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NGC 2903
spiral galaxy in Leo
NGC 2903 is a large, bright barred spiral in Leo, often overlooked because it sits near the better-known Leo galaxies. It has a bright core and rich star-forming regions along its arms.
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// Key facts
- Catalog
- NGC 2903
- Type
- spiral galaxy
- Constellation
- Leo
- Size
- 12′ across
- Brightness
- Magnitude 9
- Distance
- about 30 million light-years
- Peak month (any location)
- Feb
- Typical prime months
- Nov to Apr
- Difficulty
- Intermediate
- Filter
- No filter (broadband); a light-pollution filter is optional
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How to image NGC 2903
- At 12 arcminutes, use 1,000 to 1,500 mm.
- It sits in a sparse star field, so the background is clean.
- Best in spring evenings from northern sites.
Framing: what focal length?
NGC 2903 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 15% |
| 2,000 mm | about 30% |
| 3,000 mm | about 45% |
How high does it climb from your latitude?
The highest point NGC 2903 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) | 57° | Workable |
| 45°N (Minneapolis, Milan) | 67° | High in the sky |
| 35°N (Los Angeles, Tokyo) | 77° | High in the sky |
| 25°N (Miami, Cairo) | 87° | High in the sky |
| 35°S (Sydney, Santiago) | 34° | Workable |
Also worth imaging
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