Dominic Ford

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  • in reply to: Discussions #611222
    Dominic Ford
    Keymaster

    I agree the BAA site has been quite quiet over the past couple of months, though traffic on this site has always been rather variable, and midsummer is usually a sleepy period.

    So, I’m not overly concerned and I suspect what we really need is for a naked-eye comet to come along. 🙂

    But of course, if there are reasons why people are finding it difficult to contribute, please do let the website operations team know – either on the forum, or by private message. We can’t promise immediate changes, but we will certainly give serious consideration to any feedback we receive.

    in reply to: New website feedback #609311
    Dominic Ford
    Keymaster

    I just attempted to upload a GIF movie to my image folder and although it played properly it continually flashed in its thumbnail form,it was so bad I have had to delete it before I cause epileptic fits or seizures. Would it be at all possible to include WMV movie format (obviously still within the 2 megabyte size limit)?

    Hi Alun,

    I’m sorry to hear you’ve been having trouble.

    There is a bug that I’m aware of that the teaser images for GIF animations can sometimes get messed up in the way you describe. Unfortunately this is a bug in the underlying software that is used to generate the thumbnails (ImageMagick), and so I think it’s rather difficult to fix without switching to using different software, which would clearly be quite a large job. It’s on my to-do list to look into it, but unfortunately fixing it is likely to be a long-term project.

    Unfortunately, we’re also unlikely to allow members to post video files into the BAA image gallery in the near future. While I realise this a frequently-requested feature (it’s already been discussed in at least one other forum thread recently), hosting galleries of video files is a very different problem to hosting image galleries. The trouble is that video comes in all sorts of different formats (WMV, MP2, MP4, OGGV, WEBM, AVI, MOV… to name a handful that come to mind). Most of those are not compatible with all web browsers and operating systems. In fact, the only ones which are (almost) universally compatible are MP4 and WEBM. Even then, you need to use very specific encoding settings (called H.264 if you want the full gory details), and so if we allowed users to upload MP4 files, we’d doubtless receive files some people couldn’t view. Websites like YouTube have very clever software behind the scenes which converts whatever video file you upload into an appropriate format that the viewer’s computer can accept. So, in order to allow video uploads to the BAA site, we’d need to do an awful lot of work to reproduce that. And we’d no doubt receive lots of user feedback that such-and-such video file wasn’t working, for some deeply technical reason.

    So, for the time being, I think our advice remains that it’s best to upload your videos to a personal YouTube account, and then you can post a web link to it in the BAA Observation Gallery, along with a still image from the video.

    Sorry we can’t be more helpful currently,

    Dominic

    • This reply was modified 3 months, 1 week ago by Dominic Ford.
    in reply to: New website feedback #609271
    Dominic Ford
    Keymaster

    https://britastro.org/observations/observation.php?id=20181111_015500_44cd9ab1092010e3 contains a reference to https://britastro.org/node/19348 (this is just a specific example of no importance otherwise), which link is now broken. I can easily fix isolated examples in my own pages but perhaps they may be corrected globally with a script? AFAICT, and assuming the old pages are still available in an archive somewhere, a relatively straightforward pattern matching exercise should match old with new URLs.

    Hi Paul,

    We already have a script which does this, but apparently it’s not working properly. I shall flag this up with the relevant individual.

    Cheers,

    Dominic

    in reply to: can no longer jump to a point in a video #609094
    Dominic Ford
    Keymaster

    From William’s description, my guess would be that the web server is not allowing partial-content downloads, and so the video player is not able to start downloading the video file part-way through. Hence, it has to download the whole preceding part of the video before the jump facility starts working.

    If this is the problem, it may be fixed by some lines like the following in the relevant htaccess file:

    Header set Access-Control-Allow-Origin “*”
    Header set Access-Control-Expose-Headers “Content-Type”
    Header set Access-Control-Expose-Headers “Accept-Encoding”
    Header set Access-Control-Expose-Headers “Range”

    … with the last line being the particularly important one. However, WordPress possibly has a switch somewhere for controlling this behaviour.

    I vaguely recall seeing exactly this same problem on another website, many moons ago… possibly the previous BAA website, in fact!

    in reply to: Images and attachments to forum posts #608997
    Dominic Ford
    Keymaster

    Hi Nick,

    This was not a conscious decision, and I agree it’s a bug. What’s happening is that we are rolling out off-the-shelf solutions – which typically come with default restrictions which may not be appropriate to the BAA – and then looking at what configuration changes we need to make.

    This iterative process may move a little slower than many would like, since we currently have around 30 open bug reports and a relatively small team working through them. But I have passed your feedback on to the relevant individual who I’m sure will get it fixed as soon as he can.

    Cheers,

    Dominic

    in reply to: Video observations #608636
    Dominic Ford
    Keymaster

    Hi Steve,

    You should be able to post links in the description of your image, though unfortunately the software doesn’t automatically spot web addresses and turn them into hyperlinks currently.

    When editing your observation, you just need to select the text of the web address, and then click on the “link” item in the formatting toolbar above the description editor (the icon on the far right which looks like a pair of handcuffs). A pop-up window will then invite you to enter the URL you want your text to link to.

    Best wishes,

    Dominic

    in reply to: Video observations #608590
    Dominic Ford
    Keymaster

    Dear Steve,

    I saw some of your videos on Facebook, and they’re absolutely stunning!

    Unfortunately you’re right that there’s not really a way to post large videos on the BAA site currently. Basically, hosting video files comes with a whole load of additional complications (very large file sizes, different codec / container choices, the need to stream lower-resolution transcoded video files to mobile devices, etc, etc). We took a conscious decision when setting up the observation archive that hosting video would be an entirely different project from trying to host images. Inevitably, whatever quality setting we picked in the transcoder, I suspect half the BAA would complain the quality wasn’t high enough, meanwhile the other half would complain the files were too big to fit down their dodgy internet connections. 🙂

    The facility to post animated GIFs was a compromise solution we added to allow small animations to be posted.

    My recommendation would be that you upload the videos to YouTube, and then post a still-image from the video to your member album, with a link to the full video on YouTube? That way, we outsource the difficult video-streaming problem to YouTube. This is actually the same approach the BAA takes to hosting its meeting videos nowadays.

    Best wishes,

    Dominic

    in reply to: Barred Spiral Galaxies #585181
    Dominic Ford
    Keymaster

    This is still a somewhat contentious question among theorists, but essentially the density waves that create the spiral pattern in spiral galaxies are only stable in the outer parts of a galaxy, beyond a certain radius called in “inner Lindblad resonance”. In the inner parts of the galaxy, different mechanics operate.

    Simulations suggest that in these inner parts, density waves still occur, but they tend to cause material to pile up into a linear feature (i.e. a bar) rather than a spiral pattern. However, the timescale for the bar to appear is quite long, and so young spiral galaxies may not have had time to grow a bar yet, even if their spiral structure is well developed. They may well start acquiring a bar in the future.

    Moreover, when spiral galaxies collide with one another, or have close gravitational encounters, this tends to mess up the delicate spiral structure and bar formation processes and cause them to ultimately become elliptical galaxies.

    Edwin Hubble believed that elliptical galaxies turned into spiral galaxies over time, but we now believe that the opposite is true.

    in reply to: 2021 – how was it for you? #585063
    Dominic Ford
    Keymaster

    Happy New Year, everybody.

    My Pi Gazing meteor cameras monitor sky clarity in Cambridge by taking one-minute stacks (with a Watec 902H2 Ultimate) every four minutes and counting how many stars they can see. In good conditions, the images go down to mag ~6.

    The bar charts below show the number of days in each month when my automated system thought it was clear.

    Amber means there were at least 7 images with 800 stars visible (mirky conditions for 30 minutes). Green means there were at least 15 images with 1000 stars visible (good conditions for an hour). I invented these thresholds mostly at random.

    I’m sure these figures are somewhat dependent on when I last cleaned the cobwebs off the cameras.

    Interesting, the autumn doesn’t appear so bad here, though most of the clear skies have been at 4am.

    in reply to: Awards citations #585021
    Dominic Ford
    Keymaster

    Ron,

    I would add to what David said, that the original citations are submitted to Council by the nominating individuals, usually without the knowledge of the award recipient and without any official input from the BAA. While many citations may be very well written, there is no guarantee that the original citation is accurate and does a good job of summarising a member’s lifetime work. Nor is there any guarantee that the recipient themselves is happy with the way it presents their work.

    I think, precisely because an award can celebrate many years of an individual’s work, it’s natural that the BAA may want to tidy up the citation and check it with the award recipient before it appears in print. It’s not at all about being mean and saving space!

    Best wishes,

    Dominic

    in reply to: Awards citations #585007
    Dominic Ford
    Keymaster

    Hi Robin,

    Yes – that would be really nice, though I fear it’s unlikely to happen for a little while.

    At the moment the website operations group is focused on preparing for the launch of the new-look BAA website, due in a few weeks’ time. And after the launch, I suspect there will be a crazily busy period of fixing glitches and helping our many contributors to find their way around the new content management system.

    So I fear any non-urgent website issues are likely to end up on a to-do list that we won’t have a chance to look at before the spring!

    Best wishes,

    Dominic

    in reply to: Awards citations #585004
    Dominic Ford
    Keymaster

    I absolutely agree that in the past the BAA has published surprisingly little (consistently) about the recipients of awards. I think it would be great if they were announced with a news story on the front page of the website, and a matching article in the Journal.

    in reply to: J-BAA Electronic #584974
    Dominic Ford
    Keymaster

    As Jeremy says, your paper subscription to the BAA Journal actually already includes access to the electronic version (in PDF format) which you can download here: https://britastro.org/journal

    So, feel free to try reading it on your tablet and see how you get on with it.

    For the record, I switched to an electronic subscription a few years ago when I was living abroad and was anxious not to accumulate too much “stuff”. But Jeremy’s point (1) is absolutely right: I read far less of the Journal now than I used to.

    In case you’re wondering, the December Journal isn’t available electronically yet, as it normally appears online shortly after the paper copies arrive.

    in reply to: La Palma volcano eruption #584732
    Dominic Ford
    Keymaster

    As requested, I’ve deleted the comment which didn’t belong in this thread, and have copied that content into a new thread.

    Karl – as others commented, I’m sure your post will be of interest many people, but it didn’t belong in this particular thread!

    While I’m here…. I was curious about Paul’s comment above that he’d not heard whether the WHT was opening up currently. Am I right in thinking the WHT is (still) offline all this year for WEAVE commissioning? But presumably that’s now reached a point where they’re doing on-sky calibration work most nights? (Assuming the engineers are actually able to travel to La Palma at the moment!)

    in reply to: BAA AGM & Meeting. #584713
    Dominic Ford
    Keymaster

    Hey folks,

    I’m afraid the university / academic sector is taking an extremely cautious approach to Covid right now. If you think the IoP is going over-the-top in demanding pre-registration, you should compare it to the situation in Cambridge. Here, there’s no prospect of public events happening on-site before Christmas – today is, in fact, the first day in 18 months we’ve been allowed visitors of any kind in our building.

    I know a few organisations have tried polling their membership (as Robin suggests), but generally the polls only show that there’s a huge spectrum of different opinions. So, I’m not sure how useful such a poll would be, especially since the BAA is constrained by restrictions dictated by venues anyway.

    I hope the BAA manages to have a face-to-face Christmas meeting (for those who are comfortable with it), but I fear the BAA will find it tricky to find venues for meetings for a little while to come.

    Cheers,

    Dominic

    in reply to: Multiple copies in Deep Sky Section image archive #584564
    Dominic Ford
    Keymaster

    Apologies it took me so long to get onto this.

    It’s now fixed…. or at least, considerably improved. The duplicate results are gone, but the result counter may not be entirely accurate.

    Among other fixes I rolled out this evening, the plate-solution indicator now appears red (“pending”) when images are still in the queue for the plate solver.

    There’s also now a much better interface for searching for images of particular objects, either by type <https://britastro.org/observations/object_search.php> or by catalogue reference <https://britastro.org/observations/object_catalogues.php>.

    Solar system objects can be sorted by current brightness and/or position, but that’s based on orbital elements and absolute magnitudes I hoover up from various online sources, so beware that accuracy is not always guaranteed – especially for comets. Indeed, I have deliberately hidden my magnitude estimates for comets as the BAA Comet Section webpages have much better and more up-to-date information available.

    in reply to: Images #584546
    Dominic Ford
    Keymaster

    Hi Tor,

    Currently the BAA only allows members to upload images that are public to all. We don’t offer storage of private data, and I suspect it’s unlikely the BAA ever will.

    The difference between public and private collections is simply whether the grouping of images is publicly visible or not. If you want to make a grouping “My favourite images of Jupiter”, for example, you can choose whether your member album page allows other people to see that grouping. In any case, the individual images will still appear in your album.

    The “Add image” button at the top is used to upload images to your album, and not to add images to collections.

    To add an image to a collection, you should navigate to the image in question, and scroll down to the top of the comments area, below the image. There you should find some controls to add (or remove) the image to/from your collection(s).

    Hope that helps,

    Dominic

    in reply to: How the Moon got there? #584529
    Dominic Ford
    Keymaster

    In the past, I think people did indeed tend to sweep the question of where the impactor went under the carpet.

    In the past 10-20 years, it’s become possible to do full hydrodynamical simulations, and that’s where things start getting awkward. You need a pretty big impactor to knock a Moon-sized chunk out of the Earth. And in the vast majority of orientations, most of the impactor ends up in the Moon, with relatively little in the Earth. That totally mucks up the Moon’s composition.

    You can get it right, with precisely the right orientation. From memory, a low-velocity and fairly oblique impact. But, the skeptics would ask, what are the chances nature would manage to play exactly the right snooker shot?

    In the new era of robotic exploration of the Moon, I suspect we’ll see a lot more debate about this. The Apollo missions returned lots of rock from a small number of sites, and some people question how representative they actually are.

    in reply to: How the Moon got there? #584527
    Dominic Ford
    Keymaster

    The giant-impact hypothesis was widely popularised as a direct result of the Apollo samples, most notably by Hartmann & Davis in 1975.

    It seems very likely that the Moon has a fairly uniform composition all the way down, because its physical density is compatible with that. And its lack of magnetic field also suggests there isn’t any metallic core at the Moon’s centre.

    That is quite suggestive that the Moon is indeed a big chunk of Earth mantle which got knocked off at some point. It’s hard to think of another way to form the Moon with such a similar composition to the Earth’s mantle, but systematically missing all the siderophillic metals which the Earth has in its core.

    The theory goes that the impacting body would have been entirely melted / vapourised in the collision, and got thoroughly mixed with the (now molten) Earth’s mantle before the mixture divided into the Earth and Moon. That bit of the theory is certainly the weakest link, and people still run computer simulations and argue about how possible it is. It’s hard to make it work – but not impossible, with a finely-tuned oblique collision.

    But as things stand, the debate is basically over the details of the impact geometry. Nobody has yet presented any credible alternatives to the broad outline of the Hartmann & Davis model, despite it seeming to require extreme fine-tuning to give the right result.

    I think Andy has already answered the question about the Earth’s orbit. Yes, the Earth’s orbit will have changed. But it found a new orbit. In the solar system’s early history, that would have been commonplace.

    in reply to: BAA Journal DVDs #584435
    Dominic Ford
    Keymaster

    John,

    PDF password protection is indeed (usually) rather easy to get around. Simply by opening the PDF in any third-party viewer other than the official Adobe Reader, you can usually circumvent all the restrictions, including printing (plus editing, page extraction, etc).

    Taking a quick look at a handful of files, I believe the BAA has used various different security settings when preparing Journal PDFs at different times. All the ones I’ve looked at do allow printing, but block other actions. I could well believe that some might have restricted printing – presumably unintentionally.

    It would be interesting to know exactly which PDF files are giving you trouble, though in the short term it will probably be much easier for you to circumvent than it will be for us to fix.

    Cheers,

    Dominic

Viewing 20 posts - 1 through 20 (of 142 total)