1. Magnetic Splinter Meeting

2. ASM inter-satellite comparison

4. VFM calibration: Swarm A residual analysis in-flight determination of 18 VFM parameters, including temperature dependencies

7. Model of VFM perturbation field (responsible for ASM-VFM residuals)
Determining the Sun vector
Ecliptic Plane
Earth Spin (23.5˚)
Summer Solstice X Z
Spacecraft Quaternion
Inertial
Space
Ecliptic
Plane
Sun
Aligned
𝑣 𝑠𝑢𝑛 = 𝑞 𝑠/𝑐 −1 𝑡 ∙ 𝑀 𝐶𝐼𝑆 −1 𝑡 ∙ 𝑀 𝐸𝑂 −1 ∙ 𝑀 𝑆𝐴 −1 𝑡 ∙ 𝑛 𝑥
Sun vector in baffle
Max sun
absorption
angle
𝑣 𝑏𝑎𝑓 = 𝑟 𝜃 𝜑 = 𝑠𝑖𝑛 𝛼 0 𝑐𝑜𝑠 𝛼 𝑐𝑜𝑠 𝛼 0 −𝑠𝑖𝑛 𝛼 ∙ 𝑣 𝑠𝑢𝑛
𝛼=70°
Flight direction
Baffle Heat model
𝐵𝑎𝑓 𝑚𝑜𝑑𝑒𝑙 = 0 𝑒𝑐𝑙𝑖𝑝𝑠𝑒 0 𝜃<0 𝑠𝑖𝑛 4 𝜑 ∙ 𝑠𝑖𝑛 4 𝜃 𝑒𝑙𝑠𝑒

8. Comparing Model predictions with observations
Measurements
Simulation

9. Kursk anomaly against MF7
100 90
MF7 degree 60

10. Kursk anomaly against MF7: gradients}
100
0.2 nT 90
MF7
degree 60

11. NGDC Main field model (based on NEC data) Swarm B residuals with MF7 subtractedX Y Z
rms = 6.4 nT
rms = 12.7 nT
rms = 3.2 nT

12. BGS Field Modelling (based on NEC data)
Swarm Z misfits
Misfit statistics
Satellite
mean std dev X Y Z
Observatory X Y Z

13. Euler angle determination, 3 day, adjusted offsets
X axis looks fine
Y axis: Swarm A drifting off at about 1 arcsec/10 days
Z axis Swarm B: 25 arcsec shift. Does toroidal magnetic field change by 8 nT with altitude?

14. Field Modeling and Euler angle estimation (based on VFM + STR data)
sun lower than +10 above horizon

15. Variation of inter-boresight angle, Swarm C

16. Summary ASM-VFM perturbation VFM calibration
“empirical model” (GFZ)
“engineering model” (DTU)
Provide perturbation model predictions
Merging of the two models
ASM vector data: Provision of more data for Cal/Val activities
VFM calibration
Estimate VFM parameters using night/corrected data (ESA)
… after applying empirical correction from GFZ
… after applying “engineering model” prediction from DTU
Co-estimation of perturbation model and VFM calibration parameters
Updated L1b data with new Euler angles
Replace pre-flight values with in-flight determined (which?) ones
IGRF team needs updated L1b data by 1 August 2014 for IGRF determination
Need for more information (e.g on flags, “ASM-VFM perturbation” tasks, …)
data rejection based on which flags / thresholds
Sharing of information, coordination, documentation of data sets

18. Estimation of static Euler angles (DTU)
“dark regions”, but including “twilight data”: sun lower than +10 above horizon
SW-A
SW-B
SW-C a
1.8130 b g
9.1141
In-flight (degrees):
SW-A
SW-B
SW-C a
1.7931 b g
9.1525
Pre-flight (degrees):
SW-A
SW-B
SW-C Da
23.2
-25.1
-16.3 Db
4.6
4.9
0.2 Dg
14.6
38.8
21.1
Difference (arcsecs)

19. Estimation of static Euler angles (GFZ)
SW-A
SW-B
SW-C a
1.7727 b g
9.1799
In-flight (degrees):
SW-A
SW-B
SW-C a
1.7931 b g
9.1525
Pre-flight (degrees):