NGC 55

 BARRED SPIRAL GALAXY IN SCULPTOR (THE APPARATUS SCULPTORIS)

(Image centered at: ra 00h:15 m / dec - 39º 13')

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ANNOTATED IMAGE 100% RESOLUTION

December 2025, Observatorio Cielos Albertnos, Buenos Aires, Argentina

DATA

TYPE: Spiral Galaxy

APPARENT DIAMETER:  31,2 x 5,9 arc minutes

APPARENT MAGNITUDE (V): 8,4

DISTANCE: 6.5 million light years

IMAGE INFORMATION

INSTRUMENT: Orion Optics UK 6" Newtonian with Ultra Grade Optics working at f 4.5

CAMERA: QHY  183WS Mono Camera

MOUNT: Vixen GPDX Guided off axis with QHY 5II  Mono Camera 

FILTERS: Optolongr LRGB Set 

SKY CONDITIONS: Bortle 3 skies

OBJECT DESCRIPTION AND IMAGE SESSION

NGC 55, also known as the String of Pearls Galaxy, is a Magellanic type barred spiral galaxy located about 6.5 million light-years away in the constellation Sculptor. It was discovered on 7 July 1826 by Scottish astronomer James Dunlop from Parramatta. NGC 55 is one of the nearest members of the Sculptor galaxy group which also includes four other bright galaxies, NGC 253, NGC 247, NGC 300, NGC 7793 and a number of dwarf galaxies.

Confusion still remains regarding NGC 55 overall morphology. Conclusions about its morphological type have ranged from barred spiral to Magellenic irregular type. Recent consensus suggests it is a magellenic irregular type with its bar seen end on. There is considerable active star formation occurring in NGC 55 particularly in its central region. Large shell structures and plumes have been identified which are signatures of recent supernovae and stellar winds from massive stars. Recent star formation has almost certainly occurred near the center of NGC 55 as recently as 8 million years ago although a fairly steady production of stars has occurred during the last 100 to 200 million years. Compared to other galaxies, NGC 55 has experienced a remarkably uniform star forming history (*)

(*) Text from Robert Gendler essay 

NGC 55 - ANNOTATED IMAGE 100% RESOLUTION

BARRED SPIRAL GALAXY IN SCULPTOR (THE HEAT GENERATOR)

(Image centered at: ra 00h:15 m / dec - 39º 13')

Image Plate Solver script version 5.6.2

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Referentiation matrix (world[ra,dec] = matrix * image[x,y]):

-1.97208796e-04 -4.40264019e-05 +6.27704533e-01

+4.40522453e-05 -1.97228503e-04 +2.41230655e-01

WCS transformation ....... Linear

Projection ............... Gnomonic

Projection origin ........ [2771.682549 1842.175387] px -> [RA: 0 15 10.249 Dec: -39 15 01.84]

Resolution ............... 0.727 arcsec/px

Rotation ................. 12.586 deg

Reference system ......... ICRS

Observation start time ... 2025-12-13 01:17:48 UTC

Observation end time ..... 2025-12-13 01:20:48 UTC

Geodetic coordinates ..... 58 50 00 W 34 48 03 S

Focal distance ........... 680.49 mm

Pixel size ............... 2.40 um

Field of view ............ 1d 7' 13.1" x 44' 40.0"

Image center ............. RA: 0 15 10.232 Dec: -39 15 01.67

Image bounds:

top-left .............. RA: 0 18 24.109 Dec: -39 00 23.39

top-right ............. RA: 0 12 46.940 Dec: -38 45 48.77

bottom-left ........... RA: 0 17 35.521 Dec: -39 44 03.43

bottom-right .......... RA: 0 11 55.017 Dec: -39 29 19.71