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NGC 6309 (Box Nebula)
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Image Details:
- Camera: Canon Digital Rebel (300D)
- Mount: Celestron AS-GT
- Scope: Celestron C8-N (8" f/5 Newtonian)
- Configuration: Negative Projection (Barlowed)
- Additional Optics: TeleVue 2x Barlow
- Filter: None
- Effective Focal Length: 2844mm
- Effective Focal Ratio: f/14.2
- Exposure: 25 x 1min @ ISO 3200
- Total Exposure: 0hrs, 25min
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- Date: 7/5/2004, ~10:30pm PDT
- Location: Saratoga, CA, USA
- Acquisition: DSLRfocus
- Focus: DSLRFocus
- Dithering: None
- Guiding: None
Processing:
- IRIS: Dark subtraction, flat field, registration, stacking
- Photoshop: Noise reduction, cropping, JPG conversion
Image Description:
NGC 6309, the Box Nebula, is a planetary nebula in the constellation of Ophiuchus. It's a fairly dim target, having a mean surface brightness of only 11.0 (Mag per square arc-second). As with the other images shot at this focal length, this magnification pushes the limits of my mount, especially without [auto]-guiding. Only 25 of the 54 frames were useable. The rest showed severe smearing/trailing and had to be tossed. This is a crop of the full-size frame. North is up.