| Tecnical data | Value |
| Object | NGC3521 |
| Constellation(s) | Leo |
| Telescope | Schmidt Camera 600/400/300 (Zen optics): focal length 600 mm, f/2 |
| Location | Druogno, Val Vigezzo, province of Verbania, near Lake Maggiore, Italian Alps, 860 m height |
| Tracking | Manual with illuminated reticle eyepiece |
| Filter | |
| Exposure | 11 min |
| Film | Kodak Technical Pan 2415 |
| Development | MWA2 9 min 20°C |
| Film ipersitized? | yes |
| Film iper notes | 16h 50°C 1,7atm |
| Date | 20/02/1990 |
| Hour | 21.59 UT |
| Quality | good |
| Notes | |
| Processing notes | |
| Ambient temperature | 9 °C |
| Scan resolution | 4800 dpi (CanoScan 9950F) |
