Performance in near-IR

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0.5um     1.26e-6
0.63um    1.12e-6
0.79um   8.19e-7
1um       5.15e-7
1.26um   2.9e-7
1.58um   1.5e-7
2um       7.27e-8

Assuming H band, 1.65 um, 20% wide band.
At 1.65um, zero point magnitude = 115e-11 W.m-2.um
2.4m telescope: diffraction limit at 1.65um = 0.142"
Zodi contribution over diffraction spot = 7.09e-20 W.m-2 um
Zodi = star for mH=25.5

Note: same computation for V band gives mV=29.32

• There is a calibration floor of 2.5 uas per star
• Stars fainter than the zodi limit are excluded
• The precision is 2x photon noise limit

Relative precision ratio between H and V band, equal magnitude. Both assume same bandwidth (20%).
PSF size: x 0.303 
Photon noise: x sqrt(0.355) = x 0.596

Overall: factor 30 = 3.7 mag
-> a mH = 20.0 star offers the same astrometric precision as a mV = 23.7 star

Astrometric accuracy per star:
mH=10.0 : 0.1 uas
10 mag -> factor 100
accuracy = 0.1 uas 1.585^(mH-10.0)

awk '{if(($8>15.0)&&($8<18.0)) print $8}' Sources.1degrad.H.txt | sort | awk '{print NR,$1,sqrt(2.5*2.5+(0.2*1.585**($1-10.0))*(0.2*1.585**($1-10.0)))}' | awk '{a=a+1.0/($3*$3); print $0,sqrt(1/a)}' > SourcesH.txt

ASTROMETRIC ACCURACY, 1 SQ DEG

mH range	accuracy [uas]  #sources/sq deg

10-11	0.40891		  38
11-12	0.27721		  86
12-13	0.21021		 151
13-14	0.174132	 241
14-15	0.150903	 391
15-16	0.133318	 721
16-17	0.12757		1413
17-18	0.116261	3546
18-19	0.123128	6938  # incomplete
19-20	0.44229		 989  # incomplete

Correcting for incompleteness, assuming each magnitude bin has 2.5x as many sources as the previous magnitude bin, each faint magnitude bin contributes at the 0.11 uas level.
Up to bin mH=24-25 (above zodi level).

Overall astrometric accuracy, counting from mH=15 to mH=25: 0.03505 uas for 1 sq deg
With 0.3 sq deg FOV -> 0.064 uas