SOS – The Plane's on Fire – No More News

Is Google getting sloppy? A short while back the question would have been unthinkable, but now it seems the answer might be yes. And the failures are coming from Google's core competency of search.

SOS

In order to listen to music without filling up the drives of my work laptop or my tablet, I have a lot of songs uploaded to Google Play Music. Google doesn't upload everything, they search what is already on their servers and match it to the music being uploaded. This saves space on the servers, and time for the uploader.

One of the songs I have uploaded is ABBA's SOS (which Wikipedia informs me "is the only Hot 100 single (or #1 single in Australia) in which both the title and the credited act are palindromes"). But a strange thing happened when I tried to listen to it in Google Play Music: it had changed language!

ABBA's version of the song is in English, but ABBA singer Agnetha Fältskog also released a Swedish version under her own name. It is (presumably) this version of the song that Google is serving, despite it not being the version I own. Unfortunately, Google are so (falsely) confident in their algorithms that there is no way of telling the system 'you got it wrong – this is not the right song'. 

Another part of Google's system is that you can re-download the music you have (allegedly) uploaded. This means I can now download Fältskog's version of SOS, courtesy of Google, without having to pay for it. While I have little interest in owning this particular song, there are bound to be other mis-matches in the system and Google could find it has accidently given away large quantities of music for free.

The Plane's on Fire

On the evening of Saturday 9th August, JetBlue flight B6 704 from San Juan to New York JFK suffered an engine fire whilst taxiing prior to take-off (apparently due to 'bird ingestion in the number one engine'). This led to the evacuation of the passengers via the emergency slides and the temporary closure of the main runway at San Juan. In other words, it was a pretty major event – and was picked up by many news outlets.

Google, however, completely missed it. It wasn't that Google search didn't find any news about it – it did. But Google search on mobile has recently introduced 'cards' that (claim to) give you the status of a flight you search for. You can simply say "OK Google JetBlue 704" and it not only gives you search results but tells you the current flight status.

But there's a problem – it's talking nonsense. While the plane was sat on the tarmac in San Juan surrounded by firefighters and news crews, Google was claiming it was in the air and would be arriving on time at JFK. Every other search result knew what had happened, but Google did not. It would appear that the flight status cards are simply linked to the schedules and do not reflect the actual status of the flights.

No More News

A couple of weeks back we had a press release on an enormous gas stream found with Arecibo. As usual, I used Google to monitor the coverage. However, I hit a problem – clicking on 'all N news sources' on the mobile search (both in the app and on the website) went to the mobile news front page, rather than the 'full coverage' page. Fortunately it was still working on the desktop version so I was able to request the desktop version of the website and search on that. (Oddly, the link for full coverage is called 'explore in depth' on desktop search.)

This problem has now been fixed, but it took over a week from the time I spotted it, and it had probably been present prior to that. For an absolutely core element of Google's business, this was an amazingly long failure and lead to me  trying Bing as an alternative. 

Bing geolocated that I was in Puerto Rico and refused to give me any results in English, even though I have English set as my language in my Microsoft account. No matter how badly Google fails, Microsoft is still able to make them look good!

Why Hobby Lobby is bad for religious freedom

Last week's Hobby Lobby decision at the Supreme Court has been widely promoted both by its supporters on the right and its detractors on the left as a victory for religious freedom ([1]; [2]). It is nothing of the sort – it is a victory for employer freedom.

Many people, including many Americans, don't realise that constitutional rights only apply to interactions with the government. As workers, the only rights Americans have vis-a-vis their employers are those granted by ordinary law, not by the constitution, and are thus secondary to any rights the employer has under the constitution. For religious freedom, as with many other freedoms, these rights are granted by the Civil Rights Act of 1964.

But there are exceptions to the rights granted by the Civil Rights Act. In order not to trample on employers' First Amendment rights Title VII, which deals with religious freedom, has a specific exemption for 'religious corporations' ([3]).

The Supreme Court has now ruled that Hobby Lobby and other similar companies are, in plain English, religious corporations. They have First Amendment rights, and would therefore appear to be exempt from the religious discrimination clauses of the Civil Rights Act.

How bad could this be? For minority beliefs, the answer is 'very'. A recent study by researchers at the University of Connecticut showed significant discrimination in hiring in the southern states of the US against Muslims, atheists, pagans and Catholics, even though this is illegal ([4]). The indications from politics are also not encouraging, with corporations ordering their workers to attend political rallies without pay as a condition of employment ([5]; [6]). 

The argument is sometimes made, particularly by those on the right who wish to avoid legislation, that corporations who mistreat their workers will be shunned by the market. This has not been shown to be particularly effective outside of a few fairly narrow sectors: Hobby Lobby don't appear to be suffering, nor do the mining companies who forced their workers to campaign for Romney, while the well-documented abuses of Walmart and Amazon go similarly unpunished. 

Using the model of what has been allowed on the political sphere, this exemption from Title VII would mean employers such as Hobby Lobby could enforce membership of a particular 'corporate church' religion (presumably including tithing their salary if the corporate church so demands) and – without pay – attendance at corporate church events. 

For-profit employers also gain the right to punish workers for failing to live their corporate religious values – which, as the Court only requires that they be sincerely held, could be virtually anything. Given the number of Catholic colleges opposing their workers' right to unionise, it also doesn't appear to matter if the claimed exemption is diametrically opposed to the teaching of the church they are affiliated to ([7])! From allowing religious discrimination it's also not a great stretch to covert racial discrimination – 'No Catholics', for instance, could easily be code for 'No Hispanics' in Arizona.

In short, the ruling that companies can have religious characters and rights is a victory for corporate might – and a disaster for religious freedom.

Why the Summer Solstice isn't the start of summer

This weekend was (in the northern hemisphere) the summer solstice – the "official start of summer", also known as the "start of astronomical summer", "the first day of summer", and "midsummer's day". Only the last of these makes any sense.

This idea seems to have grown out of a human desire to have major transitions well marked. It reminds me of something I once saw that divided the day into four parts: morning, afternoon, evening, and night. The transitions were dawn, noon, sunset, and midnight. That's right – this system had the 'night' starting at midnight.

There are at least two reasons why claiming the start of summer occurs at the summer solstice is wrong. The first is common sense, the second is science.

From a common sense perspective, we know when summer is – it's when the evenings are long and the days are hot. Similarly, winter is marked by cold days and early evenings. Yet 'astronomers' tell people shovelling snow off their driveways in mid-December that winter doesn't start for another week, tell sunbathers in early June that it isn't summer yet, and claim it is still summer as the equinoctial gales roll in. The message this sends out is that astronomers don't know much about the real world. 

The meteorological summer covers June, July, and August and pretty much matches our perception of what is 'summer'. This corresponds to the Memorial Day to Labor Day definition of summer in the US, for instance. Similarly the first of March – the start of meteorological spring – is when the daffodils are supposed to bloom for St David's day. Meteorologists clearly know about the real world.

So what about science? Saying the summer solstice is the start of astronomical summer implies there is something scientific going on. Is there a good reason why the astronomical seasons lag the meteorological and cultural seasons?

Sadly, nothing could be further from the truth. The Sun is responsible for the seasons, but the Earth takes time to warm (or cool), so the meteorological seasons actually lag behind their astronomical driver. The opposite of what we tell people.

This lagging is the reason why midsummer's day does not fall in the middle of the meteorological summer, but precedes it by about three weeks. The astronomical seasons should (if we insist on four seasons) start on the cross-quarter days. Now widely neglected, but well known in the past, these fall midway between the solstices and the equinoxes and are marked by traditional festivals. 

The exact dates of the astronomical cross-quarter days for 2014 (from archaeoastronomy.com) are 3rd February, 5th May, 7th August, and 7th November. These correspond (approximately) to the traditional cross-quarter days of Candlemass (a.k.a Groundhog Day), May Day, Lammas, and All Hallows in the Christian tradition; or Imbolc, Beltane, Lughnasadh, and Samhain in pre-Christian Celtic tradition. 

These dates tie in to genuine science about how the Earth is heated by the Sun. That they fall a bit before the meteorological seasons is explained by the lag in the Earth's response to this heating – effect lags behind cause. When people say in late August that it is still summer, we can answer that the Sun has already moved into autumn, but the Earth's captive heat means we still experience summer weather. The disconnect from people's experience can now be explained with real physics.

So, I hope you had a good midsummer's day, but don't go calling it the start of summer. Astronomically and meteorologically, summer has already been going for quite a while.

A Dark Galaxy in the Virgo Cluster?

While updating my work website recently, I came across an old page on a dark galaxy candidate, VIRGOHI 21, that I had worked on back in 2004 - 2007. The page had not been updated since then, despite things having changed in the meantime. While updating it, I decided to write this blog post, giving some personal recollections and an explanation of my current thinking on the subject.

In 2005, I was first author on a paper about VIRGOHI 21 called “A Dark Hydrogen Cloud in the Virgo Cluster”. We had found the 'dark cloud' in a neutral hydrogen survey of the Virgo Cluster carried out a few years earlier with the Lovell Telescope at Jodrell Bank, and had already published initial results in an paper by Jon Davies the year before, “A multibeam HI survey of the Virgo cluster - two isolated HI clouds?”. The second cloud, VIRGOHI 27, was observed with the Giant Metrewave Radio Telescope in India and found to be a very faint galaxy, but deep optical images of the area of VIRGOHI 21 from the Isaac Newton Telescope in the Canary Islands did not show anything. Another oddity was that VIRGOHI 21 looked As if it was, like most galaxies, rotating - in observations with Arecibo we could see that the velocity changed from north to south. This made it look like a galaxy without any stars - a dark galaxy!

Isaac Newton Telescope image from our press release, the ellipse shows the extent of VIRGOHI 21 based on observations with Arecibo

We considered whether VIRGOHI 21 could be tidal debris. At that time, it was generally thought that the only way to form long streams was through slow, tidal interactions. We were able to rule this out as there was no large galaxy in the right position to have pulled VIRGOHI 21 into the shape we saw.

Sloan Digital Sky Survey image of VIRGOHI 21 from their Image of the Week gallery. The orginal caption reads: Radio telescopes at Arecibo and Jodrell Bank Observatory detect a large cloud of hydrogen gas at the center of the region of the sky covered by this image, but no corresponding objects can be seen in it. The rotation of this cloud indicates the presence of a significant mass of dark matter (matter that we cannot currently detect directly) as well.

The discovery led to headlines such as "Astronomers claim first 'dark galaxy' find" (New Scientist), "Astronomers find star-less galaxy" (BBC) and "Not even a twinkle out of galaxy with no stars" (The Times). VIRGOHI 21 even got its own entry in Wikipedia. But the story was far from over...

At the time the first paper was published, we were already planning high-resolution observations with the Westerbork Synthesis Radio Telescope in the Netherlands. We hadn't been able to detect VIRGOHI 21 with the Indian telescope earlier, but this time we saw it. These observations showed that VIRGOHI 21 was linked to a nearby galaxy, NGC 4254 by a bridge of hydrogen. This galaxy has an unusual, lopsided structure, with one very large spiral arm, and we had already discussed internally whether this could be linked to VIRGOHI 21 and dismissed the idea as something we did not have enough evidence to speculate on. Now we had the evidence.

We also had even deeper optical imaging from the Hubble Space Telescope that still failed to reveal any visible galaxy. The Hubble observations also answered an alternative scenario that some simulations suggested - a fast encounter that would rip gas out of NGC 4254 but would also, necessarily, pluck stars out of that galaxy and leave them floating freely in space in the same area as the gas. Had they been there, these stars would have been visible to Hubble - but we saw no evidence of them.

A three-colour (i, r, and B bands) image of VIRGOHI 21 from the Isaac Newton Telescope overlaid with contours of neutral hydrogen density (green) from observations with the Westerbork Synthesis Radio Telescope. The extent of the galaxy is remarkably similar to the ellipse from the Arecibo data (above).

We published our Westerbork and Hubble results in a paper called “21-cm synthesis observations of VIRGOHI 21 - a possible dark galaxy in the Virgo Cluster”. At about the same time, the ALFALFA team published their map of VIRGOHI 21, which showed that the neutral hydrogen stream extended further to the north. This wasn't particularly shocking - seeing a 'leading arm' in front of an interacting galaxy is not uncommon.

Animation of the neutral hydrogen data cube from Westerbork. Up indicates increasing recessional velocity. VIRGOHI 21 is the structure in the centre, connected by a bridge to NGC 4254 (near the top of the image). The ring-like structure near the bottom of the image is NGC 4262.

Both the ALFALFA data and our Westerbork data were then used by a team in France who were modelling the system as a 'hyperbolic' interaction, a kind of cosmic 'hit and run' where another galaxy shot past NGC 4254 very quickly and then left the area before it could be identified. It may seem surprising that we gave our data freely to someone who were trying to prove us wrong - but that's the way science works!

The French team found that: “High-speed collisions, although current in clusters of galaxies, have long been neglected, as they are believed to cause little damages to galaxies except when they are repeated, a process called ‘harassment.’ In fact, they are able to produce faint but extended gaseous tails.” In other words, it was possible to explain VIRGOHI 21 as part of a tidal tail, formed from a high-speed galaxy encounter rather than the low-speed encounters we had considered.

While this did not absolutely rule out the hypothesis that VIRGOHI 21 was a dark galaxy, it presented a less exotic alternative - and as a general rule (known as Occam's Razor, after the medieval monk William of Ockham), the least exotic idea is considered the most likely explanation. But the simulations were far from being a great match to the observations, and further observations (unpublished) of the northern end of the stream showed it continuing at the same velocity as VIRGOHI 21 - more consistent with it being a leading arm than with the simulations. Could these simulations really explain VIRGOHI 21?

You're probably wondering why we didn't publish the new observations of the northern end of the stream, and point out the other inconsistencies between the simulations and the data. There are two reasons for this. The first is that while the simulations may not have been a great match to the data, they established the principle that it was possible to get long streams of neutral hydrogen via fast interactions. Once the stream was drawn out, there were many different forces acting within the cluster environment that could have altered its shape in myriad ways, so no simulation could be expected to provide an exact match.

The second reason is more complex, and is (to my mind) the most conclusive evidence against VIRGOHI 21. To understand this, it is necessary to go back to earlier in the story and look at predictions we made around the time the Arecibo surveys were starting up.

When we announced the Westerbork results, Jon Davies said in our press release that “We’re going to be searching for more Dark Galaxies with the new ALFA instrument at Arecibo Observatory. We hope to find many more over the next few years – this is a very exciting time!”

This wasn't just idle speculation - a year earlier we had published a paper, "The existence and detection of optically dark galaxies by 21-cm surveys", where we had argued that if VIRGOHI were a dark galaxy it implied the existence of many more dark galaxies. If these existed, they should be discovered by the next generation of neutral hydrogen surveys then getting started at Arecibo - and in large numbers. These dark galaxies would make up almost a quarter of the sources found in the deep AGES survey, while over a thousand would be seen by the shallower but much larger ALFALFA survey.

This meant that the final test of whether or not VIRGOHI 21 was likely to be a dark galaxy was whether other dark galaxies could be found. If there turned out to be a large population of dark galaxies then VIRGOHI 21 would be vindicated, but if no other examples were found it would imply that VIRGOHI 21 was nothing more than tidal debris.

So, what happened? To date, AGES has found very few confirmed HI sources without optical counterparts, and none like VIRGOHI 21. ALFALFA has found around 50 candidates - far fewer than required, and these are (as I understand it) potential mini-halos in the Local Group rather than objects similar to VIRGOHI 21. The only conclusion that can be drawn is that the predicted population of dark galaxies doesn't exist - which means, whatever the evidence for it individually might be, VIRGOHI 21 is highly unlikely to truly be a dark galaxy.

So - VIRGOHI 21 is almost certainly not a dark galaxy. Less exotic explanations have been given for its existence, and more recent surveys have failed to discover any similar dark galaxies. Does this mean we were wrong to publish what we did? No - the less exotic explanation was only discovered in response to our papers, and the surveys that should have uncovered more dark galaxies happened after our discovery. By publishing, we advanced science, even if those advances ended up showing that we were wrong!

Kayaking Lago Dos Bocas

I had intended last weekend to blog about the work I presented at the AAS meeting, but then I went kayaking instead - so I'm now going to blog about kayaking on Lago Dos Bocas.

Lago Dos Bocas (Lake Two Mouths) is a reservoir in the mountains near Arecibo. It was built in 1942 as part of a hydroelectric scheme (also involving Lago Caonillas, another reservoir upstream of Dos Bocas, built in 1948). Since then, the reservoir has lost over half of its original capacity to silting, but it still produces electricity and, since 1996, water from the reservoir has also fed the 'Superacueducto' that supplies the San Juan metropolitan area.

The 'two mouths' of the name refers to the two rivers that meet just above the Dos Bocas dam: the Rio Grande de Arecibo and the Rio Caonillas. These form the two arms of the lake. A third river, the Rio Limón, joins the Rio Caonillas branch about 2 km above the dam.

Chart of Dos Bocas from Soler-López 2012, USGS Scientific Investigations Map 3217

 A short way south of the dam, on the western shore where it is easily accessible from Route 10, there is a ferry terminal, or 'embarcadero', run by the department of transport. This has car parking and a free passenger ferry that serves lake-side houses and restaurants, and a jetty that is used by the restaurants' own boats. Most importantly, for our purposes, it has a slipway from which we can launch our kayak.

El Embarcadero

On previous occasions, we have headed up the Rio Grande arm and into that river and have explored quite a way up the Rio Limón. This time, we planned on heading up the Rio Caonillas arm. Our kayak is a 4.4m Feelfree Tri-yak, a sit-on-top tandem kayak. Due to its length, it tracks well (keeps going where it is pointed, rather than spinning off in a random direction) and has a third central seat that we use as storage space.

It took us about 30 minutes from arriving at the embarcadero to get the kayak off the car, carry it down the slipway, clip on the seats, get our equipment together, put on our buoyancy aids, and get out onto the water. We set out across the Rio Grande branch then headed on east, up the Rio Caonillas branch, passing an abandoned restaurant on the point where the two arms meet. A bit under a kilometre up, the lake turns south, but before we reached the corner a rain shower swept down from the mountains.

Abandoned restaurant on the point

We quickly pulled our ponchos out of the kit bag and scrambled into them. Visibility dropped, and the wind whipped around us as we ploughed on. Fortunately, winter showers don't tend to be thunderous, and rain is seldom cold in Puerto Rico! As soon as the rain stopped, we started to feel hot again. The ferries and restaurant boats zoomed past us, throwing up low wakes that seemed quite large enough from a kayak. We waved to the tourists as they went by in their ferries - quite a few even waved back!

We passed the mouth of the Rio Limón after about 30 minutes paddling, entering waters we had not kayaked before. Another shower came through, then our objective came into view. We had been to our favourite Dos Bocas restaurant, the Rancho Marina, many times by ferry, but this was our first visit by kayak.

The Rancho Marina

Kayak on the beach at the Rancho Marina

We watched a ferry disgorging passengers onto the jetty, then ran the kayak onto the beach and ran a mooring rope around a handy post. We did not have time for a full meal - we had to get back to the embarcadero before dark - so we skipped straight to desert. Kayaking and Key Lime Cheesecake - what could be better!

Key Lime Cheesecake!

Creating the Radio Sky Planisphere

Meetings of the American Astronomical Society have, for the last couple of years, included a ‘schools outreach’ event. Arecibo Observatory participated in this for the first time at the Long Beach meeting in January 2013. For that meetings we had stellar-evolution bookmarks (with graphics by +Rhys Taylor), which the students finished by putting coloured beads on a ribbon, each colour corresponding to an evolutionary stage. Unfortunately the age-range attending turned out to be somewhat older than the target range for the activity, so we didn’t want to repeat it this year. We also wanted to do something more radio-astronomy oriented (we are a radio observatory after all) and that still left the students with something they could bring home afterwards. And we wanted (if possible) to out-do the model pulsars made by the Fermi gamma-ray telescope!

Thus the Radio Sky Planisphere was born.

The idea came from my wife, who has worked in outreach, and the folks at the Visitors Center were enthusiastic, so I set about working out how to make it a reality. There were two major problems to be overcome: firstly, I needed to find out how to calculate the window shape for a planisphere; secondly I needed to get an all-sky radio map in the correct projection for a planisphere. This is the azimuthal equidistant projection, and is fairly simple to work in using polar coordinates: hour angle (or right ascension) is the angle and 90 - dec (or 90 + dec for a projection centred on the south pole) is the radius.

To make the window, I first looked about on the internet, but couldn’t find anything existing so I coded it myself in IDL. This involved solving the spherical trigonometry equations to find the declination and hour angle of the horizon. Fortunately, at the horizon many of the angles are 0 or 90 degrees, so sin and cos reduce to 0 or 1. The equations I ended up with were:

sin(Dec) = cos(Lat)*cos(Az)

cos(HA) = tan(Lat)*tan(Dec)

By sweeping around 360 degrees in Az(imuth) and inputting the Lat(itude), this meant I could solve for Dec(lination) and then for H(our) A(ngle). There were a few other complications, such as making sure I got the negative hour angle solution out as well as the positive, but this was essentially solved. I could make windows, and I could make them for any arbitrary latitude. The IDL code to do this is at http://www.naic.edu/~rminchin/idl/planisphere.pro. I also set this up so multiple windows could be printed on a single planisphere, leaving the selection of the exact latitude to the person cutting it out.

The next challenge was getting the actual map. I decided to use the 408-MHz Bonn all-sky survey (Haslam, Salter, Stoffel and Wilson, 1982) which is available via the Max Planck Institute for Radioastronomy’s surveys page at http://www3.mpifr-bonn.mpg.de/survey.html. As an added bonus, Chris Salter - the second author on the survey - works down the corridor from me at Arecibo.

This proved a bit trickier. It turned out that the ‘arc’ projection (which should be what I wanted) was actually returning a straight pixel map, but with the coordinates for the azimuthal equidistant projection! Once I realised this, I was able to download the straight pixel map and then wrote a simple IDL code to convert this into a set of radius, angle coordinate pairs for the polar projection, with a corresponding set of flux values for each coordinate. I could then use IDL’s built-in polar_contour function to plot these, using filled contours and an appropriate colour map to get the radio sky-wheel to put inside my planisphere. In order to get a good spread of colours, I used the built-in hist_equal function to get a histogram-equalized distribution of the flux values. Overall, this ends up looking very similar (except for the projection) to the colour map in Haslam et al.’s paper.

The last step was to plot on some optical sources so people could orientate themselves, and see how these correspond to the radio sky. I chose asterisms/constellations I can actually recognize, so apologies if your favourite one is missing. The ones I went with were the Plough (a.k.a. the Big Dipper) and the nearby stars of Arcturus and Polaris; Cassiopeia; Cygnus and the two other nearby stars from the summer triangle (Altair and Vega); Scorpius; the Southern Cross and Pointers (alpha and beta Centauri); Orion along with Sirius and the Pleiades star cluster; and the Large and Small Magellanic Clouds along with the bright southern star of Canopus. The stars are shown as filled circles, while the ‘fuzzy’ extended objects (Pleiades and the Magellanic Clouds) are shown as open circles. For both stars and extended objects, the diameter is proportional to 5 - magnitude (as brighter stars have lower magnitudes, this means that brighter objects are larger; a magnitude of 5 is about the limit of what is visible with the naked eye).

All that was left was to prettify what was currently rather clinical looking IDL output. I did this in Adobe Illustrator (for the planisphere body) and Photoshop (for the sky wheel). This also involved reducing the size of the sky wheel from around 50 MB for the IDL postscript output to around 500 kB for the Photoshop PDF output - it’s quite unusual for rasterizing a vector image to reduce the size, but that was certainly the case here!

The Radio Sky Planisphere was a great hit at the AAS meeting. We got far fewer schools at the actual outreach event than hoped, as the Maryland public schools were closed due to the freezing weather, but we gave out planispheres to teachers, outreach professionals, and astronomers over the remaining couple of days of the meeting and ended up getting rid of all 250 that we had brought. I also had enquiries about a southern hemisphere version, which I have now also produced.

There are now three versions available for download from Google Drive, along with a ‘Guide to the Celestial Features on the Radio Sky Planisphere’: the AAS meeting version (which can be cut to latitudes between 20 and 60 degrees north), the northern hemisphere version (5 to 65 degrees north), and the southern hemisphere version (5 to 55 degrees south). Note that all of these are sized for US Letter paper with fairly narrow margins, to match the printer we have at the observatory. If you print these yourself, you should scale them to fit your page - as the planisphere body and the sky wheel are in the same document, they should scale by the same amount so everything should still fit.

The AAS meeting version was designed to cover (to within 5 degrees) the US from Puerto Rico (or Hawaii) up to Anchorage in Alaska, therefore also taking in large swathes of the rest of the world along the way, but missing out on places closer to the equator and (of course) the whole southern hemisphere. The northern and southern hemisphere versions between them can be cut to match (to within 5 degrees) every town with a population over 10,000 on the Earth. If anyone wants one for the Antarctic, then please contact me!

Controlling the world's largest telescope with a Nexus 7

it's 5:30 in the morning, and I'm playing with my tablet. But this isn't a Candy Crush all-nighter, or even a Minecraft marathon. This is work - I'm using the tablet to observe. Via a combination of free apps from the Google Play store, I've taken control of the biggest telescope in the world, the Arecibo 305-m.

Remote observing allows observers to connect to the telescope from anywhere in the world (if they have an internet connection). People use Linux boxes, Macs, Windows PCs and, nowadays, tablets. I'm using a +Nexus 7, its high-resolution screen making it ideal for this sort of task.

To connect to the telescope, I'm using two pieces of software - an SSH  client and a VNC viewer. The first of these isn't, strictly speaking, necessary. I use it only to log in to the Arecibo Linux network and start up a VNC server, something I could do from a different computer at an earlier time. However, computers crash and there's no absolute guarantee that a VNC session started earlier will still be running, so I like to have the SSH client to hand. I use JuiceSSH, which is simple and does everything I need it to do.

The second app, the VNC client, is absolutely essential. By connecting to a VNC session running on the Arecibo system, it transforms the tablet into a remote terminal that can do (almost) anything I could do from the control room. I use the bVNC app, which supports SSH tunnelling in its free version, allowing me to connect through the gateway machine to a computer in the control room.

Once I'm in, the operator turns over control of the telescope to me, and I'm away. I can tap a source on the graphical display and bring up its information, then hit another button to send the telescope to point at that source. I can tweak the settings for the observations, or even change to a completely different observing mode. I can call up monitoring software and watch the data flow in, or even run a quick data reduction script to see if I've found anything.

This is all great fun, right up to the point where the operator says "time's up" and I have to hand the telescope over to the next user. And to think - I can do all this from the comfort of my armchair, with a computer I can hold in the palm of my hand!