Seven Steps to Calibrated Modulation Profiles

• STEP 0: INPUT LEVEL-0 PACKETS

  
  

  Select a time range.

  Input level-0 event data packets for the selected time range.

  IDL SNIPPET:

  t_start=0

  t_end=2^21 ; (binary micro sec for nominal half rotation)

  
  

• STEP 1: SCORE CREATION

  
  

  Select an energy range and a subcollimator.

  Form a score, listing individual events satisfying these criteria.

  Attribute of each event: Time 4-bytes (64 bus resolution)

  IDL SNIPPET:

  energy_edges=[50.,100.] ; ( keV)

  atten_state=0

  det_index=8 ; (0-8)

  ang_pitch=348.30 ; (asec-to be converted to microrad)

  hsi_packet2score,packet,score ; TBD as of 5/99

  
  

• STEP 2: TIME-BINNING

  
  

  Select time-binning parameterization.

  Group events in the score into time-bins with predetermined widths.

  (Special case: Each time-bin = 64 bs.)

  There should be one entry per time bin, EVEN IF NO EVENTS

  Attribute of each time-bin.

  Time: 4-bytes (64 bs resolution)

  counts: Number of events 4-bytes

  IDL SNIPPET:

  bin_length=512 ; ( binary microsec)

  counts=hsi_score2hist( score, icoll,bin_length=bin_length)

  counts=histogram(time,min=t_start,max=t_end,binsize=bin_length)

  bin_times=bin_length/2+bin_length*lindgen(n_elements(counts))

  
  

• STEP 3: ASPECT ASSOCIATION

  
  

  Associate an aspect solution with each time-bin.

  time: Time 4-bytes (64 bs resolution)

  counts: Number of events 4-bytes (counts)

  y_asp: Pitch offset 2-bytes (microradians)

  x_asp: Yaw offset 2-bytes (microradians)

  roll_angle Roll angle 4-bytes (microradians)

  IDL SNIPPET:

  aspect = Hsi_aspect_solution( time )

  x_asp=aspect.x_asp

  y_asp=aspect.y_asp

  roll_angle=aspect.roll_angle

  xy_interpolated=roll_interpolate(x_asp,y_asp, etc)

  
  

• STEP 4: LIVE-TIME ASSOCIATION

  
  

  Associate a live-time measure with each time-bin.

  The actual time of the time-bin can be dropped. It is no longer needed and in any case, can be reconstructed.

  Attribute of each time bin:

  counts: Number of events 4-bytes

  livetime: Live-time measure 2-bytes (binary fraction)

  y_asp: Pitch offset 2-bytes (microradians)

  x_asp: Yaw offset 2-bytes (microradians)

  roll_angle Roll angle 4-bytes (microradians)

  IDL snippet:

  hsi_livetime_sim, score, deadtime_sim_params,livet_ctr_str

  
  

• STEP 5: ASSOCIATE GRID CALIBRATION

  
  

  Select a map center, relative to sun center. Select desired harmonic

  of grid response. Determine the grid response matrix parameters

  associated with each time bin. (This is assumed to include

  source-location independent factors such as detector efficiency.)

  
  

  Attribute of each time bin:

  counts: Number of events 4-bytes

  livetime: Live-time measure 2-bytes (binary fraction)

  y_asp: Pitch offset 2-bytes (microradians)

  x_asp: Yaw offset 2-bytes (microradians)

  roll_angle: Roll 4-bytes (microradians)

  grm.modphz: Modulation phase 2-bytes (TBD)

  IDL snippet:

  x_map=600.

  y_map=200. ; select a map center close to flare

  ;Map-center in spacecraft coords: (Sun spins CCW as roll_angle increases.)

  x_map_sc=x_asp+X_map*cos(roll_angle)-Y_map*sin(roll_angle) ; asec

  y_map_sc=y_asp+Y_map*cos(roll_angle)+X_map*sin(roll_angle) ; asec

  R_map_sc=sqrt(x_map_sc^2+y_map_sc^2)/3600 ; convert to degrees

  azimuth_map_sc=atan(y_map_sc,x_map_sc)

  offax_position=fltarr(2,n_elements(roll_angle))

  gridtran=0*roll_angle

  modamp=gridtran

  peak_resp_offset=gridtran

  h=1 ; We'll do only the fundamental

  for i=0L,n_elements(roll_angle)-1 do begin

      offax_position=[R_map_sc[i],azimuth_map_sc[i]]

      hessi_grm, energy_edges, det_index, grm, atten_state, offax_position

      gridtran[i] = (grm.gridtran)[h-1]

      modamp[i] = (grm.modampl)[h-1]

      peak_resp_offset[i]=(grm.modphz)[h-1] ; presumably has units of ang_pitch but hessi_grm.pro doesn't say yet

  endfor

  ;peak_resp_offset will be a constant vector until Gordon updates hessi_grm

  
  

• STEP 6: DETERMINE PHASE CALIBRATION

  
  

  Combine map center, modulation phase, pitch and yaw offsets into a phase offset.

  counts: Number of events     4-bytes

  livetime: Live-time measure     2-bytes (binary fraction)

  roll_angle: Roll angle     4-bytes (microradians)

  grm.modphz: Phase offset     2-bytes (TBD)

  IDL snippet:

  nx=64L

  npixels=nx^2

  pxl_size=1.0

  ;square map of size nx X nx: (Map center is between pixels if nx is even)

  x_pixoff=pxl_size*reform((findgen(nx)-(nx-1.)/2.)#replicate(1,nx),npixels)

  y_pixoff=pxl_size*reform(replicate(1.,nx)#(findgen(nx)-(nx-1.)/2.),npixels)

  xasp=x_asp[iroll] & yasp=y_asp[iroll]

  rollangl=roll_angle[iroll] ; S/C rotates CW against sun as roll increases

  phase_map_ctr=2*!pi*h*(x_map_sc*cos(grid_angle)+y_map_sc*sin(grid_angle) + peak_resp_offset)/ang_pitch

  etc