Target guide · open cluster
M21 with a smart telescope
M21 is a open cluster about 13 arcminutes (0.22°) across, magnitude 5.9. It is highest around midnight in June, best placed for the southern hemisphere, and bright enough to image from a suburb or even a city. Of the 12 smart telescopes we track, Odyssey, Odyssey Pro, Seestar S50 frame it best.
Key facts
| Catalogue | M21 |
|---|---|
| Type | open cluster |
| Apparent size | 13′ × 13′ |
| Magnitude | 5.9 |
| Position (J2000) | RA 18.08 h, Dec -22.5° |
| Highest at midnight | June (±2 weeks) |
| Sky needed | City-friendly |
In the best-matching frame
Imaging tips
Star clusters and star groups are bright and forgiving: they show well from a city and need only short sessions. A wider field of view shows the whole group with some surrounding sky. M21 is one of the easier targets from light-polluted skies.
Which smart telescope frames it best
| Telescope | Field of view | Fit |
|---|---|---|
| Unistellar Odyssey | 0.75° × 0.56° | fits well |
| Unistellar Odyssey Pro | 0.75° × 0.56° | fits well |
| ZWO Seestar S50 | 1.29° × 0.73° | fits well |
| Celestron Origin Mark II | 1.32° × 0.75° | fits well |
| DWARFLAB DWARF mini | 2.13° × 1.2° | small in the frame |
| ZWO Seestar S30 | 2.14° × 1.21° | small in the frame |
| ZWO Seestar S50 Pro | 2.45° × 1.38° | small in the frame |
| Vaonis Vespera II | 2.5° × 1.4° | small in the frame |
| Vaonis Vespera 3 | 2.5° × 1.4° | small in the frame |
| Vaonis Vespera Pro 2 | 1.6° × 1.6° | small in the frame |
| DWARFLAB DWARF 3 | 2.93° × 1.65° | small in the frame |
| ZWO Seestar S30 Pro | 3.99° × 2.24° | small in the frame |
How high it gets from where you live
Highest altitude above a flat horizon. Below about 20° the image suffers from haze and light pollution; trees and roofs often block it completely.
| Latitude | Highest altitude |
|---|---|
| Oslo, 60° N | 8° |
| Amsterdam, 52° N | 16° |
| Madrid, 40° N | 28° |
| Miami, 26° N | 42° |
| Equator | 68° |
| Sydney, 34° S | 79° |
Nearby in the sky
Objects close to M21 in the sky, so you can image them in the same session.
Questions and answers
- Can I photograph M21 from a city?
- Yes. It is bright enough to image from a suburb or even a city.
- Which smart telescope is best for M21?
- Odyssey, Odyssey Pro, Seestar S50 frame it best in a single frame, based on its size and each telescope's field of view.
- When is the best time to photograph M21?
- It is highest around midnight in June and best placed for the southern hemisphere. From 52° north it climbs to about 16° at most.