After a late-ish first night of imaging under the dark Atacama Desert sky, I managed to sleep in until about 10:45 AM, but woke up with a raging headache. Likely a combination of altitude, mild dehydration, and a late night. Luckily we were well-stocked in the drug department, so I took some altitude sickness medicine and some ibuprofen. And coffee. The cure-all!
One of my two travel companions, John, cooked us a yummy breakfast of breakfast burritos. We couldn't find any sour cream at the grocery store, or cheddar cheese, so we had the Chilean favorite gouda and some salsa we did manage to find. He also did the dishes. We told him he'd be allowed to sleep inside, with a blanket, and if he served us alcohol later in the day, maybe he could have a pillow too ;D
The water pressure had dropped during breakfast, so I waited to take a shower. Finally in the early afternoon, it seemed to have gone back up, at least partially. It took several minutes to warm up, but that was fine. But then, halfway through my shower, the pressure dipped again, and it got cold! So I wrapped up fast and hopped out. Boo!
We decided not to go anywhere that day -- we were tired, particularly from the altitude, and after all of the adventures we'd had so far, a break was much needed. So I worked on backing up photos and getting things organized.
At sunset, I went and found the Atacama Lodge owner Alain, who had dug up another counterweight for me, flipped the telescope around on its dovetail so that I'd have more room to push it forward for balance, and installed a Pegasus electronic focuser. That one was a surprise, so I quickly got the driver installed for it. Ultimately, however, I wasn't able to get my computer to talk to it, so I had Alain come back and disengage it so I could focus the ol'-fashioned way. He told me to just use FWHM instead of a Bahtinov mask since it led me astray the night before.
I got it focused and went to align the mount, but then the power cable fell out. Alain had split the cable coming out of the power supply to share with the focuser, and I think the plug he had on it was a little loose. I tried the one on my ZWO camera to see if it was just the power supply or something else, but although the hand controller turned on, the mount itself didn't, and the hand controller said it didn't have any communication with the motors. After being unsuccessful at finding another cable, and with Alain busy with tour groups, I gave up on the mount and turned my attention to my own Sky-Watcher Star Adventurer with my DSLR.
I put my 35mm f/1.8 lens onto my Nikon D5300 and pointed it toward the southern Milky Way, centering it on the Coal Sack Nebula. It also captured Alpha Centauri, Beta Centauri, and the Southern Cross.
Coal Sack Nebula, with my Nikon D5300, 35mm lens @ f/1.8, ISO-1600, 60s
With the DSLR off and running, I went back inside to process my solar eclipse images until the scopes freed up after the tour groups left. I wanted to make my composite corona image and get it out there before too much time elapsed after the eclipse! The processing went really well, and you can see the result
here on AstroBin. I wrote in my
eclipse day blog post about capturing the image, and then after the 2017 solar eclipse in the US, I wrote up a post about
how I created the composite for that eclipse, and I used the same method for this one.
One of the tour groups
Later on, Alain took a look at the powerless mount, but couldn't immediately figure out what was wrong. He helped re-polar-align my Star Adventurer, which went on to provide great images the rest of the night. I pointed the camera up high in a gorgeous part of the Milky Way and let that run.
*drools*
Back in the lodge, John melted some of the chocolate over warmed crossaints, which made for a delicious and warm midnight snack on a chilly night.
We wandered up to the scope field after that, since all of the tour groups were gone, and split some time on the scopes with parts of the French group. Now, I sometimes pepper in visual observations in between fussing over my cameras, mounts, and computers when I'm at the club's observatory or at a star party, but since the mount wasn't running and the 35mm lens on the Star Adventurer hooked up to AC power required little attention, I spent most of the rest of the night witnessing the wonders of the southern sky with my own eyes. I love astrophotography -- pulling signal out of the noise, getting this incredible image of an amazing object that is hard to believe really exists -- but there is a special kind of wonder with visual observing. There's the challenge of finding the object, then observing deeper into it to see what can be seen, and on top of that, there's the knowledge that some photons that were emitted thousands or millions or lightyears away are finally coming to a rest in your eyes.
First, the French had the the Tarantula Nebula up in the 28-inch Dob, an enormous nebula in the Large Magellanic Cloud (like actually in it, meaning that it's something like 1000 lightyears across!), which under low power looked "dim and chunky, with three chunks" according to my hastily-typed notes.
At our request, we looked at the massive globular cluster 47 Tucanae, which is just off the edge of the Small Magellanic Cloud (but belongs to our galaxy). It has something like ten thousand stars packed into 120 lightyears, and is second only to Omega Centauri in brilliance. It was dazzling in the 28-inch Dob under dark, steady skies! It seemed to spiral around in my eye.
Next,we looked at NGC 253, the Silver Dollar or Sculptor Galaxy. It's nearly edge-on to us, but not quite. It looked positively 3D in the telescope! Very cool effect standing out against the background darkness.
Over in the nearby 24-inch Dob, another one of the French group had pulled up the Helix Nebula. The other nebula filter was off somewhere, so it just looked like a formless smudge, unfortunately.
Back over on the 28-inch, a higher-power eyepiece had been inserted, and the Tarantula Nebula re-acquired. I took a look, and HOLY COW it was incredible! It had so much structure in light! And it was in another galaxy!! It showed a green-blue color, forked with dark nebula clouds spreading out from the middle. There was so much detail to take in, you could just stare at it forever. What an incredible thing to see!
By this time, it was about 4 AM, and I looked east, hoping to spot the zodiacal light. And there it was! A dim, but definitely noticeable, column of light that extended at least up to zenith. Alain showed us the latest image pulled down from his all-sky camera, which is extremely sensitive, and it showed the arc going all the way across the sky, from horizon to horizon! It was really cool. Zodiacal light is caused by sunlight that is scattered by interplanetary dust in the plane of the solar system (aka, the plane of the ecliptic). It's called zodiacal light because the the band it lights follows the Zodiac signs, since these are constellations that are along the plane of the ecliptic. The small particles of dust range in size from 10-300 microns (ten-thousandths of an inch)! It is best observed in the western sky in spring after twilight, or the eastern sky in the fall before sunrise, when the ecliptic is highest. In northern Chile, being in the southern hemisphere, the ecliptic was almost directly overhead, so it made for excellent conditions.
Not the best photo of it, since I didn't have a fast-enough, wide-enough lens to do it justice, but you can kind of see the zodiacal light right behind the Pleiades! Taken at 4:32 AM.
The French located a galaxy cluster in Fornax that I didn't quite understand what they were saying the name was, but it was a gorgeous, tight grouping of 5 galaxies I think, of which I spotted 4. I also enjoyed some binocular views of the Pleiades, the Lagoon Nebula (M8), and the Andromeda Galaxy with my 10x42 Meade sport binos. I could see Andromeda naked eye as well as a dim smudge, low on the horizon.
Back at the scopes, we looked at M17, the Swan Nebula, which was absolutely gorgeous. I always think it looks like a fountain spring. It showed lots of structure and detail, especially with the OIII filter. I suggested we also look at M20, the Trifid Nebula, with the 24-inch while I was over there. I could see the emission part of the nebula (which is red in pictures, but I just saw the blue-green component), and the dark nebula that criss-crosses it, but I couldn't quite eke out the reflection nebula portion. Maybe if I'd spent more time with it. It was also getting lower in the sky by this time of the morning.
After shutting down my gear, I finally crawled into bed at 5:45 AM. What a night!
[ Update July 25, 2019 ]
Now that I'm finally writing this post, I'll include a blurb on the Coalsack Nebula image that I mentioned above, only now it's processed! I knocked that one out last Wednesday after work.
Date: 7 July 2019
Location: Atacama Lodge, San Pedro de Atacama, Chile
Object: Coalsack Nebula
Attempt: 1
Camera: Nikon D5300
Telescope: Nikon 35mm f/1.8G at f/1.8
Accessories: N/A
Mount: Sky-Watcher Star Adventurer
Guide scope: N/A
Guide camera: N/A
Subframes: 33x60s (33m)
Gain/ISO: ISO-1600
Acquisition program: Intervalometer
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 56 (46F)
Biases: 20 (46F)
Flats: 0
Temperature: mid-40s
The Coalsack Nebula is a massive dark nebula just above the Southern Cross constellation. It's relatively nearby, only 600 lightyears away, and spans about 70 lightyears. Dark nebulae are clouds of molecular dust that absorb light, and the Coalsack appears as a "hole" in the Milky Way (although really is stands between us and the galaxy's core). In some Australian Aboriginal cultures, the Coalsack was the head of a massive emu in the sky. In others, it's the head and shoulders of the "law-man," watching the people to keep the traditional laws. In Inca astronomy in South America, it was known as Yutu, which is a partridge-like southern bird, also known as a tinamou. It's also featured in several sci-fi references, including the original Star Trek series, 2001: A Space Odyssey, and many more.
In PixInsight, I did:
- Created master bias with ImageIntegration
- Generated superbias from master bias
- Calibrated dark frames with superbias (Linear Fit clipping)
- Calibrated lights with darks and superbias
- SubframeSelector
- 23.07 arcsec/px
- 0.115 e/ADU
- Best frame: DSC_0234 (85.502)
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
- Linear Fit clipping
- Cropped with DynamicCrop
- Applied DynamicBackgroundExtraction
- Denoised with MultiscaleLinearTransform
- Color corrected with PhotometricColorCalibration
- Stretched with HistogramTransformation
- Tweaked with CurvesTransformation
- Used star mask and ColorSaturation to reduce pink color of stars
- Tweaked again with CurvesTransformation
This one had some purple-y stars that were difficult to reduce, but I was able to correct them somewhat. It's an artifact of the lens.
[ Update August 18, 2019 ]
Getting closer to the bottom of the data pile! I need to start working on making videos out of my timelapse data too...
Anyway, here are the Magellanic Clouds!
Date: 7 July 2019
Location: Atacama Lodge, San Pedro de Atacama, Chile
Object: Magellanic Clouds
Attempt: 1
Camera: Nikon D5300
Telescope: Nikon 35mm f/1.8G
Accessories: N/A
Mount: Sky-Watcher Star Adventurer
Guide scope: N/A
Guide camera: N/A
Subframes: 44x30s (22m)
Gain/ISO: ISO-1600
Acquisition method: Intervalometer
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 30
Biases: 0
Flats: 0
Temperature: 31-36F (mostly 33)
For this dataset, I had accidentally left the camera set to 30s, but it worked out all right anyway, since the shorter exposure time that less periodic error could creep in, which gave me a crisper image. The red glow on the right side is from being low on the horizon (I rotated the camera to squeeze them both in).
As I was starting to process this one, it struck me that I have imagery of the Magellanic Clouds! I'm so happy that I got to go image in the Southern hemisphere. I knew I wanted to do it at some point, but I didn't think I'd get to do it this soon! Super super thankful.
Here's the PixInsight process:
- Integrated darks with ImageIntegration to make master dark
- Calibrated lights with master dark
- SubframeSelector:
- Scale: 23.07 arcsec/px
- Gain: 0.115 e/ADU
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
- Combination: Average
- Normalization: Additive
- Pixel rejection: Linear fit clipping
- Cropped with DynamicCrop
- Applied DynamicBackgroundExtraction
- Denoised with MultiscaleLinearTransform, with lum mask
- Color-corrected with PhotometricColorCalibration
- Applied Deconvolution, with range_mask-star_mask, DynamicPSF, 10 iterations
- Stretched with MaskedStretch
- masked_stretch_2: undid stretch, did another DBE but division to help with gradient, then
did MaskedStretch
- MaskedStretch pulled out some weird star gradients
- Undid MaskedStretch and stretched with HistogramTransformation instead
- Tweaked with CurvesTransformation
- Went back to un-stretched image, applied DBE again with more sample points in red area
of upper right hand corner to target the gradient
- Stretched with HistogramTransformation, adjusted with CurvesTransformation
There is usually some trial-and-error involved!
[ Update: October 13, 2019 ]
I've gotten sidetracked on processing data from my backyard, and I forgot I had one more dataset from Chile: another Milky Way shot! The one I showed the image of on my DSLR screen above.
I struggled with the pink-purple tone added to the stars from chromatic aberration of the lens, but got it down to acceptable levels I think. Love the dusty detail here!
Date: 7 July 2019
Location: Atacama Lodge, San Pedro de Atacama, Chile
Object: Milky Way
Attempt: 10
Camera: Nikon D5300
Telescope: Nikon 35mm f/1.8G at f/2.2
Accessories: N/A
Mount: Sky-Watcher Star Adventurer
Guide scope: N/A
Guide camera: N/A
Subframes: 38x120s (1h16m)
Gain/ISO: ISO-1600
Acquisition method: Intervalometer
Stacking program: PixInsight 1.8.7
Post-Processing program: PixInsight 1.8.7
Darks: 23 (38F)
Biases: 0
Flats: 0
Temperature: 34-39F
This view is through my 35mm f/1.8 lens, and peers deep into the southern part of the Milky Way, but still up high near the core. Just off the right edge is a part of the Milky Way familiar to northern observers -- a little bit of the Pipe Bowl Nebula, the Butterfly Cluster (M6), and Ptolemy's Cluster (M7) above. To the left of that area you can see some of the pink fuzziness of the Cat's Paw Nebula. Near the center lie the beautiful open clusters of Collinder 316, Trumpler 24, and NGC 6231, with open cluster NGC 6124 nestled in the dust clouds below. The left portion of the image is within the southerly constellation Norma. The bright dot in the far lower right corner is interloper Jupiter. You can
check out the labeled image in AstroBin.
Sometimes my wide-field Milky Way images can come out with over-dominant stars, but this one did okay. I did reduce the stars a bit using
this tutorial from Light Vortex Astronomy that works reasonably well most of the time.
Here's the whole process:
- Stacked darks with ImageIntegration
- Calibrated lights with master dark using ImageCalibration
- SubframeSelector:
- Scale: 23.07 arcsec/px
- Gain: 0.115 e/ADU
- Highest-scoring subframe: DSC_0265 (85.351)
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
- Combination: Average
- Normalization: Additive
- Pixel rejection: Linear fit clipping
- Cropped with DynamicCrop
- Background removal with AutomaticBackgroundExtraction
- Denoised with MultiscaleLinearTransform, with luminance mask
- Corrected color with PhotometricColorCalibration
- Stretched with MaskedStretch
- Adjusted with CurvesTransformation
- Reduced pink tone in stars by making a star mask with StarMask, then desaturating with ColorSaturation
- Reduced star sizes use Light Vortex method
- Increased saturation with CurvesTransformation
- Used dilated star mask to reduce pink tone again, expanded ColorSaturation de-saturation into purple
- CurvesTranformation with the star mask helped some more
- Tweaked a bit more in Camera Raw in Photoshop
What a great trip! I got so many amazing images! Now to decorate my house with them. 😁 (
You can too!)
