Hemisphere:  Southern  ·  Constellation: Sculptor (Scl)  ·  Contains:  NGC 253  ·  Sculptor galaxy
NGC 253 'Silver Coin' galaxy in Sculptor (20.7 hours), 


            Barry Brook
NGC 253 'Silver Coin' galaxy in Sculptor (20.7 hours)
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NGC 253 'Silver Coin' galaxy in Sculptor (20.7 hours)

Technical card

Imaging telescopes or lenses: Orion ED80T CF

Imaging cameras: Orion StarShoot G3 Mono CCD

Mounts: Skywatcher AZ EQ-6 GT

Guiding telescopes or lenses: Orion ED80T CF

Guiding cameras: ZWO optical ASI120MM-S

Focal reducers: TeleVue 0.8x Photo Reducer/Flattener TRF-2008

Software: Cartes du Ciel  ·  Nebulosity 3  ·  Stark Labs PHD2 v2.2.2g  ·  DeepSky Stacker 3.3.4  ·  EQASCOM  ·  StarTools  ·  AstroTortilla 0.7

Filters: Astronomik Ha 12nm 1.25''  ·  ZWO optical ZWO RGBL Filters

Accessory: Orion Thin Off-Axis Guider (TOAG)

Dates:Sept. 2, 2014

Astronomik Ha 12nm 1.25'': 15x600" bin 1x1
ZWO optical ZWO RGBL Filters: 218x300" 3C bin 1x1

Integration: 20.7 hours

Darks: ~70

Flats: ~100

Bias: ~100

Avg. Moon age: 7.43 days

Avg. Moon phase: 50.53%

Bortle Dark-Sky Scale: 6.00

Mean FWHM: 2.80

Temperature: 8.00

Basic astrometry details

Astrometry.net job: 359350

RA center: 0h 47' 33"

DEC center: -25° 17' 27"

Pixel scale: 1.550 arcsec/pixel

Orientation: -175.740 degrees

Field radius: 0.429 degrees

Resolution: 620x563


A deep integration of the famous galaxy (brightest member of the Sculptor group). With a visual magnitude of 8.0, it is appears as a long, oval bulge and mottled disk, some 25' x 7' min size (true size of some 70,000 light years across), with complex dust lanes north of the core.

It is part of a group of galaxies located 11.4 million light years from the Milky Way, and is viewed by us almost side on spiral (Sc type), giving it the shape of a coin. There is intense starburst activity in its outer arms, and some prominent HII regions, whereas the core is older and redder with a 5 million solar mass black hole at its centre.

The image was captured from my Adelaide surburban backyard, using an Orion ED80T CT apo astrograph (at f/4.8), mounted on an AZ-EQ6. The CCD camera was an Orion StarShoot G3 mono, guided with PHD2 using a think OAG and an ASI120MM-S guide camera.

The image is composed of the following:
Lum = 62 x 5 min
Ha = 15 x 10 min
R, G & B = 52 x 5 min for each channel

After rejections, this led to a total integration time of 20.7 hours.

I used a synthetic luminance channel by blending an exposure-based weighting of the L, Ha, R, G and B luminances. All subs were unbinned.

Captured over the period 24 Aug to 2 Sept 2014, as weather permitted. Pre-processed with flats (light box), bad pixel map (based on 70 darks) and bias in Nebulosity. Aligned and Drizzled in DSS. Post-processed in StarTools.


Sky plot

Sky plot


NGC 253 'Silver Coin' galaxy in Sculptor (20.7 hours), 


            Barry Brook