M107

NGC 6171 · Globular cluster in Ophiuchus

Magnitude: 7.9
Size: 13′
Effective surface brightness: 21.8 mag/arcsec²
Best months: May, Jun, Jul
Declination: -13°
Filter: None (broadband target)

A loose, dust-dimmed globular in Ophiuchus. Modest but straightforward.

Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.

How long with each smart telescope

Total integration for a solid image of the M107, default sub length, recommended filter, and how much of each frame it fills. Click a cell for the full Bortle 1 to 9 table.
Telescope	In frame	Bortle 3 (rural)	Bortle 5 (suburban)	Bortle 7 (urban edge)
ZWO Seestar S5010 s subs	30%	24 min144 subs	38 min229 subs	1 h 40 min598 subs
ZWO Seestar S50 Pro10 s subs	16%	27 min160 subs	42 min252 subs	1 h 48 min651 subs
ZWO Seestar S3010 s subs	18%	27 min162 subs	41 min246 subs	1 h 43 min616 subs
ZWO Seestar S30 Pro10 s subs	10%	29 min172 subs	45 min268 subs	1 h 55 min688 subs
DwarfLab DWARF 315 s subs	13%	32 min128 subs	53 min214 subs	2 h 29 min595 subs
DwarfLab DWARF mini15 s subs	18%	24 min95 subs	38 min152 subs	1 h 39 min398 subs
DwarfLab Draco30 s subs	17%	19 min39 subs	31 min62 subs	1 h 22 min165 subs
DwarfLab DWARF II15 s subs	12%	1 h 44 min415 subs	2 h 23 min572 subs	5 h 14 min1,255 subs
Vaonis Vespera II10 s subs	15%	24 min144 subs	38 min229 subs	1 h 40 min598 subs
Vaonis Vespera Pro10 s subs	13%	58 min350 subs	1 h 28 min528 subs	3 h 37 min1,304 subs
Vaonis Vespera 310 s subs	15%	23 min137 subs	36 min218 subs	1 h 35 min573 subs
Vaonis Vespera Pro 210 s subs	13%	55 min331 subs	1 h 23 min501 subs	3 h 28 min1,247 subs
Unistellar eQuinox 24 s subs	38%	31 min470 subs	40 min601 subs	1 h 18 min1,177 subs
Unistellar Odyssey4 s subs	39%	2 h 45 min2,481 subs	3 h 17 min2,960 subs	5 h 37 min5,053 subs
Celestron Origin10 s subs	25%	6 min35 subs	10 min59 subs	27 min163 subs
Celestron Origin Mark II10 s subs	29%	7 min44 subs	13 min78 subs	38 min229 subs

Open in the calculator

Imaging the globular cluster

Globular clusters are point sources packed tight, so they come quickly: the core resolves into stars within a handful of minutes on any smart scope. More time deepens the halo and pulls in the faint outer members. Use short subs so the core does not saturate into a white blob, and no filter.

M107

How long with each smart telescope

Imaging the globular cluster

Per-telescope pages