Snapdragons population synthesis & mock survey data generation code
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Snapdragons population synthesis & mock survey data generation code Please cite the Snapdragons paper, if you use it for publications Hunt et al. 2015, MNRAS, 450, 2132

Input: N-body model. Output: Stellar data.

The code has a Makefile in the main directory, which compiles the source code in src. For anyone unfamiliar, to compile just type 'make' in the main directory

(If you want to increase MN to include more than ~9125000 N-body particle model you may need to add -mcmodel=medium after TGAS-errors.F)

(Note that the extinction maps are also available on Some people have reported problems downloading them from git-lfs)

Input in pop_synth.F is


c *** x,y,z(kpc),vx,vy,vz(km/s),metallicity(z),age(Gyr),mass(solar)

read(30,*,end=603) x_p,y_p,z_p,vx_p,vy_p,vz_p,z,tss,m_p

Output to GeneratedStars.dat or GeneratedStars.bin depending on the flag at the beginning

c *** Output to binary (1) or ASCII (0)? ***


You should also set magnitude limit up to which to generate the stars:

c *** Minimum magnitude necessary ***


  write(6,*) 'Limited to V<‘,ChosenLim

For differnt data releases, set the error parameter in the beginning of PopSynth.F Gaia end of mission -> error=1
Gaia TGAS -> error=2 Gaia TGAS (Hipparcos stars only) -> error=3 Gaia DR2 -> error=4

The Attached pop_synth.F has the full range of outputs turned on, but you can adjust that by taking out fields from the below print statement, and editing the 102 format label to show correct length.

Let me know if you can’t get it to work, or have any questions about what’s going on in there…

jason.hunt.11 (at)

Cheers, Jason

Outputs are: write(10,102) (a(j),j=1,6),(ao(j),j=1,6) & ,(ae(j),j=1,6),(p(j),j=1,2) & ,(po(j),j=1,2),(pe(j),j=1,2) & ,vgen,d_p,x_p,y_p,z_p,vx_p,vy_p,vz_p & ,mgen,GRVS,VIgen,ex31,avgen & ,avgen-aigen,z,PAge,od_p,xo_p,yo_p & ,zo_p,vxo_p,vyo_p,vzo_p,vro_p,vroto_p & ,rp,vr_p,vrot_p,rop,makms,mdkms & ,makmso,mdkmso,l_p,b_p,lo_p,bo_p & ,vl_p,vb_p,vlo_p,vbo_p & ,ugen,bgen,rgen,jgen,hgen,kgen & ,Ue,Ve,We

Which are:

1 true ra 2 true dec 3 true parallax 4 true pmra 5 true pmdec 6 true rv 7 observed ra 8 observed dec 9 observed parallax 10 observed pmra 11 observed pmdec 12 observed rv 13 ra standard deviation 14 dec standard deviation 15 parallax standard deviation 16 pmra standard deviation 17 pmdec standard deviation 18 rv standard deviation 19 G Magnitude 20 G_bp - G_rp 21 observed G Magnitude 22 observed G_bp - G_rp 23 G Magnitude Gaia standard deviation 24 G_bp - G_rp Gaia standard deviation 25 apparent V mag 26 distance from sun
27 x 28 y 29 z 30 vx 31 vy 32 vz 33 mass (solar mass) 34 G_RVS 35 V-Igen 36 extinction 37 absolute V mag 38 absolute V-i 39 metallicity z*10^6 40 Age (log10years) 41 observed distance 42 observed x 43 observed y 44 observed z 45 observed vx 46 observed vy 47 observed vz 48 observed galactocentric vr 49 observed vrot 50 galactocentric radius 51 galactocentric vr 52 vrot 53 observed galactocentric radius 54 pmra (km/s) 55 pmdec (km/s) 56 observed pmra (km/s) 57 observed pmdec (km/s) 58 l 59 b 60 observed l 61 observed b 62 vl 63 vb 64 observed vl 65 observed vb 66 u mag 67 b mag 68 r mag 69 j mag 70 h mag 71 k mag 72 Error on U 73 Error on V 74 error on W