NGC 5139, ω Centauri, is the largest known globular cluster in
the Milky Way. Located 17 kly from us, ω Centauri contains
about 10 million stars and has a diameter of 150 ly. It
is an easy naked eye object and a beautiful target
for binoculars if you are far enough south.
Hover over the picture for an annotated version
Date: 16 and 18 January 2026
FOV: cropped to 90' × 60'; the angular size of NGC 5139 is about 55'
Most of my globlar cluster pictures are set in a standard 45' × 30'
field of view so it is easy to compare their relative sizes. ω Centauri
is so large that I used twice the frame size so it would fit.
Rotation: -0.359°
Telescope: Askar FRA300 pro (300mm f/5 Petzval)
Guiding: ZWO ASI120MM mini mono guide camera,
SVBony SV165 Mini 40mm f/4 guide scope
Computer: ASIair pro Raspberry Pi
Mount: ZWO AM5 harmonic drive
Camera: ZWO ASI6200MC Pro Cooled (-10°C) Color CMOS with gain 100
Pixel size: 3.76 μm
Resolution: 2.594 arcsec/pixel
Frames:
16 January 2026: 9 taken with Optolong L-Ultimate filter
18 January 2026: 16 taken with Optolong UV-IR cut filter
Stacking: twenty-five 300 second frames using Pixinsisght
Calibration frames: 20 dark, 20 flat, and 20 bias each session
Total Time: 2 hours 5 minutes
Processing: Pixinsight – SPPC, DBE, SPCC, BlurXT, NoiseXT, DynCrop → Linear
MStr, GHS, HST, PMath MStr + GHS + HST →
Stars, HDRMST6PhLm, Sat
Location: Corzones Draw Ranch near Terlingua, TX
