#344 - Saturday, May 23, 2020 - More Success! And some useful diagnostic tools

After finally getting all of my gear working, I had several nights that were mostly clear, but had lots of passing thin, high clouds that kept wrecking things and causing my sequence to abort midway through the night.  So data has been coming in very slowly.  However, the last couple of nights have been crystal-clear!

Also, side-note: Google has finally updated the user interface for Blogger!  Thank goodness.  It really looked like it was still stuck in 2002.  They took away the option to re-size images, so sorry they're kind of small.

Context Camera

When using a long-focal-length telescope, it can be hard to tell when there are clouds or tree branches in your frames.  Many people use their guide camera to see this, but since I'm using an off-axis guider, it's pretty much impossible to see those things.  So two weeks ago, I finally implemented a plan I've had for a little while.

I scrounged through my box of extra gear I haven't put to good use yet -- lots of old cameras, lenses, and other stuff people have given me.  (I will find a use for them all!).  One of my friends from when I was living in the Midwest, Will, gave me a color Meade DSI when I bought his Orion ST-80 off him to use as a guide scope on my old setup.  It's not a very good camera by today's standards, but I don't need a good camera for this.  I also grabbed my shortest focal length CCTV lens that my friend John gave me, a little 25mm guy.  A while back, I bought a T-thread to C-mount converter so I could attach these kinds of lenses to my astro cameras, so I grabbed it too from my tool box, and assembled everything together.  After installing the Meade Autostar Envisage software to run the thing (Meade cameras don't do ASCOM :( ) and seeing what kind of spacing I needed to bring distant things into focus, I figured out that I didn't need any spacers at all -- the CCTV lens was designed to sit right in front of the sensor, I guess.  Woot!  

The next task was to figure out how to rig it up on my telescope.  Currently, I have my Celestron 8-inch Schmidt-Cassegrain on my new Paramount MyT mount.  I have a short Vixen-sized dovetail bolted to the telescope tube still from back when I was running my DSLR piggyback on it a while ago, so I grabbed one of the Vixen-sized clamps I have.  Unfortunately, neither the camera nor the lens has a tripod attachment or any other useful way of attaching it to something tripod-esque.  So I did what any good engineer does -- I used some Velcro to strap it to the clamp!  It sags a big under gravity, but I don't need it to be perfectly co-boresighted with the telescope, just pointing in the same general direction.  It won't fall off the way I've got it rigged up, and that's the main thing I care about.

I figured out on the second night using it that I could use the Meade software to take a timelapse, so I set it to save an image every 30s throughout the course of the night.  This would let me go through and see why the sequence aborted, and also throw out frames where thin clouds were rolling through (this can be hard to tell in the subframes).  

It's really been paying off -- now I can see if I got too close to a tree, or if the reason I can't get a guide star is because of clouds or something else.  

New Problems, New Solutions

When more parts of your system are working, smaller issues tend to present themselves where they were buried under other issues before.  Some of my targets have had no issues, such as galaxy M88 at the beginning of the night and the Ring Nebula (M57) at the end of the night, but the Whirlpool Galaxy (M51) and some of the Hercules Cluster (globular cluster M13) have been having some strange issues.  In many of the frames, the stars appear to form a diamond pattern.

At first, I thought this was a result of diffraction around a tree branch.  But since I have added the context camera, I could go to the timestamp of when those weird subframes were taken and check and see what was going on.  No tree branches in sight.  So I wondered what the guide graphs looked like, and wished there was a way to see the whole night's guide graph.

I was poking around through the PHD2 software settings and decided to see what all the log file had in it that might be useful.  Well, as it turns out, every data point from the whole night is contained in it!  Every correction, guide star SNR, RMS error, etc.  So I decided I'd write up some code to plot the points so I could look at the whole night.

Well, before I was about to start writing the code, I did a Google search to see if anyone else had already done it.  I should have known -- of course other people have done it.  There's a nicely-packaged executable that shows you everything from the file -- it can be found here.  It will show you the calibration run as well, the data plotted in frequency-space so you can look at drive harmonics, the guide graph shows when the guide star was lost, the star's SNR, and a bunch of other useful statistics.  It's available for Windows, Mac, and Linux.  Thanks Andy Galasso!  

So I went to the portion of the night where I was imaging M51.  And the source of the diamond pattern was very obvious!

M88 guide graph -- looks good

M51 guide graph -- what the heck???

So clearly there is something weird going on with my mount in that part of the sky.  

My other two targets for the night -- M13 and M57 -- had some troubles too though.

M13 guide graph

M57 guide graph

Hmm.  Most strange.  Two thoughts:

1) My calibration isn't great -- it's not terrible, but it's not orthogonal either.  I've had this issue a lot with the off-axis guider.  I had a good calibration earlier this month, but after M88 wound up having to sit in a not-ideal place in the image in order to get a guide star in the guider's field-of-view, I rotated the off-axis guider and had to re-calibrate.  I'll try re-calibrating again tonight to see if it helps.

2) Since it's springtime, there's a lot of pollen, spiders, and spiderwebs on various parts out of the mount.  Might need to do some cleaning.  I cover it with a Telegizmos 365 cover during the day, but plenty of stuff gets on it during the night.  The gear boxes seemed sealed pretty tight, but I'll run through with a duster and air-duster and see what I can do.

Happiness

Despite these issues, I'm so happy to be finally honing in on perfection.  Or, at least, as good as I can do with all of this light pollution and air pollution!  When I have good data to work with, then I can focus more on my image processing.  

There is nothing quite like waking up in the morning, going out and powering down the telescope, and seeing that the sequence completed successfully!!

Lots and lots of hard work are, at last, paying off. :D

Next post: #346 - Monday, May 25, 2020 - For Science!!

Previous post: #334 - Wednesday, May 6, 2020 - IT'S WORKINGGGGG

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#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

- WoWeEEE

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

So cool! :D

Next post: #199 - Tuesday, July 23, 2019 - New Scope!

Previous post: #197 - Tuesday, July 9, 2019 - Shooting with an Astro-DSLR

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#197 - Tuesday, July 9, 2019 - Shooting with an Astro-DSLR

I managed once again to sleep in until 12:45 PM, and thank goodness!  I was starting to feel more adjusted to the altitude, and all three of us felt ready to go do some daytime exploring.  So I copied last night's data off of my memory cards, drank a hearty cup of coffee, and we left at 2:30 PM to go to dome sightseeing.

Our first stop was the Valle de la Luna, or "Valley of the Moon," but they only allow car entry between 8 AM and 1 PM, so we missed our chance.  Try again tomorrow...so instead we set our GPS for one of the sites in the salt flats, Salar de Atacama.  On the highway, we crossed the line of the Tropic of Capricorn!

Salar de Atacama was both the name of the general area, and supposedly a particular lagoon in the salt flats.  Unlike salt flats in other parts of the world, the one here in the Atacama Desert was not really that flat.  Well, the landscape was flat, but the salt formed stalagmites that stuck up out of the ground!  We pulled off to give it a closer look, and it was extremely hard stuff.  The salt chunks were also very sharp -- I was glad I had my hiking boots on with Vibram soles!  It also sounded hollow in places.  John used his Leatherman and some other tools he had in his pockets to bang on the crystalline structures, and with the different tones, he was making some music!  It was very cool and also very strange.

We wound up not finding a particular location or lagoon of Salar de Atacama, so we drove back northward to try Laguna Cejar.  But my phone's GPS said we wouldn't get there till 6:30 -- after sunset.  So we just drove back to the Atacama Lodge instead.  A day of bad luck!  But the drive was gorgeous, so there's that at least.  There were rocks strewn everywhere from volcanic eruptions, and there were some places where the road was washed out due to an earthquake re-routing a stream and launching all kinds of water down the mountain.  We also passed by the entrance to the radio telescope array ALMA, and we could see the workshop from the road.

Once we got back to the lodge, I went and found Alain to ask for help re-polar-aligning my Sky-Watcher Star Adventurer again once it got dark, and to get a status update on the Sky-Watcher AZEQ6 mount I was supposed to be borrowing, but it had quit working.  He said since he couldn't fix it right away, I could instead borrow an astro-modified Sony a7s with a Rokinon 135mm f/2.8 lens!  I was so all over that.  Astro-modified means that a standard DSLR camera has had its spectrum filter removed.  Consumer cameras has a special filter on the camera chip that passes the different wavelengths of visible light (the colors) at different amounts in a way that matches how the human eye responds to color.  This way, images come out looking mostly like how you saw them in real life.  However, the human eye is not particularly sensitive to red, which unfortunately is what a lot of the pretty stuff in the universe emits, especially nebulae.  With the spectrum filter removed, far more red can make it to the camera chip, which increases your signal-to-noise ratio at those wavelengths by quite a bit.  I've seen some amazing images from astro-modified DSLRs.  I've thought about doing it myself, but I think I'll save the money and get a color astro camera instead (such as the ZWO ASI1600MC, the color version of my ASI1600MM Pro) so that I can also have the cooling system.

We had a few issues at the start getting it rolling though.  It had one of those spare battery and memory card compartments attached to it, and for some reason it wasn't liking some of the batteries.  So we finally put just one battery in instead of two, and it seemed happier.  Then, when I was scrolling through the menu options (after having Alain help me change it from French to English), it kept seeming to push buttons on its own!  Finally I called Alain over to take a look, and he just gave me another astro-modified Sony a7s to use instead.  That one seemed to work.  

The Sony a7s is a mirrorless camera, meaning that much like point-and-shoot cameras and video cameras, the viewfinder is electronic.  In order to actually see anything, the image gets stretched quite a bit, so it was far easier to get the camera pointed at what I want, since I could see it on the screen so easily!  It also went up to stupidly high ISO values, like 64,000 (not 6400, 64,000!).  

Now, the Sky-Watcher Star Adventurer actually has two camera-connection screws: one on top of the declination adjustment plate, and one further down on the dovetail.  So what did I do?  Yes that's right.  I put both DSLRs on it - the Sony a7s, and my own Nikon D5300!  Actually, having the D5300 in the lower camera spot, which is toward the middle of the camera-counterweight balance point, helped balance it quite a bit, which was perfect.  The only issue I ran into was that I had to point the cameras carefully, since they would run into each other.  It meant I couldn't quite point both where I wanted to, but I got close enough.  I wound up swapping out the 300mm lens for the 35mm to avoid problems.

Simply glorious -- allllll the imaging!

It was a challenge to focus the Rokinon lens since the focus point was very tight!  But I finally got close, and then pointed the Sony toward Eta Carinae and the Running Chicken Nebula area.  I had to rotate it sideways to avoid seeing a refractor at the front of the shed.  I set the exposure time to 30s because at ISO-1600, one minute was overexposing the image!  The images looked very red due to the lack of spectrum filter, but that will all come out in processing.    Then I pointed the D5300 up to the Rho Ophiuchi region, which took a while to finesse into place so that I could get the most of the dust clouds, but not also get super-bright Jupiter in the scene.

Once that was all set and rolling, I wandered back over to the scopes to see what John and Beth were up to.  John had the 28-inch looking up at Jupiter, which was incredible in the eyepiece!  So bright, and so much detail.  It's so much higher down there than it is up in the US, plus the skies were very clear and steady.  It was breezy out, which made it feel much colder, and the moon was still up and brightening the sky, so we went inside to warm up and wait for it to set.  In the meantime, we worked through some wine we had bought and needed to finish before we left on Thursday.

I went back to the shed later to swap batteries and re-position cameras, including on my Nikon D3100, which I had set up on my mini-tripod to do star trails/timelapse facing south over the robotic scope domes.  

Then it was back to more visual observing -- M25 open cluster, Sculptor/Silver Dollar Galaxy again, NGC 1365, Stephan's Quintet, more Tarantula Nebula, and more 47 Tucanae.  NGC 1365 is a gorgeous barred spiral galaxy in the constellation Fornax, and I could see its shape!  Very very cool.  It's about 60 million lightyears away.  I also tried to find the Bug Nebula, but was unsuccessful.  At some point, I went back over to the shed and changed the Sony to imaging the Large Magellanic Cloud, and the D5300 over to both clouds with its 35mm lens.

Large Magellanic Cloud single frame at f/2, ISO-1600, 30s

Don't worry, the red will process out...

Single frame at f/2.2, ISO-1600, 60s

Caught a meteor in one of the frames!

After over an hour of imaging at those spots, I discovered that I had accidentally left the D5300 set on 10s instead of Bulb from when I was centering the Magellanic Clouds!  It had been imaging for quite a while at that point, but I switched it back to Bulb anyway for the 60s images I had set on the intervalometer.  At 5 AM, I was tired and ready for bed, but since it was still dark until about 6 AM, I left the cameras running this time.  I had started the Sky-Watcher far enough east that I was pretty sure it wouldn't hit the mount before I woke up to shut off the power, and the shed would close at sunrise to protect from the sun (I was pointing south anyway, away from the sun).  Plus, the batteries would die at some point.  So I left it running and went to bed.  

Another fabulous night (and day)!

[ Update July 27, 2019 ] 

Large Magellanic Cloud

Still plowing through datasets...so many left to go!  But each one is a joy!

Here's the Large Magellanic Cloud, from the astro-modified Sony a7s with the Rokinon 135mm f/2 lens, both borrowed from the Atacama Lodge owner, Alain Maury.

Date: 9 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Large Magellanic Cloud

Attempt: 1

Camera: Sony a7s (Alain Maury's)

Telescope: Rokinon 135mm f/2 lens at f/2

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 259x30s (2h9m30s)

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: 30-32F

See on AstroBin

😁😁😁😁😁😁😁😁😁😁😁😁

Wowee!  So much detail!  So cool!!

The Large Magellanic Cloud is a dwarf galaxy that is very close to our own -- only 160,000 lightyears away.  It was previously thought to be orbiting the Milky Way galaxy, but we now know from velocity measurements that it's actually just passing through, although it's expected to collide with us in about 2.4 billion years.  It's a disrupted barred spiral galaxy, with the disruption being due to the gravitational interaction between the LMC and the Milky Way.  It's easily visible naked-eye from relatively dark places, and from the darkness of the Atacama Lodge, I could make out structure, especially with averted vision.  It's home to the massive and incredible Tarantula Nebula as well.

Using an astro-modified Sony a7s was fun!  The images were very low-noise -- I didn't have to do any denoising at all while processing these, and I don't even have dark or bias frames for calibration!  The stars were also nice and small, and the detail was just awesome, largely due to the lack of noise I think.  When can I get one of these??

My PixInsight process was as follows:

- Since no darks/biases, started with SubframeSelector

- Scale: 12.82 arcsec/px

- Gain: 0.316 e/ADU (est.)

- Highest-score frame: DSC00136 (86.020)

- Debayered

- Registered with StarAlignment

- Stacked with ImageIntegration

- Combination: Average

- Normalization: Additive

- Pixel rejection: Linear Fit

- Cropped with DynamicCrop

- Applied DynamicBackgroundExtraction

- Color correction with PhotometricColorCalibration

- Applied deconvolution with Deconvolution, with a PSF generated from the image with DynamicPSF, 30 iterations, range_mask - star_mask masking

-  Adjusted curves with CurvesTransformation and ColorSaturation

- Enhanced contrast with HDRMultiscaleTransform

Large and Small Magellanic Clouds together

This one was with my own Nikon D5300!  Like I mentioned, I accidentally took a ton of 10s photos before I realized it and switch to 60s, but together I got about an hour and 45 minutes out of it.  And it came out quite well!

Date: 9 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Magellanic Clouds

Attempt: 2

Camera: Nikon D5300

Telescope: Nikon 35mm f/1.8G @ f/2.2

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 48x60s

   355x10s

   Total: 1h47m10s

Gain/ISO: ISO-1600

Acquisition method: Intervalometer

Stacking program: PixInsight 1.8.6

Post-Processing program: PixInsight 1.8.6

Darks: 72 (30F)

Biases: 20 (28F)

Flats: 0

Temperature: 29-30F

See on AstroBin

Not much is visible of the Tarantula here, but the globular cluster 47 Tucanae shines bright just beside the SMC.  The stars in my 35mm lens often come out with a pink-magenta-ish tinge, so I had to use a star mask that I enlarged a bit in order to reduce the pink-purple saturation just for the stars.

My PixInsight process:

- Generated master bias & superbias

- Calibrated darks with superbias, integrated with ImageIntegration

- Showed a weird pattern down at the bottom of the frame - calibrated with master bias instead and stacked, looked much better

- Calibrated 10s frames with master bias, and 60s frames with master bias and master dark

- SubframeSelector:

- Scale: 23.07 arcsec/px

- Gain: 0.115 e/ADU

- Highest-scoring 60s frame: DSC_0735 (89.446)

- Debayered

- Registered with StarAlignment

- Stacked with ImageIntegration

- Linear Fit clipping

- Combination: Average

- Normalization: Additive

- Cropped with DynamicCrop

- DynamicBackgroundExtraction

- Denoise with MultiscaleLinearTransform, with lum mask

- Color corrected with PhotometricColorCalibration

- Tried Deconvolution with generated PSF and range_mask-star_mask, but wasn't doing much

- Stretched with HistogramTransformation

- Reduced pink tinge in stars with ColorSaturation and star mask

- Applied HDRMultiscaleTransform, 9 iterations

- Dilated star mask, tried reducing magenta star tone with ColorSaturation again

- Cropped again to cut out telescope shadow and some coma

- Applied ACDNR for some additional noise reduction in brighter areas

Eta Carinae & Friends

This was one of the first datasets I processed after I got home because I was so excited about capturing hydrogen regions with the Sony a7s.  And I was not disappointed!!

Date: 9 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Eta Carinae Nebula and Running Chicken Nebula

Attempt: 3

Camera: Sony A7s (borrowed)

Telescope: Rokinon 135mm f/2 (borrowed)

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 43x30s

Gain/ISO: ISO-800

Acquisition method: Intervalometer

Stacking program: PixInsight 1.8.6

Post-Processing program: PixInsight 1.8.6

Darks: 0

Biases: 0

Flats: 0

Temperature: mid-40s

Just look at all of those stars!!  And they look nice and tight, with tons of detail on the nebulae!  And loads of dark nebula streaks.  I am super excited about this one.

Here's my PixInsight process:

- No darks or biases, so went straight to SubframeSelection:

- Scale: 12.82 arcsec/px

- Gain: 0.158 e/ADU (est.)

- Highest-scoring frame: DSC09400 (94.882)

- Debayered

- Registered with StarAlignment

- Stacked with ImageIntegration

- Combination: Average

- Norm: Average

- Pixel rejection: Linear fit clipping

- Applied DynamicBackgroundExtraction

- Literal tears in my eyes!

- Denoised with MultiscaleLinearTransform

- Didn't necessarily need it, but softened the image a bit in a good way

- Color correction with PhotometricColorCalibration

- Deconvolution with generated PSF from DynamicPSF, range_mask-star_mask, 30 iterations

- Stretched with HistogramTransformation

- Fine-tuned with CurvesTransformation

- Ran DarkStructureEnhance script

Yes, when I ran the DynamicBackgroundExtraction process after carefully adjusting every sample point so as not to be over a star or nebulosity, by jaw hit the floor.  It was so beautiful!

DynamicBackgroundExtraction forever!!

I will write a blog post on my new workflow and provide a step-by-step.  I haven't had time -- it takes a ton of time to do that!  But I will, I promise!

[ Update August 17, 2019 ] 

Still working through my Chile data...very excited about this image of the Milky Way with the Sony a7s and Rokinon 135mm lens!  Got some nice detail in the twisting dust clouds, and some nice color.

Date: 9 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Milky Way (Sagittarius)

Attempt: 10

Camera: Sony a7s (ILCE-7S) (astro-modified)

Telescope: Rokinon 135mm f/2 @ f/2

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 236x30s  (1h58m)

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: 40-45F ish

Here, we are looking at several nebulae, star clusters, and a ton of dark molecular dust in the core of the Milky Way. The big pinkish nebula right of center is M8, the Lagoon Nebula, with M20, the Trifid Nebula, lying just below and to the right. Just to the right of M20 is open cluster M21. The large open cluster in the lower right of the image is M23, which contains about 150 stars in an area 20 lightyears wide. Close inspection of the image reveals a lot of intricate detail in the twisting dust clouds above and below the main dark band of the galactic center.

PixInsight process:

- No darks/biases, so started with SubframeSelector:

- Scale: 12.82 arcsec/px

- Gain: 0.316 e/ADU (est.)

- Highest-scoring frame: DSC09658 (85.816)

- Debayered

- Registered with StarAlignment

- Stacked with ImageIntegration

- Combination: Average

- Normalization: Additive

- Pixel rejection: Linear Fit clipping

- Tried denoising with MultiscaleLinearTransform, but didn't really need it, and killed the 

dimmer stars

- Color corrected with PhotometricColorCalibration

- Same as 1, but I did Deconvolution with range-star mask, PSF from DynamicPSF, 15 iterations

- Stretched with MaskedStretch

- Adjusted with CurvesTransformation

- Cropped to center portion that I liked more

- More CurvesTransformation

- DarkStructureEnhance

So much fun :D

[ Update August 31, 2019 ] 

Almost through all of my Chile data!  Tons of great widefield Milky Way shots.  Here's another one!

Date: 9 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Milky Way

Attempt: 11

Camera: Nikon D5300

Telescope: Nikon 35mm f/1.8G @ f/1.8

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 171x60s (2h51m)

Gain/ISO: ISO-1600

Acquisition method: Intervalometer

Stacking program: PixInsight 1.8.6

Post-Processing program: PixInsight 1.8.6

Darks: 46F: 56

   40F: 40

   34F: 20

Biases: 46F: 20

40F: 20 (actually 42F)

34F: 0

Flats: 0

Temperature: 35-47F

I learned something interesting in processing this dataset.  The first half of the night had a pretty bright moon (hence the large temperature difference through the dataset), so I stacked the image twice: once with all of the images (that made it through quality check), and once with just the ones without moonlight.  There was actually not much difference at the end of the day between the two datasets!  I had to do some extra gradient removal on the moonlit one, but it wasn't too hard, and I actually liked the result better.  Here's the one without any moonlit frames (which amounted to be 70x60s):

The blue gradient is still there (I didn't try to remove it in this one), and I prefer the look of the first image.  (The main reason the two look different is just slightly different processing -- I didn't save out every process to exactly repeat all of the steps).  So that is a really interesting result -- I can do just about as well with moonlight as without!  For bright objects like the Milky Way, at least.  Processing can do a lot for you if done well.

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

Previous post: #196 - Monday, July 8, 2019 - High-Tech Star Hopping

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#196 - Monday, July 8, 2019 - High-Tech Star Hopping

After hitting the sack at 5:45 AM, I managed to sleep until 12:45 PM, thanks to my sleeping mask!  It was so bright though that I could see light through it still :/  My travel companions John & Beth saved the shower for me this time, so I had some hot water and water pressure, which made for a much more enjoyable experience than the day before!

We just hung around the lodge again all afternoon, and I worked on organizing data.  We then decided to drive over to this beautiful lookout spot that overlooked a jagged, rocky miniature canyon only a few miles from us, where people gathered every night to watch the sun set over the rocks and the Andes mountains in the background.

I took a bunch of images to make a timelapse, which I haven't made yet, but I'll add it here once I do!  It was beautiful to watch; the shadow of the mountains on the other side slowly creeped across the landscape, the sky above the Andes was orange, and the mountains themselves a peach-pink.  A dark band appeared above the mountains later on, and then the sky faded to dark blue.  

After sunset, we drove back to the lodge, made hamburgers on the stove for dinner, and then around 7:45 PM, I went to set up my Nikon D5300 on my Sky-Watcher Star Adventurer mount with my 70-300mm lens.  Since Alain, the Atacama Lodge owner, had helped me polar align it the night before, and I had weighted down the tripod with some heavy stuff I found on the floor of the roll-off shed (a counterweight and a few other random items), it should track pretty well even at 300mm!  I pointed it at the Eta Carinae Nebula and took some test shots, which showed that I could go as long as 90s without streaking.  Not bad for 300mm unguided!  My next project for the Star Adventurer is to get a guidescope attached to it.  I have some CCTV lenses and a C-mount to T-thread converter; now I just need to figure out a way to attach it to the mount.  Anyway, I got a good amount of detail to show up at 90s -- can't wait to stack it!

Eta Carinae Nebula, single 90s frame, Nikon D5300, 300mm, f/5.6, ISO-1600

It was nice and warm out that evening -- my digital thermometer in the roll-off shed said 46F, which is downright balmy after the 32F the previous two nights!  So I went over to the 20-inch-ish Dob near our lodge and looked for a bunch of stuff with John and Beth.  The large French were having some big fancy dinner in one of the other lodges, so we had it to ourselves.

First, we viewed the Eta Carinae Nebula with the OIII filter, which Beth had been absorbing all evening.  There is so much to see!  It is seriously impressive at the eyepiece.  As was massive globular cluster Omega Centauri of course, sporting hundreds if not thousands of resolvable stars under the dark, steady skies.  It's thought to contain as many as 10 million stars, making it the king of globular clusters in the Milky Way galaxy.  Many of its stars are 12 billion years old!  These millions of stars are packed into an area only 150 lightyears across, which from Earth appears nearly as large as the full Moon on the sky.  It's estimated that the average distance between stars is only one-tenth of a lightyear!  Now imagine living on a planet with that many bright stars in the sky.

I wanted to see Centaurus A next.  It's a big enough Dob that I couldn't quite figure out how to star-hop, especially since many of the stars were unfamiliar, and I couldn't tell which was which between my phone app map and the eyepiece.  So instead, I brought a little technology to the task!  I looked up Centaurus A's current altitude and azimuth in my SkySafari app (there's a free version known as SkyPortal, FYI).  I then used my phone's compass to point the scope in the right direction, and a level indicator in an app I use all the time called GPS Status to get the elevation set close.  Then I fished around for a bit, looking for star patterns that matched up with SkySafari, and boom, there it was!  It wasn't terribly bright, but you could definitely make out the hamburger shape.  It's quite large on the sky, so it's rather diffuse in the eyepiece.  I found an object in a Dob all by myself, woo hoo!

We swung by the nearby Southern Pleiades, a gorgeous open cluster that you basically trip over anytime you're looking from something around Eta Carinae, and then hopped over to Saturn.  It was incredibly sharp in the high-altitude, steady desert air, making the Cassini division very easy to see, in addition to several cloud bands.  And it was so dark that I saw more moons than I had ever seen before!  I checked their positions in SkySafari.  Previously, I'd only seen Titan and I think Tethys once or twice, but clear as day, there were Rhea, Dione, Enceladus, and Tethys!  Titan was pretty far outside the view in the eyepiece.  So cool!

We checked out the open cluster in the Coalsack Nebula, and then I went hunting for the Running Chicken Nebula, but could only see the open cluster Lambda Centauri and no nebulsoity.  Darn!

Photo by John - light is from the moon

Throughout the night, I ran around taking pictures of stuff with the sky in the background using my 35mm lens on my other DSLR, my Nikon D3100.

After a snack back in the lodge, I went back over to my Star Adventurer to change my D5300 over to somewhere in the vicinity of M8 & M20, the Lagoon and Trifid Nebulae.  They were up at zenith, which would make for some very clear shots!  It also made it hard to aim the camera.  While I was adjusting my headlamp out of the way, it snapped off, and the pieces went flying.  So I fumbled around for a few minutes until I found all the batteries and plastic, snapped it back together, and went back to finding M8 & M20.  I finally found it, but then I worked on getting it centered, which took another several minutes!  Finally got it where I wanted it.  Mostly.  Or I just gave up.  I really wanted to get the cloud below M8, which I have tried to capture before but haven't succeeded.  I can just barely see it in the subframes, so here's hoping it comes out in stacking!  It probably will, stacking is magic.

M8 & M20, Single raw 90s frame, Nikon D5300, 300mm, f/5.6, ISO-1600

After another snack around 11:30 PM (staying up all night is a lot of work!), I went over to the big telescopes, since the tour groups had cleared out.  I tried my hand again at finding stuff, and found quite a few things in the 28-inch and 24-inch Dobs!  A few from the French group were there, and they pulled up the Lagoon Nebula through the 24-inch, and helped me find the Dumbbell Nebula (way harder than it should have been!).  Then I spent quite a bit of time hunting down the Veil Nebula up in Cygnus, and I did finally find the Western Veil.  The OIII filter had disappeared somewhere, so I didn't get to see it with that (which would have been awesome), but it was really cool to see this giant, gray whispy thing there in the eyepiece!  I went looking for the nearby Eastern Veil as well, but didn't quite find it.  I did see some other nebulosity though, potentially some of the Pickering region.  I got to see that through a 16-inch Dob at the Green Bank Star Quest in 2017 when it was way up at zenith, which was quite amazing to see, especially with an OIII filter.  

One really cool object that I am super proud that I found (with my high-tech technique!) is the Skull Nebula, NGC 246.  It's a planetary nebula in Cetus, and lies about 1600 lightyears away.  It's about twice the size of the Ring Nebula on the sky, making it somewhat diffuse and difficult to spot at higher magnifications.  It really popped out against the dark sky though as a fuzzy gray circle.  With an OIII filter, it really changed character -- I could see structure in it!  Like it had large lumps.  It doesn't climb very high in the northern sky, unfortunately.  It was super cool to see!  And I found it by myself!

While I was doing that, some of the French folks found a cluster of galaxies that I didn't quite catch the name of.  It was a really pretty grouping.  One thing that was interesting is that under the murky skies at home, adding more magnification to something usually fuzzes it out.  But the seeing was so good here that adding more magnification actually made it sharper!  My brain was too fuzzed out to remember what constellation we were looking in though, so darn.

Finally, the Large Magellanic Cloud was up high enough to image at about 3:30 AM, so I moved my D5300 over to that.  But I must have moved the tripod or mount or something a little because I was getting streaky stars!  So I gave up on that and went back to the telescopes.  Since the LMC was up, that meant it was Tarantula Time!  We got the 28-inch Dob pointed at it, and gasped in amazement.  It was beyond belief!  So much detail and blue-green color.  Truly breathtaking!  We kept taking turns looking at it.

Beth looking at the Tarantula Nebula in the 28-inch.

Since the Milky Way was now much lower in the sky, it was a great opportunity to take some epic-level images with scopes and stuff in the foreground.

Proooooobably the most epic selfie I've ever taken.  Just sayin'.

Nikon D3100, 35mm, f/1.8, 10s, ISO-3200

3-panel mosaic of the 28-inch Dob

Nikon D3100, 35mm, f/1.8, 10s, ISO-3200

I took one last look at the Tarantula Nebula, and then shut everything down and went to bed at about 5:30 AM.  Another truly, truly excellent night!

[ Update July 29, 2019 ] 

Processing the Eta Carinae Nebula

So 90 seconds proved to be a little too long at 300mm, unfortunately.  Either that, or the polar alignment got knocked out earlier than I thought.  In either case, I had to dump a lot of frames, and the frames I kept were barely marginal in the star shape.  But I processed it anyway, and it's not too bad of a result.  Dark skies buy you a lot.

Date: 8 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: Eta Carinae

Attempt: 2

Camera: Nikon D5300

Telescope: Nikon 70-300mm f/4-5.6 G at 300mm, f/5.6

Accessories: N/A

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 48x90s (1h12m)

Gain/ISO: ISO-1600

Acquisition program: Intervalometer

Stacking program: PixInsight 1.8.6

Post-Processing program: PixInsight 1.8.6

Darks: 0

Biases: 20

Flats: 0

Temperature: 38-41F

This one wound up with an unusually green background somehow (airglow?) even after I ran the color correction, so I just tweaked the histogram at the end of stretching to kill the green background a bit more.  It worked nicely, and I was able to adjust the red and the blue as well so that the colors looked more natural.  I wound up with some blue halos from this lens, which I was able to reduce using Noel Carboni's Astronomy Tools for Photoshop when de-saturating blue with a star mask in PixInsight didn't really do anything.  Of course, the algorithm also killed the blue in the nebula a bit, which I had to add back using the Curves tool in Photoshop, which added back some of the blue halos.  Oh well!

Here's the PixInsight process:

- Created master bias with ImageIntegration

- Generated superbias from master bias

- Calibrated lights with superbias

- SubframeSelector:

- Scale: 2.69 arcsec/px

- Gain: 0.115 e/ADU

- Highest-scoring frame: DSC_0010 (90.716)

- Debayered

- Registered with StarAlignment

- Stacked with ImageIntegration

- Combination: Average

- Normalization: Additive

- Pixel rejection: Linear Fit Clipping

- Cropped with DynamicCrop

- Applied DynamicBackgroundExtraction

- Denoised with MultiscaleLinearTransform

- Corrected color with PhotometricColorCalibration

- Tried Deconvolution, but didn't work very well

- Stretched with HistogramTransformation

- Eroded stars with MorphologicalTransformation

- Morphological Selection, 0.30

- Undid the erosion; caused some weirdness

- Adjusted with CurvesTransformation

- Reduced blue halos in Photoshop

It's a gorgeous nebula nonetheless!  Still have several more datasets to process.  Should I be packing for my upcoming move?  Yes...Am I? No...processing astrophotography is more fun than organizing my office!

[ Update August 30, 2019 ] 

I actually processed this one a month ago, but forgot to write it up in here!  Despite the subframes not being terribly exciting, this one came our rather nice.

Date: 8 July 2019

Location: Atacama Lodge, San Pedro de Atacama, Chile

Object: M8 Lagoon Nebula & M20 Trifid Nebula

Attempt: 3

Camera: Nikon D5300

Telescope: Nikon 70-300mm f/4-5.6G @ 300mm, f/5.6

Accessories: N/A

Mount: Sky-Watcvher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 9x90s (13m30s)

Gain/ISO: ISO-1600

Acquisition method: Intervalometer

Stacking program: PixInsight 1.8.6

Post-Processing program: PixInsight 1.8.6

Darks: 0

Biases: 20 (28F)

Flats: 0

Temperature: 29-36F

That 70-300mm lens does have a bit of chromatic aberration, which causes the blue halos around the stars.  I have a Photoshop tool from the Noel Carboni Astronomy Tools for Photoshop kit that is great at removing those, but when they're in the middle of a big bright nebula (as is the case with M8), then holes are left where the halos once were, and the effect is worse.  I also tried to kill them in PixInsight using a star mask and desaturating blue, but it didn't help much, unfortunately.

Here's the whole process:

- Calibrated lights with previously-made superbias

- SubframeSelector

- Scale: 2.69 arcsec/px

- Gain: 0.115 e/ADU

- Highest-scoring frame: DSC_0225 (95.216)

- Debayered

- Stacked with ImageIntegration

- Combination: Average

- Normalization: Additive

- Pixel rejection: Winsorized Sigma Clipping

- Cropped with DynamicCrop

- Applied DynamicBackgroundExtraction

- Denoised with MultiscaleLinearTransform

- Color corrected with PhotometricColorCalibration

- Tried Deconvolution with DynamicPSF and range_mask-star_mask, but at a number of iterations low enough to not cause weirdness, effect is negligible

- Applied MaskedStretch, but stars got super blue; undid

- Stretched with HistogramTransformation instead

- Applied CurvesTransformation

- Tried to kill halos in PixInsight and Photoshop, but didn't help or caused problems

- Applied HDRMultiscaleTransform

- Tweaked with CurvesTransformation

- Denoised with ACDNR

- Sharpened with MultiscaleLinearTransform

- Applied DarkStructureEnhance

- Increased saturation of nebulae using range_mask and Saturation in CurvesTransformation

M8, the Lagoon Nebula, is the one at the center, and M20, the Trifid Nebula, is toward the upper left.  Also making an appearance is open cluster M21, beside M20.  There's a sort of bumpy nebula below M8 that I have tried to capture with M8 before unsuccessfully that I finally got some of this time!  M8 & M20 are near the heart of the Milky Way, so there's a lot of glowing stars and gas, along with dark dust, sharing the field as well. I had to ditch most of the images in this dataset because of polar alignment issues, but the nine I got to keep made a decent image despite that (thank you dark skies!)

The Lagoon Nebula is a large star-forming region somewhere between 4000-6000 lightyears from Earth. It's enormous, spanning 110 lighyears on the long axis. It also contains a number of Bok globules, which are dense clouds of dust that are in the process of collapsing into a star.

The Trifid Nebula contains three types of nebulae in one: emission, reflection, and dark. Emission nebulae are clouds of gas that are energized by a star and re-emit light, usually a red hydrogen glow. Reflection nebulae are clouds of gas that reflect starlight. Dark nebulae are clouds of molecular dust that absorb starlight. I got to see both of these in big telescopes at the Atacama Lodge as well, and they were awesome! No red color (our night vision has poor color), but some blue and the dark nebulae too.

Next post: #197 - Tuesday, July 9, 2019 - Shooting with an Astro-DSLR

Previous post: #195 - Sunday, July 7, 2019 - With My Own Eyes

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