#574 & #575 - October 8 & 9, 2021 - Hidden Hollow Star Party

 After a two-year absence, it was very exciting to return to the Hidden Hollow Star Party!  It's a small star party up at the Warren Rupp Observatory hosted by the Richland Astronomical Society, south of Mansfield, OH.  The weather is usually less than ideal, but it's only a two-hour trip for me, and it's a fun group of people at a nice summer camp location in the woods.  One of the awesome things about Hidden Hollow is their enormous 36-inch Newtonian telescope, "Big Blue."  It's a treat to look through between the clouds!

Because the forecast was not looking promising at all, I decided to only bring one rig.  I recently bought this awesome 3D-printed bracket on Agena Astro for the Rokinon/Samyang 135mm f/2 lens, ZWO EAF focuser, and ZWO ASIAir.  

I mounted it on my Celestron AVX.  Eventually I'd like to get it running on my Sky-Watcher Star Adventurer, but for this trip I wanted slew control, target centering, two-axis guiding, etc.  

What is all on this rig:
- Rokinon 135mm f/2 lens
- Red box: ZWO EAF electronic focuser. It's attached to a belt and notched circle that come with the kit to focus the camera lens.  It works really well actually.
- On top: Orion 50mm guide scope + ZWO ASI120MM-S guide camera, as well as a red dot finder
- On the other side: ZWO ASIair Pro
- On the back: ZWO ASI294MC Pro camera + Starlight Xpress 5-position 2-inch filter wheel.  Inside the filter wheel is an Astronomik L Type 2c luminance filter, Astronomik CLS-CCD light pollution filter, and Optolong L-eXtreme dual-narrowband filter.

Part of my goal for the weekend was to try using the ASIair to control the rig (except for the filter wheel, which is not ZWO and therefore can't be controlled by it).  Unfortunately, while everything connected to the ASIair when I was at home, neither of the cameras wanted to talk to it once I got out to Hidden Hollow.  I had brought along one of my capture laptops (a 2012 Lenovo running Windows 10) just in case, so I used that instead.

Here it is all set up at Hidden Hollow:

Yes it's a bit of a cable mess, but since this isn't (yet) one of my standard rigs, I don't have a cable harness made for it yet.

Friday

I had originally planned on going out on Thursday, but the weather not only looked cloudy but also rainy, so I didn't think anyone would be there.  So I drove up Friday instead.  I brought my awesome little camper along with me.  I forgot to get a picture at Hidden Hollow, but here's another photo:

I drove my car up by where I planned on setting up and got unloaded and the mount built and balanced.  After chit-chatting and greeting lots of people I'd seen in the past there, I finally snagged a few minutes to heat up a couple of bratwurst on the stove in my camper before it got fully dark.  

The forecast called for lots of clouds, but I was hoping to get enough of a northern view to at least get polar aligned so that I would be ready for any opportunity I had the next night to image.  The sky was clear in segments, but they kept covering up the north star.  Finally I got several minutes of clear sky up north to get polar aligned using SharpCap, woot!  It actually cleared out a decent bit, so I decided to try some imaging and get whatever I could get.  By the time I finally got polar aligned, it was about 10:30 PM, so my main target for the weekend, the California Nebula, was up and ready to roll.  The AVX slewed there no problem being controlled by CPWI, but the plate solver wasn't working -- I couldn't get either PlateSolve2 nor ASTAP to work, they both kept coming back with "invalid solve" after only a little bit of searching, not the usual wide search they'll do.  I uploaded an image to astrometry.net to make extra sure that the pixel scale I put in Sequence Generator Pro was right -- 7.07 arcsec -- and it was.  While I was trying to think of what else to do, I went ahead and got PHD2 calibrated for autoguiding, and then more clouds rolled in.  I decided to give up for the night because the clouds were coming in stronger and I was pretty damp from the high humidity.

Saturday

Saturday started out foggy and cloudy, but cleared out later in the day.  I spent the day attending talks on topics from meteorites to "spooky" celestial objects, as well as running around with my two DSLRs doing timelapse videos.  

By mid-afternoon, the forecast had much improved for the night!  I went around exclaiming the good news.

In the Astrospheric app

I got to give a talk in the late afternoon about my trip to Chile in 2019, which was a lot of fun and I got a lot of compliments on it.  (You can see a version of that presentation here).  

After my talk was the raffle drawing, and they had some fun and nice stuff this year.  I put in for a waterproof case and some green laser pointers among other things, and ended up winning a fun Star Trek ornament instead!

Deep Space Nine version of Worf holding his bat'leth

After having another quick bratwurst and some leftover pasta salad I brought along, it was time to get set up for the night.  During twilight, I tried again to get the plate-solver to work, this time connecting my laptop to my cell phone's wifi to make sure that the plate solve catalogs were still downloaded in my OneDrive.  I also shut everything down and rebooted.  Finally, I apparently Googled the right thing because I had a solution in about thirty seconds: untick the "highest accuracy solution" button in PlateSolve2 when doing widefield stuff.  Whoops! Had forgotten that little tweak.  Finally, plate solving worked!  The California Nebula wouldn't be high enough until 10:30 PM or so, so I did a short run on the Andromeda Galaxy as well.  I hit "go" in Sequence Generator Pro about a half hour before astro-darkness and went off to go gleefully look through other people's telescopes.

Saturn and Jupiter were on full display in the early evening, so I looked through a few scopes at them.  Venus and the crescent Moon also made a brilliant display as they set in the west.

I also looked at a few globular clusters and M82 through people's Dobs.  One guy had a white night vision monocular that he had a visual hydrogen-alpha filter attached to.  We took turns looking around the Milky Way -- you could see all of our hydrogen regions!  It was incredible!  All the nebula of the Cygnus region just jumped out, M8 and others in Sagittarius shone brightly, and you could easily see the Heart, Soul, and Elephant Trunk nebulae up north.  It was so cool to see them at 1x magnification on the sky!  Another night vision monocular was on one of the Dobs, and they were looking at M13 I think when I was over there.  I snagged a few pictures!

I couldn't quite get my smart phone camera (Samsung Galaxy Z Flip 3) to center on the eyepiece, but it was really cool anyway.

Looking through Big Blue

Of course, you can't go to Hidden Hollow and not look through the 36-inch, 9-meter focal length monstrosity that is Big Blue!  In order to reach the eyepiece, they use a scissor lift, which definitely takes some skill to drive around the dome.  They have a computer and monitor up on the lift that is connected to a system on the telescope so that you can give it one alignment point and then slew the telescope to your target by hand with a distance counter on the monitor showing you how much farther N-S and E-W you have to go, and it's quite accurate.  They also have a wireless remote up there to rotate the dome.  It's a really awesome setup.  But it is difficult to move the lift around the scope, and there is only a limited set of the sky you can look at because of the length of the telescope, how far the dome slit opens, whether you can maneuver the lift around, and the eyepiece location -- the scope is equatorially mounted, so the eyepiece rolls around out of reach in some parts of the sky.  Most of the evening was spent looking at Jupiter and Saturn, which displayed an incredible amount of detail at that insane focal length and aperture.  I could count more cloud bands on Jupiter than I think I'd ever seen before, and I could spot a small storm.  Saturn had something like five moons on display for us -- Rhea, Iapetus, Enceladus, Tethys, and Dione, with Hyperion on the edge of the FOV.  

After everyone got their fill of the planets, they tried to move the scope to M27, the Dumbbell Nebula, but it turned out to be blocked by the top of the slit, which I guess normally opens further but wasn't that night for some reason.  So I suggested we try the Ring Nebula instead, but that turned out to be too far west -- the eyepiece rolled over the top, where we couldn't reach it.  I was up on the lift with one of the club members who was operating the scope, so I hurriedly scrolled through my SkySafari list to see what would work, and globular cluster M2 was not far from Jupiter, which we knew we could reach.  Globular clusters are awesome in big ol' telescopes.  I got to slew the scope and rotate the dome to get on target, which was fun!  I found it in the finderscope, and then in the eyepiece, and it was awesome to look at.  The club member (couldn't tell who it was in the dark) maneuvered the scissor lift, which was a tough job!  It took us a while to get in position.  It was a fun time.  All the while, my telescope rig was running on its own, so I didn't have to worry anymore about getting sidetracked and missing a filter change or target change or meridian flip.  Soooo nice :D

Transparency had degraded, and everything was getting soaking wet, so most of the visual observers on the pad were packing up for the night.  I was chit-chatting with a few folks, and felt like it must have been after 1 AM or something.  But no, by the time I got to my camper to get ready for bed, it was only five minutes before midnight!  I went to bed and got a nice long night's sleep.

Death of the D3100

This weekend finally saw the end of my Nikon D3100, my first DSLR, as well as its kit 18-55mm lens.  The lens started its death spiral about a year ish ago when I accidentally knocked over my other DSLR, my Nikon D5300, during a timelapse in my backyard in California, which knocked the front section of the lens out of alignment, but I was able to get it back into place.  This time around, something must have broken recently because I couldn't get it back into place, and I couldn't get it to sit straight.  Almost at the same time, I was looking through the timelapse images I'd just taken with the D3100 (which earlier hadn't turned on, but eventually did), and the shutter was only opening partway for the first couple frames, and then didn't open at all after that.  I tried to lift it with my finger, but only the front plastic part was going up, not the rubbery second layer.  I'm not sure how they're normally attached to each other, but I think there's something wrong with the little hinges in there.  

The D3100 has been a real workhorse.  I bought it in July 2014, almost exactly one year before I got my first telescope.  It's traveled with me on many hikes and a few backpacking trips, always hanging around my neck or shoulder.  It was my first astro camera, capturing my very first astrophotos through my Celestron 8-inch Schmidt-Cassegrain on the NexStar alt-az mount of Saturn and the Lagoon Nebula, and has come along as a timelapse and widefield camera to star parties and astro weekends from Washington and California to Texas and Wyoming to Ohio and West Virginia.  It captured wide shots of both the 2017 solar eclipse in Wyoming and the 2019 solar eclipse in Chile.  Over the last seven years, it has captured nearly 130,000 images, according to the shutter count, which is right around the mean lifetime for the D3100.  My second DSLR, bought in 2016, already has over 300,000 shutter actuations!  

It looks like I might be able to replace the shutter myself, or send it to Nikon for repair.  I might just do that.  My D5300 has been having trouble with exposure metering, so it'd be good to have a DSLR that can still do that.  However, I had already been kicking around the idea of getting a new DSLR to replace the D3100 that has the computer control capability that the D5300 has...we shall see.  

Unfortunately on the lens front, they don't make that 18-55mm kit lens anymore.  There's a VR (vibration reduction) version that technically works with my D5300, but the VR part isn't compatible.  I found one of the same model as my kit lens on the used camera gear retailer KEH, but they just emailed me and said that it's not actually in stock after all. :(  That lens I definitely need to find a replacement for ASAP!  I'm open to suggestions...

Results

The sequence ran until about 4:30 AM, when the clouds and fog started rolling in in earnest, according to an all-night timelapse I had set up.  I got 44x300s images on the California Nebula, and 22x300s on M31.  Not too shabby!  I also got nine timelapse videos that I'll be putting together into a single video with some music.

The California Nebula came out all right.  Using a narrowband filter with a fast f/2 optic is problematic since the light gets shifted a bit off-band by the optics (and stopping down the lens doesn't help since you're not changing the optics), which results in lower transmission.  I was surprised at first to barely be able to see the nebula in subframes (it jumped out using an H-alpha filter with my ZWO ASI1600MM Pro on my C8 last year), but then I remembered this fact.  It came out all right anyway, if a bit noisy!  And since I forgot to stop the lens down to like f/2.8 or so, the coma around the edges was pretty bad.  But I did get some nice color!

Date: 9 October 2021

Location: Hidden Hollow Star Party, OH

Object: California Nebula

Attempt: 2

Camera: ZWO ASI1294MC Pro

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

Accessories: ZWO EAF focuser, Optolong L-eXtreme 2" filter

Mount: Celestron AVX

Guide scope: Orion 50mm guidescope

Guide camera: ZWO ASI120MM-S

Subframes: 38x300s (3h10m)

Gain/ISO: 120

Acquisition method: Sequence Generator Pro

Stacking program: PixInsight 1.8.8-8

Post-Processing program: PixInsight 1.8.8-8

Darks: 75

Flats: 25

Temperature: -15C

The M31 image had a few problems -- one was that I rapid-cooled the 294, thinking I had time for the frost spot to go away, but it stuck around for quite a while.  Normally, to keep the frost spot from forming, I cool it by 5 degrees C over 5 minutes at a time.  This works quite well, but I haven't figured out how to script it yet, so I have to sit there and do it.  (And yes, I have recharged the dessicant).  But here it is anyway:

Date: 9 October 2021

Location: Hidden Hollow Star Party, OH

Object: M31 Andromeda Galaxy

Attempt: 21

Camera: ZWO ASI1294MC Pro

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

Accessories: ZWO EAF focuser, Astronomik L Type 2c 2" filter

Mount: Celestron AVX

Guide scope: Orion 50mm guidescope

Guide camera: ZWO ASI120MM-S

Subframes: 22x300s (1h50m)

Gain/ISO: 120

Acquisition method: Sequence Generator Pro

Stacking program: PixInsight 1.8.8-8

Post-Processing program: PixInsight 1.8.8-8

Darks: 75

Flats: 25

Temperature: -15C

Despite the iffy forecast, Saturday night was decently clear and a fun night.  The whole weekend was a really nice time -- getting to see quite a few people I haven't seen in a while and getting to give a talk, and just enjoying some fresh air and camping and stargazing.  It was a nice weekend, and I'm looking forward to next year!

Previous post: #510 - Saturday, April 17, 2021 - New Off-Axis Guide Cam!

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#510 - Saturday, April 17, 2021 - New Off-Axis Guide Cam!

On long-focal-length telescopes like Schmidt-Cassegrains (and especially Schmidt-Cassegrains, with their floppy mirrors), off-axis guiding can provide better guiding than a guide scope.  I've been using an off-axis guider with my C8 since 2018, and despite some troubles, it has still largely been a better solution than when I was using a guide scope.

I initially paired it with my QHY5 (the original red puck), but found it to be not sensitive enough to pick up guide stars, even at f/6.3 (1280mm).  I picked up the more-sensitive QHY5L-II CMOS guide camera not long after, which typically gets just barely enough signal-to-noise ratio to hold onto a guide star on my setup.  Of course, it performs better under dark skies, but any drop in transparency, and I'm barely holding onto a star, especially in the spring when the density of stars around out-of-galactic-plane targets tends to be a lot lower.

A good night of guiding in February...just enough SNR to hold onto the star.

While the QHY5L-II worked more often than not for me, I started growing tired of losing images because of lost guide stars, and losing hours of the night while Sequence Generator Pro made attempts to recover.  So I've been kicking around the idea of getting a Lodestar, which is a tiny CCD camera made by Starlight Xpress with big juicy pixels and high sensitivity.  The current iteration of this camera is the Lodestar Pro, which was 8.6 micron pixels and 77% quantum efficiency.  Unfortunately, it costs almost $600, which is a bit hard for me to justify when my system mostly works. 

However, I recently came across a used original-model Lodestar being sold by an area astronomy club member, so I pounced on it (along with an enormous 315mm electroluminescent flat panel and a network-enabled sky-quality meter).  The older version of the Lodestar has 8.4 micron pixels and 65% quantum efficiency, so not a huge difference technically (several other specs are the same as well), although the read noise is lower in the new version.  

The first thing to do was to make sure it would talk to my laptop.  I installed the ASCOM driver for it, connected it to SharpCap, and it started taking frames right away.  Woot!  Shining light on it showed a response.

Focusing the Guide Camera

The next challenge was getting it on the off-axis guider.  This is an event.  Getting it focused is not easy.  You have the three-fold problem of not being in focus, not having a star in the field bright enough to show up when very unfocused, and it's very hard to tell where the OAG is looking to get a star placed in it.

The first night I tried it, Wednesday, didn't go well at all.  There were low clouds running across the sky, and once I got a bright star in my main camera and started slewing around to see if it would show up as a big unfocused blob in the guide camera, a cloud would inevitably cover the star.  I gave up that night and went to bed.

Saturday night was much better, and had better transparency.  Bonus points, the waxing crescent Moon was high enough above my lemon tree to see with my C8.  A super-bright object is a lot easier to land in the guide camera because you can see it coming from off the edge.  I slewed the scope over to the Moon, centered and synced it in the main camera, and then slewed above and below the main camera image to see where it would show up in my guide camera.  Pretty quickly I could start to see the guide camera image lighting up, so I adjusted the exposure time down for seeing the Moon's surface, and got the guide camera roughly focused.  I also created a field-of-view indicator element in TheSkyX where the Moon was in my guide camera compared to the main camera so that I could more easily land a star inside of it.

The center rectangle is the main camera; the smaller one above is my old guide camera; the rectangles above and below are the E and W side of the pier positions of the guide camera, respectively.

Next, I slewed the main camera to Regulus and centered it, synced the mount to it (so that it would be in the correct position with respect to my camera FOVs on the map), and then slewed the mount so that Regulus would show up inside the guide camera box.  And bang, there it was!  Now time to critically-focus.

Now, I use two different brands of filters: Astronomik CLS-CCD & RGB, and Chroma narrowband filters.  They have different thicknesses, and thus adjust the main camera's exact focus point a bit.  ("A bit" on my PrimaLuce Esatto focuser is still like 20,000 steps).  So to set the guide camera position so that it's mostly in focus for both focus points of the two sets of filters, I take the CLS-CCD filter's in-focus point and the H-alpha filter's focus point and split the difference.  I set the focuser there in the middle of the two, and then moved the camera in and out until the star was as small as it would get.  Now, since we're so far off-axis and this is a Schmidt-Cassegrain, the star shapes are pretttttyyyy yucky, so "in focus" is hard to determine.  But I got it about as small as it would appear in the camera, and called it good.  

Unfortunately, that focus point has the Lodestar just barely inside the tube!  I put on a C-mount extension tube, but it has a lip on it that won't let me insert it far enough to get the camera in focus.  So I need to hunt down an extension tube that doesn't have a lip.  We'll see if I can find one.  

Left to right: ZWO ASI1600MM Pro, ZWO electronic filter wheel, 21mm spacer, Lumicon off-axis guider + Lodestar, PrimaLuce Lab Esatto focuser

Time to Test

Next, I needed to re-calibrate guiding in PHD2 for the new camera.  I slewed the scope to somewhere roughly due East and about 50 degrees up the sky and started looping 8s exposures.  Now, I had already discovered during initial connection testing that this Lodestar has a lot of hot pixels.  And because of the way the camera is read out, some kind of interlacing to increase the speed, the hot pixels really look rather star-like.  I did try to take a dark library in PHD, but they never work for me -- they always over-subtract, and I end up with a bright gray image with black specs where the noise pixels used to be.  However, this is one place where the gross shape of the stars off-axis in a Schmidt-Cassegrain actually works out in my favor: they're way bigger than the hot pixels.  After some trial and error, I set the HFD (half-flux diameter) minimum value in the settings (brain icon) to be 3 pixels, and this did the trick.  PHD grabbed what appeared to be dim, blobby stars rather than the star-like noise pixels.  

The hot pixels really mess with PHD's auto-stretching algorithm, so I could barely even see the guide star.  However, your ability to see it isn't what matters -- only PHD's ability to see it.  This is given by the SNR (signal-to-noise ratio) reading.  The higher the value, the better (until it says "SAT" which means you're saturated, which diminishes PHD's ability to calculate the centroid of the star).  While I have been used to values between 5-20 on the QHY5L-II, the Lodestar showed values of 50-90, even in star-poor galaxy regions!

This was very exciting and very promising indeed.  So I got the main camera cooled and started running the sequence for the C8 for that night, which consisted of planetary nebula Abell 31, planetary nebula Sh2-313 (Abell 35), galaxy NGC 5248, and M16 Eagle Nebula.  Abell 31 had some initial trouble with the guide star wandering off, but it was almost behind the tree anyway, so I had SGP just advance to the next target.  Despite Sh2-313 being really low in the south for me, the PHD2 screenshot above was taken there, showing good SNR even through muddy and light-polluted skies.

The rest of the night was quite successful -- all of my targets ran and got a lot of subframes, and it looks like the night finished strong with M16, which is in an area with plentiful bright stars to choose from.

0.55 arcsec RMS guiding is pretttty good :D  And so is that SNR and star profile!

Single luminance (CLS-CCD) subframe, 300s, M16 Eagle Nebula, on the C8

Previous post: #457 - Monday, December 21, 2020 - Conjunction Junction

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#365 & #366 - Saturday-Sunday, 20-21 June 2020 - Astro-Camping Weekend!!

A little before 11 AM on Saturday, I was scrolling through Facebook and commented on my fellow astronomy club member Richard's post about his overnight trip to a secret dark sky site, expressing jealousy.  Another astro-friend of mine from the Sacramento astronomy club, Cary, commented that he and a few others would be spending the weekend up at the Sacramento club's dark site, and he invited us to join.  Needless to say, I was extremely tempted.  I immediately began to think if there was any reason I couldn't go, but nothing came to mind.  So I started packing!

The site was at an airstrip up in the mountains to the northeast of Sacramento, about 2.5 hours away from me inside the Tahoe National Forest.  I haven't camped since I moved out here to Berkeley last August, and my camping gear was scattered throughout the house.  They had electricity but no water.

I worked methodically through my mental packing list, going in sections: camping gear, clothes, food, and astronomy gear.  It ended up taking me about 4 hours to get everything organized and loaded into the car, and another hour at the grocery store.  But I finally hit the road at 4:30 PM.  I have to say, I love my Paramount MyT even more now; it's so easy to tear down and set up!  Just two pieces: the tripod and the mount.  (Well, and the counterweight bar and counterweights, and telescope of course).  I've got my cables all bundled up in cable wrap, and all my power cables and adapters contained inside a rainproof box, so everything stayed pretty organized.  

The site

Getting to the site was pretty easy -- the airstrip is just off the freeway.  It's currently only used by Cal Fire during wildfire season and by student pilots who practice takeoffs and landings there; there's no hangar, fuel, or anything else.  There was, however, a cell tower, which was great because I got full bars of 5G on my phone :D I had prepared for not having cell phone access, but it looked like that would not be a problem.

Yay, Google has updated more of the Blogger UI and I can change image sizes again!

The Sacramento Valley Astronomical Society and some of its members have several domes and roll-off sheds set up out there, which is super cool!  There is a bathroom in the main building, but that building is closed due to COVID.  The site is rated at the low end of Bortle 4 on dark-sky maps; the astronomy club members called it Bortle 3.5.

As soon as I arrived, I immediately got to chatting with the other folks who were there, and learned that everyone in attendance would be doing astrophotography that weekend.  How fun!  I had hoped for a few looks through people's Dobsonians, but oh well.  

Setup

I started getting set up, and the MyT was built in no time.  Another club member there had recently purchased a MyT, but wouldn't be getting it for a while, so I showed off all the cool features.  One awesome hardware feature about the mount is that it screws onto the Helium tripod with just one large bolt, so if you're really off on polar alignment, you can rotate the entire mount without having to shift the tripod (which is difficult and dangerous when it's fully loaded, plus you lose your leveling).    At home, I've been running my 8-inch Celestron Schmidt-Cassegrain on it, but with so few hours of darkness, I decided to bring my faster (f/5 vs f/6.3) Takahashi FSQ-106N refractor instead to do some larger summertime targets.  I brought along my ZWO ASI1600MM Pro camera, ZWO 2-inch 7-position electronic filter wheel, and my Orion 50mm mini guide scope with my QHY5 camera that I leave attached to it because it's in perfect focus.  The Takahashi has a Robofocus electronic focuser on it, although I didn't have focus offsets for my filters programmed for it yet.  (Something I can do during twilight).  

In addition to the MyT, I like to have little side projects to work on when I go out to dark sites to take advantage of the dark skies (or, sometimes, to get "consolation prize" data if the main rig doesn't work!).  I brought my Sky-Watcher Star Adventurer camera-lens tracker mount, and my ZWO ASI294MC Pro with my Nikon 50-200mm lens that I've been running on my Celestron AVX mount at home the last couple weeks.  Pairing the 294 with a camera lens is like having an astro-modified DSLR that is also cooled.  :D I've updated the layout of the rig since I originally wrote about it back in January; I've swapped out the filter wheel for my Orion SkyGlow light pollution filter (one that's meant to attach to a Schmidt-Cassegrain that my uncle gave me a while back; I'm not sure it's meant for photography, but it's working out fine so far), and I swapped out the 300mm Nikon lens for my 50-200mm Nikon lens, which has a lot less chromatic aberration and field curvature.  

Also, I have a guide scope attached to it now, woo hoo!

In addition to all that, I also set up my Nikon D5300 DSLR on a little tripod and took an all-night timelapse.

Shot from my timelapse; I forgot to get pictures of my setup!

To polar align the MyT before I ran the re-calibration of the T-point model in TheSkyX, I opened up SharpCap and ran its polar alignment routine after finding a bright star by hand and using it for focus.  (I keep a separate Celestron red dot finder aligned for each one of my telescopes to make this process much easier).  After I polar-aligned, I ran the automated re-calibration routine on about 20 stars, and then used TheSkyX's Accurate Polar Alignment using Arcturus.  Much to my delight, SharpCap and TSX agreed perfectly on polar alignment!  This was quite exciting.  I got all this done during the long summer twilight.

Next, I calibrated the autoguiding software PHD2, and got my sequence created in Sequence Generator Pro.  Oftentimes when I'm at a dark site, I try to squeeze in as many targets as I can, getting enough data on them to have a reasonable image, but never enough for a great image.  So I decided to focus on only one target this weekend: the Pelican Nebula.  Located up in Cygnus right next door to the North America Nebula, it's a gorgeous region of gas and dust with a lot of really cool structures.  The two nights were really short due to the summer solstice -- only about 5 hours of astronomical darkness each.  

PHD finished calibrating, and I connected the camera, mount, focuser, and filter wheel in Sequence Generator Pro, and hit the "Run Sequence" button.  And everything ran perfectly!  

This is the first time I've run a mobile setup and everything worked the first time.  GUYS THIS IS BIG NEWS!!  And I mean everything.  Got the mount built, didn't forget any parts or adapters, all my devices connected on the first try, polar alignment and alignment were easy, PHD calibrated with no issue, autofocus ran perfectly, filters changed like they should, plate solving worked, and the sequence started itself and ran with no issue.  If you spend any amount of time dealing with hardware or software in your life, then you know just how rare an occurrence this is!!  But it hasn't come without many, many nights of blood, sweat, and tears!  You'll notice that this was night #365 since I started doing observational astronomy; it has taken a lot of iterations, problem-solving, fine-tuning, and experience to get to this point.  But boy is it paying off now!!

The sky

With the main scope running smoothly, I took a moment to check out the skies.  It was really quite dark!  I haven't seen skies that dark since last year's Texas Star Party, in May 2019.  There was quite a bit of light to the southwest from Sacramento, and a little bit to the northeast from Reno, but the southeast and northwest skies looked great.  Clouds were dark in those sections, and I spotted M51 just off the handle of the Big Dipper naked-eye again, like I was able to in West Virginia.  

The Milky Way glittered across the eastern sky, with the Cygnus region looking particularly dazzling.  Toward midnight, Saturn and Jupiter burned brightly in the southeast, with Mars poking up from behind the trees.  The Moon was new that weekend, so the skies remained dark all night.

My other DSLR, my Nikon D3100, was busy at home doing a several-week-long timelapse of my peace lily blooming, otherwise I would have brought it along with my 35mm f/2 lens to get more Milky Way shots.  Oh well!

A little outreach

One of the other astronomers out there that night, a Navy vet, invited up some young women he knew, three sisters, to check out the dark skies and hang out with us for a while.  One was in college, and the other two in high school, I think.  I talked to them for quite a while about all things astronomy; how my astrophotography rig worked, some cool asterisms like the Teapot in Sagittarius, some NASA missions like Kepler and Hubble and what they have given us; all kinds of stuff.  They were really interested, and we had a great time.  I had brought along my handheld binoculars, which they passed around to scan through the Milky Way and see the Galilean moons of Jupiter.  I gave them my contact info to chat more.  It was a great time!

The second rig

Since everything was running smoothly on the main rig, I eventually turned my attention to the Sky-Watcher Star Adventurer, ZWO ASI294MC Pro, and Nikon camera lens rig.  I have been having some trouble with the red dot finder for this rig since the battery doesn't sit well inside its housing, so I had to point it blindly at the intended target: the Cygnus Loop, or Veil Nebula.  I've been trying for quite a while to get the whole thing in one shot to come out well, but don't really have a good enough camera lens for it.  But I figured I'd give it a try with this rig.  The Veil was difficult to see in a single frame, and with the wide field of view I couldn't really tell where I was pointing, so I needed the help of technology to get me on target.  The Star Adventurer tracks but doesn't have go-to, so I kind of had to do the centering process by hand: I took a 10s image, uploaded it to astrometry.net (I couldn't figure out how to use PlateSolve2 separately from inside a sequence in Sequence Generator Pro) (I tethered my laptop to my phone's 5G connection), waited a few minutes for it to plate solve, look at the superimposed image on a sky map on the Worldwide Telescope website, and then guesstimate re-positioning the camera and take another image.  I iterated on this process for a while, but just couldn't quite land on it.  

End of the first night

While all the rest of this was happening, I found some time at around 1 AM to finally set up my tent.  I didn't bring my canopy on this short of a trip, so I set up on the west side of the main observatory building so that I could have shade from the morning sun and be able to sleep in for a while.  I wound up chatting with people all night and didn't go to bed until dawn was creeping in at 4 AM!  It was somewhere in the mid to upper 50s in temperature, so I slept pretty well inside my down sleeping bag on my air mattress.  I have a Coleman dark tent that helps block a lot of sunlight and heat, so I was able to sleep in until 10 AM, thanks also to my sleeping mask and earplugs.

Night #2

Most of the folks went home, but a couple stuck around for a second night.  Being a student is a great time to do astronomy because I don't have to be at work or work specific hours, so getting home whenever on Monday was no big deal.  

I spent the day walking the airstrip, running daytime timelapses, reading my friend Sabrina's upcoming book, and moving my chair from shady spot to shady spot as the day wore on. The forecast promised another clear night, with even fewer clouds than we had the night before.  

As dinnertime approached, I pulled out my camp stove and grilled some of the bratwurst I had brought along, which was an excellent life choice.  I set up the grill in the shade of one of the trailers there, which worked out great.  

Summertime is great and all, but the long days and short nights make it hard to be patient for darkness!  But darkness finally did fall, and my main scope again started up without issue.  I had some time to squeeze in some hydrogen-alpha and oxygen-III images as well as the LRGB I was doing since everything ran so smoothly.  

Over on the Star Adventurer, I had spent some time during the day figuring out what to do about my mostly-broken red dot finder, and wound up jury-rigging a finder that attaches to my DSLR's camera shoe into the Synta-type dovetail bracket on top of the ZWO clamp, which was close enough to at least give me some indication of where it was pointing.  Between the finder and plate-solving in astrometry.net again, I finally landed the camera on the Veil Nebula and started acquiring images.  I had roughly polar aligned the Star Adventurer using the polar scope, but since I had the ZWO on it this time rather than my DSLR, I was finally able to use SharpCap to fine-tune the polar alignment.  Even with that though, it's kind of a wobbly mount, so I was only able to get reliable exposures at 60s exposure time at 200mm of focal length.  Oh well -- I was able to get a couple hundred of them though, which should help in getting the target to come out in processing.

After chatting some more with the remaining people, I got myself to bed at 1 AM this time so I could get home in enough time on Monday to hopefully get a little work done.  I let the scopes continue to run the rest of the night.

Results

After making it home before noon on Monday morning, my brain was too fizzled to work on school things, so I processed the Pelican Nebula data instead!  The data looked really good, so I tried a couple different things for processing.  

Details:

Date: 20, 21 June 2020

Location: Blue Canyon Nyack Airport, CA (Sacremento Valley AS dark site)

Object: IC 5070 Pelican Nebula 

Attempt: 3

Camera: ZWO ASI1600MM Pro

Telescope: Takahashi FSQ-106N

Accessories: ZWO 7-position 2-inch filter wheel, RoboFocus, Astronomik CLS-CCD 2-inch filter, 

Astronomik RGB Type 2c 2-inch filters, Chroma 3nm Ha & OIII 50mm filters

Mount: Paramount MyT

Guide scope: Orion 50mm mini-guider

Guide camera: QHY5

Subframes: L: 26x300s

   R: 17x180s

   G: 13x180s

   B: 11x180s

   Ha: 5x600s

   OIII: 5x600s

   Total: 5h53m

Gain/ISO: 139

Acquisition method: Sequence Generator Pro

Stacking program: PixInsight 1.8.8-5

Post-Processing program: PixInsight 1.8.8-5

Darks: 100 each

Biases: 0

Flats: 0

Temperature: -20C

The narrowband data didn't have a whole lot of subframes, and the luminance channel didn't have quite enough subframes to do really good deconvolution, but overall it came out all right!  I enhanced the red and luminance channels with the Ha, and enhanced the green and blue channels with the OIII.  (Details on how to do this can be found on the Light Vortex tutorial website).  

For fun, I processed just the Ha data as well, and I removed the stars using the Starnet++ plugin.  (The readme file includes installation instructions.  You can also run it outside of PixInsight).  It's quite a dramatic image.

I love the monochrome Ha starless image. It's so cool!  It looks familiar yet alien at the same time.

Over on the Star Adventurer, the Veil Nebula came out okay.  It's probably the best of the times I've attempted it with a camera lens, largely because the ZWO ASI294MC Pro is a lot more sensitive to red (and more sensitive in general) than my DSLR.

Date: 21 June 2020

Location: Blue Canyon Nyack Airport, CA

Object: Veil Nebula

Attempt: 2

Camera: ZWO ASI294MC Pro

Telescope: Nikon 50-200mm lens @ 200mm, f-something

Accessories: Orion SkyGlow filter

Mount: Sky-Watcher Star Adventurer

Guide scope: N/A

Guide camera: N/A

Subframes: 88x60s

   2x120s

   Total: 1h32m

Gain/ISO: 120

Acquisition method: Sequence Generator Pro

Stacking program: PixInsight 1.8.8-5

Post-Processing program: PixInsight 1.8.8-5

Darks: 100

Biases: 0

Flats: 0

Temperature: -20C

I didn't get great detail on the nebulae if you were to look up close, but I did pick up a fair bit of the Pickering region, which was exciting!  Unfortunately, this lens is not really ideal for astrophotography, so my stars are enormous and dominate the image.  Later this year, I'll be purchasing the Samyang or Rokinon 135mm f/2, most likely.  I got to use one on my trip to Chile last year and it was amazing!

The reason I say "f-something" for the focal ratio is because I don't actually know what it is.  My Nikon 50-200mm lens has electronically-controlled aperture than than manually-controlled, so in order to open the aperture, I cut a toothpick into small pieces and inserted them in the groove where the aperture lever is to keep it open.  I initially tested it fully wide open, but there was some pretty significant field curvature, so I took out one of the toothpicks so now it's only half-open.  Also, I've taped down the focuser and the zoom so that they don't move with some gaffer's tape.  It was still in focus both when I got out to the campsite and when I got back!

Imaged here with both toothpicks in, fully opening the aperture.

They're the same height as the lever, so they don't interfere with attaching the camera to the lens bayonet adapter I have on my image train for the ZWO camera.

Conclusion

It was a really, really great weekend!  I was glad to get out of the house for a bit during all this lockdown, we had really nice weather, and I got some great astro images.  My gear worked really well, and I met some great people.  Hopefully I'll be able to go up a couple more times this summer.  The itch to finally get a camper-trailer is getting at me again, if I can find room in my budget, especially since I towed a trailer when I moved out here last summer and partly got over the fear of towing.  We shall see...

I'm really glad I got to do this!  Can't wait for more!

Next post: #379 & #380 - Saturday & Sunday, July 18-19, 2020 - Family camping, auto-guiding the Star Adventurer, and my new trailer!!

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

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

As with many complex mechanical and digital systems, fixing one thing often causes two more problems. (Or more!)  Thus has been the case with all of my recent equipment upgrades.  Luckily, I love troubleshooting (big reason why I became and experimental physicist), so I've spent the last couple nights attacking some new problems.

Focus offsets

I got my new PrimaLuce Lab Esatto focuser installed on Saturday!  The SCT-threaded connection on it slides into the focuser, and you tighten three set screws into a groove on the adapter.  That way, I could set it to the exact angle I wanted, and it's a nice stable connection.  On the camera side, I got the 2-inch eyepeice-type adapter because that's the only way to connect my Lumicon off-axis guider, but this one, unlike my previous JMI EV-1 focuser, has a compression ring with three set screws rather than one.  So hopefully that will hold things in place much more firmly.

From the scope: Meade 0.63x focal reducer, PrimaLuce Lab Esatto focuser, Lumicon off-axis guider (set for ZWO camera backfocus), QHY5L-II guide camera, ZWO 7-position 2-inch electronic filter wheel, and ZWO ASI1600MM Pro camera.

I am now using two different brands of filters -- Astromonik CLS-CCD (light pollution) and RGB filters, and Chroma narrowband filters.  They have different thicknesses, so due to the difference indices of refraction, the focus points are shifted between the two filter brands.  Since I have an electronic focuser, I can measure the different focus points, program them into Sequence Generator Pro, and it will automatically move the focuser to the difference between the two when I switch filters.

The first step was to measure those offsets.  I set the CLS-CCD filter, and then ran the autofocus utility in Sequence Generator Pro four times.  (For the new PrimaLuce Lab Esatto focuser I have, I set the step size to 7,000 steps -- this is how far it will move between focus test points.  I didn't want it to move too much, or the more out-of-focus points would be too out of focus for SGP to get accurate star size measurements).  I recorded the focus position and HFR (half-flux radius, or measurement of the average size of the stars across the image), and then had it autofocus again.  I repeated this for the Ha and OIII filters.  

Then I took the average and standard deviation of those measurements, and set those as the focus positions in Sequence Generator Pro.

I don't actually have an SII filter -- it's just a filler until I get one later on.  Right now, that slot is empty.

Lastly, I needed to get the order of things ironed out in SGP.  This has been kind of tough, since I can't just say "do this, then that, then that;" SGP has its methods, and I kind of have to mess with different combinations of settings to bend it to my will.

I tried first to have it adjust the focus position per filter, and then focus with that filter (by turning off the "Auto focus with filter" option in the auto focus options).  With the variances in the offset measurements, I wasn't sure just setting the offset would be enough. 

Note: SGP doesn't use these offsets as absolute positions; rather, it will look at the last time you focused and which filter you used, and calculate the difference between that focus point and what you have set in the offset.  For example, if I have the CLS-CCD filter set at 200,000 in the filter wheel data, and the Ha filter at 210,000, and I just ran autofocus with the CLS-CCD filter and it found focus at 190,000, then it will take the difference between the actual focus (190,000) and the value in the filter list (200,000), and adjust accordingly, so that the Ha focus position is set to 200,000.  Make sense?

So I tried having it autofocus with the CLS-CCD filter, then change to the Ha filter and offset the focuser to get it close, and then autofocus with Ha to make sure it's in focus.  However, autofocusing with 3nm-wide narrowband filters doesn't work very well.  Even with 20s exposure times, I had several stars when it was near focus, but not enough for it to make accurate measurements when it was far from focus.  Plus, it took forever to run that way -- 9 focus test points, times 20s exposure time each, plus the time it takes to download and measure the stars in the image.  

So what I did instead tonight was to have it focus always with the CLS-CCD filter (a setting in the Autofocus options), and then it sets the filter offset when it changes filters.  Hopefully, this focuser would prove to be good enough that focus would be close enough just using the offsets.

Guide camera

The focus offsets caused another problem: my guide camera wasn't really in focus anymore.  I'm using an off-axis guider, and it's before the filter wheel in the optics train because trying to get a guide star through a narrowband filter would be basically impossible.  However, its focus is fixed, and moves with the camera, so when I drop in the narrowband filter, and the main camera focuses with the index of refraction difference of that filter, my guide camera is then out-of-focus.  Enough so that when I tried running things on Sunday, PHD couldn't hold onto any guide stars, and I didn't get any frames that night.  

Then I got a piece of advice from my astro-buddy Tolga: put the guide camera in focus with the main camera when the focuser is set for halfway in between the Astronomik and Chroma filters.  That way, it'll be a little out of focus for both, but not super out of focus for one or the other.  Smart!  (Of course, the real solution would be to get Chroma filters for my LRGB as well, but that's going to run me like another thousand dollars, and I'm not ready for that yet).  So on Monday night, I set the focus for halfway between the two, focused the guide camera, and then PHD was better able to hold onto the guide stars.  So that worked!

Dialing in polar alignment

I was curious about how well the mount performs unguided, so on Monday night, I opened up PHD and unticked the "Enable guide output" option in the brain dialog box.  This allowed me to see how the guide star moved around without actually sending guide commands to the mount.

It didn't exactly go running off, but it wasn't very good either.  Doing this reminded me of a tool in PHD that I've only tried one other time: drift align.  It's a way to fine-tune polar alignment by looking at how a star drifts due south and due east or west near the horizon, and then you adjust the altitude and azimuth knobs in an iterative process.  I don't have screenshots, but basically you first slew to a star at the meridian and 0 declination for the azimuth adjustment, hit Drift and watch the direction of a plotted trendline for enough samples to even out the noise, and then adjust the azimuth knobs until that trendline is mostly flat.  Then you do the same for altitude, but for a star that is due east or west, near the horizon.  There's a helpful document for this here.  I found that instead of moving the star all the way to the magenta circle, I needed to move it only like halfway to the circle -- all the way would far overshoot.  Drift alignment is a real pain and a slow process, but I've been told that it can have a real benefit for permanently-mounted scopes.  I'm not mounted on a pier, but I also don't take my gear down, so it stays pretty steady.  (Until the next earthquake, of course...)

After this, I checked whether I needed to update my T-Point model or not after this adjustment -- I slewed to a star, and while it didn't land in the middle, it wasn't super far off, and they already weren't landing in the middle before.  So I didn't touch the model.  I did re-calibrate PHD, and it looked pretty good.

A different autoguider?

Because my guide stars are so ugly -- partly because the off-axis guider is, well, off-axis, and deep in the coma of my Schmidt-Cassgrain, and partly because the stars aren't quite focused -- I decided I'd give another piece of guiding software a try, just for yucks: Metaguide.  I've used it recently for collimation, and I thought it'd be interesting to try out guiding with it.  It uses a different principle than every other method of autoguiding out there: Instead of doing long integrations (3-10s) to avoid "chasing the seeing," it sends corrections many times per second to the mount, sort of acting like a slow adpative optics-type thing.  It totally turns the thinking on its head, but the author (who spoke about it on TAIC recently) swears by it.  My hope was that it would be better able to grab oddly-shaped stars.  The interface looks a bit messy at first, but it has a lot of options and tools built in that are really handy.  

I had previously got it set up on my mount and guide camera when I was collimating my C11, so the tricky bits with doing that were already taken care of.  Calibrating ran quickly and without issue on a bright star.  Then I just needed to play with gain and exposure settings to see how short of an exposure time I could get away with.  Unfortunately, I had to do 2s exposures in order to get the guide star some of the time, so it more or less defeated the purpose.  It also didn't talk to SGP as smoothly as PHD2 does: it would frequently not "hear" the pause or stop commands, so that when SGP tried to resume, it was still already running, and SGP just sat there until its timeout ended and it's like "sure I'll just go ahead and continue the sequence anyway, assuming it's running."  

So the first frame came down, and oof.  It wasn't great.  It didn't like run away or do anything crazy, but the guiding was kind of all over the place.

Cropped image of some stars near M100, 10m exposure in OIII

The next frame was no better.

Are there some settings I could may adjust?  Perhaps.  But with 2s exposure times, when M100 has a pretty bright star right inside my guide camera, I don't think it's going to work out.  Not with an off-axis guider at least!  Might work better with a guide scope with brighter stars. 

So I switched back to PHD.

At last, success

After all these tweaks over the past couple of nights, I finally, finally had a great night.  The forecast called for an exceptionally clear sky.  The Moon was full, so I swapped out some of my wideband targets for narrowband ones.  The sequence had Ghost of Jupiter Nebula, M100, M51, and M57 Ring Nebula.  I did H-alpha on the two galaxies, and Ha and OIII on the two nebulae.  I ran out of time on the Ghost of Jupiter, so I didn't get any frames there (it goes behind my lemon tree at about 10 PM, leaving little time after astro-dark), but the rest of my M100 images and my M51 and M57 images came out really, really well.  Nice, tight, well-focused and well-guided stars, I could see signal in all the frames, no clouds, everything was great.  I didn't get a great number of frames because all my narrowband frames are 10 minutes long, but it did run all night without issue.  Yayyyyy!!!!

I settled on the following autofocus options:

Note: Step size depends entirely on your focuser.  My new focuser has a full range of some 400,000 steps.  My last focuser had a full range of only 8,000 steps, so the step size was very different.

I am also doing all plate solving with the CLS-CCD filter as well.

There's not much to see on the galaxy narrowband images, but here's a zoomed-in image of the Ring Nebula, a single 10-minute frame in Ha:

I can't see the dim halo around the Ring that I've seen in other images, but it may yet appear on stacking.  We shall see :)

Seeing in the morning that the sequence had run flawlessly the whole night and got a bunch of great images put me in a really, really good mood for the whole rest of the day.  A little bit of starshine in these difficult days.

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

Previous post: #331 - Friday, May 1, 2020 - A Night of Problems

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