All posts by ttfnrob

Exploring the MWP: Coordinates and SIMBAD

One of the most common questions posted on Milky Way Talk is “What is [that thing] in this image?”, and science team members try to respond to some of those where we can. The galactic plane is so incredibly rich at these infrared wavelengths and the Galaxy is so vast that even with the combined experience of the whole science team we usually don’t know the answer.

To help everyone out, we’ve created a new tool that lets you search one of the world’s best astronomical databases from within the Milky Way Project. SIMBAD is a huge astronomical database, maintained by the Centre de Données astronomiques de Strasbourg (CDS) and contains 7 million astronomical objects documented in the literature. When astronomers want to see what is known about any part of the sky, many of them start with a SIMBAD search. Our new Coordinates Tool lets you search the images from the MWP for SIMBAD data, to help show you what different objects are.

The Coordinates Tool

You access the new Coordinates Tool directly at http://www.milkywayproject.org/tools/coordinates/

This will take you to a default page, exploring the area around the coordinates 0, 0. The MWP images use the galactic coordinate system, which expresses positions in galactic latitude and longitude – concepts that should be familiar if you know about geo-coordinates here on Earth. The “equator” of the galactic coordinate system (the latitude = 0 position) is roughly coincident with the disk of the galactic plane.

Looking down on the galactic plane (Image: NASA/JPL-Caltech/R. Hurt)

In this picture, the galactic latitude tells you how much an object lies above or below the plane of the Galaxy, and the longitude specifies the angle away from the Galactic Centre. The above image shows a schematic diagram of what we think the Milky Way Galaxy looks like, with an indication of our own location and a galactic longitude grid. Galactic latitude runs from -90 to 90 degrees, and longitude from 0 to 360 degrees, although sometimes you may also see it noted as -180 to 180 degrees.

To search the area around any set of coordinates, you simply include them in the URL for example, to search one of my favourite regions, at longitude 18.4 degrees and latitude 0.2 degrees, you would visit

http://www.milkywayproject.org/tools/coordinates/19.0/0.0/

This will display one of the MWP images that containing those coordinates (see below). It will also list the other MWP images containing these coordinates. This lets you explore the region at different scales and in different contexts. The specified coordinates are shown on the image with a box. A link to the image’s Talk page is also included.

You’ll see that as you move the cursor around the image, coordinates are displayed to help you navigate. You can double click on any point to jump to that centre and see the images available. By default a small, square box is drawn onto the target area. If you want to draw a specific box you can give the width and height (in arc minutes) as URL parameters:

http://www.milkywayproject.org/tools/coordinates/19.0/0.0/?h=15&w=30&zoo_id=AMW102de6d

You can also reach the Coordinate Tool from the main Explore page. just double click on the map to just to more detail on that region. A link has also been placed on the images in the My Galaxy section of the site, for logged in users.

SIMBAD

Also present on the Coordinate Tool is a button with the words ‘SIMBAD Search’. Clicking this performs a SIMBAD search on the current viewing area and displays the results directly on the image. Here’s an example from the URL I gave above:

Any objects SIMBAD finds in the astronomical literature are displayed as circles. If,you hover your mouse over them you will see their object name and type. Clicking on these objects takes you to the objects page on the SIMBAD site, where you can find out more.

Many of the objects found in the MWP will be stars – the galaxy is full of them! – and many will be IRAS and 2MASS objects – these names derive from previous infrared surveys that mapped the regions covered by the MWP data. In the above image you can see one 2MASS object near the centre of the bubble on the right:

The SIMBAD page for 2MASS J18252813-1224187 explains that may be an Asymptotic Giant Branch (AGB) star. These objects are interesting, and there are plant of them to be found in the MWP images.

Some interesting regions that are worth a SIMBAD lookup with the tool include the rim of a broken bubble, a dying star and the pulsating heart of a gorgeous bubble.

This tool is still a bit rough around the edges, but we are keen to invite comments and ideas from anyone that would like to try it out. You can either leave comments on this blog post, or email us on team@milkywayproject.org. We have more updates on the way!

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Bubbles on the Tree

We’re often told how festive the images in the Milky Way Project look – so for the Zooniverse Advent Calendar we’ve made some festive MWP tree decorations. You can download these template PDF files (first, second, third), follow the simple instructions, and you’ll have a star-formation laden tree this year!

To create your Milky Way Project bauble, you need to cut-out each of the four images and then fold each one in half (as below).

Using a glue stick, stick the four sections together to form the bauble – remembering to insert a bit of ribbon, paper or string to hang the decoration onto the tree.

Printing the images onto good quality paper or card will produce a better result – but there you have it: citizen science on your Christmas tree!

Mapping Interestingness in our Galaxy

I’ve posted a lot lately about how we’re reducing down all your bubble drawings into one amazing catalogue of bubbles. However you also draw many other things onto the MWP image, such as green knots, red fuzzies, galaxies, star clusters and more. Unlike the bubbles, which require careful elliptical annuli to be drawn, these other objects are simply marked with an approximate box. This makes combining all of the different boxes much simpler than combining bubbles.

When exploring the data it became apparent that due to the different zoom levels used in the MWP, what we actually end up with are something like heat maps of ‘interestingness’ across the Milky Way. Users drawing on the low zoom levels draw broader, less-accurate boxes because they are constrained by low image resolution, users on the highest zoom level draw very precise images and may draw multiple regions within the same larger box. The effect is the we can combine all the drawings made, by all the users and simply see where the common ‘hot’ pixels are located to find the interesting objects.

This all becomes very with an example. Below is one of my favourite regions around 19 degrees longitude:

Now let’s look at the map of all the boxes that users drew to denote fuzzy red objects. Each user drawing is show with a little transparency, at 20% opacity. In this way, if 5 users drew over the same pixel, it will appear white.

You can see that the Milky Way Project volunteers are collectively very good at marking where the red emission lies. We can look at this result in a better, more useful way though. If we use the second image to mask the original one then we strip out the areas we aren’t interested in and just see all the fuzzy red objects. This subtraction is shown below:

Of course, users mark all sorts of interesting things in these images. So let’s take a look at this region on a per-object basis. First let’s look at the green knots – the bright green emission that shows us where there may be young stars or other star-formation activity:

You can see that the red fuzzies and the green knots often sit right next to other. Next let’s see where the dark nebulae are:

You can tell here that using a box doesn’t work so well with the dark nebulae, because they are so long and windy. This is one area where we could improve the interface for the second-generation of the Milky Way Project. Perhaps we could offer volunteers a paintbrush tool instead? Now let’s look at the star clusters:

and the galaxies (there are only two of them it seems):

There is also the ‘other’ category, designed to catch anything else:

It’s great to see that on this ‘other’ image we see a lot of the #yellowballs that were talked about on Milky Way Talk.

Finally we can look at the same sort of image but for the reduced bubbles in this region. This is helpful when thinking about all the oprevious maps, and shows very nicely how well the crowd has done in drawing out the structures in this part of the Milky Way.

We say in all our text around the site that we want you to help us measure and map the galaxy. It seems that not only are you capable of doing just that, but you do it very well! Well plan to publish full catalogue papers of all of these types of interesting objects, for the whole of the GLIMPSE survey.

Spitzer and Herschel

Yesterday was a busy one for the Milky Way Project, and for the Zooniverse. A BBC News story drove tens of thousands of visitors to the site in just a few hours. The story featured a beautiful image of RCW 120, a bubble (above) that has been described as ‘nearly perfect’ by Matthew Povich on our science team.

The story also seems to have captured the attention of Chris North at Cardiff University, who is the UK’s Herschel Outreach Officer. One of the Herschel space telescope’s first image releases was of this exact region and Chris put up a post yesterday showing how the Spitzer and Herschel views of this beautiful bubble compare.

Herschel has a bigger mirror than Spitzer and sees longer wavelengths (and thus colder material). The two observatories’ images complement each other very well. Spitzer shows fine-grained detail and structure in the ring’s edge, Herschel shows the extent of the cold dust that makes up the bulk of the region. Chris explains a bit more in his blog post about this composite image. These two observatories will no doubt be used together many times in the years to come. Spitzer’s main period of observations is over, but Herschel still has coolant and lots of planned observing time left to go.

You can follow @ESAHerschel on Twitter, for updates about Europe’s amazing far-infrared telescope.

Happy Half-Birthday

The Milky Way Project is now 6 months old, so happy half-a-versary! More than 25,000 of you have now drawn over 1.5 million objects onto our galaxy – congratulations. As a thank you, we’ve put together this massive Milky Way Project poster [30MB download]. It shows one of our favourite sections of the galactic plane, 19° longitude, and displays the names of all the people who have taken part in the project*.

Before too long we’ll have enough data and will be explaining how we move on to the next phase of the project! Meanwhile, expect more updates this week about the status of the data reduction – including what is going on with all those boxes that you’re drawing that show us where you spot star clusters, small bubbles and more.

*Names are only shown for users who gave permission for us to show their name on the Zooniverse account settings. To update your settings login to  https://www.zooniverse.org/account and update the ‘name’ field.

Green Lantern

A few months ago, gaming company Hide&Seek approached us with an idea for a Milky Way Project/Green Lantern movie tie-in. Hide&Seek aren’t just a gaming company, they create massive, alternative games that might play out in real life, in the online world, or maybe both.

Hide&Seek had spotted the obvious link between the green rings in the Milky Way project, and the mythos of the Green Lantern franchise. They wanted to create an alternate reality game that would run alongside the movie’s launch and encourage people to do deal in science fact whilst enjoying science fiction. Perfect! Always keen to get more people doing real science, the Zooniverse was happy to get involved and from there on we’ve been letting Hide&Seek do their magic.

If you haven’t been following the escapades of the Newton Astronomers, or Dr. Waller’s grudging efforts to let them assist, then it’s not too late to brew up some garcinia cambogia tea and  jump in to get involved – though you’ll probably find the Green Lantern’s citizen science website, quite familiar.

Creating a Bubble Catalogue

In recent weeks, I’ve spent much of my time figuring out how to use all of your drawings to determine where the bubbles are in the Spitzer data. About a month ago we had a breakthrough. Thanks to a lengthy conversation with MWP science guru Matthew Povich, I realised that one of the reasons it is so hard to determine where a bubble should be drawn is that sometimes there is no right answer! There are many bubbles in the MWP that people would disagree on how to draw – the reason is that there is often not necessarily a right answer to the question “where is the bubble?”.

An example of just such a bubble is shown below, with all user drawings shown next to it. You can see that this bubble just isn’t that easy to draw and that there are even two or three structures within the image that one could call a bubble. Instead of trying to make this fit a rigid one-bubble definition, we realised that we should be using the human ability to recognise patterns. After all – this is exactly what you are all so good at, and computers are sometimes not.

Myself and Matthew decided that what we should do in these instances is simply allow two (or even three) bubbles to be deemed as ‘real’. The inner, red structure is a kind of bubble, and so is the open-ended green bubble just outside of it. One could also perceive a third bubble just below and to the left of these, and many people appear to have drawn just that. (This is in addition the multitude of smaller bubbles around the edge, of course). Whatever catalogue is produced by our data reduction, it probably should include at least the first two structures if enough people drawn them.

This decision has made creating a cleaned bubble catalogue much easier. The data reduction process described in my February blog post is still the process I’m using, although it has been greatly refined. More importantly, since February an enormous number of new bubbles have been drawn and this means the averaging process produces better results. Below you can see some results of the latest efforts and hopefully you’ll agree that what is being produced is a good catalogue, based on what you have all drawn. For the sake of testing, I am using one 3-by-2 degree section of the data. This is the region +12 degrees from the galactic centre and contains several interesting and complex features – which makes it a good testing ground.

Below you can see the 3×2 degree tile on its own, with all of your 7,000+ bubbles drawn on top and with the resultant ‘cleaned’ bubbles as well. You can click on any of the images to see the full version.

I have also been looking into other techniques for extracting the bubbles as the crowd sees them. Below you can see just the raw bubble data, drawn by users for this tile. With the background removed, we can use a simple contrast ratio to create a threshold, which we use to cut-out the bubbles from the original image.

This is another method for extracting data, and although it is harder to define a rigid catalogue of bubbles using this method, it may still have use in mapping regions of star formation in our galaxy.