I collected data for NGC 6946, a spiral galaxy in Cepheus, in July and again in September. The color data from July was very suspect and I did not like either version I produced at the time. I took more color data in September and added it to the mix. The final result is below. I like the color but if I go back to it I will stretch the luminance a bit more to bring out faint details in the extended area.

I did use Bob Franke’s eXcalibrator software to get the core color balance. It was very helpful.

Here is version 2. More stretched in the luminance, but the color I don’t particularly like.

Finally, version 1. I think you’ll agree the color and details here just don’t work very well.

Last night at AIC I made an off hand comment to Mike Hernandez of Sacramento Mountains Astro Park about earth moving equipment being an Astronomy Picture of the Day. And what do you know, it shows up again.

First seen on November 22, 2006, the giant piece of mining equipment showed up again today.

Jerry Bonnell and Robert Nemiroff did do a great job featuring AIC imagers during AIC. That was much appreciated.

But I do wonder what the joke is with the big earth mover.

AIC 2010 day three started off with a fine breakfast. The food is definitely upgraded. Two presentations this morning.

First was Al Kelly talking about the importance of proper color balance in your source data, and using G2V stars to calculate it. A significant point he made was that an after the fact Multiplier correction is not enough to fix a big difference in color balance in source data because the signal to noise ratio won’t match. To calculate the balance, pick a high G2V star, take 5 short images of each color each color, dithering, calibrate, register, and stack with a mean combine. Measure the flux of the star (Maxim, AIP) and use this to calculate the balance.

The second talk was Martin Pugh speaking about High Definition Imaging. Strong emphasis was put on on equipment optimization. Use CCDStack FWHM measurement to pick best frame for the master for all subsequent aligns. And most of all, discard bad data! As others have Suggested, increase the contrast of a and b in the Lab color space to increase saturation. I also learned that there is a Photoshop edit log you can turn on in preferences. That will record all of your image edits.

Both of these presentations, in fact all of the presentations, will be worth looking at later once they are posted.

Many good door prizes were handed out—thanks to the sponsors. And you must be present to win!

AIC 2010 day two is about to start. I’ll see if I’m able to live blog the event through the WordPress iPad app.

Update 10:15am PDT
Excellent morning sessions so far. Russ Croman received the Hubble award and went through a processing example. The key points I took away: The darker your sky, the longer your exposure time. A dark location challenges you to go very long to really get depth in the image. He also discards one half to two thirds of his data, keeping only the best frames.

Rogelio Bernal Andreo gave an excellent talk on wide field processing in PixInsight. It was good to hear about something besides Photoshop. He emphasized the need ton make the basic steps on an image (e.g., gradient removal) on the linear image. He also made great use of wavelets to do multi-scale processing. For example, retaining layers 1 and 2 to only capture the small stars.

Update 1:00pm PDT

Todd Klaus of NASA’s Kepler mission gave a great presentation on the instruments and data gathering process of this planet-finding mission. The data calibration process is really impressive as they pull multiple layers of noise away from the data.

A fine lunch followed.

Update 4:39pm PDT

Quick update on the afternoon. Good information from the Founders Presentation. Adam Block has a great new 32 inch telescope on Mt. Lemon. The Mt. Lemon Sky Center has to be on the visit list as soon as I can make it. We got the full story of the making of the new Hubble 3D movie.

Kevin Nelson of QSI gave a good presentation on FFT transformations. But he started with a forecast on CCDs. We are getting to the limit on size of chip since that drives all other factors — scope, mount, camera size, filter, etc. Look for smaller pixels. On FFT, a way to look at the frequency of items in an image, similar in concept to wavelets. A powerful image analysis and processing tool.

Just getting a nice overview of work from Michael Joiner of BYU. He runs the West Mountain Observatory that sits near Utah Lake.

Bob Fera coming up now.

Update 5:00pm PDT

Bob’s key points: Don’t clip your blacks, protect stars when sharpening, and try out eXcalibrator a G2V calculator.

Finally, John Smith of CCDSoft on the Alsubai Project, an automated exoplanet search. Very cool project using off the shelf components. A 40 degree square coverage. 10 class A candidates for exoplanets. Wow.

All for today!

AIC 2010 under way from a new venue, the Hyatt Regency Santa Clara. Apart from some problems last night with hot water, it seems to be quite nice.

My first session was Stan Moore and CCDStack. Lots of good imaging theory as usual. Essentially, normalization of images is critical for proper data rejection. This involves both equalizing the bottom point and the slope of the brightness in the image. He also recommends using dark adjustment in software, based on a library of good darks no more than 5 degrees C from the images. Lots of darks with long exposures. Stan is very concerned with read noise as a contributor to overall noise in an image.

The second session is Tony Hallas on advanced Photoshop techniques focused on adding narrowband data to RGB images. Several ways to take colorized, via hue / saturation, images on top of the RGB image.

Off to the exhibition hall!

A quick update to complete day one. Neil Flemings presentation on narrowband was excellent, and Brad Moore’ talk on the imaging tran was very good as well. The evening program was nice after a good dinner, and I am looking forward to the new Astro-Physics command center application.

Back in September I took 3 hours of Hydrogen-Alpha (Ha) data of NGC 7635, the Bubble Nebula. I captured the image using Maxim DL and CCD Commander, calibrated and stacked it in CCDStack, and processed it in PixInsight.

In PixInsight, I found an interesting way to pull the details out of the image. Here is the full processing sequence:

1. Flipped the image with a vertical mirror transformation. Somehow, the bit order for 32-bit floating point in CCDStack does not agree with how PixInsight is reading it, so it needs to be flipped to start.
2. Cropped the image to eliminate the border areas where alignment left behind some artifacts. This is important for stretching the image later as there can be extreme values in the border artifacts that can show up as clipped data later when they are really just noise.
3. Created a Star Mask.
4. Stretched the image with the histogram tool and slightly with the curves tool to just the edge of the noise floor. This is my base non-linear image.
5. With a clone of that image, performed a series of HDRWavelet transforms, with the number of layers from 2 to 6. For each number of layers, I saved the transformed image and returned to the original non-linear image. This gave me a gallery of images with different scaled features highlighted.
6. I then created a PixelMath expression that averaged all of the images and allowed me to weight each image. The expression was as follows. I started out with the weighting factor even across the images. Mean(
1.0*Base_Image,
1.0*HDR_Image_Scale2,
1.0*HDR_Image_Scale3,
1.0*HDR_Image_Scale4,
1.0*HDR_Image_Scale5,
1.0*HDR_Image_Scale6
)
7. I then combined the image using a variety of weights. As it turned out, a pure average of the images gave what I feel is the best result, so the weighting factor did not come into play on this image.
8. After that it was only a very slight stretch in curves and some delicate noise reduction using ACDNR to produce the final image.

Here is the final image. Clicking on the image will open the image the gallery.

NGC 7635—The Bubble Nebula

Here are the six images that went into creating the final. The first image will link to an animation showing each of the images in sequence. Clicking on any image will open a larger version.

Animation showing all the images in sequence (Warning—Over 2mb)

Original non-linear stretched image

HDR Wavelet with 2 Layers

HDR Wavelet with 3 Layers

HDR Wavelet with 4 Layers

HDR Wavelet with 5 Layers

HDR Wavelet with 6 Layers