Zakalwe

Here's another one for the newer GSO focusers:

http://polluxchung.com/gso_crayford_fix/

25 minutes ago, badgerchap said:

Hi all,

 

Not sure if this is the right category for this question really, but then it doesn't necessarily fit anywhere I don't think. Anyway...

I have a TS Optics 6" F4 Newtonian which optically is great but its (2") focuser is absolutely woeful. It was bad when I got it, now it's almost unusable. It can be made firm, but whether it can be made firm at the focal plane accurately enough for imaging is debatable. Adjusting the focus for imaging is essentially impossible excluding luck.

I don't really have the cash to fork out for a decent focuser - at least not after forking out for my new C8 and building an Obsy. I am wondering, however, if I could use a helical focuser (such as that linked at the bottom of this post) attached to my current focuser? I'd fix the current focuser roughly in place and then use the helical for fine adjustment.

I'm worried a) about reaching focus, b) misunderstanding the purpose of helical focusers (which I've never used).

Any help would be appreciated, including alternative ideas! Thanks,

 

Guy

 

https://www.rothervalleyoptics.co.uk/baader-125-helical-focusing-eyepiece-holder-t2.html

Have you "tweaked" the current one? Astronomy Shed has guides on how to improve a standard focuser.

They usually can be improved to a fair degree with some gentle tweaking.

USB3 is very sensitive to cable quality and length. I have the same camera and it would work on a 4 metre USB 3 cable. I know use the shortest cable possible from the camera to a powered quality USB 3 hub. I have nothing else plugged into that hub.

I wouldn't use an unpowered hub with this at all. Try changing the cables too, the quality really does vary.

Download the latest version of DSS:  http://deepskystacker.free.fr/english/index.html

Go to Settings:RAW/FITS DDP Settings

Go to the FITS section. Tick the tab as below. Then select the correct camera type or the correct Bayer matrix in the drop down.

Your camera is supported (as listed on the LIBRaw page: https://www.libraw.org/supported-cameras )

There's a good tutorial here: https://astrobackyard.com/deep-sky-stacker-settings/

Make sure that you are using the correct version of DSS to suit the camera.

An image taken with a camera phone will always be over-exposed as the imaging system in the camera will be using the whole frame (or a large part of it) to set the exposure level. As most of the image will be black the camera will set an exposure based on that, which naturally overexposes the small percentage of the image that contains Jupiter. The same will happen with a DSLR unless you change the settings to use spot metering. You are telling the camera to set the exposure only on a small area (normally one of the auto-focus points) and ignore the rest of the frame.

https://imaging.nikon.com/lineup/dslr/basics/18/01.htm

L12_07_20 Lunt DS Full Disc Normal Proms Inverted Disc Mono by Stephen Jennette, on Flickr

12_07_20 Lunt DS Full Disc Inverted Proms Normal Disc Pseudo Colour by Stephen Jennette, on Flickr

12_07_20 Lunt DS Full Disc Inverted Proms Normal Disc Mono by Stephen Jennette, on Flickr

L12_07_20 Lunt DS Full Disc Normal Proms Inverted Disc Pseudo Colour by Stephen Jennette, on Flickr

All on Lunt L60DS and ASI178 camera

Thanks for looking.

22 minutes ago, RayD said:

Satellite trails?........... Where? 😉

You won't see them........ they're above  the wall-to-wall couds🙄

On 01/07/2020 at 18:03, PhotoGav said:

Fascinating discussion folks, thank you for contributing. It's very interesting to see that we are not all of the same opinion.

Anyway, here is a quick data update. I haven't gathered the whole set yet, but thought it would be interesting to see how the rejection gets on with those trails. So, with minimal processing beyond calibrating, stacking and combining the LRGB data sets in APP...

Here it is with no rejection:

 

 

 

And here it is with sigma rejection:

 

 

There is hope after all (as expected!)...

 

(This does not mean I now condone the satellite mega-constellations!)

 

Clear sat-free skies to you all

That's a great result and a damn fine image.

Looks like the outrage bus won't be as full as we first thought.

In other news, tonight's launch of the next batch of Starlink will be testing visorsto shield the antennae from the Sun. https://arstechnica.com/science/2020/07/spacex-will-try-to-launch-starlink-satellites-with-visors-on-tuesday/

5 hours ago, cuivenion said:

It's 2020, where's my moonbase?

Get in the queue...I'm still waiting for delivery of Eagle from 1999....

😄

3 hours ago, Philip R said:

Apologies in advance if this appears political.

The FCC; (i.e. Federal Communication Commission; a.k.a. 'Funny Candy Company'); is the US communications regulator of communications via TV, radio, internet, etc. It does the same as OFCOM here in GB/UK. Other countries have their own communications regulators.

Both FCC and OFCOM; (and those of other countries); issue and decline the licences to the operators.

Maybe 'we' should be lobbying the FCC. If the GB/UK is planning to start launching its own satellite network service; then perhaps 'we' should start lobbying OFCOM too.

AFAIK, OneWeb has already received permission from the ITU and authority from OFCOM to use the necessary frequencies, so you've missed that boat.

I wouldn't worry about it though, the chances of the UK actually completing on this, modifying the Sat's to carry military grade GPS kit, get the Sat's into an orbit way, way, way higher than they are designed for and for them to be able to broadcast to the ground is somewhere between none and infinitesimally small. It's another pile of taxpayers money gone up in smoke to salesmen smart enough to fool a government minister (a low bar, I know). It'll be like the millions wasted on an app that didn't work, the ferry company with no ferries and the millions paid to ferry companies that have ferries when the gov cancelled the contract.

No more on that though... straying close to political waters.

25 minutes ago, PhotoGav said:

Very true. That is why I suggest to people who only see them in the first 'marching' phase and are amazed by them, thinking 'how cool', that once they are less conspicuous to the naked eye, they are still very much an issue for astronomers. That's all.

Wouldn't it be ironic if it were the Starlink satellites themselves that ended up defending the Earth from an incoming hazardous object as the shield they form around the Earth broke up the offending rock as it hit them!!

That'd be like expecting the impact of a fly on your windscreen to significantly slow your car down at motorway speeds 😆

1 hour ago, cuivenion said:

I don't see how I can be missing the point when I've been directly quoting you. You say you're fine with amateur astronomy being impacted to achieve SpaceX's goals, but what about professional scientific observations? They will arguably be much more effected expecially near earth asteroid hunters, who from my understanding observe nearer to twilight than the rest of us. This is a point you've consistantly refused to answer.

 

Its hardly fair to accuse me of "consistently" refusing to answer that point when it's the first time that anyone has mentioned observing near to twilight.
I'm not "fine" with amateur astronomy being impacted, but if that's the price we pay to make mankind interplanetary then it's a price that I'm willing to pay. Does that help with your understanding?

Regarding the professional bodies, I am hopeful that they trash a solution out. As I said earlier, these mega-constellations are not going away and we are only at the start of them. Does a solution exist now? It doesn't appear so. Will a solution exist in the near future? I am hopeful...after all SpaceX have consistently said that they want to minimize the impact and appear to be the only company holding regular talks with the scientific community,

1 hour ago, cuivenion said:

I would argue it's more important to see the random piece of rock coming in the first place which Starlink in it's current form will make a lot more difficult.

It's a fair point, hence why it's important that a solution be found.

1 hour ago, cuivenion said:

Significant Mars colonies are still pie in the sky at this point and despite what you're saying I don't see any reason why they can't fund it without Starlink. Also I don't think Amazon and others will have such lofty goals.

It's only impossible until someone comes along and does it. Ten years ago respected people in NASA were openly scornful of Musk's idea to make orbital-class boosters reusable. That was supposed to be pie in the sky too. Here we are less than 20 years after SpaceX's inception and they are the biggest launcher on the planet and the cheapest, specifically because they did the impossible possible and made an orbital class booster land after flight. I doubt that I will see "significant Mars colonies" in my lifetime, but I would wager a large sum that I will see SpaceX landing rockets there.  The 7th iteration of the Superheavy test vehicle has been stacked and the 6th is heading to the pad for testing. They are building one booster per month at the moment and I would think that we will see a sub-orbital flight within 12 months. Personally I think that it'd be a brave man to bet against Musk on this.

Regarding funding, Gwynne Shotwell would disagree with you. I'd be more inclined to accept her position in relation to this.

No, Amazon aren't aiming for Mars. One of Bezos' professors in Uni was Gerard O'Neill and he clearly influenced Bezos's thinking. He (Bezos)  outlined his vision in 2019 for having a trillion humans living in orbiting O'Neill cylinders. Blue Origin's progress is very slow though....it's not much younger than SpaceX and it has yet to reach orbit with any craft. Having said that, the methane burning BE-3 is developing well. This will be used to power their New Glenn rocket which will also be reusable and land on a drone ship a-la SpaceX.

Regarding their mega-constellation, they have plans for nearly 600 sats, with launches dependant on the development of the New Glenn booster. Their sats have a longer lifetime than Starlink with their orbits naturally decaying in 10 years.  https://spacenews.com/amazon-lays-out-constellation-service-goals-deployment-and-deorbit-plans-to-fcc/

1 hour ago, cuivenion said:

Regarding the reflectivity of the darksat they achieved a magnitude reduction of 55%, which sounds great until you realise it still leaves a big white streak through a photographic image.

Pretty good for a first stab at it then. I did mention this earlier in the thread that the blackening reduced the visibility, but not to zero. The albedo reduction also caused significant overheating of the sats.

1 hour ago, PhotoGav said:

The negative impact of the Starlink satellite constellation and other similar large satellite systems is far from 'fake news'. Have a look at any current professional astronomical discussion of the subject, especially the impact this is having / will have on wide field survey projects (e.g. the Vera Rubin Observatory). They are having to try and find work arounds, but there is no guarantee that these will be found or will be effective.

I My apologies, I wasn't trying to infer that all negative reporting on Starlink was "fake news". my point is that on a science-based board dedicated to a science-based hobby there is plenty. Just re-read this thread and see how many people are happy to spout sound-bites without making any attempt to fact-check first.

1 hour ago, PhotoGav said:

 The least that SpaceX can do is enter into a discussion. Thankfully, we astrophotographers have sigma rejection algorithms to help tidy up our pretty pictures.

I will keep watching this developing story with great interest. I will also keep telling people that the 'amazing lines of satellite clones marching across the night sky' are not amazing at all...!

Currently SpaceX is the ONLY developer of mega-constellations that is in active discussions with astronomers (as far as I am aware).

Worth remembering too that the 'amazing lines of satellite clones marching across the night sky' are only visible in the initial days after launch. The sats soon move themslves into different orbital altitudes and planes as they boost themselves into their final orbits.

1 hour ago, Hallingskies said:

And for what?  “Better” internet access?  Some folk may be happy with that, and think it is “progress”. 

I’m not, and I don’t.   

Do a search on here for slow broadband access and gauge their comments. Especially those that now are working from home.

2 hours ago, inFINNity Deck said:

Hi Stephen,

when using a tilt adjuster, what process do you use to adjust them? I understand that in static images the NRs are hard to see, so what is the easiest and best way (presumably these result in two answers)? I noticed that my last animation also show faint NRs, so could do with improvement, although an artificial flat would do.

Nicolàs

 

It's just trial and error, to be honest. One thing that I do is to put the axis of tilt along the long axis of the sensor. This keeps the difference in focal plane across the chip to the minimum.

2 hours ago, inFINNity Deck said:

PS: Inspired by our last conversation, I created a second solar imaging tutorial on a Dutch forum, of course referring to you (should translate nicely in Chrome).

Cool!  I'll have a look later.

Starlink will provide, certainly at first, the US with Internet access.

Gravity is a Hollywood film, and a pretty terrible one at that. It's depiction of how orbital mechanics operate was tenuous at best.

Cuivenon seems determined to miss my point. I'm not particularly in favour of Starlink and certainly if there was another way to achieve SpaceX's goals then I'd be in favour of it. However, on the balance, I'm happy to trade a small part of amateur astronomy to achieve those goals. I do think that the impact won't be as bad as some of the hand-wringers make out.

What I am absolutely against is the spread of disinformation and, dare I say it, fake news. This is primarily a science-based hobby discussed on a science-based board. If we can't get simple facts about orbits, reflectivity, and maths correct then the general public has no chance. Parroting nonsense about objects  in very low Earth orbits lasting for decades, or making it impossible to transverse  LEO, especially when those things can be checked in seconds doesn't bode well. We are better than that, people.

anyhoo, an interesting debate.

12 minutes ago, Philip R said:

More satellites [maybe] coming to the skies near you. This was released on BBC news earlier today...
https://www.bbc.co.uk/news/uk-politics-53192842

We can kiss that money goodbye....

1 hour ago, Paul M said:

 

Only because they were oblivious to the issue now at hand and have become worried that the following wind they are presently favourd by becoming a headwind.

It's research that should have been done in the planning stage.

It's up there for a long time, long after the technology has been abandoned (a couple of decades?) so I don't share your confidence!

Well, this IS the planning stage.

Regarding the second point, a bit of basic research wouldn't do any harm. The sats are in very low Earth orbit, so their orbits will decay quickly. Even if a sat dies and cannot use it's thruster then it will take about a year to de-orbit..

1 hour ago, MarkAR said:

Just out of interest, anyone know what the carbon footprint of each of Musks launches are ?

If he's launching strings of 16 satellites at a time its going to be 2625 launches to get his proposed 42000 lumps into space.

The first stage burns about 440 tonnes of RP1 (refined jet fuel). In comparison, a Jumbo jet burns about 10 tones per hour in cruise. In the great scheme of things the impact of launches is negligible. Everyday Astronaut did an excellent article a few months ago on this very subject.
When SuperHeavy flies it will burn methane and LOX in comparison to the Falcon9's RP1/LOX combination. The main reason is methane can be readily made in-situ on Mars using the Sebatier process by extracting CO2 from the atmosphere and combining it with hydrogen extracted from water electrolysis.

By the way, it's 60 sats per Falcon9 launch, not 16. And once SuperHeavy and Starship are operational it will be 200 sats per launch.

If environmental concerns are a big concern of yours (and rightly so, I might add), then you should really be a big fan of Musk. After all, no-one has done as much in the last decade to take fossil fuels out of transportation, via Tesla. One of his other companies, Solar City, are also doing great work in PV installations and development.

56 minutes ago, cuivenion said:

So there is an impact that SpaceX are trying to mitigate? It's a bit strange that you've made light of issues that SpaceX themselves are trying to fix. I'd heard of earlier attempts to reduce the sats brightness that hadn't made a significant difference. The deployable visor sounds hopeful and shows that at least SpaceX are listening which is good.

The rest of the post reads as, if you don't like it, tough. I've never been a fan of that argument.

Regarding your first point, I do wish you'd read what I said. I never made light of the impact.

Regarding the second point, some of the impact was known pre-launch (that's why the sats do not transmit on the frequencies used in radio astronomy. The deployable visor is one of three different mitigation strategies that are being currently tested, but this list is not exhaustive. The blackening paint made a significant reduction in brightness (though not enough to render the sat invisible). It had a knock-on impact in that it caused the sats to overheat, however. A third technique, where the sats re-orient themselves to prevent reflecting light onto the ground is also in testing.

Lastly, to address your third point "if you don't like it, tough." Again. please re-read what I have said and not what you think I said. Starlink, and other mega-constellations, are an unfortunate fact of life. The FCC have issued the necessary licences to SpaceX (and also to LeoSat, Kepler and Telesat). They do not need to ask for anyone else's permission. Now, rather than pearl-clutching and venting, we have to work with these companies to mitigate their impacts.  Jim Lowenthal,  along with a working group from the AAS, for example meet once a month with SpaceX to discuss our, as astronomers, concerns about Starlink. It's also interesting to note that SpaceX is the only company that is meeting like this with concerned professional astronomers. Talking and agreeing a plan is the way forward, not ranting about shooting sats out of the sky.

Anyhoo, must dash. The outrage bus is due at my stop any moment now. 😆

35 minutes ago, Paul M said:

 

I can't help thinking that with an increasingly high density of orbital junk to track, LEO is getting almost too dangerous for manned passage.

Not  in the least.

1 hour ago, cuivenion said:

Zakalwe you seem to be trying to make out this is just about a few complainers in bobble hats in their backyard, starlink is going to effect (ironically) near earth asteroid detection as well as other scientific endeavours.

No I'm not.  I'm well aware of the concerns. I'm also well aware that these sats are easiest to spot in precisely the conditions that we have in Summertime.  They are also easiest to spot in the days and weeks after launch when they are in their initial orbits. Once they move up to their operational orbits they are far less visible.

SpaceX are also experimenting with a number of mitigation techniques. The next launch (tonight) ill carry sats with deployable  visors to prevent sunlight from reflecting off them.

No matter where you stand on these mega constellations there is one incontestable fact and that is they are here to stay and they will grow in size. Amazon are planning a similar mega constellation. Heck, even the British government are toying with pumping £millions into buying the failed One Web company now that they've realised that we don't have the cash or wherewithal to build a UK GPS alternative (though I'll not comment on this latest B word fiasco as it's against the rules).

As these constellations are here to stay we and the professionals had better get used to them, as well as working with the owners. SpaceX are listening and as a direct result of feedback from the AAS they have introduced experiments to mitigate the impact (as above).

50 minutes ago, PhotoGav said:

That's an interesting angle on this.

Just to broaden the discussion - do you think that Man is going to be able to 'planet hop' within our solar system successfully and on a 'beyond a tourist visa' basis? The next star system is unknown and too far away for quite some time to come yet, I would imagine. Is Mars really the answer for Homo Sapiens? Bearing in mind that Mars is just as likely to be struck by some random piece of rock. In fact, I would imagine that it is actually far more likely to be struck by rocks, given its lack of atmosphere and proximity to the asteroid belt. I can see that it doubles the chance of survival, given that if one goes we have a back-up to rely on.

This is such a fascinating area of astronomy / space travel / ethics / philosophy / technology!

I think that it's only a matter of time. We are an exploring species, so it's in our make-up. Mars has loads of challenges, but ultimately there's nothing in physics to stop us, so the problems (and they are big problems) are ultimately engineering problems. We can overcome these. It was less than a century and a half ago that people thought that inhabiting the west coast of America was nigh on impossible. The journey was impossibly long, dangerous, expensive and a one-way ticket. Yet people did it.

Part of me wants them to go to the Moon again, but then again, the Delta V needed to go to Mars is not much greater than that needed to go the Mars.

13 hours ago, PhotoGav said:

The motivation is profit.

Strictly speaking, the motivation is to provide funding to make Man an interplanetary species, just in case a lump of rock from the sky wipes us out. Our species is unique and leaving it on one planet to the vagaries of some random piece of rock is too risky.

I'm comfortable with some home astronomers having their hobbies affected if that's the price.

3 hours ago, tomato said:

That’s an aeroplane though, not Starlink? Some of the trails look quite diffuse and there is a lot of variation in brightness.

I agree, it would be very special software that could fix that one.

Yep, definitely a 'plane...you can see the belly nav lights in the trail.

Right, I'm off to throw rocks at my nearest airport....

25_6_20- Full Disc Pseudo Colour by Stephen Jennette, on Flickr

25_6_20- Full Disc Pseudo Mono by Stephen Jennette, on Flickr

25_6_20 Inverted Disc Normal Proms Mno by Stephen Jennette, on Flickr

Lunt L60 DS and ASI178

25_6_20 Large Prom, Inv disc Mono by Stephen Jennette, on Flickr

25_6_20 Large Prom, Inv disc Pseudo Colour by Stephen Jennette, on Flickr

Quark on Esprit 120 and ASI174

Thanks for looking.

14 hours ago, PhotoGav said:

I’ve just gathered tonight’s first 1200s Luminance sub of the Iris Nebula and this is what I am up against... 

It’s as though that Musk person knows exactly how to wind me up.

 

 

Two things:

Sigma rejection in stacking will almost certainly remove the trails.

You are imaging when there is no true darkness. Satellite trails will be at their brightest when the Sun is just below the horizon which is exactly where it is in the summer months. You might as well complain about there being no true darkness and damn whoever put the Sun in the sky. Complaining about that wouldn't be as fashionable though.