Get excited and make things with science

Last weekend, 19th & 20th June 2010, saw the first Science Hack Day at the Guardian offices in London. Jeremy Keith organised a venue, food and drink and sponsorship for around 100 people to spend two days building small science projects. Saturday morning saw a series of short talks to introduce the event,  give people some ideas of what they might make, and what tools were available to help them make it. 24 hours of hacking and building followed, with presentations and prizes for the best hacks on Sunday afternoon. Ed Gomez has a great write-up of the hack day itself, and the winning hacks. My personal favourites were the Aurorascope, which shows auroral activity by lighting up LEDs inside a ball representing the Earth, and Random Orbit, a RESTful service to track satellites in real time.

I was asked by Jeremy to give one of the talks at the beginning of the hack day, so I chatted a bit about the work we’ve done with to tag Flickr photos with their celestial locations — astrotagging.

Continue reading Get excited and make things with science

Generating astrotags for Flickr photos

In December, I talked at London Web Standards about tagging astronomy photos with position and name information. I mentioned that around 400 photos have been tagged already on Flickr but this is only a tiny fraction of the 4,900 photos that have been solved by It would be great if the remaining 4,500 photos could also be tagged, and it ought to be straightforward to generate tags for those photos too. Inspired by the iNaturalist Taxonomic Tagging Tool, I’ve written a little astrotagging form for Flickr photos.

When the robot solves a photo on Flickr, it leaves a comment identifying the coordinates of the photo and listing the names of objects in the field.

(RA, Dec) center:(82.4668973542, 6.33857270637) degrees
(RA, Dec) center (H:M:S, D:M:S):(05:29:52.055, +6:20:18.862)
Orientation:161.45 deg E of N

Pixel scale:67.93 arcsec/pixel

Parity:Reverse (“Left-handed”)
Field size :53.14 x 39.85 degrees

Your field contains:
The star Rigel (βOri)
The star Betelgeuse (αOri)
The star Aldebaran (αTau)
The star Bellatrix (γOri)
The star Alnilam (εOri)
The star Alhena (γGem)
The star Alnitak (ζOri)
The star Saiph (κOri)
The star Mintaka (δOri)
The star Cursa (βEri)
IC 2118 / IC 2118 / Witch Head nebula
NGC 1976 / NGC 1976 / Great Nebula in Orion / M 42
NGC 1990 / NGC 1990
IC 434 / IC 434 / Horsehead nebula
IC 443 / IC 443
NGC 2264 / NGC 2264 / Christmas Tree cluster / Cone nebula

View in World Wide Telescope

Posted 3 weeks ago. ( permalink | delete )

These comments are always in the same format, so it’s straightforward to parse them and extract the astrometry metadata as a list of tags. I’ve written a small form which does this, using YQL to grab the comments from a Flickr photo then parsing them using standard DOM traversal and manipulation methods.

If you have a photo which has been solved, generating tags is straightforward. Copy the address of a Flickr photo page into the tagging form and press the big blue ‘Get astrotags’ button. The script should find the comment from and print out the tags for celestial coordinates and names, which you can then paste into the ‘Add a tag’ form on Flickr.

The code to do this is fairly simple, and reproduced below. After initialising the page, we can take advantage of YQL’s HTML parser to fetch all of the comments for a Flickr photo page by selecting all paragraphs inside divs with a class of ‘comment-content’ at that URL.

select * from html where url='' and xpath='//div[@class="comment-content"]/p'

We then loop through the results of this query, looking for paragraphs which contain the text ‘blind astrometry solver’. If we have a match, we add this paragraph to the DOM so we can parse it with standard DOM methods. The code then loops through the child nodes of the comment paragraph, running regular expression matches against any text nodes it finds to extract the coordinates of the photo.

Names are slightly more tricky. For those, we grab every line of text between ‘Your field contains:’ and the line ‘—–‘ above the signature, strip out whitespace, split each line on ‘/’ to get individual names and store these in an associative array, keyed on name to remove duplicates. That done, we can then just loop through the arrays of coordinates and names and print them out.

Here’s the full code:

 var url = "";
 var comment_holder;
 var position_output;
 var names_output;
 function init() {
   var url_input = document.getElementById('photoURL');
   var url_button = document.getElementById('updateURL');
   comment_holder = document.getElementById('comment');
   position_output = document.getElementById('position');
   names_output = document.getElementById('names');
   url_input.disabled = false;
   url_input.value = url;
   url_button.disabled = false;
   position_output.disabled = false;
   names_output.disabled = false;
   addEvent(url_button, 'click', function(e) {
     return false;
   addEvent(url_input, 'focus', function(e) {;
   addEvent(position_output, 'focus', function(e) {;
   addEvent(names_output, 'focus', function(e) {;
   // Mark up nodes which this script updates as
   // ARIA live regions.
   comment_holder.setAttribute('aria-live', 'polite');
   position_output.setAttribute('aria-live', 'polite');
   names_output.setAttribute('aria-live', 'polite');

 function getFlickrPhotoComments(url) {

   // YQL query to get all comments from a Flickr photo page.
   var yql = "select * from html where url='"+url+"' and xpath='//div[@class=\"comment-content\"]/p'";
   var yql_url = ''+escape(yql)+'&format=xml&callback=getAstrometryComment&diagnostics=false';
   position_output.value = '';
   names_output.value = '';
   comment_holder.innerHTML = 'Looking up '+url;
 function makeYQLRequest(yql_url) {
   var script=document.getElementById('yqlscript');
   var newscript=document.createElement('script');
   newscript.type = 'text/javascript';

function getAstrometryComment(data) {
  var results = data.results;
  var comment = 'Sorry, that photo has not been solved by <a href=""></a>.';
  for (var i in results) {
    var text = results[i];
    // Comments left by the solver contain the text 'blind astrometry solver'.
    if(text.match(/blind astrometry solver/gi)) {
      comment = text;

function parseComment(comment) {
  var astro = {};
  var names = {};
  var parsing_names = false;
  comment_holder.innerHTML = comment;
  var children = comment_holder.firstChild.childNodes;
  for (var i in children) {
    var child = children[i];
    var text = '';
    text =;
    if (text) {
      if (text.match(/(RA, Dec)/g) && text.match(/degrees/g)) {
        astro.RA = text[0];
        astro.Dec = text[1];
      } else if (text.match(/Orientation/g)) {
        text = text.match(/[-0-9\.]+/g);
        astro.orientation = text[0];
      } else if (text.match(/Pixel scale/g)) {
        text = text.match(/[0-9\.]+/g);
        astro.pixelScale = text[0];
      } else if(text.match(/Field size/g)) {
        text = text.match(/[0-9\.]+ x [0-9\.]+ (degrees|arcminutes|arcseconds)/g);
        astro.fieldsize = text[0];
      } else if(text.match(/Your field contains:/g)) {
        parsing_names = true;
      } else if (text.match(/-----/g)) {
        parsing_names = false;

      if (parsing_names) {
        names = addNames(names, text);

  if (astro.RA) {

function addNames(names, text) {
 text = trim(text);
 text = text.split('/');
 for (var j in text) {
   var name = text[j];
   name = trim(name);
   if (name && name !='Your field contains:'){
     names[name] = name;
 return names;

function renderPositionTags(astro) {
  position_output.value = '';
   for (var tag in astro) {
     position_output.value += 'astro:'+tag+'="'+astro[tag]+'" ';

function renderNameTags(names) {

  names_output.value = '';
   for (var name in names) {
     names_output.value += 'astro:name="'+name+'" '

function trim(text) {
  // Trim leading and trailing whitespace from a string.
  text = text.replace(/^\s+/, '');
  text = text.replace(/\s+$/,'');
  return text;

function addEvent(obj, evType, fn) {
  if (obj.addEventListener) {
    obj.addEventListener(evType, fn, false);
    return true;
  } else if (obj.attachEvent) {
    return r;
  } else {
    return false;

Searching astro:name with YQL







select * from where astro_name = 'M 31'


select * from where text = 'orion'


London web standards: Introducing astrotags

Here are the slides from my talk at the December LWS meetup – Introducing astrotags: astrometry, machine tags and YQL (20MB pdf). The examples and demos should all be in the YQL category on this blog.

If you’re interested in the nuts and bolts of the automated astrometry robot, I recommend having a look at and reading Making the sky searchable: Fast geometric hashing for automated astrometry.

Look out honey cos I’m using technology




// of the nmsi.cosmosculture YQL table definition.
var env = '';
var yql = "select * from nmsi.cosmosculture";
// Example alternate query - fetch everything linked to the Moon

// Specify JSON as the return format.

// Set a canvas for Raphael to draw on.
var height = 600;
var width = 800;

var startx = 0;
var starty = 0;
var dragging = false;
var draggedSet = null;

$.getJSON(url, function(json){
	var items = json.query.results.MuseumObject;
// Loop through the items array
// Ignore items which don't have a photo
			var src = item.Image.Source;
// The smallest available image size is 'Inline'.
			src = ''+src;
// Generate a random x,y position for the photo
// Generate a random angle between 350 and 10 degrees.
 			var rot = 10*Math.random();
 				var s = paper.set();
// Rotate the set by our random angle
// Otherwise, bring to the front and store the mouse
// coordinates for future use. {
 					if (dragging) {
 					}else {
 						dragging = true;
 						startx = e.clientX;
 						starty = e.clientY;
 						draggedSet = s;
// Listen for mouse movement on the document.
// If dragging, move the dragged set to the
// x,y coordinates of the mouse.
// Store the current coordinates for the start
// of the next move.
 				document.onmousemove = function(e){
 					if(dragging) {
 						dx = e.clientX - startx;
 						dy = e.clientY - starty;

 							var node = draggedSet[j];

 						startx = e.clientX;
 						starty = e.clientY;

Science Museum Cosmic Collections competition



use "";
select * from nmsi.cosmosculture

Try it

or retrieve an individual item, given the accession number:

use "";

Try it


use "";
select * from nmsi.cosmosculture
where LinkedPlaces.Place.PlaceName like '%Italy%'

Try it


YQL updates for nmm.collections



select * from
Try it


select * from nmm.collections.authorities
where authority = 'vessels' and title = 'Aquitania'
Try it


select * from
where searchterm='' and (authority,category) in
(select authority,id from nmm.collections.authorities
Try it


Searching the sky with YQL Execute




Demo URL:

Example queries

The Carina Nebula

        select * from
        where ra > 155 and ra < 165
        and dec > -65 and dec < -55

The Orion Nebula and surroundings

        select * from
        where ra > 70 and ra < 100
        and dec > -20 and dec < 10

Get lots of photos of Orion (may be slow)

        select * from,200)
        where ra > 70 and ra < 100
        and dec > -20 and dec < 10

Find nebulae from the New General Catalogue (names beginning NGC)

      select * from
      where name like 'NGC%'

Find nebulae from the Messier catalogue (names beginning with M )

      where name like 'M %'

Find all photos of the Rosette nebula

      select * from,200)
        where name = 'Rosette nebula'

Explicitly declare all the table columns


Building a KML feed with YQL and coldfusion




Continue reading Building a KML feed with YQL and coldfusion