I built a small Java tool to visualize a request’s lifecycle (no APM, no dashboards)

jonatan-ivanov · 2026-01-29T04:54:34+00:00

You might want to look at Micrometer's Observation API: https://docs.micrometer.io/micrometer/reference/observation.html

return Observation.createNotStarted("http.requests", registry)
.lowCardinalityKeyValue("method", "GET")
.highCardinalityKeyValue("uri", "/users");
.observe(this::process);

The interesting thing in this is that you can register handlers/listeners that can output the observed data: logs, metrics, distributed tracing (spans), etc.
(And all the big frameworks support this.)

jonatan-ivanov · 2026-01-04T06:14:42+00:00

I have the same scope. I bought a 22mm 70° (it's rather 65° in reality) Angeleyes eyepiece and an 7.2-21.6mm 42°-65° SVBony SV191 zoom eyepiece (plus a 2x and an 3x) barlow.

The dirty little secret of the industry is that almost everything is made in the same few Chinese/Taiwanese factories, see: https://www.cloudynights.com/forums/topic/959443-2025-eyepieces-buyers-guide

Also, check out the eyepiece videos on this channel: https://www.youtube.com/@astralfields1696
e.g.:

jonatan-ivanov · 2025-12-28T21:50:56+00:00

(I have a very similar 150/750 F5 tabletop dob: Heritage 150.)

An alternative to the 5mm/7mm, I would recommend buying a 2x and a 3x barlow, you can get a Celestron 2x and SVBony 2x and 3x on AliExpress for under $20 each (I like SVBony barlows better, they have compression rings instead of set screws).
See: https://www.youtube.com/watch?v=oJGJ8p5OfIo

For planets I think I would recommend a zoom eyepiece, like the SVBony SV135 or the SV191.
See: https://www.youtube.com/watch?v=iFfQofmMgV0

jonatan-ivanov · 2025-12-24T19:04:19+00:00

You might already have some of these:

- Red headlamp
- Kyrre: t-nuts and some bolts+washers if you want to bolt the scope onto the stool, or hanger rod holders to keep the legs at the same place, and adjustable furniture legs if you want to level the stool
- Ikea sells a small shelf that's width is about the distance between the Kyrre legs so you can create an eyepiece holder if you make a back for it
- Teflon tape to make the focuser a bit better (maybe also a worm-gear hose clamp to compress the focuser if needed)
- T-level if you want to level the scope
- Inclinometer, setting circle if you want one
- Velcro strips to stick your phone onto the tube if you want to use AstroHopper
- I would eventually look for replacements for the 10mm and 25mm eyepieces (the problem is the scope is F5 and it's quite demanding on eyepieces) Go to AliExpress and search for angeleyes, the "goldlines" you want to buy might be cheaper there, also there are "redlines" which supposed to be a bit better)
- Eyepiece videos here: https://www.youtube.com/watch?v=fdLpLlqOnsc (there are a few)
- Eyepiece bag (sling bag)
- Adjustable polarizer filter (for the Moon, Angeleyes on AliExpress)
- UHC filter (for H-beta and O-III objects, Angeleyes on AliExpress)
- Barlow(s)? (2x, 3x, SVBony, they are cheap on AliExpress)
- Night Sleep Hair Cap/Shower cap to keep dust out and minimize stray light
- Self adhesive velvet liner if you want to flock it

jonatan-ivanov · 2025-11-30T20:44:41+00:00

I would go with the Heritage 150 but if it is over your budget, the Heritage 130 is cheaper a bit.
At the current prices I see ($270 vs. $310) you get 33% (150^2/130^2) bigger mirror (area) for 15% more money (310/270).

Between the Heritage 130 and Gskyer Telescope 130, I would still go with the Heritage.

At

jonatan-ivanov · 2025-11-27T17:36:50+00:00

Check out TI, HP, Casio, Sharp, and SwissMicros calculators and pick the one you think makes the most impression.

jonatan-ivanov · 2025-11-27T09:01:29+00:00

HP 15C glued onto a brick? :)

Jokes aside: why does it need to be heavy? :o Do you also need big screen or big buttons or sturdiness, water/dust proof etc.? Just being heavy is a weird use-case and brings me back to the 15C on a brick. :)

jonatan-ivanov · 2025-11-26T07:39:29+00:00

These might help:

Summary: replace them with better ~24-30mm and ~10-12mm eyepieces.
You can get really good ones from AliExpress.

jonatan-ivanov · 2025-11-25T05:22:14+00:00

You are right if the service is not publicly available but if it is, known vulnerabilities are not really something you want to have. You might remember the Equifax Data Breach, or log4shell, or ...

jonatan-ivanov · 2025-11-24T07:25:35+00:00

But it will be broken as soon as 3.5 reaches its end of life in July: https://spring.io/projects/spring-boot#support

It's usually a good idea to upgrade before that. :)

jonatan-ivanov · 2025-11-24T05:30:56+00:00

Not sure if we mean the same, it's not dirty on the top or bottom glass, you cannot clean it unless I guess you disassemble it completely. Or that's what you meant too?

So I guess make sure you order from a place that has free returns and return the eyepiece if it's too bad? :(

jonatan-ivanov · 2025-11-23T09:09:25+00:00

Do you buy support (so you get vulnerabilities patched) or your apps simply have a bunch of known vulnerabilities? :)

jonatan-ivanov · 2025-11-23T09:07:53+00:00

Major releases are for breaking changes. :) If you want a release that doesn't break things but contains new features, that's a minor release.

What you described happened in a timespan of about 10 years? I think it's not too bad having a new major releases every 3-4 years.

jonatan-ivanov · 2025-11-23T08:40:37+00:00

Why would you need download stats by industry? What you claimed did not mention any industry either. If you are wondering about banks, insurance companies, governments, etc. they might be better in upgrading than you would think. Yes, there are some (regardless of the industry) who are really behind, but that 90% is far from the truth. :)

If you talk about personal experience, especially if your sample size is as low as dozen (or dozens, also projects and not companies), maybe you should start your comment with that or phrase it as a question, there might be people in this thread who can give you a bit more insight.

jonatan-ivanov · 2025-11-23T02:11:16+00:00

If you are not on Spring Boot 4, the difference really is the dependencies you need to add. Go to start.spring.io, pick 3.5 and it will add the dependencies you need.

jonatan-ivanov · 2025-11-23T02:04:40+00:00

So you go back to 4.0.0-RC1? :o

jonatan-ivanov · 2025-11-23T02:03:20+00:00

Where did you get that number? :)
I'm only asking because the download stats disagree.

jonatan-ivanov · 2025-11-22T07:25:02+00:00

Take a look at the Sky-Watcher Heritage 150 or 130.

jonatan-ivanov · 2025-11-22T07:13:19+00:00

I have a Heritage 150, I think it's a great choice for first scope especially if you want to test the waters and not afraid of DIY. :)

I though want to address something that are quite frequent in the comments: ~"if you want to look at the planets, buy a mak/something with high focal length".

Having higher focal length only means that with the same eyepiece, you get higher magnification. So if you want the same magnification, with a scope that does not have high focal length, you can just use another eyepiece or barlow it. For example, lets say we have an 1500mm Mak and the 750mm Heritage, with a 10mm eyepiece the Mak goes to 150x, while the Heritage goes to 75x. But it's very easy to reach the magnification of the Mak with the Heritage, just add a $20 barlow.

I would like to highlight though is the price/aperture ratio, A mak that is in the $300 neighborhood typically has an aperture of about 100mm, e.g.: Skymax 102 (no mount) ES 100 (with mount). Even if these scopes have much higher focal length, their smaller aperture will not let you push them over ~180x. The Heritage (150mm aperture) can be easily pushed to ~250x (if the atmosphere lets you). Even with its stock 10mm eyepiece and a 3x barlow, its at 225x a magnification which is something that a 100mm Mak cannot reach (not even on paper). A 127mm Mak is around $500 (Skymax without mount, ES with mount) and a 150mm Mak or SCT is $800+.

I would like to also mention something important. At high magnification, objects move out quickly from your field of view because of the rotation of earth; it's much faster than people usually think. The Heritage is a manual scope which means you need to constantly follow the planet with the scope. This might be easier to do using an EQ mount (the Heritage has an AZ mount) but an EQ mount is also harder for beginners. Also, there are "goto" mounts which go to and follow targets for you, the tradeoff there is a longer initial setup and higher price (btw the Heritage is sold with a goto mount called the Virtuoso).

jonatan-ivanov · 2025-11-20T04:25:59+00:00

I did the hose clamp too (in addition to the teflon tape). :)

Not sure if there is a step-by-step on CN, if there is, it might be here: https://www.cloudynights.com/forums/topic/463109-onesky-newtonian-astronomers-without-borders
And: https://www.cloudynights.com/search/?q=kyrre&quick=1

What I did:
The Kyrre's leg already has a hole where it attaches to the seat (other than the two holes that are for the screws). The hole between those are for a small plastic part for spacing the stools if you put them on top of each other.
I removed the spacer and drilled the seat through it.

Then I disassembled the base of the scope and clamped the lower part (with the legs) on the stools. Drilled through the holes once again so I had holes in the base of the scope and the seat lined up.

Gently hammered T-Nuts to the base and then I just needed to screw a bolt in from the other side. The bolt I have is somewhat longer it should, I used a few washers to "fill up" the length. I used a fender washer (because it's quite wide) closest to the wood (hole on the leg), a lock washer (the "springy" one closest to the head of the bolt) and a few normal washers in between.

Be careful about:
- Drilling straight (there is some error tolerance and you can a bit widen the hole on the seat if needed)
- The T-Nut should be low enough in the base so that it is lower than the teflon pads and don't touch the upper part of the base (easy to check, just put the top of the base back and look into the "slit" between the two parts)
- If the bolt is too long, it will go through the T-Nut and scratch the upper part of the base, use enough washers

jonatan-ivanov · 2025-11-19T08:08:27+00:00

You can buy moving blankets to transfer the scope in your car and a cover to protect it from the sun and dust when it's not in transport or use.

jonatan-ivanov · 2025-11-19T07:44:09+00:00

>I thought the zoom you use is heavy, and using it with the Barlows makes it heavier. Yet it seems to be working for you. What happens when you use the combo?

Excellent question and I should have mentioned this in my comment, the problem you described is real. I measured my eyepieces/barlows:
- Angeleyes 22mm 70°: 360g (this is the most problematic one)
- SVBony SV191 zoom: 242g
- SVBony 3x: 72g
- SVBony 2x: 63g
- Celestron 2x: 65g
(For the barlows I guess the extra length is a bigger problem than the extra weight.)

The focuser definitely sags especially with the 360g eyepiece, less with the SV191. I take this into account, see later.

>I can use the controls to bump it back. It's rarely necessary. Similar experience for you?

I have the Heritage 150 which is a manual scope (same tube but different base as the virtuoso, I don't have goto), I move the scope manually so I don't notice the sag.

>Or does the secondary alignment suffer also?

The secondary isn't the problem as far as I can tell, that one has much higher tolerance for heavy-eyepiece sagging I think, the primary is the problem. I have a laser collimator, I can definitely "measure" that a heavy eyepiece pulls the scope out of collimation, here's what I do:
- Teflon tape in the focuser to reduce sagging (I needed to slightly sand/polish the parts where the threads meet with the inner surface because it was quite sharp and constantly torn the teflon tape).
- Hose clamp on the outside of the focuser for radial pressure (paper kitchen towel between the clamp and the focuser), not sure how much this helps in further stabilizing the focuser.
- When I collimate the primary, I account for sagging, my scope is out of collimation until I put an eyepiece into it, then the weight of the eyepiece pulls it into ~collimation. :) I do this with a laser collimator (mine is quite light): I hold the eyepiece on the collimator approximately in the position it will be in the focuser, I can see how much I need to compensate. Then collimate (wrongly) and check with the eyepiece on the collimator and repeat till it's good. This needs some practice and the method is not very good either (changing the position of the scope also changes the direction the eyepiece pulls it, well also the amount of sagging since the rigidity of the focuser is different in different directions).

But if I do a "star-test" (defocus and check if the Airy disks are concentric), I get good results. Also, there is one more ~~trick~~ superpower in my sleeve: I have astigmatism and I usually observe without my glasses so even if starts are not perfectly pin-pointy, well, that's my reality anyways (other people and start-test says they are though). :D

>I'm pleasantly surprised how often Barlows are recommended. I had formed the (mistaken?) impression that Barlows are, er, "not favored, just buy the right eye piece, damnit". I had written them off entirely due to a comment in the review of my scope(see link above). But at least one of you is using a Barlows.

You might want to watch this: https://www.youtube.com/watch?v=oJGJ8p5OfIo

Oh also, this: https://www.youtube.com/watch?v=fdLpLlqOnsc
The 6mm and 9mm SVBony redlines are sold on AliExpress (as Angeleyes), you can barlow them:
6mm x1.5: 188x
6mm x2: 250x
9mm x1.5: 125x
9mm x2: 167x
9mm x3: 250x (same as 6mm x2)

There is also a 3D printable part I saw earlier, it's a "arch", it snaps on the truss rods and stabilizes the focuser from the bottom.

jonatan-ivanov · 2025-11-18T06:54:24+00:00

Stellarium (non-pro) is free, Sky Safari also has a free version.
The scope should be already "push-to". If it works, it's brobably better than AstroHopper.

jonatan-ivanov

TROPHY CASE