SaratogaSkies Jim Solomon's Astropics

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Jupiter and Moons   [obsolete]

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/54.2
Exposure: 9 x 1/2 second @ ISO 800
Date: 6/22/2004, 9:28pm PDT
Location: Saratoga, CA, USA
Acquisition: Manual
Focus: Manual
Dithering: None
Guiding: None

Processing:

  • IRIS: Dark subtraction, flat field, registration, stacking
  • Photoshop: Compositing of IRIS moons and Jupiter images, sharpening, saturation, scale, JPG conversion

Image Description:

An interesting shot of Jupiter and the four Galilean moons. The f/ratio is so high because I put the aperture mask on the end of the telescope, effectively turning the 200mm obstructed Newtonian into a 52.5mm unobstructed offset-Newtonian. For those familiar with telescope optics, the Newtonian design has a secondary mirror in the path of the light that hits the primary mirror, and this so-called "obstruction" can cause a loss of contrast, especially on objects like planets that have low contrast to begin with. By putting the aperture mask on, the secondary is out of the path of the light hitting the primary (now effectively only 52.5mm instead of 200mm), preserving all of the contrast. However, the lower effective aperture could conceivably cause a loss of resolution, but since this is a relatively low effective focal length (2844mm), that loss of resolution isn't evident, and is overwhelmed by the seeing conditions in any case. [In retrospect — what was I thinking!?!? <grin>]

 
IC 5146 (Cocoon Nebula)
SaratogaSkies Jim Solomon's Astropics

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December: Test shots with new scopes/mounts

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IC 5146 (Cocoon Nebula)

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: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 23 x 8min @ ISO 800
Total Exposure: 3hrs, 4min
Date: 10/31/2005 7:33:51 PST (start)
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

Processing:

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

Image Description:

This is IC 5146, aka the Cocoon Nebula, in the constellation of Cygnus. The transparency was quite awful the night this was shot, but the combination of auto-dithering and tons of exposure time made for a decent shot. A higher-resolution image is also available. North is up.

 
B33 (Horsehead Nebula)
SaratogaSkies Jim Solomon's Astropics

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December: Test shots with new scopes/mounts

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B33 (Horsehead Nebula)

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

Image Details:

Camera: SBIG ST-2000XM
Mount: Astro-Physics 1200GTO
Scope: TMB 152/1200 APO Refractor
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: Astrodon SII, Hα, OIII 6nm Filters
Effective Focal Length: 1200mm
Effective Focal Ratio: f/7.9
Exposure: {5 SII, 5 Hα, 5 OIII} × 32min @ -20°C
Total Exposure: 8hrs, 0min
Date: 2/7/2008 8:19 PM PST, 2/8/2008 7:20 PM PST (Start)
Location: Saratoga, CA, USA
Acquisition: CCD Commander
Focus: FocusMax
Dithering: CCD Commander
Guiding: Self Guided

Processing:

  • IRIS: Registration
  • JimP: Dark subtraction, Flat field, Kappa-Sigma Stacking, White balance, ASINH stretching
  • Photoshop: JPG conversion
  • Neat Image: Noise reduction

Image Description:

This is B33, aka, the “Horsehead Nebula”, a dark nebula silhouetted against the bright nebula IC 434 in the constellation of Orion. Compare this closeup with the true color, wide-field, DSLR image, which shows the Horsehead in context with the bright belt star, Alnitak.

Mousing off the image reveals a “Hubble Palette” narrowband image, with R:G:B = SII:Hα:OIII. Mouse-over the image to see the H-alpha only image in grayscale. A higher resolution image is also available. North is left.