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!


M1 (Crab Nebula)

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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: {1 Hα, 1 OIII, 1 SII} × 32min @ -30°C
Total Exposure: 1hrs, 36min
Date: 1/28/2008 11:49 PM PST (Start)
Location: Saratoga, CA, USA
Acquisition: CCDSoft
Focus: FocusMax
Dithering: None
Guiding: Self Guided


  • IRIS: Dark subtraction, registration, White balance, ASINH stretching, Richardson-Lucy Deconvolution
  • Photoshop: Cropping, JPG conversion

Image Description:

This is M1, aka, the “Crab Nebula”, a Supernova Remnant in the constellation of Taurus. This is First Light after a repair and cleaning of my ST-2000XM camera, and also First Light for my new motorized, electronic, focuser attachment for the TMB 152/1200's FeatherTouch FT3545 focuser. Along with FocusMax, a freeware focusing software package, the electronic focuser allows one to absolutely NAIL the focus every time. After fighting some USB hardware problems, I managed to capture some narrowband exposures of this target. Mousing off the image reveals a “Hubble Palette” narrowband image, with R:G:B = SII:Hα:OIII. Mouse-over the image to see a pseudo-“True Color” image, in which those narrowband emission lines are mapped to their approximate color as seen by human vision. Specifically, the red SII and Hα wavelengths are mapped to red, and the aqua (blue-green) OIII wavelength is mapped to both green and blue. Also, a smidge of Hα is added into blue to simulate the Hβ wavelength. Compare the stunning amount of detail in this narrowband image, and especially the pseudo-true-color image, with that in this older true color image, though, of course, the latter was captured with much more modest equipment. A higher resolution image is also available. North is up.