M75
NGC 6864 · Globular cluster in Sagittarius
- Magnitude
- 8.5
- Size
- 6′
- Effective surface brightness
- 20.8 mag/arcsec²
- Best months
- Jul, Aug, Sep
- Declination
- -22°
- Filter
- None (broadband target)
A remote, tightly packed globular. Small and faint, but its dense core shows up fast.
Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
How long with each smart telescope
| Telescope | In frame | Bortle 3 (rural) | Bortle 5 (suburban) | Bortle 7 (urban edge) |
|---|---|---|---|---|
| ZWO Seestar S5010 s subs | 14% | 9 min57 subs | 13 min80 subs | 30 min179 subs |
| ZWO Seestar S50 Pro10 s subs | 7% | 10 min63 subs | 15 min88 subs | 32 min194 subs |
| ZWO Seestar S3010 s subs | 8% | 10 min62 subs | 14 min85 subs | 30 min183 subs |
| ZWO Seestar S30 Pro10 s subs | 4% | 11 min67 subs | 15 min93 subs | 34 min205 subs |
| DwarfLab DWARF 315 s subs | 6% | 13 min53 subs | 19 min77 subs | 44 min178 subs |
| DwarfLab DWARF mini15 s subs | 8% | 9 min38 subs | 13 min53 subs | 30 min119 subs |
| DwarfLab Draco30 s subs | 8% | 15 min30 subs | 15 min30 subs | 25 min50 subs |
| DwarfLab DWARF II15 s subs | 6% | 36 min145 subs | 47 min187 subs | 1 h 32 min370 subs |
| Vaonis Vespera II10 s subs | 7% | 9 min57 subs | 13 min80 subs | 30 min179 subs |
| Vaonis Vespera Pro10 s subs | 6% | 22 min133 subs | 30 min180 subs | 1 h 05 min388 subs |
| Vaonis Vespera 310 s subs | 7% | 9 min55 subs | 13 min76 subs | 28 min171 subs |
| Vaonis Vespera Pro 210 s subs | 6% | 21 min126 subs | 29 min172 subs | 1 h 02 min371 subs |
| Unistellar eQuinox 24 s subs | 18% | 10 min155 subs | 13 min190 subs | 23 min344 subs |
| Unistellar Odyssey4 s subs | 18% | 51 min768 subs | 1 h896 subs | 1 h 37 min1,455 subs |
| Celestron Origin10 s subs | 12% | 5 min30 subs | 5 min30 subs | 8 min49 subs |
| Celestron Origin Mark II10 s subs | 13% | 5 min30 subs | 5 min30 subs | 11 min69 subs |
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.
Per-telescope pages
- How long to image the M75 with the ZWO Seestar S50
- How long to image the M75 with the ZWO Seestar S50 Pro
- How long to image the M75 with the ZWO Seestar S30
- How long to image the M75 with the ZWO Seestar S30 Pro
- How long to image the M75 with the DwarfLab DWARF 3
- How long to image the M75 with the DwarfLab DWARF mini
- How long to image the M75 with the DwarfLab Draco
- How long to image the M75 with the DwarfLab DWARF II
- How long to image the M75 with the Vaonis Vespera II
- How long to image the M75 with the Vaonis Vespera Pro
- How long to image the M75 with the Vaonis Vespera 3
- How long to image the M75 with the Vaonis Vespera Pro 2
- How long to image the M75 with the Unistellar eQuinox 2
- How long to image the M75 with the Unistellar Odyssey
- How long to image the M75 with the Celestron Origin
- How long to image the M75 with the Celestron Origin Mark II