NGC 2122 and NGC 2136/7

Three distant objects, located in a nearby galaxy – the Large Magellanic cloud – 160,000 light years away in the constellations of Mensa and Dorado.

NGC 2122 (top left) is described by Safari+ as an open cluster; and by Wikipedia (Italian version)  as a diffuse nebula.

My image shows it is both.

The Night Sky Observer’s Guide (vol 3) confirms this. It describes NGC 2122 as an “impressive 4′ patch of nebulosity embedded in a cluster of 11th and 12th magnitude stars loosely scattered over the glow”.

Also in the image (lower right) – approximately 42′ away across the border into the constellation of Dorado – are two adjacent open clusters NGC 2136 and NGC 2137.

Acknowledgments to – I may never have identified these objects without its amazing ability. With my mount still not accurately aligning at the time, I had actually targeted a different object in the LMC and I had no idea what was in my image!

Embarrassing but true. 😳

Since taking this shot six weeks ago, the indications are that I may have resolved this persistent alignment glitch.

Object Details:

NGC 2122 NGC 2136 NGC 2137
Constellation Mensa Dorado Dorado
Visual Magnitude +10.4 +10.5 +12.7
Apparent Size 4.5′ 1.9′ 0.8′
Diameter 209 light years 88 light years 37 light years
Distance 160,000 light years 160,000 light years 160,000 light years

Altitude: approx 54° above southern horizon at time of imaging.

The brightest star (near centre) is HD 40156, a 7th magnitude double star. It is in our own galaxy, a mere 192 light years away.


Exposure: 8×30 sec = 240 sec
Gain: 163
Date: 2019-01-04 approx 11.45 pm
Location: The Oaks, NSW.
Conditions: Mostly clear.
Sky: semi-dark rural..
Moon: no


Image acquisition: SharpCap live stack.
Image post-processing: GIMP.
Cropping: yes.

Imaging telescope: Skywatcher Esprit 120ED Super APO triplet refractor.
Focal length: 840 mm, focal ratio: f/7.
Imaging camera: ZWO ASI 071 MC Pro
Guiding: no.
Telescope mount: SkyWatcher EQ6-R Pro.
Polar aligning method: QHYCCD PoleMaster.
Polar alignment error: 1’25”.
Field flattener: yes; filter: no.


My open cluster portfolio.
The annotated astrometry image from  Open then click to enlarge.

Geek Log:

[ZWO ASI071MC Pro]
Output Format=PNG files (*.png)
Capture Area=4944×3284
Colour Space=RGB24
Hardware Binning=Off
Turbo USB=100
Frame Rate Limit=Maximum
Timestamp Frames=Off
White Bal (B)=54(Auto)
White Bal (R)=61(Auto)
Cooler Power=100
Target Temperature=-15
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Mono Bin=Off
Anti Dew Heater=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.346534653465347
#White Point
Display White Point=1

Image © R.Powell

Leave a comment or ask a question . . . .

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s