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:

• Links
• Help
• About Me

IC 1287 (Reflection Nebula)   [obsolete]

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: 20 x 1min @ ISO 1600

Total Exposure: 0hrs, 20min

Date: 7/20/2004, ~11pm PDT

Location: Saratoga, CA, USA

Acquisition: DSLRfocus

Focus: DSLRFocus

Dithering: None

Guiding: None

Processing:

• IRIS: Dark subtraction, flat frame, registration, Kappa-Sigma stacking, and noise reduction
• Photoshop: Color mixing, crop (2/3 x), image scale (3/8 x), JPG conversion

Image Description:

IC 1287 is a very faint reflection nebula in Scutum. In this image it is just barely visible as a blue "halo" around the bright star in the center in the field (SAO 161569). This image could have used more exposure, but tracking problems ruined most of the frames I shot. The transparency and seeing were pretty lousy too. Those diffraction spikes look cool, though, don't they!? <g> This is approximately 2/3's of the full frame, scaled for display on the web. North is up.

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:

• Links
• Help
• About Me

C/2004 Q2 [Machholz] (Comet)

Image Details:

Camera: Canon Digital Rebel (300D)

Mount: Celestron AS-GT

Scope: Orion ED80 (80mm f/7.5 APO Refractor)

Configuration: Focal Reduced

Additional Optics: Celestron F/6.3 Reducer/Corrector (0.63x)

Filter: None

Effective Focal Length: 420mm

Effective Focal Ratio: f/5.2

Exposure: 65 x 2min @ ISO 800

Total Exposure: 2hrs, 10min

Date: 2/1/2005 7:24:34 PM (start)

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, cropping
• JimP: N through M stacking, sequence ASINH stretching
• Photoshop: Compositing, levels, image scale, JPG conversion
• Premiere: AVI creation from individual frames

Image Description:

This is my second attempt at Comet C/2004 Q2 (Machholz), named after the San Jose Astronomical Association (SJAA) member Don Machholz who discovered it. See the ST80 image for a description of the processing steps and for a comparison picture. Perhaps the best-resolved object in this picture is Trumpler 3, the small Open Cluster of stars in the lower left (above the copyright notice).

To process this image, I used the technique described in this thread in the CloudyNights Forum. The difference is that I did all the machinations after ASINH stretching each individual frame, whereas I believe the author worked on the linear frames and only stretched the final result.

I had some major problems with the capture of this image:

1. The ED80 was severely out of collimation when this was shot.
2. The ED80 with Celestron f/6.3 Reducer has some field flatness issues, causing aberrations beyond the center of the frame. The collimation problem mentioned above exacerbates this.
3. The framing of the comet, while asthetic in that there's "room" for both the ion and debris tails, places most of the interesting detail outside the "sweet spot" of the ED80 + focal reducer, making the signal to noise of the ion tail (in particular) quite low.
4. There was tons of light pollution to the NorthWest, the direction this was shot on that night.
5. My polar alignment was less than marvelous, causing roughly 0.5? of field rotation over the course of the imaging session. While IRIS is quite capable of derotating the frames, part of me believes that this function causes a loss of detail and an overall decrease in signal to noise.
6. The comet was actually moving twice as fast (in arc-seconds per minute) than predicted by The Sky software. Had I known this, I might have gone for even shorter integrations (1min) at higher ISO (1600), since that would have been less than a pixel's worth of movement over the course of each frame, theoretically resulting in less blurring of each individual frame since I was guiding on a star, not the comet.
7. The transparency that night was pretty awful.

So, that's my sob story, and all of the above show in the (lack of) detail in this image. Sniff. The movie (1MB AVI) is pretty cool and worth checking out. North is up.