targets

An object whose ANCILLARY_TARGET2 value includes one or more of the bitmasks in the following table was targeted for spectroscopy as part of this ancillary target program. See SDSS bitmasks to learn how to use these values to identify objects in this ancillary target program.

Program (bit name) Bit number Target Description Number of Fibers Number of Unique Primary Objects
PTF_GAL 19 A nearby galaxy identified in PTF imaging with an SDSS counterpart 178 173


We do not yet have a complete catalog of galaxies within 200 Mpc (Kasliwal 2011), hampering studies of nearby transients and the fine details of the large-scale distribution of galaxies. The Palomar Transient Factory (PTF; Law et al. 2009) is performing a narrow-band survey in two filters, centered at 656 nm and 663 nm, to complete the catalog of galaxies in the local universe out to 200 Mpc.

Target Selection

A sample of galaxies denoted by the PTF_GAL target flag was selected for spectroscopic confirmation. Galaxies without known redshift were observed if they had an SDSS counterpart, a color m656 – m663 > 0.7 mag, and relatively blue broadband color (gmodel – imodel < 1.3 mag). Images of all candidate galaxies were first manually inspected to avoid spurious detections.


Kasliwal, M. M. 2011, PhD thesis, California Institute of Technology

Law, N. M., et al. 2009, PASP, 121, 1395