The unstoppable

Fireworks Galaxy

Main Objects: NGC 6946, NGC 6939, SN 2017eaw

The star death of 22 million years ago

gallery/sn2017eaw_2400
gallery/sn2017eaw_terkep
gallery/sn2017eaw_2400_annotatedd

Let's start: SN 1917A, SN 1939C, SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, SN 2008S and SN 2017eaw. Long, almost endless listing. Each of them is the name of a supernova, which was detected in the galaxy NGC 6946 in the past 100 years. The galaxy (with an apparent magnitude of 9.6) is located at the edge of the Cepheus and Cygnus constellations. The galaxy received its name ("Fireworks”) from the frequent supernova-explosions.

​​​​​​​The supernova SN 2017eaw was detected on May 14, 2017 in the Fireworks Galaxy (NGC 6946), 22 million light-years away. At its discovery, its apparent magnitude was 12.8; at the time when the photograph was taken, this value was around 13.1. This means that it has barely faded over three months.

The NGC 6939 open cluster at the top of the picture is already in our Milky Way, approx. 4,000 light-years. The star group includes several variable stars. NGC 6939 about. 2 billion years old. In addition, we can observe three very pale galaxies in the image, which are members of the PGC catalog.


The photo was taken three nights. On the first night, 15th of August 2017, a “primer” was taken for 50 minutes, the vast majority of the added photo was made on 23/25/2017 (2 and 3 hour exposures). The brightness of the supernova has changed very little in ten days, so the brightness seen in the photo is not damaged when the exposures are stacked together. Unfortunately, the last night's horrendous transparency left the picture a bit depressed, and the last two times the atmospheric calm disturbed the recording. An amateur astronomer has to compromise with our atmosphere, no fairy tale…

Nonetheless, it is a great pleasure for me to capture an "actual" - a 22 million years ago - astronomical event in an impressive picture.

Name:

Fireworks Galaxy, NGC 6946, C12, SN 2017eaw

Constellation:

Cepheus, Cygnus

Coordinates:

R.A. 20 h 34 m 52 s Dec. +60° 09′ 13″

Type:

Barred spiral galaxy - SBc

Distance:

22.5 ± 7.8 million light-years

Brightness:

9.6m

Apparent size:

11' 30" x 09' 48"

Size:

40,000 light-years

Observable: 

Spring, summer, autumn

Date:

15/08/2017; 23/08/2017; 25/08/2017

Total exposure time:

6 hours

Location:

Tápióbicske, Pest, Hungary

Camera:

Nikon D3300 (unmodified)

Telescope:

Sky-Watcher 150/750 mm Newtonian reflector

Mount:

Sky-Watcher NEQ-5 Pro GoTo

Guiding:

ZWO ASI 120 MC camera - PHD2

Corrector:

Sky-Watcher f/5 coma corrector

Focal ratio, length:

f/4.5, 682 mm

ISO:

800

Light:

36 x 600 s

Dark:

9

Flat:

13

Bias:

13

Processing:

PixInsight, Adobe Lightroom, Adobe Photoshop

Location

Annotation