SIMBAD references

F. Ciabattari and E. Mazzoni, Borgo a Mozzano, Italy, report their discovery of an apparent supernova (mag 17.2) on unfiltered CCD images (limiting magnitude 19.5) obtained on June 26.93 and 27.87 UT with a 0.5-m Newtonian telescope in the course of the Italian Supernovae Search Project. The new object is located at R.A. = 18:18:18.80, Decl. = +47:41:54.2 (equinox 2000.0; astrometry with respect to USNO-B1 stars) which is 6" east and 8" north of the center of the presumed host galaxy. Nothing is visible at this position on digitized plates of the Palomar Sky Survey from 1990 June 26 (J plate, limiting mag 20.3) and 1991 Aug. 7 (F plate, limiting mag 20.3), or in their images from 2011 Sept. (limiting magnitude 19.0). The variable was designated PSN J18181880+4741542 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2012dg based on the spectroscopic confirmation reported below.

Additional CCD magnitudes for 2012dg: June 29.314 UT, 17.0 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end figures 18s.80, 54".0; image posted at website URL http://www.flickr.com/photos/43846774@N02/7470408806/); 30.963, 16.9 (Federica Luppi and Luca Buzzi, Varese, Italy, 0.38-m f/6.8 reflector; position end figures 18s.77, 54".1; reference stars from CMC-14 catalogue; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_P61709.jpg); July 3.934, R_c = 16.7 (Massimiliano Martignoni, Magnago, Italy, 0.25-m f/10 Schmidt-Cassegrain reflector; position end figures 18s.77, 53".8).