Saturday, August 17, 2019

#201 - Saturday, August 3, 2019 - Final Members Night

With the movers coming on Monday to pack up my house for my move to California to start my PhD at UC Berkeley, I attended my last member's night with my astronomy club.  There was a pretty good turnout of about 20 people, along with a few who were camping on that nice weekend in trailers.  The forecast was iffy on the cloud situation, meaning that there would probably be some high-altitude scuzzy stuff.  Sounded like a perfect night to test out a new camera!

At least the clouds were pretty!

I didn't feel like bringing all of my gear, especially for an iffy forecast, so I planned on using one of the club's telescopes: an 8-inch Celestron Schmidt-Cassegrain on a Celestron CG-5 mount.  The new camera was one that my astro-friend John had very generously given to me recently: a ZWO ASI294MC Pro. It's the successor to my ASI1600MM Pro, but the color version. I had planned on buying the color version of my monochrome camera at some point for outreach events, transient phenomena (comets, Jupiter shadow transits, etc), and short nights, but now I have one much sooner! It would be a good night to test it anyway since I didn't have a way to mount my guidescope on the C8, so I'd just do short exposures until the cloud situation became unfavorable.

After some potluck dinner (theme: "Pies & Pints," for which I brought an apple pie), the thin crescent moon was setting in the west, and I grabbed some video on it before it dipped below the trees.  As I was prepping to move to Jupiter, someone spotted a weather balloon, and I just caught a glimpse of it in our 16-inch Dob!  But it had dropped its payload, separated, and deflated before I got my telescope over in its direction.  Darn, so close!  (And a perfect application for a one-shot color camera!)

I also enjoyed some yummy cake that some of my astro-friends got for me!

Having missed the weather balloon, but it not being quite dark yet, I imaged Jupiter and Saturn.  The atmosphere wasn't that great, however, so I'll have to see how those come out.

I didn't end up doing any deep sky imaging, but I did observe a dim M22 globular cluster, as well as M13, through the Dob.  I hung around until 11:15 PM, and then packed up and bid farewell to many of my astro-buddies.  It was a bittersweet goodbye, but we will be sure to stay in touch on social media.  I will miss them all dearly!

It has seriously been one heck of a ride so far.  After going it on my own for about 6 months after I got my first telescope in July 2015, a friend in the local astronomy club convinced me to check it out, so I went to a members night with him in February 2016, and joined the club shortly thereafter.  It was at that members night that my uncle messaged me asking if I would be interested in his Celestron computerized German equatorial mount and 11-inch Schmidt-Cassegrain, which really upped my game in astrophotography, especially once I figured out how to guide.  I also got to use a lot of astronomy club equipment, in addition to the awesome observatory facility we have (and really under-use!).  Many of my favorite images were taken on club equipment! Many club members gave me advice, tips, and even equipment, and even more gave me encouragement and friendship.  I cannot thank enough the many people in that club who have helped me along the way!

Clear skies, and I hope to catch you at the next star party!  (And don't worry, I've already found the astronomy club of the East Bay area!)

[ Update September 1, 2019 ] 

I said up above that I didn't do any deep sky imaging, but when I was working on my tablet yesterday, I found a folder of images of M20 Trifid Nebula that I had taken that night and forgot about!  I had to delete quite a few due to periodic tracking error and clouds, but I still managed to get a reasonable image out of the frames I did have.

Date: 3 August 2019
Object: M20 Trifid Nebula
Attempt: 7
Camera: ZWO ASI294MC Pro
Telescope: Celestron C8 (club's)
Accessories: N/A
Mount: Celestron CG-5 (club's)
Guide scope: N/A
Guide camera: N/A
Subframes: 34x20s (10m10s)
Gain/ISO: 139
Acquisition method: SequenceGenerator Pro
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 0
Biases: 0
Flats: 0
Temperature: -20C

So when I went to process this, I ran into a problem pretty early on while trying to debayer.  The Bayer matrix pattern was not written into the FITS header, so PixInsight couldn't figure it out automatically.  The internet said it was RGGB, but when I tried that, I got a bright blue mess!

Now, I am pretty used to having weird color casts over images from one-shot color cameras, but they're usually green, and usually you can still see the object.  I thought that maybe RGGB was actually wrong then, so I tried every other option.  Some gave a green cast and looked almost normal, but when I zoomed in, I could see the pixel pattern, which told me it wasn't right.  Finally, I decided just to see what happened when I used RGGB and then ran PhotometricColorCalibration.  This yielded a correct-looking result after all.  I then discovered after doing some forum searching that sometimes you have to unlink the RGB channels in the auto-stretch process ScreenTransferFunction, and when I did that, then the colors appeared normal.  Very strange!  The rest of the processing went smoothly.

Since I don't have any calibration frames for this camera yet, and I didn't have a large number of exposures, the image turned out quite noisy.  I had to run MultiscaleLinearTransform twice and ACDNR once to get the noise down, but they did a pretty good job.

Here's the process:
- No darks/biases yet, so just stacking lights (short exposure anyway)
- SubframeSelector
- Scale: 0.47 arcsec/px
- Gain: 0.115 (not measured yet; borrowed value for unity on ASI1600MM Pro)
- Highest-scoring frame: frame45 (82.104)
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
- Combination: Average
- Normalization: Additive
- Pixel rejection: Linear fit clipping
- Had to unlink the RGB channels in ScreenTransferFunction to actually see the image properly
- Applied DynamicBackgroundExtraction
- Denoised with MultiscaleLinearTransform, with lum mask
- Corrected color with PhotometricColorCalibration
- Ran Deconvolution with a range_mask-star_mask, PSF from DynamicPSF, 20 iterations
- Stretched with MaskedStretch
- Further stretched and adjusted with CurvesTransformation
- More denoising with ACDNR
- Increased contrast with HDRMultiscaleTransform, 8 iterations
- Applied DarkStructureEnhance script
- More denoising with MultiscaleLinearTransform

I'm liking this camera!

Thursday, August 15, 2019

#200 - Friday, August 2, 2019 - Outdoor Outreach

For the last three years, I have averaged 50 nights of outreach per year.  I almost made the mark again in my fourth year -- hit my 200th astronomy night just two weeks after my fourth anniversary of amateur astronomy!  Still going strong :D  Of course, many clear nights at the Texas Star Party and in Chile helped.  We had a lot of clouds this past year in my Midwestern home location.

For my 200th astronomy night, I did an outreach event at a county park about a half hour from my house, where I've done a few other outreach events and talks.  The movers were coming on Monday to pack up my stuff for my move to California (I'm starting my PhD at UC Berkeley!), and they offered to come Friday, but I said come Monday and Tuesday instead! This let me still have the mount on my outreach telescope, my Celestron NexStar 8SE.  (My plan was to take the telescopes with me in my car, and let the movers take all my mounts).

I was really glad I had my outreach scope because there were a ton of people there!  It was largely an event for kids, and there were about 30 people or so there total.  We had two other astronomy club members present with telescopes as well, but we each still had lines to look through them.  Several other club members came out without telescopes to support.

First, I pointed my scope to the thin crescent moon that was sinking into the west, which was quite beautiful both with and without the telescope.  We got a little bit of earthshine on the darkened portion before it set.  I didn't have my DSLR, or else I would have grabbed some shots!  Next, I pointed it to Jupiter, which had the Great Red Spot for about twenty minutes before it slid around the  back of the planet, and then I moved over to the crowd-pleaser and personal favorite: Saturn.  It's always an absolute delight in my 8-inch, and despite some waviness from the primary mirror still cooling off, it did not disappoint!

At one point, a young girl (maybe about 9 or 10?) was over at my compatriot Phil's scope, and he was telling her about how the computer-driven mount worked.  She said she wanted to be an astronomer, which of course was very exciting.  When Phil gave a command for the scope to slew somewhere, her jaw positively dropped!  It was a lot of fun.  I let her control my scope later, and answered some questions about black holes and other space things.  I told her about the Event Horizon Telescope after I showed her the recent radio-wavelength image of the black hole at the center of galaxy M87, and about the incredible resolution of the effectively-Earth-sized telescope (achieved through advanced interferometric processing algorithms).  The resolution of this telescope collaboration would be equivalent to imaging an apple on the Moon, or reading a paper in New York from a cafe in Paris!

I missed the moment of maximum jaw droppage, but she was very impressed!

After the last few people left around 10:30 PM, I set up my ZWO ASI1600MM Pro with my electronic filter wheel onto my 8-inch, including the IR photometric filter I had recently added to the previously empty slot.  The seeing turned out better that night than expected, and I got some very nice results of Jupiter and Saturn!  I've only processed Saturn so far,  but I'll put up Jupiter when I get to it.

UTC: 3 August 2019, 03:51:09
Object: Saturn
Attempt: 20
Camera: ZWO ASI1600MM Pro
Telescope: Celestron C8
Accessories: Astronomik RGB Type 2c 2-inch filters, Schuler IR Johnson-Cousins photometric filter, 
Starlight Xpress filter wheel
Mount: Celestron NexStar SE
Frames: IR: 345/1000
R: 713/1001
G: 537/1000
B: 413/1000
Exposure: IR: 250 ms
R: 120 ms
G: 120 ms
B: 200 ms
ISO/Gain: 300
Stacking program: RegiStax 6
Processing program: PixInsight 1.8.6

It's quite small in the field-of-view of my camera, so this is cropped quite heavily, so I don't have great resolution (pixels) on it.  But when I eventually live somewhere where the seeing conditions are good enough to support using a Barlow or eyepiece projection, I definitely will do that!

I love outreach events!  They give me so much energy and joy :D

#199 - Tuesday, July 23, 2019 - New Scope!

I checked the evening forecast when it was clear earlier in the day, and it looked promising, so I used some award days off I'd earned to go do some astronomy and process some Chile photos.  One of my friends from the astronomy club, Rikk, gave me a Vixen 8-inch f/4 Newtonian in June, which I was very excited to try out!  It was a little heavier than my 8-inch SCT or my Takahashi, so it would also be an experiment for how well my Celestron AVX could handle it.

I loaded up the car with the scope, mount, ZWO ASI1600MM Pro camera, my tackle box of astro accessories, table, chair, tablet computer, and eyepiece case, and got out to the observatory around 8:15 PM.  I got everything assembled and balanced in not too much time.  I left the scope rotated up with the camera on top because I hadn't installed a finerscope/guidescope dovetail on the other side yet.

It may look front-heavy with the camera, but the primary mirror is where all the weight is in this telescope, so it balances out pretty closely.  

I realized on the drive over that I had forgotten to grab a guidescope, so this would also be an experiment to see how long the mount could track for without guiding.  The focal length on this scope is 800mm, so not too long to catch every error, but not so short as to hide all of the error either.  

Rikk said it probably needed some collimation, so I pulled out my laser collimator and hit up the internet to see what I needed to look for.  I looked down the tube, and the secondary seemed pretty close to the center of the primary, but the primary didn't have a center dot, so I couldn't tell for sure.  Shining the laser light down the tube through the eyepiece, I couldn't see the return dot on the collimator, but it might have already been in the very center.  I decided not to mess with it and I'd wiggle things around in daylight to see exactly where that spot was at.  But it seemed close enough, unless the dot was all the way off of the collimator or something.  But I could see my eyeball in the secondary when I looked through the empty eyepiece tube, so I took that as a good sign.  

Another thing I realized I forgot was the power cable to my mount...things are still mixed up after the Texas Star Party.  Luckily, the club owns a couple of Celestron mounts, so I borrowed one of the power cables from those.  It was still pretty bright out by the time I finished putting everything together, but Jupiter was readily visible in the twilight, so I slewed over there to check whether I could achieve focus.  First, however, I needed to align the finderscope, so I pointed it at a distinctive treetop, got the image centered in the camera's view on my computer, and adjusted the finderscope to match.  Then I could find Jupiter.  Once there, I was able to achieve focus!  Better yet, the focuser was racked pretty far out, which meant that I had a good amount of backfocus to play with as far as adding additional accessories in the future, like an off-axis guider, better focuser, or rotator.  

I slewed back to the home position and started polar alignment using SharpCap, which went smoothly.  Alignment went pretty well as well, with each star plopping into the field-of-view on the first guess.  Always a great start to an evening!

It was still pretty light outside when I was done setting up, but Jupiter was shining bright in the twilight, so I slewed over there to get focused.  I realized that the finderscope wasn't even close to aligned, so I slewed over to a distinctive tree and looked at the camera image on my tablet to get the finderscope aligned.  Once that was done, it was easy to find Jupiter, and I was able to achieve focus!  Better yet, I had to rack the focuser pretty far out, which meant that I had a good amount of distance to be able to add other things in the future, like a better focuser (or an electronic one), an off-axis guider, or a rotator.

I slewed back to the home position to do the polar alignment, which went smoothly.  Then I went through the alignment routine, which placed all of the stars in the field-of-view of the camera, woot!  Makes my life easier, and it's a good sign that the mount is going to cooperate that night.

With alignment complete, it was time to choose a target.  I had a number of criteria to consider: it couldn't be too small, but I also didn't want one that would fill up a large amount of the FOV, since I saw that there was some vignetting, and I wasn't sure about the collimation.  (I did have a coma corrector on too, by the way).  I wanted something bright that I could expose for 30s or less, since I didn't have a guidescope, but I also didn't want something I already had a good image of already -- with a clear night, I wanted some new images!  There were a few galaxies westward that would make good targets, but that's right in the thick of the light pollution from the nearby city.  I thought about doing the Cocoon Nebula, since I haven't imaged it with my monochrome astro camera yet, but I knew I wouldn't get a whole lot of signal in the blue and green, and wanted to do longer exposure times for that one, especially to get a good view of the dark nebula.  I finally settled on the Iris Nebula, which was well-positioned, bright, and I didn't have a good image of it yet.  Bonus, the bright star in the middle would be really pretty with diffraction spikes :D  One of the things I'm really looking forward to with a Newtonian.

I took some test shots, and at 60s, the stars were nice and round!  My little AVX was still performing great.  This was really exciting.  On the left part of the image, the stars had a bit more of a donut-shape to them, so I figured this must be an effect of non-perfect collimation.  I tried for 120s, but the stars showed some stretching, so I dropped to 90s.  Some frames showed periodic error, but several were good, so I went ahead and pressed with that.

Single 90s luminance frame on the Iris Nebula

I set up my SequenceGenerator Pro sequence for 2.5 hours of LRGB imaging, and it was 10:30 PM by the time I started the script.  The sky was clear and had good transparency -- I could see quite a few stars.  There was so much light pollution though compared to Chile!  I missed it already!  The temperature was very nice, only requiring a light jacket, and there was no wind at all.  However, the humidity was really high!  Luckily, it takes quite a lot to dew up a Newtonian, and I didn't get any dew that night.

I hung out inside on my laptop, and then went back out at 1:15 to go pack up.  The moon was just rising in the east, still behind the trees.  Some clouds had rolled in though, including over my target!  So I'd have to see how many frames I'd get from the green and blue channels, which ran last.  I left the observatory around 1:45 AM, and enjoyed a gorgeous yellow-brown half-moon on the drive home.  A successful night!

[ Update August 15, 2019 ]

I actually got this image processed on July 25th, but I was still getting caught up on blog posts from Chile, and I haven't had time to finish this one during my move to California.  It came out fairly noisy due to low numbers of subframes, but otherwise surprisingly decent!

Date: 23 July 2019
Object: NGC 7023 Iris Nebula
Attempt: 4
Camera: ZWO ASI1600MM Pro
Telescope: Vixen MyStar G-R 200S f/4
Accessories: High Point Scientific coma corrector
Mount: Celestron AVX
Guide scope: N/A
Guide camera: N/A
Subframes: L: 29x90s
   R: 9x90s
   G: 10x90s
   B: 5x90s
   Total: 1h19m30s
Gain/ISO: 139
Acquisition method: SequenceGenerator Pro
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 20
Biases: 0
Flats: 0
Temperature: -25C (chip)

The Iris Nebula, or NGC 7023, is a bright reflection nebula, where a star is surrounded by gas and dust, some of which reflects the light of the star.  The star in question is magnitude +7 star SAO 19158, which is actually a double star, whose companion is +13.4 magnitude and lies 2.3 arcseconds away, or 1,220 astronomical units (Earth-Sun distance), from the brighter star.  The nebula lies 1,300 lightyears from us in the constellation Cepheus, and spans 6 lightyears.

My PixInsight process:
- Created master bias and superbias with ImageIntegration and Superbias
- Calibrated darks with superbias with  ImageCalibration
- Created master dark with ImageIntegration
- Calibrated lights with master dark and superbias with ImageCalibration
- Still issue with bias frame (I think it's all the -25C biases), so calibrated light with just bias-cal'd dark frame, which looked fine
- SubframeSelector
- Scale: 0.98 arcsec/px
- Gain: 0.59 e/ADU
- Registered with StarAlignment, with highest-scoring L frame as referece
- Stacked with ImageIntegration
- L: Linear Fit clipping
- R,G,B: Winsorized Sigma clipping
- Cropped with DynamicCrop
- Applied DynamicBackgroundExtration to each channel
- Applied LinearFit to the RGB channels, with L as reference
- Combined RGB channels
- Denoised L & RGB with MutliscaleLinearTransform, with luminance mask
- Color corrected with PhotometricColorCalibration
- Stretched L and RGB with HistogramTransformation
- Had to adjust each color channel individually, since blue peak much wider than red and green
- Adjusted colors with CurvesTransformation
- Denoised with MultiscaleLinearTransform, with lum mask
- HDRMultiscaleTransform, 7 iterations
- More curves
- Denoise with ACDNR

Looking forward to more from this scope!

Thursday, August 8, 2019

#198 - Wednesday, July 10, 2019 - Last Dark Night of the Atacama

This morning, I was only able to sleep in until 10:30 -- it was too warm inside, and I became worried about whether the cameras I had left running on my Sky-Watcher Star Adventurer would have moved far enough to hit the mount or something.  So I got up and went to check -- all was well.  I shut off the power, put the batteries on their chargers, and grabbed my Nikon D5300 off of the mount for use later in the day on our adventures.

We tried again to visit the Valle de la Luna, this time arriving before 1 PM.  It was a beautiful park for not having a single living plant!

The moon over the Valley of the Moon!

One of the stops along the way was to a hiking trail that went up to the top of some part-sand dune, part-rock hilltops, as high as 8400 feet above sea level!  By the time we got to the top (after several stops to rest), it felt like I had just run a 5k!  But the view was incredible, and standing on a particularly tall rock made me feel like I was standing on top of the world.

We hit a few more stops along the way, including some old salt mines.

All of the white stuff in the rocks is salt.

At the end of the road was the Tres Marias rock monument, which was really cool looking.  I had to wonder how it was formed!

The miners would pray here for safety.

On the way back to the Atacama Lodge, we stopped for gas in San Pedro de Atacama, at their one Copec gas station that was in a really weird and rather hard-to-find spot.  It also had a long line.  We decided to wander around town for a bit and hit up some ice cream and pick up some gifts.  We also walked through a really old church that was built sometime before 1557!  The ceiling was made of dried cactus, which was really cool.

We drove back to the Atacama Lodge and watched the sun set. I set up my Nikon D3100 to do a day-to-night timelapse, and I got the cameras booted up on my Sky-Watcher Star Adventurer.  I pointed the Sony a7s with the Rokinon 135mm f/2 lens I was borrowing from the owner of the Atacama Lodge, Alain, over to the Rho Ophiuchi complex, which I've tried to image several times from various locations with varying levels of success.  I had to position the camera carefully so that I wouldn't pick up Jupiter's camera-saturating glow.  

Also attached to the Star Adveturer was my Nikon D5300 with my 70-300mm lens, and I was going to do M16 & M17 up in Sagittarius.  However, it was too close to where the Sony was pointed, and the cameras were hitting each other.  So I just picked a spot further south in the Milky Way and figured I'd see at least something interesting there.  

Once that was all set up, I went back to the cabin to have some dinner (leftovers we were trying to finish off), and I got my stuff most of the way packed up for departing Chile the next day.  :(  I went to bed at 9:45, and the plan was to sleep till 2, get up and do some observing, and hit the road by about 4:45 to drive to Calama to catch our flight out.

At 2 AM, I dragged myself out of bed, got dressed, and finished packing.  I went up to the rolloff shed and packed up my cameras and Star Adventurer as well, and then went and joined my travel companions John and Beth at the telescopes.  Alain was just putting the finishing touches on a behemoth 45-inch Dobsonian he'd spent the last few years building, and we were hoping to get first light through it!  We helped him collimate it, although we couldn't quite reach collimation -- he would need to move the focuser hole inward a bit toward the primary (a task he'd set about doing soon).  But it was close enough for first light.  We brought the tall ladder over, and with each of us taking turns holding up the scope since the counterweights weren't quite right yet, we turned it to the obvious choice of first-light targets: the incredible Tarantula Nebula, in the Large Magellanic Cloud.  The stars weren't quite pinpoint because of being not quite in collimation, but what a view!  

Now we can say that we got to experience first light on the largest telescope in South America for use by amateurs!  :D  We also took a look at 47 Tucanae, the giant globular cluster.  I wish we could have seen that with this thing collimated!  Oh well, next time :)

We got the car loaded up, bid farewell to Alain, and drove an hour up to Calama, where we would fly out to Santiago.  Then my flight back to the states was later that night, at 8 PM.  The plan was to run around Santiago for a few hours, and then I would head to the airport to catch my flight home.  Due to a miscommunication, John and Beth's flight was the next day, but I was glad to be leaving earlier.  I was ready to head home!

All in all, Chile was an incredible adventure, and I had a great time.  The solar eclipse and the incredible dark, clear skies at the Atacama Lodge were obviously the highlights of the trip!  I had 21 deep sky datasets to process when I got home, plus numerous timelapse videos and single-frame nightscapes.  Not to mention all of the awesome daytime photos of all of our other adventures!  I also got to do a ton of visual observing, which was really rewarding, especially because things weren't just dim fuzzies, but really exciting to look at under those skies!  

I'll definitely have to go back!

[ Update August 5, 2019 ] 

Rho Ophiuchi Complex

I got the Rho Ophiuchi image processed, and HOLY COW did it come out well!

Date: 10 July 2019
Location: Atacama Lodge, San Pedro de Atacama, Chile
Object: Rho Ophiuchi region
Attempt: 7
Camera: Sony a7s, astro-modified (Alain Maury's)
Telescope: Rokinon 135mm f/2.8
Accessories: N/A
Mount: Sky-Watcher Star Adventurer
Guide scope: N/A
Guide camera: N/A
Subframes: 1: 324x30s (2h42m)
2: 58x30s (29m)
Gain/ISO: ISO-1600
Acquisition method: Intervalometer
Stacking program: PixInsight 1.8.6
Post-Processing program: PixInsight 1.8.6
Darks: 0
Biases: 0
Flats: 0
Temperature: 35-45F

Yes, that is only a half-hour of data! :O This image was really exciting to process. I literally got tears in my eyes a bit when it emerged from DynamicBackgroundExtraction. Here's why...

I wasn't sure how much of the nebula was really there with those short exposures, but the Sony a7s is so dang sensitive that I couldn't go much longer without saturating. It turned out to be just right! And I finally got some of that brown color in the dark nebula that I've seen others get but hadn't been able to achieve myself.

The first version of this one didn't come out quite as nice.

The stars got fatter, and the nebula regions weren't as well-defined. The main reason for this was that the focus slipped on the lens not very far into the run, but I tried stacking them all anyway for the sake of SNR. With all of the frames, I had 324x30s, or 2h42m of data. But then I decided to see how it would look with the much smaller number of in-focus frames -- only 58. The result was much better, and the SNR didn't seem to suffer (the lack of light pollution helped, and the apparently low noise of the Sony camera).

Another thing I tried was a new PixInsight process for me -- MaskedStretch. I went looking through Warren Keller's book Inside PixInsight for a section on processing dark nebulae that someone mentioned to me was in there, but wasn't able to find it (at least, not with a couple of quick looks). So I just looked through the section on stretching, and decided to give it a try. It performs a series of stretches, and the end result has the peak of the histogram exactly between the black point and the gray point. Since none of the peak was pushed past these two points, the image was still somewhat dim, so I brought it into CurvesTransformation and brightened it up from there. Then I did a few more steps, and got an end result I was very pleased with!

Here's the steps for the shorter-stack, in-focus version:
- Started with SubframeSelector because no darks/biases:
     - Scale: 12.82 arcsec/px
     - Gain: 0.316 e/ADU
     - Highest-scoring frame: DSC00227 (92.349)
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
     - Combination: Average
     - Normalization: Additive
     - Rejection: Linear Fit clipping
- Cropped with DynamicCrop
- Applied DynamicBackgroundExtraction
- Corrected color with PhotometricColorCalibration
- Stretched with MaskedStretch
- Stretched the rest of the way with CurvesTransformation
- Adjusted curves some more
- Denoised with MultiscaleLinearTransform
- Applied DarkStructureEnhance
- Applied SCNR to help kill leftover green tint

So happy with this one! And a great example of what powerful post-processing does for you.

Milky Way

My random positioning of my 70-300mm lens at 70mm pulled in a nice area of the Milky Way! Included in the scene are M8 Lagoon Nebula and M20 Trifid Nebula, M6 Butterfly Cluster, M7 Ptolemy's Cluster, the Pipe Bowl dark nebula, and more. Also, in one of the frames, I caught a nice meteor! So after processing the image the first time, I took the stacked image, added the single frame with the meteor to it using PixelMath (I'm sure there's a more elegant way to do this), and then applied the same processing steps (mostly). It came out nice! Even though there was a lot of moon in the background in the subframes.
Date: 10 July 2019 
Location: Atacama Lodge, San Pedro de Atacama, Chile 
Object: Milky Way 
Attempt: 12 
Camera: Nikon D5300 
Telescope: Nikon 70-300mm f/4-5.6G @ 70mm, f/4 
Accessories: N/A 
Mount: Sky-Watcher Star Adventurer 
Guide scope: N/A 
Guide camera: N/A 
Subframes: 54x120s 
Gain/ISO: ISO-1600 
Acquisition method: Intervalometer 
Stacking program: PixInsight 1.8.6 
Post-Processing program: PixInsight 1.8.6 
Darks: 58 (44F) 
Biases: 21 (44F) 
Flats: 0 
Temperature: 38-46F (mostly low-mid 40s) 

I tried MaskedStretch on this one too, but it blew out the blue halos around the stars from the slight chromatic aberration of the lens, so I did the stretch myself in HistogramTransformation instead. I still got some blue halos, but not as bad. Then I took it over into Photoshop and used one of Noel Carboni's Astronomy Tools for Photoshop to reduce the blue halos.

Here are all the steps I did:
- Created master bias with ImageIntegration, then Superbias
- Calibrated darks with superbias using ImageCalibration
- Created master dark with ImageIntegration
- Calibrated lights with master dark & superbias using ImageCalibration
- SubframeSelector:
     - Scale: 11.54 arcsec/px
     - Gain: 0.115 e/ADU
- Debayered
- Registered with StarAlignment
- Stacked with ImageIntegration
     - Combination: Average
     - Normalization: Additive
     - Pixel rejection: Linear Fit Clipping
- Added meteor frame to stacked image with PixelMath
     - Tried averaging the two, but it cut the meteor brightness in half (of course)
- Cropped with DynamicCrop
- Applied DynamicBackgroundExtraction
- Denoised with MultiscaleLinearTransform, with luminance mask
- Color corrected with PhotometricColorCalibration
- Tried MaskedStretch, but blue star halos got pretty bad
- Stretched with HistogramTransformation
- Tweaked with CurvesTransformation
- Sharpened with MultiscaleLinearTransform
- Adjusted some more with CurvesTransformation
- Reduce Blue Halos in Photoshop