SaratogaSkies Jim Solomon's Astropics

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M33 (Triangulum Galaxy)

Image Details:

Camera: Canon Digital Rebel (300D)
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: 19 x 5min @ ISO 400
Total Exposure: 1hrs, 35min
Date: 11/13/2004, ~10:30pm PST (start)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: Manual
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

  • IRIS: Dark subtraction, flat field, registration, normalized Kappa-Sigma stacking, background fit, cropping
  • Photoshop: Levels, image size, cropping, JPG conversion

Image Description:

This was the first decent night of weather we've had here in the Bay Area in a long time, so it was nice to get out again and capture this image. The seeing and transparency were good, not great, but far better than they've been in quite some time. M33 is a spiral galaxy, sometimes referred to as the Pinwheel Galaxy, in the constellation of Triangulum -- a constellation which is shaped like ... drum roll please ... a triangle. <grin> This is a crop of the full-size frame. North is to the left.

 
IC 1318 (Gamma Cygni Nebula)
SaratogaSkies Jim Solomon's Astropics

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IC 1318 (Gamma Cygni Nebula)

Image Details:

Camera: Canon Digital Rebel (300D)
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: 8 x 8min @ ISO 400
Total Exposure: 1hrs, 4min
Date: 9/6/2004, ~11:50pm PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: Manual
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

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

Image Description:

This is IC 1318, a patch of nebulosity around the bright star Gamma Cygni (aka Sadr) in the constellation of Cygnus. In case you're wondering, Gamma Cygni is the bright star in the center of the photo. The full-size image shows excellent off-axis coma correction, indicating that the MPCC performs pretty well when the optics are well collimated.

A new-and-improved set of Flat Field frames helped in the processing of this image. The Flat Field giving the most pleasing result was generated as follows:

  • Set of 16 individual frames, median-combined
  • Captured between 5min and 8min after sundown
  • 1/8 second exposures @ ISO 100
  • DEC equal to my latitude
  • Hour Angle equal to two hours East of the Meridian
  • Tracking on during the exposure, but off between exposures (this allows the median-combine to remove any stars captured in the individual frames)

This is the full frame, scaled for display on the web. North is up.

 
NGC 6992 (Network Nebula)
SaratogaSkies Jim Solomon's Astropics

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NGC 6992 (Network Nebula)   [obsolete]

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: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 14 x 8min @ ISO 400
Total Exposure: 1hrs, 52min
Date: 8/25/2004, ~1:30am PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

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

Image Description:

This is NGC 6992, the Network Nebula, the Eastern portion of the Veil Nebula in the constellation of Cygnus. The Network/Veil is the remnant of a supernova explosion. The entire object takes up nearly 4 degrees of sky. For comparison purposes, the full moon takes up only 1/2 a degree. Better framing would have captured more of this object, but to capture the entire object requires a shorter focal length (such as that provided by the ST80 ... hmmmm) or a mosaic of several shots. Since my main mission was to test out my new focuser, the new coma corrector, and to experiment more with GuideDog, I wasn't so much worried about the framing of the object. I regret this decision, because the shot turned out to be one of my best to date.

Anyway, a coma corrector attempts to minimize or eliminate "coma", the primary form of aberration of paraboloid optics, such as those in a Newtonian reflector. Without such a device, the stars and other details in the outer portion of an image tend to "blur outward", not unlike the tail of a comet, which is how the term "coma" came into being. ("Like I'm in coma" is pretty much how I feel the day after going to sleep at 4am after a night of astrophotography, but I digress.) Anyway, the MPCC seems to have done a good job correcting the coma in the image, as stars are much more "pinpoint" from edge-to-edge of the frame.

But to reach focus with the camera and the MPCC in place, I needed to upgrade my focuser to a "low profile" one. The JMI NGF-DX3 seemed to be a good choice, and I'm pretty happy with it so far. Also, I tried cranking the "aggressiveness" setting in GuideDog which resulted in better tracking than previous attempts. Finally, I chose ISO 400 instead of ISO 100 based on the results of a noise analysis I performed on the Digital Rebel. ISO 400 looks to be a good choice, but more experimentation is needed.

This is a (very) slight crop of the full frame, scaled for display on the web. North is up.

 
NGC 6822 (Barnard's Galaxy)
SaratogaSkies Jim Solomon's Astropics

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NGC 6822 (Barnard's Galaxy)   [obsolete]

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: 12 x 5min @ ISO 1600
Total Exposure: 1hrs, 0min
Date: 8/12/2004, ~12:30am 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: Levels, Noise reduction, cropping, JPG conversion

Image Description:

NGC 6822, also known as Barnard's Galaxy, is an irregular (as opposed to spiral or elliptical) galaxy in the constellation of Sagittarius. The seeing and transparency weren't very good the night this was shot, but the image came out ok nonetheless. NGC 6822, a member of the Local Group, is a relatively close neighbor of our own Milky Way galaxy, along with M31 (Andromeda) and others. The blue nebulous regions above Barnard's Galaxy (more visible in the higher-resolution image) are, from left to right: IC 1308, H25 V, and H25 I (Bubble Nebula). North is up.

 
NGC 6543 (Cat's Eye Nebula)
SaratogaSkies Jim Solomon's Astropics

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NGC 6543 (Cat's Eye 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: 30 x 30sec @ ISO 1600
Total Exposure: 0hrs, 15min
Date: 8/5/2004, 11:30pm PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None

Processing:

  • IRIS: Dark subtraction, flat field, registration, Kappa-Sigma stacking, Richardson-Lucy deconvolution
  • Photoshop: Cropping, JPG conversion

Image Description:

NGC 6543 is a planetary nebula in the constellation of Draco. I used 10 iterations of Richardson-Lucy deconvolution to bring out the structure in the nebula. I was very careful at every step of the aquisition and processing chain not to clip any of the nebula or its central star, in order to preserve the color and appearance of the nebula. I'm surprised this one came out as well as it did, since the object was in a fairly light-polluted portion of the sky. This is a crop of the full-size image. North is up.

 
NGC 6826 (Blinking Planetary)
SaratogaSkies Jim Solomon's Astropics

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NGC 6826 (Blinking Planetary)

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: 51 x 30sec @ ISO 800
Total Exposure: 0hrs, 25min
Date: 7/15/2004, ~2am PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None

Processing:

  • IRIS: Dark subtraction, flat field, registration, Kappa-Sigma stacking, Wavelet processing
  • Photoshop: Compositing, cropping, JPG conversion

Image Description:

NGC 6826, the Blinking Planetary, is a planetary nebula in the constellation of Cygnus. It is so named because when you stare directly at the central star through the eyepiece of a telescope, the surrounding nebulosity all but vanishes. But when you avert your vision (i.e., look slightly off too one side), the nebula blinks into view. Why does this happen? Well, the human eye "sees better" off of center; i.e., you can see dimmer things not when looking directly at them, but by looking (slightly) away from them. So, when you're looking straight at the central star, the eye has trouble seeing the faint nebula that surrounds it. But when you look slightly away, your peripheral vision is sensitive enough to detect the nebula. It's very cool to try this in a decent telescope. It's a pretty amazing effect.

I used IRIS's Wavelet Processing capabilities to bring out details in the nebula. However, that made the surrounding stars and the sky background look icky, a technical term. So I used Photoshop to composite the wavelet-processed nebula with a non-wavelet-processed background using layer masks. There, I feel much better for coming clean. Also, I was very careful at every step of the aquisition and processing chain not to clip any of the nebula or its central star, in order to preserve the color and appearance of the nebula. This is a crop of the full-size image. North is up.