A Brief Pause

The seasons have changed again, at least according to the calendar if not the thermometer. Despite the pleasant autumn I managed to be lazy and not haul my imaging gear out. I think an early cold snap convinced me it was winter. The reality is it's almost the new year, so time for a look ahead to 2024.

C9.25 and TV-102 back in service

As a last gasp of 2023 activity I did do a little bit of scope maintenance. First it was the turn of my old Celestron C9.25 to get collimated; I had cleverly manage to mess up its alignment to the point it was useless. This time I was very careful. Only small adjustments were made until I had it close to correct. I'll still have to do a finer tuning in the spring/summer when I can get the scope out under some decent stars.

The other bit of work was for my TV-102. Some years ago (nine? Amazing how time flies!) when imaging  IC 348 in Perseus, I noticed an irregularity in the flare around 4th magnitude omicron Persei. You can see it as a notch at about 5 o'clock.  

Omicron Persei with a mysterious dark notch

Here's a link to the full image on AstroBin. For comparison, here is Gamma Cas with my FSQ106, showing what a flood of starlight should look like.

Gamma Cas (FSQ-106EDX4)

The dark notch isn't awful, but it is a serious distraction. The primary suspect was something in the optical path. It was a simple thing to point the scope at a light surface and look through the objective from the focuser end. Clearly apparent was a sort of bump protruding into the circle of the objective. But what was it? Had something fallen into the OTA?

In the dangerous tradition of "monkey see, monkey disassemble," I took off the objective cell and discovered the problem. A bit of the TeleVue flocking paper inside the telescope tube had blistered up and gotten into the way of light. The fix was obvious to this monkey so I carefully filed down the petrified bump, put the objective cell back in place, and called it a done deal. 

Then something amazing happened: I had a thought. I wondered if I had gotten the cell back in place correctly, and was the scope still optically aligned? Dashing to the Internet I started reading posts about the travails people had collimating TV-102s. Also how they often had to fabricate clever jigs to do the alignment. Said jigs were far beyond my technical skill to create, so I was depressed. Not wanting to admit to myself that I might have made more trouble than I had remedied I set the scope aside and moved on to  imaging with my C9.25 (not yet misaligned), AT65EDQ, and eventually FSQ-106. I'd revisit the potential damage later.

Fast forward nine years to the other night when I put the TV-102 on the mount and actually looked through it at a star. It wasn't a complete star test, but at 90X Polaris A and B looked like pinpoints. At  450X racking in and out a touch gave decently symmetric airy disks. So maybe I got really lucky and it's fine. The old scope can rejoin the fleet now. I would like it functional for that eventual time when I return to visual observing. It works wonderfully with my 31mm Nagler Type 5 hand grenade, and to me it looks like the classic telescope. A picture of it from 2008 still graces the WhiteRock Conservancy (home of the Iowa Star party) web site.

AT65EDQ

After adding the FSQ-106 for imaging my poor AT65 has languished. It's an imaging scope that's corrected to provide astrograph flatness, meaning it's not a so great for visual use. Its FL of 420mm (f/6.5) is close to that of the FSQ with the 0.73X reducer (f/3.65 and 387mm) so it's somewhat redundant. But it is small and light and could easily sit on something less substantial than my G11. 

All it really needs to be a little sibling to the FSQ is electronic focusing, so that's what I'll be adding to it. And a nice Seahorse hard case for travel. Then I only need to rig a way to mount the Pegasus powerbox to it. More about that next time.

Veil Mosaic

I have all the data, I've been delaying processing until snowy winter hibernation mode starts. In the Twin Cities in a given year a "white Christmas" with 1" of snow or more on the ground has a chance of about 71%. But that won't happen this year!  The ground is bare and the forecast is for a record-warm 53 on Christmas Eve with a possible thunderstorm. The non-winter of 2023-24 is on track to continue into January.

When the snow finally arrives I'll start with a mosaic of the luminance data first to see what I've got, then repeat for each of the color channels.

 AstroBin Voting

I like to post my better pictures on AstroBin. It's mostly a vanity exercise but I think that posting technical details about images can be helpful to others. I know I've learned some things by seeing how other people acquire their data. 

Because AstroBin is a sort of social medium members are allowed to vote for images and there are best image designations. Some people complain that it's highly subjective, motivated by people trying to build their posse of followers, get votes in return, etc. All of that is possible but I don't care. It's fun, and I like it when I get up-votes. Although I admit I don't often understand why some of my images get more votes than others I've posted.

I've noticed something odd in the last year or so, though. Some of my dusty old posts that have been sitting quietly will suddenly get a flurry of votes from unfamiliar people. An example is this image of Jones 1 from 2015. Earlier this month it got four new votes within a few minutes of each other. Other people have imaged this object and created far better images than mine, so I have to ask why I got those votes.

Possibly it's people fishing for votes, but why would they reach back to an image from eight years ago? Why not take the time-honored approach of following someone so that they'll reciprocate and build your posse?  The near-simultaneity of the votes makes me think it might be something more devious.

Oh well, maybe the applicable adage is "don't look a gift horse in the mouth." So I say: Thank you  for your votes, mysterious time-lagged strangers! Maybe next time don't wait 8 years!

Panels and Pieces

September update with shouting headlines:

GUIDING WOES SOLVED!

After an August imaging session that featured repeated guide camera disconnects I decided that it was time to move on from my QHY5L-II. I'd read somewhere (CloudyNights?) this was one of its traits. Disconnects have been a repeating problem during its service to me. There have been nights I've retreated to my good old StarShoot Autoguider.

I had tried to work with the camera. It seemed as though the issue was insufficient power, so I used shorter and shorter USB cables, then a powered USB 3 port and a very short cable. The disconnects became less frequent but imaging time was still being lost. 

Something had to be done; I can tell you that it is not fun fussing around at 2 or 3 AM trying to get things going again after a disconnect. So I went all-ASI and purchased an ASI 120MM Mini (mono). My only qualms about the Mini were possible software collisions with my imaging camera, an ASI 2600M, and if it would be compatible with the QHY mini guide scope.

The only camera confusion was mine when I gave PHD2 the wrong camera to use. The ASI120 seems to work well with the QHY mini guide scope, although it may need a little more backfocus. And during an evening of imaging not a single disconnect, so for the moment I'm declaring problem solved. I may swap out the QHY guide scope for my old Orion 50mm guide scope, just for the added aperture.

MOSAIC DATA COMPLETED!

My ~57 megapixel mosaic of the Veil nebula has taken long enough, hasn't it? Panel 1 (of 6) was imaged June 19. Panels 2, 3, and 4 were imaged August 25 and September 11. The final panels, 5 and 6, were imaged September 17. The long summer delay was thanks to smoke, air quality, heat, clouds, and my availability. It's been a summer. 

I don't yet know how good the light frames are of these but they will have to do. Each panel is made of approximately 48 minutes of luminance, and 24 minutes of each color channel. This means it's not particularly deep, but this is the Veil Nebula and hardly the dimmest object in the sky. I could collect more data, but I'd like to move on to other targets.

DISASTER AVERTED, TWICE!

This is how my night imaging the last two panels started....

Disaster #1: The dew strap for my FSQ's objective had a short that I first noticed as a wild variation in the Pegasus Ultimate PowerBox current. It was hopping between a low, reasonable value and 4+ amps as it tried to control the situation. Its control probably prevented the Powerbox's demise, a meltdown of the strap's cable (it did become too hot to touch) and perhaps even damage to my AC to DC power supply. 

Disaster #2: Without the dew strap imaging could last only until I saw dew beginning on the imaging scope's objective. I hoped I'd be able to get at least one of the two remaining Veil panels done but it seemed doubtful. There was no breeze to keep the ambient temperature from cooling rapidly and because I was imaging almost straight up the objective would probably dew quickly.

Maybe it was convection from the power supply and the cooled imaging camera or just plain good luck but it somehow stayed dew-free for the time required to get both panels imaged.

NEBRASKA STAR PARTY 2023: SMOKE AND CLOUDS!

Okay, I didn't attend. I'll sit in judgement of it anyway, partly to justify my staying home but mainly to question the wisdom of traveling to distant places for imaging. Which is not to say I won't go next year, if someone could do something about all that smoke. As for the heat--it's not NSP without a day or two of 100-degree temperatures or hotter, is it?

Here are the day-by-day NSP 2023 imaging conditions as gleaned from the weather service and air pollution monitors.

Saturday Night: red category air quality and terrible transparency. I'm of an age that puts me in the group the air quality people always caution about being active when the air is this bad. We had a couple of days this summer where I live that were as bad as this and the surface smoke was so thick that it looked like a thin fog. Setting up camp was not something I'd have wanted to do in red air. And of course, with the smoke the greatly reduced transparency for imaging negates the point of going someplace dark like NSP.

Sunday Night: Saturday night all over again.

Monday Night (First "official" night of NSP): Clouds and a thunderstorm.

Tuesday Night: Probably clear from Midnight to 2 AM, then rain around 3 AM. Very humid (dew point temperature near 70 degrees) so super uncomfortable sleeping in a tent on the observing field.

Wednesday Night: Partly cloudy all night. 

Thursday Night (my last night at NSP had I attended): Partial clearing around 12:30 AM, then partly cloudy until 3.

So maybe a couple of hours of imaging Tuesday night and again Thursday night; for maybe a total of four hours of smoky sky imaging across six nights. Add to that unhealthy air quality on two nights.

Some years NSP can be a fun vacation in the wilds of Nebraska with very dark sky. Some years not so much. If the wildfire smoke becomes an annual problem NSP will difficult to justify as a travel destination.

On the other hand, with summer smoke affecting most of the region, where else would you go?

That's all for this dramatic update!

A Practice Mosaic Using Photometric Mosaic in PixInsight

During the time between first and third quarter moon I thought it might be good to look at methods used to make mosaics. I had no idea what was available for doing that in PixInsight.

I learned there are a few ways to go about making a mosaic. The one that's often mentioned is the Star Alignment (SA) process. SA is usually spoken of as a rough alignment suitable for two-tile mosaics. For merging more tiles together (my eventual Veil mosaic will mean combining six) other methods can give better results.

I'll give them a try, but first I wanted to get a baseline merge using SA. To do this I'll create two tiles from an image of the California Nebula I made last year. I'll just cut it into two pieces.

Here is the image as fully processed in its nonlinear form:

Original Finished Image

 

Mosaics are built from linear images, and fortunately I kept the linear version of this. The left tile will be a simple crop. The right will start as a crop and then get modified to resemble some of the differences one might see in images taken days or weeks apart. Different dithering or polar align drift might mean different cropping away of poor signal areas, so I'll change its size.  Not having a rotator means it may be off by a few degrees, so I'll rotate it by three degrees. Lastly, the second tile may have a different luminance level thanks to smoke or clouds. Most of this should be removed, but I'll leave some in to see how well it gets handled. (This is done by tweaking the right tile with the Curves Transformation.) Here are the resulting left and right tiles:

 

Left and right "tiles"

 

You can clearly see they're not the same size. The other modifications are more subtle but if not treated correctly could result in a bad  merge seam, misaligned tiles, and possibly other defects.

The easiest method for merging the two panels is Star Alignment (SA). I'm going to do this using the settings suggested by Kayron Mercieca of Light Vortex Astronomy on this page. I'm going to supply SA with previews because it's so easy to do for a 2-panel mosaic. My chosen overlap is about 40%, larger than the 30% I'm using for the Veil mosaic. Executing SA gives me this:

Rough mosaic using only Star Alignment

Inspection of the result shows no seams, and no odd stars. It's perfectly acceptable, and confirms that (at least in this case) SA is suitable for a two-tile mosaic.

Next up is Gradient Merge Mosaic (GMM). I again used the methodology prescribed by Mercieca, first building a synthetic star field and then registering the tiles to it using SA. Then the right tile is processed by the dna Linear Fit script to insure that it matches the left script's brightness. Finally, GMM merges the two tiles.

A common problem with GMM is star pinching at the overlap edge, and my result showed severe pinching. The first fix is to adjust two parameters in GMM. Doing so helped a little, but not nearly enough. When this fails the remedy is to use Clone Stamp to remove bright stars at the offending edge. This did reduce the pinching, but not only left some and created new artifacts stemming from Clone Stamp.

After considerable efforts to deal with the pinching I came to the sense that GMM does not cope will with images having a lot of stars. This is the case for the California Nebula tiles; it will also be true for my planned Veil mosaic. 

SA and GMM are the only methods described by Keller in his book "Inside PixInsight," so I was not happy. A little googling turned up another method: Photometric Mosaic (PM). PM looked very promising!

Here is a great tutorial for PM. 

I followed the tutorial with one change: I used the Mosaic Join /  Combination mode Overlay rather than the Blend or Average methods the presenter recommends. 

The result was excellent! There are no perceptible seams or artifacts at all, even when boosted autostretching is used. Here is the result, with a quick autostretch to be nonlinear:

If this lacks the contrast of the original image it's due to using only autostretch in the processing.

I think I'm now ready for building my mosaic, and it's a day past 3rd quarter--so let the clear evenings commence!

 -------------------------------------

Here's a callback to an earlier post titled "A Wristwatch for Astronomy?" The watch in question worked well in almost all regards---big, easy to read, and of course it kept time adequately. Where it failed was the luminescence. The watch hadn't been properly "charged" before wearing, so I was only able to read it using my red light. Next time I'll remember to feed it plenty of nice yummy photons!

The Start of a Mosaic

It's been kind of wild since the last post. We've had many days of air quality alerts, most of which have been for excessive surface ozone, a byproduct of smoke and sunlight and "normal" air pollution. Smoke at times thickened to concentrations similar to what was seen earlier on the East Coast. It wasn't healthy at all; hospitals reported a surge of people with breathing difficulty.

The air quality did improve for a bit and I was able to get out and do a little imaging. In fact, I managed to start one of my learning projects!

One item on my to-image list is a mosaic of the Veil Nebula that spans both the east and west sides. The Veil isn't immense like Barnard's Loop, but it's large enough to require something like a 250mm lens to fit it all in a single frame. My FSQ-106 has a focal length of 530mm and it really needs something like a 2x3 mosaic to encompass the Veil. That's 6 frames, and at about 2 hours exposure time for each it will make a good summertime project that could last into September.

Despite the ever-present smoke I was able to collect the data for subframe 1 which includes most of the East Veil (NGC 6992) and the Network Nebula (NGC 6995): left click the image below, then right click the enlarged image and choose "Open Image in New Tab" to see the image at 1/2 scale:

 

 

For fun, here's a try at a starless version using StarNet2 in PixInsight:

 

This is LRGB with all exposures 120s, L = 20 lights, R = 11, G = 12, and B = 12.

I think I dark-clipped this a little in my processing haste, but it will get another processing eventually.  Here it is tucked into its place in the eventual mosaic:

 

6995 is in the overlap area between subframes 1 and 3. The next target will be subframe 3 to complete the Eastern Veil and give me some practice using PixInsight to create a mosaic.

Some other tidbits from this too-rare night of imaging:

• The QHY-5II guide scope was flawless with over two hours of guiding without a single disconnect. It really does need USB3, it seems. 
• Not only that, but tracking errors were limited to 2 frames in 58. A rate of 1 bad frame in 29 is a lot better than the 1 in 6 that I had experienced earlier this year.
  
• NINA's Advanced Sequencer finished subframe 1 and started subframe 3 imaging without any attention on my part. This was the first time I had tried this. I wasn't willing to do another two to 3 hours of imaging so I reluctantly shut it down at that point.
• More NINA: Its mosaic feature is nicely integrated into the Framing Assistant and sets up the Advanced Sequencer for all the subframes with simplicity.
• Even More NINA: If you want to use the Framing Assistant with images while you're someplace without Internet, go to the NINA download page and grab the Offline Sky Map Cache file (2 GB) It replaces the existing cache folder AppData >  Local > NINA > Framing Assistant Cache. Don't forget to change the Framing Assistant Screen's Image Source setting to Offline Sky Map! Incidentally, installing this allows you to zoom out and use Framing Assistant like a (rather strange) planetarium.
• I seem to have gotten the hang of PI Deconvolution. I don't know why it was so temperamental before, but the key seems to be in the Deringing settings. A Global dark of 0.03 to 0.02 seems to work well, with Global bright typically between zero and 1/2 of Global dark.
  

 

Smoke and the June New Moon; A Couple of Things Fixed (maybe)

This week would be a prime time for heading out to Lac qui Parle state park for some dark sky imaging. But there's some serious smoke action ruining that plan. Here's what the smoke looks like from space.

The location of Lac qui Parle State Park is given by the red dot

Fortunately for the health of people in the Dakotas and western Minnesota it's all far above the ground and the air we breathe. 

This is a blue light satellite image from late in the day of 12 June. Both Dakotas are under multiple smoke decks; you can see the layering across western Minnesota where each layer casts a shadow onto the layer beneath it. The eastern edge of the smoke is slowly pushing eastward. 

 I can't say I'm confident this will clear out during the coming new moon weekend of 16-18 June. Western Canada continues to burn.

It's already complicated trying to forecast clouds and adding smoke makes it all the more difficult. Clear or cloudy? Transparent or murky? The decision to travel an hour or more to a dark sky location has become an exercise in nowcasting.

In some ways this is much the same as a cloud deck. It may not be opaque, but the extinction is formidable. In the image below of north central south dakota you can see contrails at flight level casting shadows onto the smoke!

---------------

Two issues may have been resolved last night. The glitchy behavior of my QHY5LII guide camera was absent with the USB cable connected to a USB3 port, and I got a beautiful PHD2 calibration after I turned off the mount's PEC. This has not been a problem in the past, so I wonder if the PEC file become corrupt while it sat unused this winter. It's going to stay off until I have a chance to retrain the mount.

---------------

I've also learned how to use NINA to acquire images for mosaics, and have set up a file to perform a six-panel mosaic of the Veil Nebula. The first two panels will complete the East Veil.

Opening Night, 2023 (M44 & NGC 6823)

Basically, my first attempt at using a state park failed. Not because of the park. It was the weather, of course. And smoke. There's not much advantage to imaging from a dark sky site when the transparency is severely reduced by a layer of heavy smoke. The camping reservations for the May new moon were canceled and I'll try again in June. 

Last night the smoke relented and even though it was a first quarter moon I got some imaging done from the club's Eagle Lake observatory site. There was time for only two targets, M44 and NGC 6823. As expected there were some rough spots, but I think some things were learned, too.

NINA

Nina  had one glitch and one nice feature I was using for the first time.

I could not get NINA's advanced sequencer to accept multiple targets; Trying to add M76 to M44 resulted in two entries for M44. I'm fairly sure I had forgotten some necessary step as this had worked before.

The NINA manual rotator worked wonderfully and let me get the images properly framed by hand. It took only a few adjustments to get within the "good enough" orientation range.

PHD2

I initially had the scope slew due south to the celestial equator for calibration. Under normal circumstances during calibration you'll see PHD nudge the mount first in one direction and then back to the starting point, then do the same along a line perpendicular to the first direction. While doing the second line it wandered a bit before doing as expected. PHD let me know it wasn't happy; at the conclusion of calibration it announced that the calibration was suspect. The mount had been polar aligned, balanced, and so far as I could see no cables were dragging, so it's a mystery to explore next time. 

Evidently the guiding calibration was good enough, as it kept the stars round in most frames.

Periodically guiding would go badly off in both RA and Dec, producing bad stars. I suspect cable snagging, but maybe it's related to the calibration issue? Either way, it's going to be something to look out for next time.

Guide Camera

I started the evening using a QHY5L-II-M guide camera, a finicky little device. Last night it frequently stopped so I swapped it out for my ancient Starshoot Autoguider. The SSAG is not terribly sensitive, but it works!

Past experience with the 5L, powered by the USB connection, suggests it's picky about the input voltage. Last night I connected through one of the convenient USB2 ports on my ASI 2600. Next time it's going to straight to a USB3 port on my Pegasus Powerbox. Maybe that will clean up its act?

Mount balancing

Confession time: While I do always try to balance the mount, I don't generally practice "east heavy" imbalance. That's going to change after last night. Initially with "near-perfect balance" tracking was only so-so. Restarting with the mount rebalanced to be east heavy significantly improved tracking, just as everyone says. If only I would pay attention

Now the images... These are preliminary processing results: neither makes use of deconvolution or sharpening. Both images were acquired the night of first quarter moon, with only about 25 degrees between the moon and M44.

M44

 

M44 is one of those objects that in my opinion is best imaged by a system that gives the stars diffraction spikes. The spikes can provide a sense of separation between the cluster and the field stars that simulates the visual impression this big cluster has in a wide-field scope. I know there's software that can add spikes, but that kind of "artistic" modding is not something I want to do.

[ Details: ASI 2600 mono ccd, Takahashi FSQ-106 @ f/5, 11x60s for each channel of RGB. Image resized to about 20% of full scale. If you look along the lower edge left of center you'll see my master flats from 2022 are obsolete.]

This result suggests that an RGB imaging scheme of 12x60s for each channel may be adequate for quick imaging of bright open clusters, and that 60s exposures are short enough to preserve star color. 

Next is NGC 6823:

 

NGC 6823 (and NGC 6820 if you know where to look)

NGC 6823 is a combination open cluster and bright nebula. The cluster is 7 arcminutes in diameter (about 1/10th the size of M44) so this is a test of what some of the smaller clusters in the Astronomical League's Open Open Cluster list may look like if I use the same camera and optics to image the list.

Can you tell 6823 is in Vulpecula? Look at all the stars, and how those stars are driven to red near-extinction by their light scattering through light years of interstellar gas and dust. 

[There is some confusion around 6823 and 6820, with 6820 often referred to as the emission nebula around 6823 (see The Night Sky Observer's Guide Volume 2, for example). This doesn't agree with the definition of 6820 being a reflection nebula. If you look a plate solve of the 6823 area, you'll see 6820 is centered around a small blue nebula well offset from the cluster of stars within 6823. This is also where SIMBAD puts it. You can barely see it in my much-reduced image as a tiny smudge just outside the upper left quadrant of the emission nebula. My color calibration doesn't get 6820's color correct.]

[ Details: ASI 2600 mono ccd, Takahashi FSQ-106 @ f/5, 21x60s blue + 20x60s green + 19x60s red. Image resized to about 40% of full scale.]

Those light frame counts tell you that I lost 12 frames out of 72. That's 1 frame in 6 and clearly is not adequate.

And what's next? Waiting for a clear night. What I'd like to see is how a full moon affects open cluster imaging. And when it's new moon time again, the boring spring sky will be at least partially replaced by the sky of summer.

Starting Imaging for 2023

[Note added 5/18/2023: The weather and smoke from Canadian fires led me to cancel this first attempt at state park imaging. I'll try again for the June new moon, if not sooner.] 

Here comes Spring! (I hope.) The May new moon is on the 19th, so I'm gearing up for this as a warm-up for using state parks this year in lieu of going to the Nebraska Star Party. The first "expedition" to a remote in-state site will have some fairly simple targets for refreshing my skills with NINA and all the hardware.

Before Midnight: 

• M44 (open cluster; big and bright, AL list member)
• M67 (open cluster; sort of a toned-down, more compact version of M44, AL List member)
• Collinder 463 (open cluster, AL List Member)

After Midnight:

• IC 4756 (open cluster)
• NGC 6633 (open cluster, same field of view as IC 4756, AL List member)
• NGC 6823 (bright nebula and open cluster, AL List member) 
• NGC 6882/6885 (open cluster and AL List member)
• NGC 6940 (open cluster)

I'm tempted to use my 200mm lens for IC 4756 and NGC 6633 to put them in the same field. It would make a pretty picture and look like this (per Stellarium) and might remind one of the well-known double cluster of NGCs 869 & 884.

This might make a pretty picture is reminiscent of the well-known double cluster of NGC 869 & 884. 

This long list assumes I'll have clear sky, which is doubtful in Minnesota in May. (Mid May sky is clear only about 1/3 of the time.)

One part of this exercise is finding a set of minimum exposures for imaging open clusters. The goal isn't super pretty pictures, but only passable images that capture the essence of the clusters. Yes, I'm still thinking about doing the AL Open Cluster list by imaging. I'd like to image them all using the same system and if possible the same exposures. I'm not sure if that's even possible, but it's worth a try.

The field of view of my FSQ and ASI is big enough for the largest clusters on the list, but the small clusters may get lost. Some are only 3 arcminutes across!

I'm going drop use of the L filter and use only short exposure RGB frames, perhaps 12x60s per channel for a start with dithering every 4th frame or so. I hope that keeps the brighter stars from saturating and still gives me enough sensitivity to harvest the dimmer stars.

The other thing I'd like to become proficient at is setting up NINA for multi-target sessions. Last year I fumbled around quite a bit with unnecessary slewing, centering, and autofocusing. 

And if by some miracle there's more than one clear night I'll finally test my ability to do solar power recharging in the field.

-------------------

The winter watch hobby is not shutting down entirely as the weather warms. I did attend a watch-enthusiast's show and swap meet, but it was a bit of a disappointment. About 4/5 of the tables were dedicated to modern (new) wristwatches and their collectors. That's not really my area of interest, so it was a short visit. I'll have to search somewhere else for inspiration.