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I believe this service is working at our end, but I fear there’s strong probability that any messages sent via these forms will get caught in spam filters nowadays (by which I don’t just mean they end up in the recipient’s spam folder; delivery may be completely refused).
The ever-rising volume and sophistication of spam messages mean that spam filters are always trying to stay one step ahead. Any email which originates from an unexpected place on the internet is treated as highly suspect, and unfortunately that’s exactly what happens when you use these forms: the BAA’s servers generate an email which appear to have come from your personal email address.
Perhaps the time will eventually come where we need to retire this service, though that would be a shame, since it’s useful to allow members to communicate without us disclosing their private email addresses.
How about Wil Tirion’s Sky Atlas 2000.0, 2ed Edition? I fear it may be becoming a collector’s item, though: second hand copies on Amazon seem to start around £50 and go up to silly prices. I picked up a copy a few years ago and I don’t remember it being that expensive.
This would be my entry for the “alternative” category. It is more colourful than the other images, at least.
This is what you get if you hold a phone camera up to the eyepiece of a telescope rather incompetently, so that it’s misaligned and not very much of the Sun is visible.
I almost chucked the picture away, but if you look closely at the full-resolution attachment, Mercury is clearly visible! I’m not sure you can see it in the low-resolution version below. Taken about five minutes into the transit.
But in this case you’ve got no shortage of photons. You are quite right that it would be madness to propose detecting a transit of a Mercury-like exoplanet.
That’s about right, I think.
I agree it’s tough, and almost certainly impossible under the UK’s changeable skies. But with a 6D at a good site, averaging over 20 megapixels, it seems tantalisingly within reach? Depends how well-behaved the noise is, and I don’t have a feel for how “good” a good site would need to be.
James: I had been wondering about doing something similar on 11 November. Set a DSLR to take frames of fixed exposure, pointed either at the sky, or in fact at the ground. Averaging the brightness across the frame, I wonder how easy it would be to detect a brightness step at Mercury’s ingress and egress from transit…
Alex,
If speakers offer us copies of their slides, there’s no problem with putting them online, but be aware that many speakers are uncomfortable about this. At a recent conference I went to, less than a third of speakers were willing to share their slides.
There can be all sorts of reasons for this: they may plan to reuse the slides at future events, they may have shown figures or images that belong to other people, they may worry that people will steal their work, and professionals may have shown results that aren’t published yet.
If you do approach speakers about this (note that the web ops team has previously advised meeting organisers not to do so), I’d recommend going very gently, and making anything you receive accessible to members only.
Best wishes,
Dominic.
My understanding is that the limitations in Dec have more to do with the altitude of the celestial pole, rather than the mounts the telescopes use (as Xilman says, most large telescopes are alt-az). Pan-STARRS is observing from a latitude of 20°N, so the pole is only 20° up and it’s not really worth wasting valuable observing time on it!
I imagine it depends what material the film is made from. Old celluloid films have a nasty habit of spontaneously combusting when they degrade. I’m not sure when films became safe, but I have a feeling cellulose acetate was still pretty common in the 70s, if not later still?
The most recent versions of all Microsoft Office programs have facilities to export documents to PDF format.
Wherever possible, please do this in preference to uploading documents in proprietary Microsoft formats (e.g. docx, pptx, xlsx, and so on). Not everyone has these programs installed on their computers.
Of course, if there’s a strong reason why people will need to open the document in Office (e.g. a form to be filled in and emailled back, or a Powerpoint file for display at a meeting), then that’s different. You might consider uploading both the original file and a PDF version to keep everyone happy.
Arrrgh! I fear I’m at least partly responsible for this. Some of the article looks like a mangled version of what’s on my website. My website says that the comet rises at 21:15 BST. I assume the summer student who wrote this article cut and pasted the rising time as the best time to see the comet.
A couple of weeks ago I changed the algorithm used by my website to decide when to list comet apparitions as news events. This resulted in some very bad predictions, which I commented on in a previous forum post. Martin and Nick convinced me I needed to fix this, but I haven’t had time to get it changed yet.
I really need to get on with it… sigh…
Hi Martin,
Thanks for the reply. It’s good to know that I’m not alone.
My reaction would be to query what the point of publishing these absolute magnitude values is, if the numbers produce such wild predictions. Surely, the only reason to publish absolute magnitudes is for people like me to use them to predict the future brightnesses of comets. Isn’t it inviting naive people like me to start telling the world that Blanpain will be a fifth magnitude comet?
In the past I’ve heard people express exasperation when comets get over-hyped, only to disappoint. And so, wouldn’t it be better to publish absolute magnitudes at the conservative end, rather than ones that lead to wildly optimistic forecasts? It would help if there was any kind of error bar quoted, to signify which absolute magnitudes are vaguely trust-worthy.
I should add that the absolute magnitudes on the BAA Comet Section pages are much more reliable than those on the MPC website – I suspect in part because the BAA only publishes values for moderately well-behaved comets. The BAA does not, for example, publish any values for Blanpain.
Even then, by my calculations, the BAA’s published absolute magnitude for 2017 T2 puts it at magnitude -1 next May, which is about 5-6 magnitudes brighter than most people seem to be expecting.
Best wishes,
Dominic
A correction to my previous post. Seen from the Sun, L4/5 are both 60 degrees away from the Earth. Seen from the Earth, L4/5 are both 60 degrees away from the Sun.
The Sun, Earth, and L4/5 form equilateral triangles, with all three interior angles being 60 degrees, and all the sides being 1 AU.
L4 and L5 are almost exactly 60 degrees away from the Sun [*], along the plane of the ecliptic, I think?
I say “almost” because as you point out, the Earth’s elliptical orbit will presumably perturb that angle slightly over the course of the year, though I imagine the perturbation is tiny.
[*] — My original forum post was incorrect, so I have edited the wording.
Due to the slightly weird way that Drupal works, error messages often get delayed until the next page you view after the one that generated the problem. So you could see these errors on any page of the site, if you view that page immediately after visiting one of the troublesome forum posts.
For the time being, I’ve installed a filter which I think should be hiding these errors. The errors are still happening, which isn’t ideal, but I think you shouldn’t see them any longer.
Roy,
About 10 days ago I installed a security update to the forum software that we use, Drupal’s Advanced Forum package.
Judging from the discussion forums associated with Advanced Forum, they mucked something up in a security update, so a lot of Drupal websites are currently being plagued by these errors.
It’s unlikely to be affected by which web browser you use. I think it’s fair more likely that it will occur on a few specific forum posts which unluckily happen to trigger this error condition.
Being free software, Drupal unfortunately tends to take its time about fixing problems, so I wouldn’t hold my breath for a quick fix to this. We do have the option to remove the latest security update if this becomes a really serious problem, but I’d prefer to avoid doing that if at all possible!
Best wishes,
Dominic.
David,
I have likewise not found any information about how the USNO calculate the values, or how accurate they are, though I have admittedly not looked very hard. I would expect they’re pretty good, though. I’m sure somebody like Jean Meeus would have noticed by now if they were publishing times that were wrong!
I think that if the times are computed using the most accurate data available, one-minute precision should be easily achievable. Both the Earth’s orbit and its rotation are very well characterised. Its rotation is measured by monitoring distant quasars with radio interferometers, which can achieve micro-arcsecond precision. That precision is required by Gaia, for example, which is doing astrometry at micro-arcsecond precision in a coordinate system defined by the Earth’s rotation axis.
The Earth’s orbit is very well characterised from spacecraft tracking work (Nick James’ day job). The idea is to track the position of spacecraft by measuring the time taken for telemetry to reach them from ground stations. In extreme cases (e.g. Rosetta) this has been done to one-metre precision or better. That requires you to know the position of each ground antenna to one-metre precision, which is no mean feat as that’s below the scale of seismic oscillations in the Earth’s crust…
So my guess would be that the Earth’s orbit is known to about one-metre precision, and the position of the celestial poles is known to micro-arcsecond precision. Of course, that’s not to say the USNO used an ephemeris that was that good. I would think it’s very likely they used some publicly-available ephemeris of lower accuracy.
Yes, I agree that amateur transit surveys are tantalisingly within reach. The hardware used by most of the ground-based professional surveys is basically high-end amateur kit. Though, crucially, with professional-grade CCDs, dark sites, and many years of software development to pull out ridiculously small signals from the photometry.
I am doubtful about the prospects for amateurs discovering even hot Jupiters by themselves. The professionals have been at this game for a couple of decades now, and I suspect all the really conspicuous transiting objects have already been found. There are bound to be plenty remaining with long periods, but amateurs will have the same difficulty as professionals that you’re unlikely to happen to be looking at the right star at the right time to record very infrequent transits (bearing in mind you have to see at least 2-3 transits of the same planet to convince anyone).
Doing follow-up on known targets sounds like a far more realistic prospect.
Though, of course, I invite you to prove my scepticism wrong! 🙂
I was about to say that I could think of few reasons why anybody would need to know the time of the equinox to the nearest minute, before realising a rather entertaining set of circumstances took place last night…
* Wed 20/03/2019, 21:58 UTC, March equinox.
* Thurs 21/03/2019, 01:44 UTC, Full Moon.The date of the equinox is used in the calculation of the date of Easter. To quote Saint Bede (The Reckoning of Time, 725), “The Sunday following the full Moon which falls on or after the equinox will give the lawful Easter.”
As I understand it, the church mucks up the calculation by defining the equinox to occur at midnight on 21st, and further defining full moon to occur 14 days after new moon.
Perhaps the BAA should start a campaign to “get back to Bede” and celebrate the astronomically-correct date for Easter this weekend.
To answer your actual question…. my impression is that these times are calculated by the US Naval Observatory and printed in the Astronomical Almanac, and that basically any and every source that quotes times for the equinoxes and solstices get them from the AA. So, I think if 21:58 is what the USNO says, basically that’s the time that everyone will quote.
I’m not sure what algorithm the USNO uses. When I have tried to do the calculation myself — which I tried to do in order to put equinox times on my website, In-The-Sky.org, I struggled to get exactly the same tiime as the USNO. For last night’s equinox, I get 21:44 UT. A difference of 14 minutes is larger than I would expect, since I used the NASA DE405 ephemeris to get the position of the Earth and Sun to high accuracy. I suspect I screwed something up — quite possibly there was an inaccuracy in my correction for the precession of the equinoxes (which is necessary to get the Sun’s RA and Dec for the epoch of the equinox, not J2000 coordinates).
I struggle to see how you come to that conclusion, Roger.
On the ground, professionals have NGTS, WASP, HAT, KELT, not the mention several smaller exoplanet search programs. In space, professionals have TESS, soon to be joined by CHEOPS, and later PLATO. Right now, professional exoplanet search programmes are incredibly active, and will remain so for at least the next decade. Probably far beyond.
There’s relatively little professional effort going into biosignatures, because it’s basically impossible to detect them with current technology. Yes, people have pointed large telescopes (e.g. the VLT) with high-resolution spectrographs at bright stars, and picked up spectral lines in exoplanet atmospheres (NB: abundant things like water, not “biosignatures”). It’s impressive work, but only possible for a handful of the brightest stars, orbited by very large planets. When the ELT comes online in 2024, it will be possible for more stars, but we’ll still be talking about molecules like water and methane in the atmospheres of small numbers of giant planets.
I’m puzzled by this talk of amateur opportunities for the “discovery of exoplanets”. The best amateurs can achieve right now is to observe predicted deep transits, if they squint really hard at their photometry. That’s already very difficult, and far short of actually discovering a transit you didn’t already know about. Perhaps you’ll prove me wrong, but I’d consider my money pretty safe if I bet that there will be no amateur exoplanet discoveries in the next decade. Unless you plan to build a replica of the NGTS in your back garden…
