NGC 3532 AKA THE WISHING WELL OPEN CLUSTER

OPEN CLUSTER CARINA (THE KEEL)

(ra: 11h 06'/ dec -58º 52')

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

DATA

TYPE: Open Cluster

Visual Brightness: 3

APPARENT DIAMETER: 50 arc minutes

DISTANCE: 1250 light years

IMAGE INFORMATION

SCOPE: AKSAR 180 FMA  

CAMERA: QSI 583 WS

MOUNT: SKYWATCHER EQ3, OAG with QHY 5II Mono

FILTERS:  OPTOLONG LRGB Set HA ASTRONOMIK 7NM

SKY CONDITIONS: Urban Skies. Bortle 9

EXPOSURES: LHARGB (45,60,45,45,45) all channels bin 1x1

OBJECT DESCRIPTION AND IMAGE SESSION

NGC 3532 (Caldwell 91),[8] also commonly known as the Wishing Well Cluster,is an open cluster some 405 parsecs from Earth[2] in the constellation Carina. Its population of approximately 150 stars of 7th magnitude or fainter includes seven red giants and seven white dwarfs. On 20 May 1990 it became the first target ever observed by the Hubble Space Telescope. A line from Beta Crucis through Delta Crucis passes somewhat to the north of NGC 3532. The cluster lies between the constellation Crux and the larger but fainter "False Cross" asterism. Below to the right of the cluster lies 4th-magnitude Cepheid variable star x Carinae (V382 Car) this star lies between the Sun and the cluster and is not a member of the NGC 3532. The cluster was first catalogued by French astronomer Nicolas Louis de Lacaille in 1752. It was also admired by John Herschel, who thought it one of the finest star clusters in the sky.

To the lower side of the image we have open cluster Trumpler 19 with a diameter of 10 arc minutes and shining at 9.6 magnitude. To the upper right corner is also visible NGC 3496 with 7 arc seconds in diameter and 8.2 magnitude. The nebula crossing the cluster is Gum 54 which lies in the direction of the Car OB2 association and parts of it may be ionized by stars in that association. Gum splits this region into several distinct nebulae and the RCW catalog itself splits the region into four sub nebulae, which are described separately as RCW 54a, 54b, 54c and 54d.

I took this image while testing the tracking performance of the sky watcher EQ3.