Monday, July 8, 2019

#192 - Sunday, June 30, 2019 - Southern Skies from Mamalluca Observatory

After a fun day driving to the small town of Elqui Pisco to enjoy some delicious pisco drinks at the Mistral pisco distillery, we drove to the Mamalluca Observatory near the village of Vicuña.  It's an observatory created for the public to enjoy in the dark skies of the Andes.  We weren't able to squeeze in on a tour that night, although the gentleman manning the gate was very helpful and asked the director if we could observe on the grounds.  We ultimately weren't able to, but there was a large parking lot just down the hill from the observatory, and we got to enjoy the dark skies from there.

There were a lot of headlights coming up the road for the activities that night -- they told us 700 people were coming that night!  But the Milky Way was up high overhead and was mind-blowingly incredible.  I set up my Vixen Polarie and my Nikon D5300 with my 35mm f/1.8 lens (50mm effectively on my cropped sensor) and did some long-exposure imaging of the Milky Way.

Southern Milky Way, Nikon D5300, 35mm, ISO-800, f/2, 120s

I brought my Meade 10x42 binoculars with me and we did some observing through those as well.  We saw a number of objects -- Southern Cross, bright star Canopus, Jupiter, Mars, constellation Lupus, the Large Magellanic Cloud, the Eta Carinae nebula, the Coal Sack dark nebula, the Jewel Box cluster, and much more.  It was fun just to rove around with the binoculars and see globular clusters and open clusters and dark nebula just everywhere.  The sky was incredible!

I also put my Nikon D3100 on my mini-tripod and took some non-tracked images of the Milky Way, and some with people.

Overlooking the town of Vicuña.  Cerro Telolo Observatory is in the background on the mountains.

Despite the headlights, it was a fun night of imaging and observing!  I took some mosaics and multiple images of the same part of the Milky Way that I will process when I get home.  So excited for more dark skies in San Pedro de Atacama in our second week!

[ Update August 29, 2019 ] 

Now that I've moved into my new place in Berkeley, CA, and I've gotten myself mostly unpacked, I finally got the Milky Way stack processed!

Date: 30 June 2019
Location: Mamalluca Observatory, Chile
Object: Eta Carinae & Coal Sack Nebulae
Attempt: 1
Camera: Nikon D5300
Telescope: Nikon 35mm f/1.8G lens at f/2
Accessories: N/A
Mount: Sky-Watcher Star Adventurer
Guide scope: N/A
Guide camera: N/A
Subframes: 19x60s (19m total)
Gain/ISO: ISO-800
Acquisition program: Intervalometer
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 0
Biases: 0
Flats: 0
Temperature: 45-47F

I should have been studying for prelim exams, but Facebook reminded me that I haven't made a post in a while...

The DynamicBackgroundExtraction process helps a lot with light pollution.  Here's a comparison of the auto-stretched versions of the same image -- one where I used the DBE process, and one without (no other processing after that).

Without DynamicBackgroundExtraction

With DynamicBackgroundExtraction

You see why it's basically my favorite process in PixInsight!

Here are all the PixInsight steps:
- No darks or biases for this set because ISO-800, so started with SubframeSelector:
- Scale: 23.07 arcsec/px
- Gain: 0.115 (just used the value for ISO-1600 because I forgot I did this at 800, and I don't have calibration frames at ISO-800)
- Highest-scoring frame: DSC_0163 (88.081)
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
- Combination: Average
- Normalization: Additive
- Pixel rejection: Winsorized sigma clipping
- Cropped with DynamicCrop
- Denoised with MultiscaleLinearTransform, with luminance mask
- Applied DynamicBackgroundExtraction
- Corrected color with PhotometricColorCalibration
- Stretched with MaskedStretch
- Tweaked colors and saturation with CurvesTransformation
- Created a star mask with StarMask, grew the stars with MorphologicalTransform, and then
used HueSaturation to reduce the magenta tinge in the stars from the lens
- Tweaked some more with CurvesTransformation
- DarkStructureEnhance

Just a few more datasets to go!

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