Dave Mitsky
2004-Oct-02, 02:24 AM
At 00:30 UT tonight I observed the recently discovered supernova SN 2004et in Cepheus using the 17" f/15 classical Cassegrain at the ASH Naylor Observatory (see http://www.astrohbg.org/gallery2/Tour-of-N...-Naylor/17_inch (http://www.astrohbg.org/gallery2/Tour-of-Naylor/17_inch) for a photograph of this instrument). This bright type II supernova was discovered on 2004/09/22.983 by Stefano Moretti. It is located in the SAB face-on spiral galaxy NGC 6946 at R.A. = 20h35m25s.4, Declination = +60°07'17".6 (U2000.0, page 20) and is positioned 247".1 east and 115".4 south of the nucleus of its host galaxy. The magnitude of SN 2004et is currently estimated to be 12.8. A finder chart is available at http://www.skyhound.com/sh/SN2004et.gif (click on the image to expand).
Although NGC 6946 has a relatively bright integrated magnitude of 8.8, its extremely low surface brightness of 14.2 magnitudes per square arc minute makes it a somewhat difficult target, particularly at a site that has been compromised by the glare of suburban sprawl, and with the rather mediocre transparency I was unable to see the galaxy at all. (The open cluster NGC 6939, which is a close neighbor of NGC 6946, was easily viewed at 162x.) I was able to identify the supernova by a triangle of fairly bright field stars that lie to the south of the galaxy (browse the image at http://www.ngc7000.org/ccd/sn2004et-20040929-m.jpg for the location of the supernova and the field stars). Observations were done at 162 and 259x using 40 and 25mm University Optics MK-70 oculars respectively. The supernova and a nearby field star of similar brightness that was farther east were not difficult to discern.
Prior to the supernova I observed the open clusters NGC 225 and NGC 457 (the Owl Cluster) and the planetary nebula NGC 40. Afterwards two more open clusters NGC 7789 and M52, the planetary nebula NGC 7662 (the Blue Snowball), and the spiral galaxy NGC 7331 were targets as the rising Moon made life hard for deep-sky objects.
Dave Mitsky
Although NGC 6946 has a relatively bright integrated magnitude of 8.8, its extremely low surface brightness of 14.2 magnitudes per square arc minute makes it a somewhat difficult target, particularly at a site that has been compromised by the glare of suburban sprawl, and with the rather mediocre transparency I was unable to see the galaxy at all. (The open cluster NGC 6939, which is a close neighbor of NGC 6946, was easily viewed at 162x.) I was able to identify the supernova by a triangle of fairly bright field stars that lie to the south of the galaxy (browse the image at http://www.ngc7000.org/ccd/sn2004et-20040929-m.jpg for the location of the supernova and the field stars). Observations were done at 162 and 259x using 40 and 25mm University Optics MK-70 oculars respectively. The supernova and a nearby field star of similar brightness that was farther east were not difficult to discern.
Prior to the supernova I observed the open clusters NGC 225 and NGC 457 (the Owl Cluster) and the planetary nebula NGC 40. Afterwards two more open clusters NGC 7789 and M52, the planetary nebula NGC 7662 (the Blue Snowball), and the spiral galaxy NGC 7331 were targets as the rising Moon made life hard for deep-sky objects.
Dave Mitsky