Bright Galaxies


Photo of Demitri Muna
Demitri Muna
The Ohio State University


A search for bright galaxies that were missed by prior SDSS spectroscopic surveys

Finding Targets

An object whose ANCILLARY_TARGET1 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
BRIGHTGAL 21 A bright galaxy that may have been missed by prior SDSS spectroscopic surveys (see Target Selection for details) 5,616 5,275


Bright galaxies were commonly missed in the original SDSS spectroscopic survey due to fiber collisions, bright limits (objects with model magnitudes r > 15, g > 15, or i > 14.5 were excluded), and errors in the deblending of overlapping images (Strauss et al. 2002). Approximately 10% of the brightest galaxies were not spectroscopically observed (Fukugita et al. 2007). To improve the completeness of the SDSS spectroscopic sample of bright galaxies, we have implemented the target selection criteria described below.

Target Selection

Objects were chosen with:

  • Petrosian radius > 1″ in r (to reject stars)
  • No saturated pixels
  • Extinction-corrected, Petrosian (Petrosian 1976; Strauss et al. 2002) r magnitude between 10 and 16.
  • Extinction-corrected Petrosian magnitude i < 20 and z < 20 (to exclude misidentified satellite tracks which would not show up in the other bands).

Galaxies without spectra (24,000 from the original list of 93,000) where then visually vetted to remove foreground stars that remained in the sample, detector artifacts (e.g. internal reflections) that were misidentified, and other sources of confusion. In cases where a foreground star was misidentified as the galaxy center, the target position was moved to the correct position. In cases of merging galaxies, we visually identified multiple targets corresponding to the centers of each galaxy. The list was cross-correlated with the Third Reference Catalog of Bright Galaxies (RC3; de Vaucouleurs et al. 1991; Corwin, Buta, & de Vaucouleurs 1994), and any targets that did not appear in the original SDSS spectroscopic survey were added to the target list (0.05% of the final list). Finally, targets within 2″ of a star that appears in the Tycho-2 Catalog (Høg et al. 2000) were removed.


Corwin, H. G., Jr.; Buta, R. J.; de Vaucouleurs, G., 1994 (Abstract from ADS), AJ, 108, 2128, doi:10.1086/117225

de Vaucouleurs, G. de, Vaucouleurs, A. de, Corwin, H.G.J., Buta, R.J., Paturel, G., Fouque, P. 1991 (Abstract from ADS), Third Reference Catalogue of Bright Galaxies, New York:Springer, ISBN 0-387-97549-7

Fukugita, M., Nakamura, O., Okamura, S., Yasuda, N., Barentine, J.C., Brinkmann, J., Gunn, J.E., Harvanek, M., Ichikawa, T., Lupton, R.H., Schneider, D.P., Strauss, M.A., & York, D.G., 2007 (Abstract from ADS), AJ, 134, 579 doi:10.1086/518962

Høg, E., Fabricius, C., Makarov, V.V., Urban, S., Corbin, T., Wycoff, G., Bastian, U., Schwekendiek, P., Wicenec, A., 2000, Link to PDF

Petrosian, V., 1976, ApJ, 209, L1 doi:10.1086/182253

Strauss, M. A., Weinberg, D.H., Lupton, R.H., Narayanan, V.K., Annis, J., Bernardi, M., Blanton, M., Burles, S., Connolly, A.J., Dalcanton, J., Doi, M., Eisenstein, D., Frieman, J.A., Fukugita, M., Gunn, J.E., Ivezić, Ž, Kent, S., Kim, R.S.J., Knapp, G.K., Kron, R.G., Munn, J.A., Newberg, H.J., Nichol, R.C., Okamura, S., Quinn, T.R., Richmond, M.W., Schlegel, D.J., Shimasaku, K., SubbaRao, M., Szalay, A.S., Vanden Berk, D., Vogeley, M.S., Yanny, B., Yasuda, N., York, D.G., & Zehavi, I., 2002 (Abstract from ADS), AJ, 124, 1810 doi:10.1086/342343