JamesF

Perhaps this might particularly appeal to @ollypenrice given his past profession though possibly he already knows.  I have to confess my complete ignorance...

My wife has been binge-watching some of the "Who do you think you are?" series recently and as we have no children at home tonight she insisted that we watch one programme whilst eating dinner (last of the great romantics, she is ).  In this case the subject of the programme was Judi Dench.  Whilst she may perhaps be best known by some for her film work, she and her husband apparently nicknamed Shakespeare as "the man who pays the rent".

She claimed at the start of the programme that she knew absolutely nothing of her Irish mother's family history, so obviously they were going to do some digging there.  It turned out that a nine times great grandfather on her mother's side, a member of the Danish aristocracy, had a sister Beata who married a chap called Otto Brahe.  In time they had a son called Tycho.  Yes, that Tycho.  Beata was apparently a senior member of the Danish court and spent some years serving the Queen at the castle in Helsingør, or in its Anglicised form, Elsinore, where Hamlet is set (also the first major play in which Judi Dench starred).

Apparently there's an engraving of Tycho Brahe from the mid-1800s showing the coats of arms of his relatives which include the families Guldesteren and Rosenkrans.  Rosencrantz and Guildenstern also appear in Hamlet.  The engraving also bears Brahe's motto, "Non haberi sed esse".  I'm not sure I follow the translation used in the programme, but they claimed it means "Not what appears (to be), but what is" and that a very similar line is also used in Hamlet.  I don't know the play well enough to comment on that one, but it strikes me as a particularly appropriate motto for Brahe.

Who knows whether Shakespeare knew of Brahe or his work, but it's a nice idea that he might have provided some little inspiration for the play.

James

In that case I'd suggest trying #10-24 UNC bolts.  They're available on ebay for a pound or three in small pack sizes, so if it isn't the right size you shouldn't have wasted too much cash.

James

And if you're interested, the source code repository appears to be here:

https://github.com/celstark/OpenNebulosity

James

A hunt around on the net suggests that 3/16" BSW is interchangeable with #10-24 UNC and if the same diameters of UNC and BSW are also supposed to be interchangeable then some #10-24 UNC bolts should do the job I think.

Could be worth waiting to see if @inFINNity Deck can confirm the sizing though.

James

To the best of my knowledge UNC threads are specified by diameter and the number of threads per inch meaning that 3/8-16 would be a 3/8" diameter thread with 16 threads per inch, but I'm fairly sure that all threads of the same diameter have the same number of threads per inch so just giving the diameter (3/16" in this case) should be sufficient to get the correct thread.

That said, I thought all UNC threads smaller  than 1/4" diameter were given numbers and tpi rather than sizes, so I'm not sure what 3/16" might actually be if you wanted to buy some.  It might be #10-24, but don't quote me on that.

A 3/16" BSW thread should also fit, I think.  BSW and UNC threads are mostly interchangeable.

I hate non-metric threads

James

1 minute ago, Swoop1 said:

Are dome bases supposed to have corners?

You need at least one, so you can tell people who can't keep their hands to themselves to go and stand in it.

James

Our posts crossed, but vlaiv appears to have confirmed what I posted, explaining it better in the process

James

The mechanical performance of the mount will obviously impose some sort of limit -- the better it tracks or can be guided, the longer exposure is possible.  My understanding is that there's also a "signal processing" type of limit as well, beyond which increasing the exposure time really doesn't usefully get you any more data.  From memory (ie, I could well be wrong ) it's the point at which the background noise from the sky swamps the read noise from the sensor.

Robin Glover (of SharpCap fame) made a very informative presentation a couple of years back that you may find helpful.  I've not used SharpCap for years, but I think there's support for doing some of the necessary calculations built into the software.  The presentation is here, amongst other places:

James

Good idea.  It's expensive enough as it is getting started in imaging.  Being able to save a bit of cash when starting out by using GIMP instead of the paid-for alternatives has got to be helpful.

James

2 minutes ago, CCD-Freak said:

I would like to thank whoever it was who thought this up.

@Peter Drew as far as I'm aware.

It being Texas however, I was expecting something much bigger

James

2 hours ago, Astro Noodles said:

I still have to get her something. We have a tradition that we get something to read, something to wear, something to eat, and something to do. I have decided on a cheese theme this year for Lesley's presents.

So it will be some cheese, a book about cheese, a t-shirt with a cheese related logo or slogan and something to do. Maybe a fondue or some of those little prongs for eating cheese with.

Much as I don't really enjoy Christmas (partly because I tell people that and they look at me like I have two heads, which I can live with, but the other head apparently feels self-conscious about it), I think this is a fun idea.

James

5 minutes ago, saac said:

I wonder if what we are really missing is perhaps what many of us (in UK at least) grew up with.  Where is the weekly programming of science and  technology,?  Come on BBC a return to the days of Tomorrows World  or decent Panorama /Horizon  documentaries.   I'd hazard a guess that these were the programmes that influenced many to follow into science and engineering.   As much as I love watching the "Repair Shop"  that doesn't really cut it . 

Also series such as James Burke's "Connections".  Barring the occasional unfortunate excesses of 1970's fashion I reckon those programmes could be broadcast pretty much verbatim today and still be really engaging.  I really should try to get hold of a copy of "The Day the Universe Changed", too.

James

37 minutes ago, saac said:

I'd say his contribution is also several orders of magnitude greater than many of those big buck presenters, but then I'm biased.

Yeah, that Barry Lineker is well overpaid, I reckon.

James

26 minutes ago, Louis D said:

Apple, pear, and grape juices often contain trace amounts of arsenic, and I've yet to see a P65 warning on them.

Quite possibly cyanide too unless they manage to pulp and press the fruit without damaging any of the seeds.

James

21 minutes ago, mikeDnight said:

Going back to the 1980's there was concern over carrot skins being radioactive.

Well why not?  Bananas contain potassium-40 which is radioactive so I'd have thought other food items might be likely to do something similar.

James

33 minutes ago, DaveS said:

And don't forget Prof Alice Roberts *sigh*.

Indeed not   She's usually the "human story" science presenter

James

38 minutes ago, saac said:

I'm not sure how you are measuring or justify the charge of "freeloader", perhaps you would expand.  General principle of people being paid for services provided I would assume apply here . Prof Cox  is under no obligation to give freely of his time or expertise to the BBC.  The BBC commissioned him and paid him as is customary practice, I'm can't see how that even comes close to "freeloading".   I'd happily spend time listening to Cox  being paid by the BBC to share his insight than say some reality show or food programme with people sharing photographs of their dinner.  I guess it is all down to personal choice, but freeloading , I just can't see that.

I'd agree.  Whilst he may come up with (some of) the ideas for the programmes and write some of it, I'd imagine the choices of location and visual style are down to others who have a target audience in mind.  I suspect that whilst many presenters with a physics background could do a good job of fronting most programmes relating to physics, those responsible for commissioning and planning science programmes contribute to what is almost "typecasting" of science presenters depending on the style of programme they want to make.  They get Brian Cox to do this sort of stuff, Jim Al-Khalili does a different style that's much more down to earth, Helen Czerski is a bit of an "action scientist", Mark Miodownik does more materials science type programmes and so on.

And ultimately, as he's the Royal Society's Professor for Public Engagement in Science, people are presumably paying him in the expectation that he will get involved in this sort of stuff.

As has already been said, many SGL members are probably way outside the target audience for this type of programme and shouldn't expect too much of it, just as many people with a strong interest in, say, horticulture, are outside the target audience of Gardener's World and somewhere on the net there's probably a forum for people who are really into cooking where they slag off whatever the latest celebrity chef is doing

James

1 minute ago, ollypenrice said:

There's a big difference between a daughter and a telescope...

One encourages you to spend more and more on it from the first day you have it, and the other ... is a telescope

James

I have always assumed that amp glow limits the dynamic range available for the data you actually want.  Depending on the well depth and integration time that may perhaps not be a problem for some, whereas it might for people who are getting into double figures of minutes per sub.

James

I have to admit that I wasn't aware of DIY electronic collimators at all, so "yet another" came as a surprise.  Interesting project though.

James

57 minutes ago, John said:

I think this is what lies behind this labeling:

https://oehha.ca.gov/proposition-65/about-proposition-65

 

Which says: "By law, a warning must be given for listed chemicals unless the exposure is low enough to pose no significant risk of cancer or is significantly below levels observed to cause birth defects or other reproductive harm."

I guess that means that the manufacturers put the warning on "just in case" as it's easier to do that than to risk the consequences of being sued.

There are some "interesting" things on the list though.  Alcoholic beverages, for a start.  Aloe vera, bracken fern, aspirin, nitrous oxide, warfarin and chinese-style salted fish are also there.  As is lead, so if lead is used to make some of the glass in the eyepiece, which seems quite possible, then I'd guess that's why the label is there.  As long as you don't make a habit of eating eyepieces then I'd imagine it's fine.  I know some of the big Naglers look good enough to eat, but one's my limit, really, and only with a nice pepper sauce and a decent full-bodied red.

James

16 minutes ago, vlaiv said:

If it is down to lanthanum - we would need to wait some time to detect it

There's probably more radioactive stuff in some of the food we eat

James

Assuming it's an issue with radioactive elements it would perhaps be informative to see a comparison with the background levels of radiation due to living somewhere such as Aberdeen (where I seem to recall the underlying rock is more radioactive than most places in the UK) or where I live, where levels of radon gas tend to be higher than average.

James

As far as I recall when this has been discussed previously, there are products used to manufacture the eyepiece that have been shown to potentially cause cancer etc., but there's in reality the risk in terms of an eyepiece is tiny.  However, in some locations the law still requires that the warning is present.

It may be due to the rare earths (or perhaps lead) used in some of the glass elements.

James

9 minutes ago, mackiedlm said:

+1 for W & W Astro

I've also found them to be very good, though (unsurprisingly, I think) on occasions over the last couple of years they have been short of stock.

James