These two months in NCT project Jeng-Lun Chiu (Alan) Department of Physics, NTHU / SSL, UCB 2007/03/20 NTHU HEAG meeting

Outline Magnetic declination survey Magnetic declination survey Ground Support Equipment (GSE) Ground Support Equipment (GSE) PIXON algorithm PIXON algorithm Future work Future work

Magnetic declination survey Magnetic declination angle = Magnetic declination angle = the horizontal angle between true north and the field vector (measured positive eastwards) Pointing & Aspect – magnetometer Pointing & Aspect – magnetometer Position feedback Position feedback Field vector (magnetic north pole) + magnetic declination angle [model]  true north pole (position feedback for motor) Field vector (magnetic north pole) + magnetic declination angle [model]  true north pole (position feedback for motor)

Alice Springs 23˚ 37’12” S 133˚ 55’12” E Fort Sumner ˚ N, ˚ W

Quadratic approach -- Method Adopted in the previous flight Adopted in the previous flight Altitude & Latitude: linear fit Altitude & Latitude: linear fit Longitude: Quadratic fit Longitude: Quadratic fit D = a + bL + cL 2 D = a + bL + cL 2  [D] = k[L]  k = [D][L] -1  [D] = k[L]  k = [D][L] -1 2 elevations x 2 latitudes x 3 longitudes  12 points 2 elevations x 2 latitudes x 3 longitudes  12 points Interpolation Interpolation

Quadratic approach -- Result Previous Fort Sumner, NM, USA Previous Fort Sumner, NM, USA ( ˚ N, ˚ W) ( ˚ N, ˚ W) May 1, 2004 (assumed in calculation) May 1, 2004 (assumed in calculation) 2x2x3 points within 0~50 km & 32~36˚ N & 96~112˚ W 2x2x3 points within 0~50 km & 32~36˚ N & 96~112˚ W  Error in Dec.: ΔD = +0.02˚ ~ -0.01˚ (OK!!) Next Alice Springs, Aus. Next Alice Springs, Aus. (23˚ 37 ’ 12 ” S, 133˚ 55 ’ 12 ” E) (23˚ 37 ’ 12 ” S, 133˚ 55 ’ 12 ” E) Dec. 1, 2008 Dec. 1, x2x3 points within 0~50 km & 21~25˚ S & 113~153˚ E (with 5,10,20˚ steps in longitude) 2x2x3 points within 0~50 km & 21~25˚ S & 113~153˚ E (with 5,10,20˚ steps in longitude)  Error in Dec.: ΔD ~ 20”, 1’, 7’ Note: accuracy for D in model is claimed to be within 30 ”

Alice Springs 23˚ 37’12” S 133˚ 55’12” E Fort Sumner ˚ N, ˚ W

Earth’s magnetic field The main field generated in Earth ’ s conducting, fluid outer core (Bm) The main field generated in Earth ’ s conducting, fluid outer core (Bm) The crustal field from Earth ’ s crust/upper mantle (Bc) The crustal field from Earth ’ s crust/upper mantle (Bc) The combined disturbance field from electrical currents flowing in the upper atmosphere and magnetosphere, which also induce electrical currents in the sea and the ground (Bd) The combined disturbance field from electrical currents flowing in the upper atmosphere and magnetosphere, which also induce electrical currents in the sea and the ground (Bd)

Earth's main magnetic field dominates, accounting for over 95% of the field strength at the Earth ’ s surface. Earth's main magnetic field dominates, accounting for over 95% of the field strength at the Earth ’ s surface. The WMM represents only the main geomagnetic field. The WMM represents only the main geomagnetic field. Secular variation is the slow change in time of the main magnetic field. Secular variation is the slow change in time of the main magnetic field. Observed magnetic field is a sum of contributions: Observed magnetic field is a sum of contributions: B(r, t) = Bm(r, t) + Bc(r) + Bd(r, t)

World Magnetic Model (WMM) Producer -- The U.S. National Geophysical Data Center (NGDC) and the British Geological Survey (BGS) produced the WMM with funding provided by National Geospatial-Intelligence Agency (NGA) in the USA and by the Defence Geographic Imagery and Intelligence Agency (DGIA) in the UK. Producer -- The U.S. National Geophysical Data Center (NGDC) and the British Geological Survey (BGS) produced the WMM with funding provided by National Geospatial-Intelligence Agency (NGA) in the USA and by the Defence Geographic Imagery and Intelligence Agency (DGIA) in the UK.NGDCBGSNGDCBGS Data -- (Danish Oersted and German CHAMP ) satellite (good global coverage & low noise level ) and (ground) observatory (hourly mean data) data provide an exceptional quality data set for modeling the behavior of the main magnetic field in space and time. Data -- (Danish Oersted and German CHAMP ) satellite (good global coverage & low noise level ) and (ground) observatory (hourly mean data) data provide an exceptional quality data set for modeling the behavior of the main magnetic field in space and time.OerstedCHAMPOerstedCHAMP Model -- The WMM consists of a degree and order 12 spherical-harmonic main (i.e., core-generated) field model. Model -- The WMM consists of a degree and order 12 spherical-harmonic main (i.e., core-generated) field model. ( comprised of 168 spherical-harmonic Gauss coefficients and degree and order 12 spherical-harmonic Secular-Variation (SV) (core-generated, slow temporal variation) field model (determined to degree and order 8) ) ( comprised of 168 spherical-harmonic Gauss coefficients and degree and order 12 spherical-harmonic Secular-Variation (SV) (core-generated, slow temporal variation) field model (determined to degree and order 8) )

Input parameters & valid entries: Input parameters & valid entries: Latitude to degrees Longitude to degrees Altitude Sea level to 1,000,000 meters (referenced to the WGS 84 ellipsoid) Date Base epoch of the current model to epoch + 5 yearsLatitude to degrees Longitude to degrees Altitude Sea level to 1,000,000 meters (referenced to the WGS 84 ellipsoid) Date Base epoch of the current model to epoch + 5 years Output -- seven magnetic components: Output -- seven magnetic components: F - Total Intensity of the geomagnetic field H - Horizontal Intensity of the geomagnetic field X - North Component of the geomagnetic field Y - East Component of the geomagnetic field Z - Vertical Component of the geomagnetic field I (DIP) - Geomagnetic Inclination D (DEC) - Geomagnetic Declination (Magnetic Variation)F - Total Intensity of the geomagnetic field H - Horizontal Intensity of the geomagnetic field X - North Component of the geomagnetic field Y - East Component of the geomagnetic field Z - Vertical Component of the geomagnetic field I (DIP) - Geomagnetic Inclination D (DEC) - Geomagnetic Declination (Magnetic Variation) At given (h, φ, λ, t) (h: geodetic altitude; φ and λ: geodetic latitude and longitude; t: time in decimal year) 1. the ellipsoidal geodetic coordinates (h, φ, λ)  spherical geocentric coordinates (r, φ´, λ) 1. the ellipsoidal geodetic coordinates (h, φ, λ)  spherical geocentric coordinates (r, φ´, λ) 2. Determine the Gauss coefficients of degree n and order m for the desired time 2. Determine the Gauss coefficients of degree n and order m for the desired time 3. Compute the field vector components X´, Y´ and Z´ in geocentric coordinates 3. Compute the field vector components X´, Y´ and Z´ in geocentric coordinates 4. the geocentric vector components X´, Y´ and Z´ are transformed back into the geodetic reference frame, 4. the geocentric vector components X´, Y´ and Z´ are transformed back into the geodetic reference frame, 5. the magnetic elements H, F, D, I, and the grid variation, GV, are computed from the vector components 5. the magnetic elements H, F, D, I, and the grid variation, GV, are computed from the vector components

Certain local, regional, and temporal magnetic declination anomalies can exceed 10˚ (not common but do exist). Certain local, regional, and temporal magnetic declination anomalies can exceed 10˚ (not common but do exist). Declination anomalies of the order of 3˚ or 4˚ are not uncommon but are of small spatial extent and are relatively isolated. Declination anomalies of the order of 3˚ or 4˚ are not uncommon but are of small spatial extent and are relatively isolated. From a global main field perspective, the declination error of WMM2005 is estimated to be less than 1.0˚ at the Earth ’ s surface over the entire 5-year life span of the model. From a global main field perspective, the declination error of WMM2005 is estimated to be less than 1.0˚ at the Earth ’ s surface over the entire 5-year life span of the model. (< 30 ” ) (< 30 ” )

Differential GPS Minimize dependence on magnetic effects Minimize dependence on magnetic effects Earth ’ s magnetic field variationsEarth ’ s magnetic field variations Gondola currentsGondola currents (~ Steve Mcbride 2005 NCT workshop) (~ Steve Mcbride 2005 NCT workshop)

Ground Support Equipment (GSE) Linux with X window for display Main Window Main Window Detector Rates Detector Rates Other Rates Other Rates (Shield rates, ) (Shield rates, Date rate history, Detector Livetimes) Card Cage Housekeeping Data Card Cage Housekeeping Data GCU Housekeeping Data GCU Housekeeping Data Command Window Command Window Pointing Display Pointing Display Spectrum Display Spectrum Display Pixel Display Pixel Display Imaging Display Imaging Display ~ S. McBride 2005 NCT workshop

GSE -- Telemetry format For NCT frame 1 frame = 80 words = 160 bytes = 1280 bits Starting with ‘ EB90h ’ in each frame from GCU to UHF Starting with ‘ EB90h ’ in each frame from GCU to UHF Starting with ‘ E0AEh ’ in each frame for events Starting with ‘ E0AEh ’ in each frame for events 1 board contains 8x2 units with 4 channels each (8x2x5) for 37x2 output 1 board contains 8x2 units with 4 channels each (8x2x5) for 37x2 output Transmission rate for telemetry = 64,000 bits/sec Transmission rate for telemetry = 64,000 bits/sec = 50 frames/sec = 50 frames/sec ~ S. McBride 2005 NCT workshop

GSE – my status Understanding the programs and data format Understanding the programs and data format Going to know about the either net, flight computer, and card cages to make a newer version GSE code for next flight Going to know about the either net, flight computer, and card cages to make a newer version GSE code for next flight

PIXON

Bayes’ Theorem: p(A,B) = p(A|B)p(B) = p(B|A)p(A) (PP93) ( p(X,Y): the joint probability distribution. ) (Puetter 1996) ( p(X|Y): the probability of X given that the value of Y is known. ) PIXON: (1). A picture element (2). A fundamental unit of information in the image. The smallest groupings of signal warranted by the quality of the data, and they are fundamental and indivisible units of picture information. An image’s pixon represent the minimum set of degrees of freedom necessary to describe the image. (PP93)

PIXON

PIXON – my status Drawing the back-projection histogram by ROOT Drawing the back-projection histogram by ROOT Trying to complete the back projection part in Andrea ’ s practice program for imaging Trying to complete the back projection part in Andrea ’ s practice program for imaging

Pointing & Aspect (III): Alan, (Boggs) Pointing & Aspect (III): Alan, (Boggs) pointing calculations (GSU & GSE) pointing calculations (GSU & GSE) pointing program pointing program magentometer/inclinometer aspect magentometer/inclinometer aspect dGPS aspect dGPS aspect solar aspect solar aspect elevation, azimuth drive testing elevation, azimuth drive testing pointing tests pointing tests flight aspect database flight aspect database Data Archiving (II): Andreas, Alan Data Archiving (II): Andreas, Alan cataloguing cataloguing data summaries data summaries storage storage GSE (III): Mark, Alan, (McBride) GSE (III): Mark, Alan, (McBride) flight GSE upgrades flight GSE upgrades card cage GSE card cage GSE commanding commanding LOS telemetry LOS telemetry

Reference Presentations in NCT NTHU in 2005/11. Presentations in NCT NTHU in 2005/11. R. C. Puetter & A. Yahil, in Astronomical Data Analysis Software and Systems VIII, D. M. Mehringer, R. L. Plante & D. A. Roberts, eds., ASP Conference Series, 172, pp , (1999). R. C. Puetter & A. Yahil, in Astronomical Data Analysis Software and Systems VIII, D. M. Mehringer, R. L. Plante & D. A. Roberts, eds., ASP Conference Series, 172, pp , (1999). (The Pixon PAGE in UCSD) (The Pixon PAGE in UCSD) (The PIXON (The PIXON

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