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Back in 2000, the RAS published an article about Pepys’ astronomical activities in their magazine A&G.
You can read it online here: http://adsbit.harvard.edu//full/2000A%26G….41d..23W/D000023.000.html
As I understand it, telescopes of this era were always measured by focal length, rather than aperture. So “12 feet” does indeed refer to the length (similarly, Herschel’s “40-foot” telescope had that focal length). The instrument apparently cost Pepys the small fortune of £9.
The article also points out that Pepys’ activities with optical glass went beyond astronomy… 26 May 1667… “I did entertain myself with my perspective glass up and down the church, by which I had the great pleasure of seeing and gazing at a great many fine women…”
My guess would be that they made the figure in some tool like Adobe Illustrator, and while they were manipulating the labels into the right places, some numpty accidentally pressed the delete key with the wrong object selected. As Alex says, it looks like some amount of the outline is still visible, so possibly they even deleted the orange fill without deleting the outline. Or they were fiddling with the settings for the dark shading where the eclipse is visible, and accidentally had Britain selected at the time. 🙂
Well said, Tracie.
It’s dangerous to assume that ancient observers had anything like the mindset of a modern amateur astronomer.
The ancient Greeks were so certain that the sky was unchanging that they insisted novae and comets were inside the Earth’s atmosphere. The experiment that Tycho Brahe did to disprove this wasn’t technically difficult — he simply measured the parallax of a nova and showed it was less than the Moon’s. The reason this had to wait until the 16th century wasn’t lack of technology, it was just that nobody was asking the right question.
I don’t doubt that in the whole history of Australia, there wasn’t some bright spark who said “Hey, Betelgeuse looks bright tonight!”. But that doesn’t count as a “discovery”. We don’t say that Hipparcos or Flamsteed “discovered” Uranus, simply because they observed it and marked it on star charts. We credit the discovery to Herschel, because he was the first to realise it wasn’t just another a faint star.
As Tracie says, ancient people probably ascribed any variability they observed to sky conditions. In most cases, that was probably the correct interpretation. In the absence of any evidence that their thinking went deeper than that, I think it’s nonsense to speculate further!
Roger Dymock: The main technical difficulty with creating live streams of meetings is that we need a very reliable and fast internet connection at the meeting venue. A dodgy Wifi connection isn’t good enough: it needs to be a rock solid wired connection.
Surprisingly few venues offer this. The internet in Burlington House is not great, and when we enquired about live streaming the Christmas meeting at UCL a couple of years ago, even that was a no go. I very much doubt Sparsholt College would be able to help us, unless they already do live streaming themselves.
In my opinion, doing this badly is probably worse than not doing it at all. If we offer a live stream, and then it keeps breaking up and isn’t actually watchable, we’re sure to annoy lots of people. So, on balance, I think it’s best to focus efforts on what we know we can achieve, which is high-quality videos of meetings after the event.
It’s a little while ago now, but David Arditti gave a memorable review of Hyperstar at the 2011 Deep Sky Section meeting. I happen to remember it because I wrote the meeting up for the Journal.
If you hover over the “Publications” tab at the top of this website, and select “Downloads”, and then go to “Journal Archive”, and then “2011 August”, you can find my write-up of David’s talk starting on page 245.
I don’t know whether the technology has moved on since 2011, or whether David’s opinions have changed, but the impression he gave seven years ago was that Hyperstar was a bit of a nightmare to install / use!
The website behind this (LEVEL5) is indeed very ancient, but it also has some very good stuff on it. It’s well worth having a look around what they have — I still routinely refer back to their cosmology tutorials whenever I need a refresher.
As I understand it, this was a NASA project in the late 1990s to make astronomical tutorial texts freely available on the web. Clearly a lot of effort was put in at the time: they are often written by authoritative authors and are clear and accessible. However, it looks like funding must have dried up in the early 2000s, and since then it’s become of museum piece.
My experience of weird USB configurations has tended to be that Linux seems a lot more tolerant than Windows. I’m guessing the kind of people who play with Raspberry Pis are much more likely to play with USB-over-ethernet, USB repeater-extension cables, etc, than the average Windows user. So I’m not sure it’s fair to assume that just because this hardware works under Linux, the same will be true of Windows! 🙂
This is a good question which I suspect many people wonder about. A lot of good things seem to quietly go on within the sections, which perhaps we could publicize better.
I recently ran a search on NASA ADS for refereed articles featuring John Rogers (Jupiter Section) as a co-author, and was really impressed by the number and range of papers which came back. John’s publication record is better than that of many professional astronomers I could think of. It’s not just John – if you key in the names of other leading BAA observers, you likewise get impressive lists of papers.
There have been proposals to put together an up-to-date summary of the BAA’s ProAm activities somewhere, which I think would be very welcome.
Another idea was to have a “Projects” area of the website, summarising ProAm observing projects people can get involved in. My only hesitation there is that many BAA members may not be that advanced yet, so it’d be nice to advertise easier options as well and have something for everyone to get involved in (including a paragraph about how the observations might be used). Perhaps rather than running one Observers Challenge on the homepage every few weeks, we should encourage all the sections to have a few of them, which run indefinitely. We could still pick one to feature on the front page each month.
Alex: once the video digitiser has de-interlaced the video, don’t you effectively get 25 frames per second — i.e. 0.04s resolution?
This is what my USB digitiser was delivering.
The time signal should be very accurate if it’s done competently. 🙂
There’s a caveat here that if you rely on the GPS unit spitting out NMEA data, that comes in ASCII format over a slow serial connection. By the time it’s made it down the wire and through your serial buffers, you’ll probably only get ~ 100ms timing precision.
The GPS chip will also produce a PPS signal, which is pin which gives you pips once a second, on the second. Using the GPIO lines on a RPi or Arduino, you can sample that at high frequency to get a very good time standard.
My Polish isn’t very good, so I don’t understand much of the attached webpage, but it seems to mention PPS towards the bottom, which implies this particular box ought to have much better than millisecond precision.
I’d be interested to hear how you get on with this.
I spent 18 months playing around with Watec cameras, using Raspberry Pis and USB video capture dongles to hunt for meteors. The project in an abeyance at the moment, and to be honest I’m not sure the USB video capture hardware was up to the job. Essentially, your video signal is mostly black, and as I understood it, the cheap capture dongles were turning the gain up way too high so we were mostly recording noise. Any real structure was totally saturated. As I understand it, better video capture hardware has brightness controls that let you adjust these things.
Having had that experience, I would be wary of putting anything in my signal chain between the camera and my digitiser. I’d want to know exactly what the video time inserter is doing. If it’s passing the analogue signal through, maybe it’ll be fine. If it’s digitising the signal and then converting back to analogue, I suspect it’ll be a disaster! 🙂
A good place to start with number (1) is the BAA Handbook. Pages 28 and 29 of the Handbook for 2018 lists daily moon rise and set times for the UK.
You can also find tables of rising and setting times for the Moon here: https://in-the-sky.org/ephemeris.php?irs=1&ima=1&iph=1&objtype=1&objpl=Moon
As Robin says, the answer is the 1920s.
The turning point is often dated to the “Great Debate” of April 1920, when Shapley and Curtis publicly debated whether the “spiral nebulae” — i.e. what we call galaxies today — were part of the Milky Way, or further away.
In fact, the debate only really gained its historical significance a few years later, around 1924-5, when Hubble demonstrated the spiral nebulae had to be much too distant to be part of the Milky Way.
The significance of the Great Debate is that it was the last time that anybody could argue against the existence of external galaxies without being obviously wrong.
I too shall follow this with interest.
I built myself a ~ £300 3D printer a couple of years ago. One tricky issue I came across was the accuracy of the printing. I never really achieved better than 0.2mm accuracy. So, mechanical components generally needed a lot of cleaning up with a file before they were usable. I didn’t have much luck fine tuning the calibration, but perhaps I was just incompetent. 🙂
As regards mechanical strength, I think you almost certainly want to be using ABS. I found that my PLA prints couldn’t be left in tension for more than about a few weeks (depending on thickness) without snapping. This improved somewhat if I made the infill 100% solid, but at the expense of using lots of plastic and taking ages to print. I gather that PLA degrades and deforms particularly fast if exposed to moisture, so in a dew-laden observatory, I’d certainly favour ABS’s chances!
There even seemed to be differences between suppliers. The plastic I bought from RepRapPro (sadly now defunct) seemed noticeably stronger than what I got from various other suppliers.
While 3D printers are a lot of fun to play with and they’re great prototyping tools, I think making a precision spectrograph is quite ambitious!
Thanks all! The message I seem to be getting is that iOptron in particular isn’t a great buy. Further to Roger’s comments about screws coming lose, I was interested to find one blog post where someone was complaining that if you loosen the azimuth adjust screws too far, the mount comes off the tripod and your camera falls on the floor. Great! 🙂
I’m afraid we currently don’t support animated GIFs. I think if you try to upload one, you will only see the first frame of the animation.
Technically, this restriction is imposed by the Drupal content management system we use. Its image processing modules don’t support animated GIFs.
From memory, with a bit of hackery we could work around those restrictions. I understand that for applications like showing transient objects like variable stars, and the rotation of planets, they’re really useful. However last time this was discussed it became apparent that animated GIFs are quite polarising and a number of people really don’t like them.
So, as things stand we don’t support this, but we are aware of the feature request.
It’s noticeable how little ever seems to have been said about the incident, so everything is “anecdotal”.
The navy seems to have been understandably embarrassed by the incident — fighter jets aren’t supposed to get lost at sea.
The Jacobus Kapteyn Telescope was part of the Isaac Newton Group of Telescopes, which was (until 1998) owned by the Royal Greenwich Observatory. For a long time, the Royal Greenwich Observatory was run by the Admiralty. I’m not sure whether that was still true in the 1980s — I think not — but the two organisations still had close ties.
So, the telescope may have effectively been navy property and I suspect the astronomers would have been disinclined to publicise their patron’s embarrassment.
A Telegraph article from 2007 (when the MoD archives were released) says the ship’s owners did indeed receive a £570k salvage payment from the Navy, which I’m guessing would have also included a confidentiality clause.
James,
The internet seems to think it was “anecdotally” the Jacobus Kaptyn Telescope.
Best wishes,
Dominic.
James,
It basically comes down to weight, I think. Putting a big telescope on an equatorial mount isn’t possible from an engineering point of view. Mirrors that big deform under their own weight when you slew them, which you need to correct for with actuators under the surface. Alt-az is a nice coordinate system, because the deformation varies with altitude, but is independent of azimuth (if you built the telescope properly!).
Another nice feature of an alt-az arrangement is that you can direct the light off sideways to a Nasmyth platform to the side of the telescope. You can even engineer it so the Nasmyth platform never moves. That means you can make the detectors as heavy and unwieldy as you like, and it doesn’t matter. Moreover, you can have multiple Nasmyth platforms with different instruments on, switching between them simply by flipping a mirror which deflects the image off sideways. Most professional telescopes have at least two Nasmyth platforms.
As Andy S says, field rotation is a piece of cake compared to keeping many tonnes of metal aligned to optical precision!
Best wishes,
Dominic.
Hi John,
I’m sorry to hear you’re having trouble. You should be able to pay without setting up a PayPal account. When we redirect you to the PayPal website to make payment, you should see a grey button at the bottom inviting you to pay as a guest. This will allow you to enter your card details without setting up a PayPal account.
We are aware of a problem that this option doesn’t seem to be available on phones, and possibly some tablets, but is certainly there on PCs. We have contacted PayPal to ask if there’s anything we can do to help users of mobile devices.
We are also aware that the dates on the online renewal form are currently out of date — this will be corrected within the next few hours with the launch of a new and much simplified form, but you can continue to use the form in the meantime.
I hope that helps.
Dominic.
