#204 - Monday, September 2, 2019 - Working Out the Bugs

Another clear night! :D I went out at twilight to add more stars to the alignment model.  I slewed to Altair, but on its way over, the cable bundle got pulled too tight, which caused the dec axis to "jump," so I had to re-do the whole alignment.  I also wanted to add some western stars to help beef up the model.  Jupiter hadn't gone behind my lemon tree yet, so I commanded it to slew over there, but partway over, the dec axis motors started wagging it back and forth at high speed!  I shut off the power and reset back to home position.  I tried it again, starting with Jupiter, but got the same behavior!  It seemed to be happening past a certain declination heading south, but only on the western side of the meridian; I could go all the way to due south from the eastern side without issue.

So I picked some western stars that were much further north and just peaking out from behind the roof of my house.  I first went to Mizar -- I figured out that in the PWI app, you don't have to use just the couple of recommended stars in the alignment list, but you could click on any star on the map and use that as the alignment star.

That worked fine, but by this point clouds were rolling in, and it was hard to find stars.  The clouds didn't show any sign of letting up, so I gave up on trying to image that night, and instead just put the caps and cover on and just took dark frames instead.  Darn!

Next post: #205 - Tuesday, September 3, 2019 - Working Out the Bugs, Part 2

Previous post: Sunday, September 8, 2019 #203 - Sunday, September 1, 2019 - Handywoman Skills

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#203 - Sunday, September 1, 2019 - Handywoman Skills

Another clear night right away to try again with the backyard rig.  After the disengagement of the dec axis gears the night before when it didn't successfully park,  I thought all was well that morning when I was able to slew the mount up around the north, but as it turned out, I was wrong.  When I had it slew to Deneb for alignment, the dec axis stopped slewing partway there.  I used the controls on the computer in the Celestron PWI app to slew the mount by hand, and sure enough, RA was slewing fine, but dec wasn't moving!  So in the dark, I took the mount apart to see what was up.

Looking down into my Celestron AVX mount with the dovetail saddle and declination axis motor cover removed.

I ran inside and grabbed my allen wrenches and screwdrivers, and then took my telescope and everything attached to it off as one rather heavy piece, carefully set it on the ground.  I started to remove the top cover of the dec axis motor box, but I couldn't get to one of the screws without taking off the dovetail saddle.  So I removed that too, and then also ended up having to take off the bottom cover of the dec axis motor box.  There was a small pile of fine golden dust in the corner of the box -- the gears must have ground on each other at some point.  Greaaaaat.  The motor drive gear and the worm drive gear had become offset from each other, and the motor drive gear was pushed in very tightly with the worm drive gear.  Having recently adjusted the motor drive gear to mesh more closely with the worm drive gear to take up the backlash, I knew exactly how to add a little separation back and get them re-aligned.  

The motor drive gear is attached to the motor shaft with some tiny hex bolts, so I loosened those and pulled the gear off.  Then I loosened the screws holding the motor to the block, and put the gear back on.  This allows you to slide the motor back and forth so you can set exactly how tightly you want the gears meshed.  So I pulled it back a bit, and once I was satisfied with the fit, I removed the gear again, tightened the motor screws, and then put the gear back on and tightened it down.  I put the dovetail saddle back on, and then tested the slewing.  It slewed normally again!  Woo hoo!  So I re-attached the telescope, hooked everything back up, and re-started alignment.  Luckily, I didn't need to re-polar align, so I just put in some stars in the eastern half of the sky where I was imaging.

I re-loaded the script with all of the targets from the night before, and checked that the settings I had changed that morning to actually succeed at parking were still set.  Everything looked good to go.  I hit the start button, and off it went!

SequenceGenerator Pro
(Check out the final image of M27!)

I came back out around 10:15 to watch it switch targets from M27 to the Eastern Veil Nebula, which went smoothly and happily.  Then I went to bed!  So glorious.

The next morning, I woke up and looked out the back door to a beautiful sight: my telescope, pointing north and parked.  The camera cooler had turned off as well, and I had a full night of images.  So amazing!!

So the plan is, I'm going to run this multi-target list every night I can, tracking targets rising in the east until the hit the meridian, and then heading back down to the next target.  It doesn't get me a lot of frames in one night, but over many nights, it will get me a lot of frames.  So long as a passing cloud doesn't end the sequence early!  Super excited about this.  Hello sleep!  The targets for the next couple of weeks are: M27 Dumbbell Nebula, Eastern Veil Nebula, Cocoon Nebula, M33 Triangulum Galaxy, and M77 Cetus A galaxy.  Right now I'm sticking to 3-minute subframes, but once it looks like that is generally working well with the autoguiding, I'll try bumping up to 5 minutes, which is at least what I'll need for narrowband imaging.  My light pollution filter (Astronomik CLS) seems to be doing a pretty good job for my Bortle 7 skies, and the histograms of my images are still pretty far to the left, so I want to try for 5 minutes.  I have my new ZWO ASI294MC color CMOS camera attached now, thank you to my good friend and astro-buddy John, and I'll be switching back and forth to the ZWO ASI1600MM Pro monochrome CMOS camera for doing narrowband once I actually get myself some filters and another carousel for my filter wheel.  Exciting times ahead!

Next post: #204 - Monday, September 2, 2019 - Working Out the Bugs

Previous post: #202 - Saturday, August 31, 2019 - New Digs!

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#202 - Saturday, August 31, 2019 - New Digs!

I recently moved to the East Bay area of California to start my PhD in physics at the University of California, Berkeley!  I found a house to rent during my first week in town, and spent the second week moving in and attending orientation events.  My house has a little backyard with a gorgeous lemon tree, as well as a plum tree, and several cement squares.  Between the cement squares grows some mint, which smells awesome!  The lemon tree also smells incredible.  It's a nice little spot.

After getting mostly unpacked and having several clear days that had cloudy nights, I finally set my telescope up this afternoon.  My backyard faces south, which is great, since there are more deep sky objects (and planets!) southward.  I have about a 100-degree-wide swath of open sky between my neighbor's large evergreen tree and my lemon tree, which only goes down to 60 degree of altitude over their backyard, but goes as low as 37 degrees above my back fence.  If I am patient and image over many nights, I should still be able to do some good imaging!  I've seen some phenomenal images from light-polluted skies, and I'm at Bortle 7.  Many of those images are narrowband, which takes a thin slice of the spectrum where there is little light pollution, but some of them are wideband using light pollution filters, or multi-bandpass filters like the Optolong-L.  It's certainly not an ideal setup, but I can still do some good with it, and best of all -- I can set it up, and go to sleep!  No one can see into my backyard unless they walk all the way up my neighbor's driveway and peak over the locked fence.

Gear:

Mount: Celestron Advanced VX

Telescope: Takahashi FSQ-106N

Camera: ZWO ASI294MC

Filter wheel: Starlight Xpress, with 2-inch Astronomik LRGB Type 2c filters

Guide scope: Orion 50mm

Guide camera: QHY5

The rest of the afternoon, I processed photos and double-checked software on my tablet.  I saw a Celestron ad in Sky & Telescope that said that their new Planewave application for controlling Celestron mounts now included several serial-based models, and not just their USB-controlled mounts!  Any mount with a NexStar+ hand controller can now be controlled by their PWI software.  This is really exciting because I can save alignment models and re-load them instead of relying on hibernation to work and hoping there's not a power cut from me doing something stupid.  It also includes some more intelligence than the hand controller alone; for example, after you do the polar alignment, it automatically updates the star alignments you already made, so you don't have to re-align after a polar alignment!  

Once twilight began, I went outside to get my tablet hooked up and get everything checked.  I decided to attach my Astronomik CLS filter, which is a light pollution filter that cuts out the waveband where high-pressure sodium lies.  I forgot that 2-inch filters are M48 and not M42/T-thread, however, so I couldn't attach it directly to the camera.  So I ran inside and got my filter wheel, swapped the luminance filter for the CLS filter, and put the filter wheel on.  I've been meaning to try using the CLS filter for luminance on my monochrome ZWO ASI1600MM Pro anyway, and now I can swap them in and out without even having to change focus.  Luckily, my Starlight Xpress filter wheel is super easy to swap filters in and out of -- it has five thumbscrews on the front, and then the filter wheel carousel just slides right out, no tools needed.  

A couple of brighter stars had appeared, so I slewed to Deneb to focus so that I could do a star alignment.  (The PWI software lets you do a "quick align," where you just say you're at the home index position and it bases your alignment model on that).  After auto-stretching the histogram in SharpCap and changing the exposure time to 1s, I could see a defocused Deneb in the frame (after I put the star in my red dot sight).  However, I ran into an immediate problem: the manual controls for my Robofocus weren't working, even though the pilot light was on.  I tried connecting it to my computer via serial-to-USB, but the Robofocus app wasn't detecting it.  Finally, I powered down the Robofocuser and just focused manually (the Robofocuser disengages a magnetic lock when it's shut off so that you can do this without breaking your focuser).  I'll have to keep investigating that.

I got focused using my Bahtinov mask, and then did an alignment with just some eastern stars, since my western view is largely blocked by my lemon tree, except up near the meridian.  After two stars and Saturn, the PWI software prompted me to do an All-Star Polar Alignment, which gave me a few options for stars near the horizon & meridian, and I chose Nunki, which was easily visible.  The mount slewed to where Nunki should be if I was perfectly polar aligned, and then I moved the mount there, and hit Done.  Easy!  The only hard part was using the mount controls via keyboard in the PWI app while also seeing my camera's live feed.  The slew controls have to be on top, but unfortunately the window their in is not separate from the main PWI window -- when I select that window, the whole PWI app comes back up on the screen, blocking SharpCap.  So I had to make each app half-screen in order to see my camera feed and have the PWI app open so I could actually slew the mount.  Very annoying!  Anyway, I'm glad Celestron has that All-Star Polar Alignment feature, since the roof over my porch, my neighbor's garage, and my plum tree block the north star.

With that complete, it was time to do some testing.  I wanted to see if the auto-meridian flip would work (and make sure cables wouldn't get snagged).  So I found a star that was about to cross the meridian, got the settings set, and gave it a try.  Plate solving was being really slow, however.  By the time I changed some settings, the star would have already crossed, so when I told the mount to slew to that target so I could test the flip, it would already flip just on the slew.  This happened about three times before I gave up and decided just to have it stop imaging about a half hour after the target transitted (my mount can go 20 degrees past the meridian).  After I calibrated guiding, my original target for the evening, M27 Dumbbell Nebula, was only about an hour away from going behind the tree, so I decided to pick a different target and settled on the Eastern Veil Nebula.  Slewing to it put it mostly where I wanted it inside the frame, so I next started testing what exposure time I could get that night.  30s had nice round stars, then 60s, then 120s.  With the CLS filter, the histogram peak was still pretty far toward the left, and since this was an experiment night anyway, I went ahead and just left it at 120s.  I'll see how far I can push it with guiding on future nights.  Guiding wasn't looking all that great, but a 530mm focal length on the telescope is pretty forgiving.

I ticked the box in Equipment Profile to park the mount upon sequence completion, set the number of frames to take, and went inside to get ready for bed.  I was worried that the park command wouldn't work, but it at least should stop the mount from tracking.  I also took comfort in knowing that even if the mount kept tracking, there was a safety stop in RA that would stop the gears if it was hit.  After I got ready for bed, I went out and checked it one more time -- everything looked good.  

While I was working outside, my neighbors behind me were on the other side of the fence sitting around a fire pit and singing.  One person played guitar, and another played cello.  It was a family choir; they even harmonized together.  It was lovely being serenaded while I worked!  I wanted to grab my cello and join!  They sang songs like Space Oddity, The Boxer, and even the Foo Fighter's "Stranger Things Have Happened," along with some tunes with which I was unfamiliar.  I did sing along to a few songs quietly, which was fun.  (I also hoped that the smoke wouldn't fuzz out my images too much!)

I slept in and got up around 8 AM the next morning, and went outside to go check it.  Sure enough, it was all the way over on one side -- the park command hadn't worked.  And the gears were still spinning!  I was very worried about this.  I cut the power to the mount and logged back into my tablet to see what had happened.  It was still trying to park it -- I think it didn't give PHD a command to stop guiding, and that was interfering with the ability for it to park.  When I manually brought the mount back to home position, the dec axis column slid down a bit -- I had forgotten that when I was troubleshooting the issue with the frozen dec axis, some extra space had been created, and the dec column wasn't quite tightened down all the way (which would have re-frozen it), so when it was tipped past the meridian, it slides out a tiny bit.  As it turns out, it's enough for the gears to disengage, which is why they were spinning freely when I got out there this morning.  This meant they weren't actually turning against a load, so I most likely didn't actually break anything.  Phew!  I will just have to set SequenceGenerator Pro to do the meridian flip shortly past the meridian so that the column doesn't slip.

Still in my pajamas, I went ahead and started troubleshooting the parking issue.  As it turns out, I didn't have a park location set, so I set that in the PWI app, which is what SGP commands to park.  I tested it, and it worked!  Then I created a dummy sequence to make sure it would work in a sequence and not just with me hitting the "park" button.  I added two targets to the target list -- two stars in Ursa Major to save me some time in slewing.  I set them just to slew and not also center since it was daytime anyway.  I also disabled guiding so that it wouldn't wait for PHD to be ready.  After some fiddling with settings, a beautiful thing occurred -- it slewed to the first star, took some 1-second exposures until I stop time that I set, then slewed to the second star, took a set number of exposures, and then parked itself in the home position!  It continued tracking, however, so I'll have to work on getting it to stop tracking too.  (If you tick the "park at end of sequence" button, you cannot also tick the "stop tracking at the end of sequence" button.)  I might be able to get around this by having it disconnect equipment at the end of the sequence.  

Things are starting to come together!  Can't wait to start getting bunches of data to process.

Eastern Veil Nebula, single 120s frame
(click here for the final result!)

Next post: #203 - Sunday, September 1, 2019 - Handywoman Skills

Previous post: #201 - Saturday, August 3, 2019 - Final Members Night

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#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

See on AstroBin

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!

Next post: #202 - Saturday, August 31, 2019 - New Digs!

Previous post: #200 - Friday, August 2, 2019 - Outdoor Outreach

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#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

Next post: #201 - Saturday, August 3, 2019 - Final Members Night

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

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#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!

Next post: #200 - Friday, August 2, 2019 - Outdoor Outreach

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

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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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