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Contains:  IC 4842, IC 4845, NGC 6769, NGC 6770, NGC 6771
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NGC 6769-6770-6771 - Interacting Galaxies

Technical card

Dates:Oct. 6, 2018

Frames: 64x900" bin 0x0

Integration: 16.0 hours

Avg. Moon age: 26.62 days

Avg. Moon phase: 9.30%

Basic astrometry details job: 2321752

RA center: 19h 19' 29"

DEC center: -60° 30' 3"

Pixel scale: 0.804 arcsec/pixel

Orientation: 215.910 degrees

Field radius: 0.298 degrees

Resolution: 2218x1479

Data source: Own remote observatory

Remote source: Non-commercial independent facility


NGC 6769-6770-6771 form this superb triple system in the southern constellation of Pavo. It is also known as the Devil's Mask. The trio are 190 million light years away, and receding. Both NGC 6769 and NGC 6770 are receding at similar velocities of about 3800 km/s - a redshift just over 0.01, while NGC 6771 is receding at a slightly higher rate of 4200 km/s.

The central bulge in all three galaxies are of similar brightness. NGC 6771 has an interesting boxy shape which is indeed a rare occurrence among galaxies. It is unusual in that it has two comparatively straight dark lanes and a fainter arc that curves towards the third galaxy

Both NGC 6769 and NGC 6770 are spiral galaxies, yet very different. NGC 6769 has very tightly wound spiral arms, while NGC 6770 has two major spiral arms, one of which is fairly straight pointing towards the outer disc of NGC 6769. The blueish colour of the spiral arms indicate the presence of many star forming regions.

IC4845, a Barred Spiral Galaxy. Its angular size is 1.207’ 0.893’ (arcmin). Surprisingly, even with a modest instrument (25 cm), the galaxy presents remarkable fine details.

Exposure Details:
Lum 37X900 Bin1X1
Red 22X450 Bin2X2
Green 18X450 Bin2X2
Blue 15X450 Bin2X2
Total time hours

Instruments Used:
10 Inch RCOS fl 9.1
Astro Physics AP-900 Mount
SBIG STL 11000m
FLI Filter Wheel
Astrodon Lum, Red, Green, Blue Filters

Software Used
CCDStack (calibration, alignment, data rejection, stacking)
Photoshop CS 6 (Image processing)

Thanks for looking



Terry Robison
License: None (All rights reserved)

Sky plot

Sky plot


NGC 6769-6770-6771 - Interacting Galaxies, 


            Terry Robison