NGC6121 or M4 in Scorpius

NGC 6121, M4, is a globular cluster in Scorpius that is

visually noted for the bar of stars across its core and a

stirrup or arc of stars (above the bar in this picture).

Large telescope views and pictures of M4 are so

bright that these feautres are difficult to see.

M4 is the first globular cluster in which

individual stars were resolved.

It is the closest globular cluster to our solar system,

6 kly, and estimated to contain 10 000 stars.

Hover over the picture for an annotated version

Date:  6 and 7 July 2024

FOV:  cropped to 60' × 40'; M4 is approximately 23'

Telescope:  Stellarvue SVX102T + SFFX-1 flattener (714mm, f/7)

Guiding:  ZWO ASI120MM mini mono guide camera,

Stellarvue F050G 50mm guide scope

Computer:  ASIair pro Raspberry Pi

Mount:  iOptron CEM40

Camera:  ZWO ASI071MC Pro Cooled (-10°C) Color CMOS with gain 90

Pixel size:  4.78 μm

Resolution:  1.334 arcsec/pixel

Filter:  Optolong UV/IR cut

Stacking:  sixty-seven 240 second frames using Pixinsight

Total Time:  4 hours 28 minutes

Processing:  Pixinsight – Crop, SPCC, DBE, BXT, NXT mask,

GHS, HST, MStr, PMath MStr + GHS + HST → PM, Sat, Scale

Location:  Cherry Springs State Park near Coudersport, PA