SaratogaSkies Jim Solomon's Astropics


Latest news

December: Test shots with new scopes/mounts

Dec 21: TMB 80/480 Arrives!

Dec 3: AP1200 Arrives!

Nov 30: TMB 152/1200 Arrives!


NGC 6309 (Box Nebula)

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
Date: 7/5/2004, ~10:30pm PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None


  • 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.