NGC 6645 — Open Cluster in Sagittarius
Good (50/100)
Observe
1Properties
Magnitude
9.0
Angular Size
5.4′
Cl, pL, vRi, pC, st 11...15
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Position & Identifiers
2How easy to spot?
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| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Medium+ |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Easy
Medium
Hard
Very hard
Impossible
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
Easy
on Seestar S50
3Visibility
Set a location in User Settings to see visibility data.
Best season
May – Jul
(peak: Jun)
4
Eyepiece View
5
Best Magnification
Explore
6
Classification Decoder
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
NGC 6647
Open cluster
Open Cluster
mag 8.0
0.5°
Sagittarius
IC 4715 C
Noteworthy asterism
Asterism
mag 4.50
2.2°
Sagittarius
M25
IC 4725
Rich open cluster
Open Cluster
mag 4.6
2.2°
Sagittarius
U Sgr
Pulsating variable, period 6.7d
Variable Star
mag 6.68
2.2°
Sagittarius
M17
Omega, Swan, Horseshoe, Lobster, or Checkmark Nebula
Emission nebula — try an OIII filter
Emission Nebula
mag 6.0
3.0°
Sagittarius
M18
NGC 6613
Rich open cluster
Open Cluster
mag 6.9
3.0°
Sagittarius
NGC 6603
Open cluster
Open Cluster
mag 11.0
3.7°
Sagittarius
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