SaratogaSkies Jim Solomon's Astropics


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December: Test shots with new scopes/mounts

Dec 21: TMB 80/480 Arrives!

Dec 3: AP1200 Arrives!

Nov 30: TMB 152/1200 Arrives!


M4 & IC 4604 (Antares / ρ Ophiuchi / M4)

[Hα+R G B]

Mouse-over to see annotations. (Requires Javascript) Click to see high-res version.

Image Details:

Camera: Mofidied Canon Rebel XT (350D): Hutech Type I Filter Replacement
Mount: Celestron AS-GT
Scope: Canon EF 200mm f/2.8L II USM lens
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: Hutech Hα Front Filter (HA-FF)
Effective Focal Length: 200mm
Effective Focal Ratio: f/2.8
Exposure: 57 x 4min @ ISO 200 (RGB), 19 x 8min @ ISO 800 (Hα)
Total Exposure: 6hrs, 20min
Date: 6/20/2006, 6/21/2006 (RGB); 6/22/2006 (Hα)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: GADFly 1.0.5
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow


  • IRIS: Dark subtraction, registration, gradient removal
  • JimP: Flat field, Kappa-Sigma Stacking, HαRGB Combination, White balance, ASINH stretching
  • Photoshop: Levels, cropping, JPG conversion

Image Description:

This is a widefield shot of a region that most astrophotographers refer to as ρ Ophiuchi, a spectacular field at the border of the constellations of Scorpius and Ophiuchus. Move your mouse over the image above to see annotations of the various stars, nebulae, and clusters in this region. The ~2.5 hrs of Hα exposure really helped bring out Siv 9 and Sh 2-9, both of which were very muted in the RGB (normal color) exposures. Note that mousing-over the above image, in addition to displaying the object labels, will switch back-n-forth between the HαRGB image and the standard RGB image, very clearly showing the effect of the additional Hα data. This new image blows the doors off of my old image, which was really just a test shot with the (then) new lens. Thanks to fellow Saratogan Rich Schuppert for letting me borrow his camera platform, which allows orienting the camera/lens combination in a "north is up" configuration. (My platform only supports "north is left".) A higher-resolution image is also available. North is up.