RCW 55

HII REGION IN CARINA (THE COMPASS)

(ra: 10h 56' 55"/ dec -63º 05')

March 2026, Home Backyard in Martinez, Buenos Aires, Argentina

DATA

TYPE: HII Region

Visual Brightness: N/A

APPARENT DIAMETER: 12 arc minutes

DISTANCE: 13.600 light years

IMAGE INFORMATION

SCOPE: 6" ORION OPTICS UK (Ultra Grade Optics) w/Sky Watcher Coma Corrector (0.9x) working at at f4.5

CAMERA: QHY 183 MONO

MOUNT: VIXEN GPDX, OAG with QHY 5II Mono

FILTERS:  OPTOLONG LRGB Set Antlia Ha 3nm

SKY CONDITIONS: Urban Skies. Bortle 9

EXPOSURES: LHARGB (45,45,45,45,45) - all channels bin 1x1

OBJECT DESCRIPTION AND IMAGE SESSION

This RCW area lies some 2 degrees to the north east of naked eye open cluster IC 2602. I visualize from an wide field image I took last season that can be seen here

RCW 55 presents two patches of dark nebula DCld 289.8-03.2 which stands out with the HII ionized background. In the center of RCW 55 we have open Star Cluster Graham 1

There is not much information about RCW 55 except what is indicated in Galaxy Map.

From my Bortle 9 sky there was almost no signs of nebulosity in the RGB channels therefore all the details comes from what the HA filter was able to collect, and thus the blending brings almost a monochromatic red cast

The RCW catalog was compiled by Alexander William Rodgers, Colin T. Campbell, and John Bartlett Whiteoak. They cataloged the southern nebulae while working with Bart Bok at Mount Stromlo Observatory in Australia in the 1960s. This Catalog is an astronomical catalog of H-alpha emission regions in the southern Milky Way, described by Rodgers in 1960.