Spindle Galaxy

M102, NGC 5866 · Galaxy in Draco

Magnitude: 9.9
Size: 4.7′ × 1.9′
Effective surface brightness: 20.9 mag/arcsec²
Best months: Apr, May, Jun
Declination: +56°
Filter: None (broadband target)

An edge-on lenticular with a thin dust lane. Small, but its surface brightness is decent.

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 Spindle Galaxy, 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	11%	11 min69 subs	16 min98 subs	37 min225 subs
ZWO Seestar S50 Pro10 s subs	6%	13 min76 subs	18 min108 subs	41 min245 subs
ZWO Seestar S3010 s subs	7%	12 min75 subs	17 min104 subs	38 min231 subs
ZWO Seestar S30 Pro10 s subs	3%	13 min81 subs	19 min114 subs	43 min259 subs
DwarfLab DWARF 315 s subs	5%	16 min64 subs	23 min94 subs	56 min224 subs
DwarfLab DWARF mini15 s subs	7%	11 min46 subs	16 min65 subs	37 min150 subs
DwarfLab Draco30 s subs	6%	15 min30 subs	15 min30 subs	31 min62 subs
DwarfLab DWARF II15 s subs	4%	45 min179 subs	58 min232 subs	1 h 57 min467 subs
Vaonis Vespera II10 s subs	5%	11 min69 subs	16 min98 subs	37 min225 subs
Vaonis Vespera Pro10 s subs	5%	27 min161 subs	37 min222 subs	1 h 21 min489 subs
Vaonis Vespera 310 s subs	5%	11 min66 subs	16 min94 subs	36 min216 subs
Vaonis Vespera Pro 210 s subs	5%	25 min153 subs	35 min211 subs	1 h 18 min468 subs
Unistellar eQuinox 24 s subs	14%	13 min192 subs	16 min237 subs	29 min435 subs
Unistellar Odyssey4 s subs	14%	1 h 04 min962 subs	1 h 15 min1,126 subs	2 h 03 min1,845 subs
Celestron Origin10 s subs	9%	5 min30 subs	5 min30 subs	10 min62 subs
Celestron Origin Mark II10 s subs	11%	5 min30 subs	6 min35 subs	14 min87 subs

Open in the calculator

Imaging the galaxy

Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.

Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.

Spindle Galaxy

How long with each smart telescope

Imaging the galaxy

Per-telescope pages