Spiral Galaxy NGC 6946                                         

Taken @ Kitt Peak National Observatory June 16 & 17, 2004    Image Credit: Fred Calvert / Adam Block / NOAO /AURA / KPNO / NSF

NGC 6946 is a face-on SAB(rs)cd magnitude 8.9 galaxy in the constellation Cepheus. This classification refers to the presence of a small core with multiple well-defined arms (cd), with a poorly-developed bar across the middle (AB) and an inner confused ring (rs). Nearly twenty million light-years from Earth, it is over seventy thousand light-years across.

Seven supernovae have been discovered in this galaxy and are listed below.

• SN 1917A occurred on July 19, 1917 when it was discovered by Ritchey. This supernova, situated 37"W and 105"S of the galaxy's nucleus, lightened up to 14.6 mag.
• SN 1939C was discovered by Fritz Zwicky on July 17, 1939 (see IAU Circular No. 793), 215"W and 24"N of the galaxy's center, and peaked at 13.0 mag.
• SN 1948B was found by Mayall when it flashed up on July 6, 1948, 222"E and 60"N of the galaxy's nucleus; it reached magnitude 14.9 (see IAUC 1161)
• SN 1968D brightened up on February 29, 1968 the leap day, 45"E and 20"N of the galaxy's center, and became as bright as 13.5 mag. This supernova was discovered by Wild and Dunlap, and was found to be of type II (see IAUC 2057 and IAUC 6045)
• SN 1969P occurred on December 11, 1969, 5"W and 180"S of the nucleus and reached mag 13.9. It was found by Rosino (see IAUC 2305)
• SN 1980K was discovered by Wild on October 28, 1980 when it occurred 280"E and 166"S of the galaxy's center; it reached mag 11.4 (see IAUC 3532 and AJ 111, 2017)
• SN 2002hh, of type II, was discovered by the LOTOSS project (W. Li) on unfiltered KAIT images taken on Oct. 31, 2002, 60".9 west and 114".1 south of the nucleus of NGC 6946 at about 16.5 mag, and reached about mag 15.0 at its maximum.

With this number of supernovae which have been found in this galaxy, NGC 6946 is leading the statistics, just one SN more than follow-up M83.

The data for this image was taken over two nights.

Equipment:

20" RC Optical System Ritchey Chretien - Cassegrain @ f 5.5

Software Bisque Paramount ME Robotic Mount

SBIG ST10XME with Color Filter Wheel and 6.3 Focal Reducer

    SBIG ST10XME CCD            20" RC Optics Telescope         Advanced Observer Facility   Me at 4:00 AM "Coffee"

Exposure Data:

Luminance = 120 minutes binned 1x1

Red = 15 minutes binned 1x1

Green = 15 minutes binned 1x1

Blue = 15 minutes binned 1x1olor filter wheel

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