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M19
globular cluster in Ophiuchus
M19 is one of the most flattened globular clusters in the Milky Way, so it looks distinctly oval rather than round. It sits in Ophiuchus close to the galactic center, in a rich, dusty field.
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// Key facts
- Catalog
- M19
- Type
- globular cluster
- Constellation
- Ophiuchus
- Size
- 17′ across
- Brightness
- Magnitude 7.5
- Distance
- about 28,700 light-years
- Peak month (any location)
- Jun
- Typical prime months
- Mar to Aug
- Difficulty
- Intermediate
- Filter
- No filter (broadband)
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How to image M19
- Its oval shape stands out best at 1,000 mm or more, where the halo is visible.
- It is low (dec -26) from northern sites, so wait for the meridian crossing and a dry night.
- Dust toward the galactic center dims and reddens it, so expect a slightly warm color balance.
Framing: what focal length?
M19 is small, so a "60% of the frame" focal length would be impractical. Here is how much of an APS-C frame it covers at common long focal lengths; expect to crop.
| Focal length | Share of the frame width |
|---|---|
| 1,000 mm | about 21% |
| 2,000 mm | about 42% |
| 3,000 mm | about 63% |
How high does it climb from your latitude?
The highest point M19 reaches in the sky. Above about 60° is excellent, 30° to 60° is workable, and under 30° you are looking through a lot of air.
| Latitude | Highest point | Rating |
|---|---|---|
| 55°N (Scotland, Alaska) | 9° | Stays low |
| 45°N (Minneapolis, Milan) | 19° | Stays low |
| 35°N (Los Angeles, Tokyo) | 29° | Stays low |
| 25°N (Miami, Cairo) | 39° | Workable |
| 35°S (Sydney, Santiago) | 81° | High in the sky |
Also worth imaging
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