Moon Mosaic Creation

Posted on by

Back over the holidays, we had a clear night but the Moon was out — almost full. After taking some Ha images of M1, I decided to try the Moon itself. It turns out that with the C-11, the new 0.75 focal reducer from Optec, and an Ha filter, a 0.11 second exposure is not blooming or over saturated on the ST-10.

So I took three series of images, one of 20 and two of 40 exposures. February’s Sky and Telescope has a very good article Lunar Photography with AviStack. Based on the advice there, I used AviStack to align and stack the images. I then took them into Photoshop where I used the Photomerge feature to create a mosaic of the three images. Here is the raw image.

Raw Moon Panorama

Raw Moon Panorama

The next group of steps were performed in PixInsight. I will go through how I used mask and several of the image enhancement functions to produce my final image.

The first step in processing was to change the areas that weren’t part of the Mosaic from white to black. To do that, I cloned my original image by dragging the name tab onto the desktop. I used the histogram tool on the cloned image, moving the black point almost all the way to the top. I then inverted the image, producing a white background with the missing corners black. Using Pixel Match, I created a new image that was the minimum of the original image and the black corners.

The next thing I needed was a mask that would allow me to apply deconvolution, A Trous Wavelets, and HDR Wavelets to the image without creating artifacts around the edge of the Moon. I cloned my new image and reduced it to almost pure black and white using the Histogram tool, moving the white and black points to just above the background sky glow. This gave me a sharp-edged mask, but what I needed was a smoother edged mask. Without a gaussian blur function, I used A Trous Wavelets to blur the image. Here are the settings I used to blur the mask (click on the image for a larger view):

Wavelets Setting to Blur Mask

Wavelets Setting to Blur Mask

This produced the following mask image. The basic idea is that you set wavelets to many levels, drop the lower levels and slightly increase the bias near the top level.

Moon Mask

Moon Mask

With this mask set on my main image, I went through key image enhancement steps with minor curves adjustments in between each. My first step was deconvolution. I had found that larger standard deviation settings brought out noise in the image, with single pixels leaping in brightness. After trial and error, I settled on a standard deviation of 1.5 and 80 iterations of Regularized Richardson-Lucy deconvolution. Here are the settings I used.

Deconvolution

This had the effect of subtly sharpening the details of the Lunar surface. While this was good, I wanted to expose more of the details in this image. So at this point I turned to A Trous Wavelets. I didn’t want to over-process the image (although some might argue that doing wavelets on top of deconvolution is already that) but I wanted more detail. I applied the following, somewhat subtle, A Trous Wavelet transformation.

Sharpen Wavelet

From there I wanted the global contrast change that you get from HDR Wavelet transformation. Note that for all of the prior sharpenings, I have been using my mask. For this transformation, I needed a sharper edge to the mask and even that left behind some brightness I needed to fix. Here is the HDR Wavelet setting I used. The number of layers is one greater than the default of 6. This matched the scale where I wanted the contrast adjustment.

HDR Wavelet

This process did leave a minor artifact. The mask left a somewhat bright area around the lower edge of the Moon. Rather than tweak the mask again, after applying a very light noise reduction using ACDNR, I took the image into Photoshop. In Photoshop, I burned the lower edge of the Moon very slightly. I also added black shapes around the missing mosaic area to hid the edge artifacts from the A Trous wavelet processing.

This is the final image:

Moon Mosaic

Thanks for the Link

Posted on by

Through the auspices of Smitty at Robert Stacy McCain’s blog, I have a link in from a prominent source. Not only is The Other McCain a fine blog, but it is written by a real journalist, who adds real reporting to the blogging. This is something few, if any, other bloggers do.

Check out his blog. It’s good reading, and the blogroll there is well worth exploring.

And thanks for the link!

Bubble Nebula & Ha LRGB Processing

Posted on by

Back in October, I took some data of the Bubble Nebula (NGC 7635) and open cluster October Salt and Pepper (NGC 7634). I took 180 minutes of data:

  • 90 minutes Hydrogen Alpha (Ha) in 9, 10-minute sub-exposures unbinned
  • 30 minutes Luminance in 6, 5-minute sub-exposures unbinned
  • 60 minutes, 20 each of Red, Green, and Blue in 2, 10-minute sub-exposures binned 2×2.

I’ll start with the finish. Here is the final image. (Click on the image for a larger version in the gallery.)

Bubble Nebula and Friend

While I do think this is a nice image, it does have the pale salmon reds typical of Ha LRGB processing in basic combine method I used. My basic approach was to make an Ha-Luminance image which was then combined with the RGB to produce the final image. This started off all right as the HaL image looks fairly good. I created the image by adding 3 times the Ha to the Luminance using Pixel Math (most processing was done in PixInsight). I used both HDR Wavelets and A Trous Wavelets to sharpen up the image. Here is the HaL image used to create the final.

Bubble and Friend (Ha - Luminance)

I then created an RGB image, adding 3 times the Ha to the red before combining with blue and green. I processed the image, stretching with histogram and curves to end up with a final RGB image. I brought both the Ha-Luminance and the RGB into Photoshop, pasting the Ha-Luminance on top of the RGB and changing the blending mode of the pasted layer to luminance. There was a lot of noise in the color image, with hot pixel color spots from each different color. Selecting the bottom, color layer, I used the spot healing brush tool to clean up the bad spots. This worked very effectively underneath the luminance layer, since only the spurious color was removed, not the details in the image. I now regret that I didn’t save a separate layer version of the image at this stage. Given the results, I figured I would go back to the beginning (and I still may).

I spent a fair amount of time tweaking the color balance, and passed the image through PixInsight’s GREYCstoration noise reduction algorithm.

Since the original processing, I have tried PixInsight’s “A New Approach to Combination of Broadband and Narrowband Data,” but my color data binned 2×2 is too noisy for it to work. I may yet try Rob Gendler’s approach. At this point, I think I am tired of working on this image.

One lesson learned from this is that when one is doing narrowband imaging, it is better to get full resolution color. This provides better data to use when creating the final image, and allows the luminance combine that creates the peachy / salmon red tones. I got better results on the Heart Nebula, but I’m not done processing that one so it will be another post.

I did try a highly stretched Ha-Luminance image to see what detail I could get out of the image. This is stretched very hard and it has brought out the noise, but there is a lot of detail in the image. This is created from the maximum of 5 * Ha or the Luminance image in Pixel Math, then stretched with curves and some blackpoint adjustment in the histogram tool. I did average in an HDR Wavelet and A Trous Wavelet to enhance the detail in the nebula. Click for a bigger image as the thumbnail is pretty small.

Bubble and Friend (Ha-Luminance)

Horsehead Nebula at f/10

Posted on by

This past weekend was the new Moon and my first opportunity to try out my new Optec 0.5 focal reducer that I picked up at the AIC. It turned out to be a lesson in why one should always use a full Moon weekend when trying a new setup.

I got the C-11 on the AP-900 without trouble. No trouble mounting the focuser, reducer, field rotator, and camera. I was a bit surprised to see that I needed all my counterweights, but everything balanced. The trouble came when I took the first images to get to rough focus and then find a star and sync the scope. I could not get the scope to focus. It turns out that with the CFW-8 (instead of Optec’s focuser) I needed another half inch to get to focus. (I’ve spoken with Optec and they will be swapping the FLR for their new 0.63 reducer — they take care of their customers.)

After some consideration, I decided that the best way to proceed was to just remove the FLR and try imaging at f10. This is very challenging with the C-11. The C-11 has 2800mm of focal length, and with an ST-10 that is 0.5 arcsec / pixel unbinned. Better than any seeing I might have and very difficult to guide. I tried several objects and could not accurately guide. I finally gave up and spent time using PEMPro to improve my polar alignment. After that correction I was able to decently guide, and I took 30 minutes of Ha data of the Horeshead Nebula, IC 434 (more on that below). At any rate, I would consider the night mostly a bust.

Now, in contrast, my friend Justin came up and set up his entire set-up of his FS128, ST-10 and piggy back guiding in the observatory. With one minor tweak to get the scope to focus, he spent the entire night imaging, and got quite a bit of good data.

Back to my Horsehead. I took six, five minute exposures, binned 2×2 through the 6nm Ha filter. This is very little time for an Ha image, even binned 2×2. The end result was somewhat noisy, but had some interesting details given the high magnification. Just for fun, here is my processing sequence, as best as I can remember it.

  • In CCDStack, calibrated, aligned, sigma-rejected, and mean combined the frames, saving as 32 bit floating point (by trial and error, I have found this the best format for transferring to PixInsight)
  • In PixInsight: Stretched the image to visibility with histogram (no clipping) and curves
  • Created a star mask. This was a but tricky and required tweaking the input histogram and output clipping of the image to get a decent star mask. This is required for HDR Wavelets
  • On a duplicate of the base image, performed an HDR Wavelet transformation with 5 (the default is 6) layers with the image masked with the star mask.
  • Combined the base and the HDR image with pixel math to create a new image. Rescaled by 100% (doubled) the image and performed an A Trous wavelets transform, emphasizing the 5th layer with a slight bias increase (0.3), with the star mask applied. Rescaled back down to the original size.
  • Created a final image of the sum of the original, the HDR and the HDR/A Trous wavelet image.
  • Applied curves to brighten the image and then a bit of Greycstoration noise reduction. Saved as a 16 bit TIFF file. I also saved a version without noise reduction.
  • In Photoshop, did a high pass filter on the non-noise reduction version to crispen up the nebular areas. Pasted this on top of the noise reduced version, masked the layer and revealed it only in key areas, blending with the soft light method.
  • Finally, some touch up on dark pixels.

So many steps for some so-so data. I think I got all that I could out of it. The striations in the nebula above the horsehead are visible, and there are nice details in the head itself. You can see some faint details below the head as well. Here is the end result (click on the image to go to see a full sized image).

Horshead Nebula in Ha

First Light and a Quick Update

Posted on by

I just noted that it has been over two months since my last post. I have been meaning to post on first light, automation software, and a wonderful night of viewing and imaging. But I haven’t found the time.

Here is the first light image, NGC 7331 and the Stephan’s Quintet. Clicking on the images will bring you to the gallery.

Deer Lick Group and Stephan's Quintet

I took more data of M33. This image has data from 2008 and 2009, all from Lake Riverside.

M33 -- The Triangulum Galaxy

Finally, here is a pretty shot of the observatory with some major convection in the background. We did not, thankfully, end up under those storms.

Convection

Roof Opener Installed

Posted on by

After much waiting, the opener mechanism has been installed on the roof. At the press of a button, I can open the roof. The opener is an industrial vertical door opener. The roof is quite heavy, I would estimate at least 2,000 lbs, so getting the roof moving takes quite a bit of torque. I know from moving the roof manually, that once it is moving, it moves fairly smoothly, but starting it takes quite a shove. With the motor, it moves quite smoothly, fully opening in about a minute. The motor does have a chain-operated backup in case power is out or the motor is not operational.

Here is a wide shot of the whole set-up. The opener is attached to the observatory wall, and the track was welded onto the opener beam. There are some finish details to be completed. The track will be enclosed in a shroud of roof metal and the motor cover will be painted to match the walls.

Opener and Track

This shot shows the detail of the motor and attachment to the roof. The chain set-up is bolted to the roof, attaching into the steel studs under the roofing material.

Opener

Unfortunately, we had thick high clouds all weekend, so there was no astronomy. But opening the roof was pretty cool!

First Light

Posted on by

After much planning, regulatory hurdles, over seven months of construction, and one item still pending, the new observatory has seen first light. Last Wednesday I put the mount and NP-101 into the observatory and viewed the sky. I aligned the scope with no issue. My rough alignment of the pier adapter was almost spot on.

The viewing was good, but not excellent that night as the transparency was not very good. M27 was the first object I viewed. The shape was quite clear in the eyepiece. The Lagoon Nebula and the Trifid Nebula together in the 41mm Panoptic eyepiece were absolutely amazing. The Omega Nebula around M17 was great. Faint and small objects like the Cocoon Nebula or the Veil Nebula were not visible. It was great not to be bothered by the incoming light from the few security lights in the valley or the lights of passing cars.

I set up the imaging equipment on Thursday, but smoke from fires in Santa Barbara county (200+ miles away!) made serious imaging impossible. I did get the equipment working and that was a good expenditure of time. I started working with ACP observatory automation software on Friday. It took several hours to get through the set-up, and I ran into some issues in the wee hours of the morning, but again, very good progress in getting the observatory fully operational. It got quite cool on Thursday night, into the upper 40s by the time I went to bed, so being able to work in the warm room was a major advantage.

We had guests on Saturday, and Art and Tod wanted to see the observatory in action, and agreed that we could image and argue with the software rather than view. We still had some issues with the observatory control software, but solved some of them and the others are likely some configuration I have wrong at this point. We successfully captured 30 minutes of data of the Deer Lick Group and Stephan’s Quintet galaxy clusters in Pegasus. Color imaging would have kept us up too late so we settled for a nice black and white image. Click on the image to go to the gallery where you can see a larger version.

Pegasus Galaxy Groups

This first light milestone comes after almost all the work has been completed. The desk is in the warm room and we are just waiting on the automation for the roof. Here is a view looking into the observatory from the warm room with the new desk in the foreground.

Warm Room Desk

This shows the scope and mount with imaging equipment attached. The mount can carry a lot more weight than I have on it now. In fact, because the scope is small, the camera runs into the mount as the scope points close to the zenith. I may piggyback the NP-101 seen here on my C-11. That would put things at the upper end of the weight range but would also move the imaging train up and away from hitting the mount when it points to the zenith.

Scope and Mount

Great progress has been made and I am looking forward to getting things automated. The roof is quite heavy and can be manually moved, but motorization will be a good thing. And while I don’t plan to image remotely, automation will allow me to get a full night’s worth of data and a full night’s worth of sleep.

Almost There…

Posted on by

It has been a while since I posted an update. We are getting the final touches in place. The exterior is complete, the floor is down in the observatory, the rope lights are up, and the warm room has a workable floor covering. Under way: Roof automation and a desk for the warm room. And now for some pictures.

This view looks to the south. The area around the pump is now orderly and neat, a major improvement. Believe it or not, the old trapped-air water tanks were on top of six inches of dirt on top of the slab on the ground. Go figure!

View to South

This view to the east shows a bit of the house down the hill on the left.


View to East

The pier and mount adapter have been aligned to north. The foam mat flooring went down quite easily. At the bottom is close-by power access and the 2″ conduit that runs to the warm room.


Pier Close-up

I have been holding off putting the mount into the observatory because there are two construction tasks left. And this weekend was no good as high clouds came in both nights, with a strong east wind coming up on Saturday night about 4am. But I expect the warm room desk and the opening motor will be complete by the time we return from my parents’ place in Upper Michigan. I am planning some time off in August to get the scope in, aligned, and finally get to first light.

Another Step — Pier in Place

Posted on by

Interior fitting of the observatory has finally begun. I’ve got the pier in place with the mount adapter attached. I’ve also cut the rope lights for the walls, and I will be mounting them about waist high. Here is a picture looking toward the warm room.

Pier

The Astro-Physics mount adapter fit perfectly onto the Sky Shed pier top. I had a little trouble setting up the rope lights, but it turned out it was just user error. The rope lights and the side lights are both on dimmers, and the rope lights work fine on the dimmer switch. There are a couple of things we need to do to get the weather stripping correct and the floor needs a good vacuum before I put the flooring in (I am using interlocking foam mats). You can see the power socket and the 2″ conduit that leads to the warm room at the base of the pier.

Temperatures inside were nicely below ambient until things started cooling off outside, so I am hopeful it will adapt quickly with the roof open. We had lows in the 40s and highs in the 90s.

I’d have moved the mount in but I discovered several holes in the drip line for the trees, and one underground in the yard. This bit of mischief added just enough maintenance so that I didn’t have time to move the mount and scope in, and I do want the final touches on the roof in place.

I am looking forward to the long weekend and several days dedicated time to get things set up.

The Weather Brush

Posted on by

This past week, June 16 to be precise, we had our final inspection from the county. We have a signed job card and the building is official in the eyes of Riverside County. The main change from the last construction report is the addition of weather stripping, or a “weather brush” as I like to call it. It is a dense nylon brush, made for door weather sealing, that we adapted for use around the roof.

This picture shows the brush along the long side of the moving roof. Bolted into the fascia material, it forms a tight seal against the stucco. Click on the image to go to the gallery.

North Side

This view is of the west wall of the observatory. The roof moves off to the west, so this brush will press up against the wall when the roof is closed.

West Wall

The eastern end was a bit trickier. There is very little overhang and the brush needs to move over the wall when the roof opens and closes. This was screwed into place using the fascia material screws.

East Wall

There are a few minor touch up items before I begin to move the pier, mount and scope inside. I did select interior lights using an exterior light fixture recommended by the good folks in the discussion group at Cloudy Nights forums.