Image of the Week

A sonification of Gaia Data

Figure 1: Score of the song: bright stars represent a high pitch, faint stars represent a low pitch Image credit: Thomas Boch (CDS)

A first sonification of Gaia data has been developed during ADASS 2018 at the hackathon. A team of engineers from the Centre de Données astronomiques de Strasbourg (CDS) and a student from the University of Maryland created "the music of light curves", an attempt to generate melodies from the light curves of Gaia Data Release 2 variable stars. The hack results can be found here on github with a PDF containing the detailed explanation. To launch the demo, click here.

Inspired by this first experiment, we decided to make Gaia stars sing to celebrate the festive season.

 

 

 
 
 

Gaia song: click on the play button to start the song. Created using Aladin Lite. You can move around the sphere to see all areas of the sky. Credit: Thomas Boch (CDS) using data from ESA/Gaia/DPAC. (There is a known issue with the sound in newer versions of the Safari browser, you can scroll down for the video version)

 

Data used

Use is made of a Gaia DR2 sample, which contains the 1000 brightest stars that have a good parallax quality. It has been retrieved from the ESA Gaia Archive running the below ADQL query. The result from the query has been retrieved as a VOTable document and is available from github as well. When checking out the sky map above, you will see that clicking on individual sources will display a popup with the Gaia data for the associated source.

 

select top 1000
ra, dec, source_id, parallax, parallax_error, pmra, pmdec, phot_g_mean_mag, phot_bp_mean_mag, phot_rp_mean_mag, radial_velocity
from gaiadr2.gaia_source
where parallax_over_error > 10
order by phot_g_mean_mag ASC

 

Assigning music notes to stars

Contrary to the music of the light curves hack, the music notes were set in advance, imposed by the song score. Thus, the aim is to find which stars play a specific note. The "Jingle Bells" score is made of 10 distinct notes: D4, E4, F#4, G4, A4, B4, C5, D5, E5, and G5. We sorted our data sample by descending magnitude (i.e. ascending brightness) and assigned the 100 first (faintest) stars to the lowest pitch note (D4), the following 100 to the second lowest pitch note (E4), and so on until the last group of 100 brightest stars are assigned the highest pitch note (G5).

 

Creating music in the browser

The Tone JS library has been used to generate sounds in the browser.

 

Background data

The background imagery is the Gaia DR2 flux map made from the 1.7 billion measurements of the table.

 

Sky map viewer

The sky map viewer is provided by Aladin Lite, an embeddable sky atlas developed at CDS able to display survey images and to superimpose catalogue data. Aladin Lite documentation explains how to embed it on a web page.

It also comes with a full-featured API allowing one to customize its interface, control the view, change the image survey to display, create catalogues and overlay layers, develop powerful interactions between a web page and Aladin Lite.

As an example, here is a page built on Aladin Lite enabling the exploration of Gaia Data Release 2 data.

 

How to make it snow!

The Snowstorm project has been used to add some snow effect and tweaked to let the snow accumulate at the bottom of the crystal ball as the song progresses.

 

Make your own song with Gaia stars!

The source code of the animation is available in this github repository by Thomas Boch. If you want to make the stars play another song, here are the detailed step-by-step instructions:

  1. Clone the repo
  2. Find a MIDI version of the song you would like to play. Midiworld.com is for example a place to search for such versions.
  3. Convert the MIDI file to a ToneJS track, using for example the MidiConvert online tool.
  4. Edit the file `data/midi-track.js` and assign the result of the previous step to a variable of your choosing, for instance:


    "var myTrack = { "header": { "PPQ": 240, "timeSignature": [ 4, 4 ], "bpm": 120, "name": "" }, ... "

  5. Open and edit file 'js/app.js' in order to update the definition of variable 'songParams' and assign myTrack as the value of 'data' attribute.
  6. You must also assign the 'trackIdx' and the 'synth' used for 'mainVoice' and possibly for the 'otherVoices'. Available synths are described in 'StarsAnimation.synths': allowed values are 'pulse', 'square', 'triangle', 'drums' and 'poly'. As an example, here is how Jingle Bells track is described:


    "var songParams = { data: jingleBells, mainVoice: {
                            trackIdx: 1, synth: 'pulse' }, otherVoices: [ { trackIdx: 4, synth: 'square' } ] };"

  7. Reload the index.html in your browser
  8. Enjoy!

 

LYRICS FOR THE SONG

To be extra festive and to wish you all "Happy Holidays", the Gaia team at ESA/ESTEC created some lyrics to go along with the song. So sing along with Gaia:

 

 

Gathering all the stars

and asteroids as well,

Gaia’s working hard

to get down all the data!

 

With DPAC on its side,

producing new releases,

Gaia’s spinning round and round

humming this new sound:

 

Jingle bells, Jingle bells,

Gaia scans the sky!

Oh what nice it is to have

a billion stars on hand.

 

Jingle bells, Jingle bells,

Gaia scans the sky!

Oh what fine it is to find

more treasures all around.

 

Changing magnitudes,

colours, brightnesses,

does it move away?

Gaia solves it all…

 

Explosions far and near,

there is no escape,

alerts are sent to the world,

scientists check them out

 

Jingle bells, Jingle bells,

Gaia scans the sky!

Oh what nice it is to have

a billion stars on hand.

 

Jingle bells, Jingle bells,

Gaia humms away...

Oh what nice it is to wish

you “Happy Holidays!"

 

Credits: ESA/Gaia/DPAC, Thomas Boch (CDS)

[Published: 21/11/2018]

 

Image of the Week Archive

2019
12/11: hypervelocity star ejected from a supermassive black hole
17/09: Instrument Development Award
08/08: 30th anniversary of Hipparcos
17/07: Whitehead Eclipse Avoidance Manoeuvre
28/06: Following up on Gaia Solar System Objects
19/06: News from the Gaia Archive
29/05: Spectroscopic variability of emission lines stars with Gaia
24/05: Evidence of new magnetic transitions in late-type stars
03/05: Atmospheric dynamics of AGB stars revealed by Gaia
25/04: Geographic contributions to DPAC
22/04: omega Centauri's lost stars
18/04: 53rd ESLAB symposium "the Gaia universe"
18/02: A river of stars
2018
21/12: Sonification of Gaia data
18/12: Gaia captures a rare FU Ori outburst
12/12: Changes in the DPAC Executive
26/11:New Very Low Mass dwarfs in Gaia data
19/11: Hypervelocity White Dwarfs in Gaia data
15/11: Hunting evolved carbon stars with Gaia RP spectra
13/11: Gaia catches the movement of the tiny galaxies surrounding the Milky Way
06/11: Secrets of the "wild duck" cluster revealed
12/10: 25 years since the initial GAIA proposal
09/10: 3rd Gaia DPAC Consortium Meeting
30/09: A new panoramic sky map of the Milky Way's Stellar Streams
25/09: Plausible home stars for interstellar object 'Oumuamua
11/09: Impressions from the IAU General Assembly
30/06: Asteroids in Gaia Data
14/06: Mapping and visualising Gaia DR2

25/04: In-depth stories on Gaia DR2

14/04: Gaia tops one trillion observations
16/03: Gaia DR2 Passbands
27/02: Triton observation campaign
11/02: Gaia Women In Science
29/01: Following-up on Gaia
2017
19/12: 4th launch anniversary
24/11: Gaia-GOSA service
27/10: German Gaia stamp in the making
19/10: Hertzsprung-russell diagram using Gaia DR1
05/10: Updated prediction to the Triton occultation campaign
04/10: 1:1 Gaia model arrives at ESAC
31/08: Close stellar encounters from the first Gaia data release
16/08: Preliminary view of the Gaia sky in colour
07/07: Chariklo stellar occultation follow-up
24/04: Gaia reveals the composition of asteroids
20/04: Extra-galactic observations with Gaia
10/04: How faint are the faintest Gaia stars?
24/03: Pulsating stars to study Galactic structures
09/02: Known exoplanetary transits in Gaia data
31/01: Successful second DPAC Consortium Meeting
2016
23/12: Interactive and statistical visualisation of Gaia DR1 with vaex
16/12: Standard uncertainties for the photometric data (in GDR1)
25/11: Signature of the rotation of the galactic bar uncovered
15/11: Successful first DR1 Workshop
27/10: Microlensing Follow-Up
21/10: Asteroid Occultation
16/09: First DR1 results
14/09: Pluto Stellar Occultation
15/06: Happy Birthday, DPAC!
10/06: 1000th run of the Initial Data Treatment system
04/05: Complementing Gaia observations of the densest sky regions
22/04: A window to Gaia - the focal plane
05/04: Hipparcos interactive data access tool
24/03: Gaia spots a sunspot
29/02: Gaia sees exploding stars next door
11/02: A new heart for the Gaia Object Generator
04/02: Searching for solar siblings with Gaia
28/01: Globular cluster colour-magnitude diagrams
21/01: Gaia resolving power estimated with Pluto and Charon
12/01: 100th First-Look Weekly Report
06/01: Gaia intersects a Perseid meteoroid
2015
18/12: Tales of two clusters retold by Gaia
11/11: Lunar transit temperature plots
06/11: Gaia's sensors scan a lunar transit
03/11: Celebrity comet spotted among Gaia's stars
09/10: The SB2 stars as seen by Gaia's RVS
02/10: The colour of Gaia's eyes
24/09: Estimating distances from parallaxes
18/09: Gaia orbit reconstruction
31/07: Asteroids all around
17/07: Gaia satellite and amateur astronomers spot one in a billion star
03/07: Counting stars with Gaia
01/07: Avionics Model test bench arrives at ESOC
28/05: Short period/faint magnitude Cepheids in the Large Magellanic Cloud
19/05: Visualising Gaia Photometric Science Alerts
09/04: Gaia honours Einstein by observing his cross
02/04: 1 April - First Look Scientists play practical joke
05/03: RR Lyrae stars in the Large Magellanic Cloud as seen by Gaia
26/02: First Gaia BP/RP deblended spectra
19/02: 13 months of GBOT Gaia observations
12/02: Added Value Interface Portal for Gaia
04/02: Gaia's potential for the discovery of circumbinary planets
26/01: DIBs in three hot stars as seen by Gaia's RVS
15/01: The Tycho-Gaia Astrometric Solution
06/01: Close encounters of the stellar kind
2014
12/12: Gaia detects microlensing event
05/12: Cat's Eye Nebula as seen by Gaia
01/12: BFOSC observation of Gaia at L2
24/11: Gaia spectra of six stars
13/11: Omega Centauri as seen by Gaia
02/10: RVS Data Processing
12/09: Gaia discovers first supernova
04/08: Gaia flag arrives at ESAC
29/07: Gaia handover
15/07: Eclipsing binaries
03/07: Asteroids at the "photo finish"
19/06: Calibration image III - Messier 51
05/06: First Gaia BP/RP and RVS spectra
02/06: Sky coverage of Gaia during commissioning
03/04: Gaia source detection
21/02: Sky-background false detections in the sky mapper
14/02: Gaia calibration images II
06/02: Gaia calibration image I
28/01: Gaia telescope light path
17/01: First star shines for Gaia
14/01: Radiation Campaign #4
06/01: Asteroid detection by Gaia
2013
17/12: Gaia in the gantry
12/12: The sky in G magnitude
05/12: Pre-launch release of spectrophotometric standard stars
28/11: From one to one billion pixels
21/11: The Hipparcos all-sky map
15/10: Gaia Sunshield Deployment Test
08/10: Initial Gaia Source List
17/09: CU1 Operations Workshop
11/09: Apsis
26/08: Gaia arrival in French Guiana
20/08: Gaia cartoons
11/07: Model Soyuz Fregat video
01/07: Acoustic Testing
21/06: SOVT
03/06: CU4 meeting #15
04/04: DPCC (CNES) 
26/03: Gaia artist impression 
11/02: Gaia payload testing  
04/01: Space flyby with Gaia-like data
2012
10/12: DPAC OR#2. Testing with Planck
05/11: Galaxy detection with Gaia
09/10: Plot of part of the GUMS-10 catalogue
23/07: "Gaia" meets at Gaia
29/06: The Sky as seen by Gaia
31/05: Panorama of BAM clean room
29/03: GREAT school results
12/03: Scanning-law movie
21/02: Astrometric microlensing and Gaia
03/02: BAM with PMTS
12/01: FPA with all the CCDs and WFSs
2011
14/12: Deployable sunshield
10/11: Earth Trojan search
21/10: First Soyuz liftoff from the French Guiana
20/09: Fast 2D image reconstruction algorithm
05/09: RVS OMA
10/08: 3D distribution of the Gaia catalogue
13/07: Dynamical Attitude Model
22/06: Gaia's view of open clusters
27/05: Accuracy of the stellar transverse velocity
13/05: Vibration test of BAM mirrors
18/04: L. Lindegren, Dr. Honoris Causa of the Observatory of Paris
19/01: Detectability of stars close to Jupiter
05/01: Delivery of the WFS flight models
2010
21/12: The 100th member of CU3
17/11: Nano-JASMINE and AGIS
27/10: Eclipsing binary light curves fitted with DPAC code
13/10: Gaia broad band photometry
28/09: Measuring stellar parameters and interstellar extinction
14/09: M1 mirror
27/08: Quest for the Sun's siblings
 
Please note: Entries from the period 2003-2010 are available in this PDF document.