Now, this is summat that's always tricky to find concise info on, it
often being spread all over the place etc, and of mixed veracity.

I culled some data sources to give a little crib sheet some time ago,
and below is the result. Cut and paste the tdf bit into notepad first
and save in Guide directory as OBass.tdf then do the same with the
data file, call it obass.dat and also save in Guide directory, dirty
great big blue name labelled ellipses for this one, with help about
distance modulus (m-M), number of stars, probable distance in
kiloparsecs, stuff like that by right clicking on the central blue
plus symbol, but no "more info" as it ain't really needed.

Default is labels on, and also visible in Guide in wide fields of up
to 20 degrees so you can see where they are, though still wider fields
might be preferred, just use the DISPLAY button in the help box.

Sorted on Galactic longitude.

Not all OB Associations are believed real by all professionals, but
the vast majority of these should be fine. Feel free to adapt or
modify tdf to taste.

Cheers

John

------tdf starts next line----------
file obass.dat
title OB Associations
RA H 10 5
units0 -2
de d 16 5
text 1 8
~c 1 8 %s\n
~c 32 4 m-M %s\n
~c 37 4 %s kpc\n
~c 42 3 %s stars\n

epoch -1
type sCff8306;+10;
field 0 200
shown 1
end

file obass.dat
title OB Associations
RA H 10 5
units0 -2
de d 16 5
sizm 22 4
siz2 27 4
resize 2

epoch -1
type 7
type sCff8306;
field 0 200
shown 1
end
---------tdf ended previous line-----------


--data starts next line, cut & paste as obass.dat in Guide dir---
SGR OB5 0.2 -1.2 162 318 12.4 3.02 34
SGR OB1 9.0 -0.6 600 240 11.0 1.58 67
SGR OB7 10.7 -1.5 18 24 11.2 1.74 4
SGR OB4 12.0 -1.0 90 54 11.9 2.40 16
SGR OB6 13.9 1.3 84 30 11.5 2.00 5
SER OB1 16.5 0.0 300 180 11.4 1.91 47
SCT OB3 17.4 -0.7 78 90 11.1 1.66 10
SER OB2 18.6 1.7 66 72 11.5 2.00 19
SCT OB2 23.0 -0.6 360 258 11.5 2.00 13
VUL OB1 60.3 -0.1 144 162 11.5 2.00 19
VUL OB4 60.5 0.5 180 420 10.0 1.00 10
CYG OB3 72.6 2.3 150 132 11.8 2.29 45
CYG OB1 75.5 1.1 180 204 11.3 1.82 73
CYG OB8 77.8 3.8 174 198 11.8 2.29 23
CYG OB9 78.0 1.5 120 84 10.4 1.20 33
CYG OB2 80.4 1.0 42 36 11.3 1.82 15
CYG OB4 82.5 -7.3 180 120 10.0 1.00 5
CYG OB7 90.0 2.0 720 834 9.5 0.79 29
LAC OB1 97.0 -17.1 120 186 8.9 0.60 2
CEP OB2 102.5 5.6 660 798 9.8 0.91 62
CEP OB1 103.0 -1.8 600 138 12.7 3.47 55
CEP OB5 108.5 -2.7 18 54 11.6 2.09 6
CEP OB3 111.2 3.8 210 174 9.7 0.87 27
CAS OB2 112.1 0.2 234 186 12.1 2.63 40
CAS OB5 116.5 -0.6 186 222 12.0 2.51 53
CEP OB4 118.0 5.2 72 156 9.6 0.83 8
CAS OB4 120.3 0.0 156 246 12.3 2.88 28
CAS OB14 120.4 0.6 84 228 10.2 1.10 8
CAS OB7 123.5 1.7 210 210 12.0 2.51 41
CAS OB1 124.1 -1.3 210 114 12.0 2.51 11
CAS OB8 129.5 -0.9 30 78 12.3 2.88 44
PER OB1 134.0 -3.8 240 150 11.8 2.29 174
CAS OB6 135.9 1.4 252 198 11.7 2.19 46
CAM OB1 142.5 2.0 1020 600 10.0 1.00 55
PER OB3 147.0 -1.1 600 612 6.2 0.17 1
CAM OB3 147.0 3.0 84 114 12.6 3.31 8
PER OB2 159.3 -17.2 342 498 8.0 0.40 7
AUR OB1 173.1 -1.6 600 696 10.6 1.32 36
AUR OB2 173.0 0.1 120 228 12.4 3.02 21
GEM OB1 189.1 1.0 204 378 10.9 1.51 41
MON OB1 203.0 0.0 840 300 9.3 0.72 7
ORI OB1 206.0 -19.0 960 720 8.5 0.50 73
MON OB2 207.0 -1.0 240 210 10.9 1.51 30
MON OB3 217.3 -0.5 150 60 4
CMA OB1 224.0 -1.4 240 246 10.6 1.32 17
PUP OB1 244.0 0.5 240 180 12.0 2.51 24
PUP OB2 244.0 1.0 240 120 13.0 3.98 13
PUP OB3 254.0 -0.3 120 90 11.3 1.82 3
VEL OB1 265.0 -0.7 360 246 11.3 1.82 54
VEL OB2 263.5 -7.3 60 90 8.5 0.50 13
CAR OB1 286.3 -0.7 246 186 12.0 2.51 127
CAR OB2 290.2 0.5 120 132 11.7 2.19 64
CRU OB1 294.7 -1.1 144 150 12.0 2.51 84
CEN OB1 304.0 0.8 282 288 11.9 2.40 102
CIR OB1 316.0 -1.0 120 120 12.0 2.51 5
NOR OB1 328.1 -1.0 90 30 12.7 3.47 8
ARAOB1A 338.0 0.0 360 360 10.7 1.38 58
ARAOB1B 338.0 0.0 360 360 12.7 3.47 23
SCO OB1 343.8 1.5 150 84 11.4 1.91 75
SCO OB2 350.1 17.3 354 660 6.0 0.16 10
SCO OB4 352.8 3.2 90 90 10.4 1.20 11
-----data file ended previous line-------