SaratogaSkies Jim Solomon's Astropics

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B86 (Ink Spot Nebula)

Click to see high-res version.

Image Details:

Camera: Canon Digital Rebel (300D)
Mount: Celestron AS-GT
Scope: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 8 x 4min @ ISO 200
Total Exposure: 0hrs, 32min
Date: 8/4/2004, ~10pm PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: Manual through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

  • IRIS: Dark subtraction, flat field, registration, Kappa-Sigma stacking
  • Photoshop: Cropping, image scale, JPG conversion

Image Description:

This is B86, the Ink Spot Nebula, in the constellation of Sagittarius. A dark nebula is a cloud of dust and gas that obscures light coming from stars and other objects "behind" it. In this case, the dark nebula obscures the massive number of stars in the Great Sagittarius Star Cloud of the Milky Way. The small grouping of blue-white stars just East (left) and South of B86 is the open cluster NGC 6520. This is a slight crop of the full-size frame. A higher-resolution image is also available. North is up.

This is my first guided image. Thanks much to Jim Shuder for bringing his guiding apparatus over to my house for a fun evening of imaging. Jim brought his 60mm guide scope with all of the associated hardware, a Philips ToUcam 740k, and his laptop computer running GuideDog software. Analysis of the GuideDog data showed RMS guiding errors to be on the order of 1.4 arc-seconds, which is excellent for a mount that has over 60 arc-seconds of peak-to-peak Periodic Error. This allowed all of our 4-minute exposures to have crisp stars, though I had to toss the one in which an airplane trespassed into our imaging field.

 
NGC 2244 (Rosette Nebula)
SaratogaSkies Jim Solomon's Astropics

Search

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!

Links:

NGC 2244 (Rosette Nebula)

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Image Details:

Camera: Mofidied Canon Rebel XT (350D): Hutech Type I Filter Replacement
Mount: Celestron AS-GT
Scope: Orion ED80 (80mm f/7.5 APO Refractor)
Configuration: Focal Reduced
Additional Optics: William Optics 2" APO 0.8x Reducer/Field Flattener
Filter: None
Effective Focal Length: 480mm
Effective Focal Ratio: f/6
Exposure: 30 x 8min @ ISO 1600
Total Exposure: 4hrs, 0min
Date: 2/22/2006 7:40:04 PM 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

Image Description:

This is NGC 2244 et. al., aka, the Rosette Nebula in the constellation of Monoceros. The catalog numbers of this object are in dispute (cf Haluk Akcam's analysis), though most seem to agree that NGC 2244 refers to the Open Cluster of stars in the center of the nebula, and NGC 2246 et. al. refer to the nebula itself.

The Rosette Nebula is extremely faint, so I upped the individual exposures (8min) and cranked the ISO (1600) in order to better resolve the nebula. Close inspection reveals that the faintest traces of nebulosity are still below the read-noise floor of the camera. The cost of these long exposures/high ISOs is, of course, a washout of the color in the brightest stars. A worthwhile tradeoff IMO.

A higher-resolution image is also available. North is up.