Visibility workshop
From RHESSI Wiki
(Difference between revisions)
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== Introduction (by G. Hurford) == | == Introduction (by G. Hurford) == | ||
+ | |||
+ | powerpoint presentation | ||
== Imaging with Visibility (by P. Saint-Hilaire) == | == Imaging with Visibility (by P. Saint-Hilaire) == | ||
+ | |||
+ | powerpoint presentation | ||
== Visibilities on the Command Line (by P. Saint-Hilaire) == | == Visibilities on the Command Line (by P. Saint-Hilaire) == | ||
+ | |||
+ | powerpoint presentation | ||
<source lang="ittvis_idl"> | <source lang="ittvis_idl"> | ||
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</source> | </source> | ||
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+ | == Visibility Pitfalls by R. Schwartz == | ||
+ | <source lang="ittvis_idl"> | ||
+ | ;Visibilities are a Data Compression Scheme | ||
+ | ; | ||
+ | ;1. Calib_eventlist is our first data compression - away from single events to time bins | ||
+ | ; | ||
+ | ;2. Stacked eventlist is a further compression - multiple rotations are epoch folded | ||
+ | ; | ||
+ | ;3. Visibilities are a further compression by a factor of 6 to 12, (half rotations) | ||
+ | ; | ||
+ | ;4. phase & amplitude fitting is inherently linear | ||
+ | ; | ||
+ | ;5. Inherent problem is tension between number of roll bins and minimum phase requirement | ||
+ | ; in visibility determination. phase gap -> throw away varying fractions of otherwise good data | ||
+ | ; | ||
+ | ;6. Once it's in visibilities you have hidden your systematic errors | ||
+ | ; | ||
+ | ;7. Viz normalization is the default. We really need to study this | ||
+ | ; | ||
+ | ;8. For well separated sources with structure, the roll binning problem cannot be overcome for visibilities | ||
+ | ; | ||
+ | ;Let's play with visibilities | ||
+ | |||
+ | hessi_data, im=im | ||
+ | ov = im->get(/obj, class='hsi_visibility') | ||
+ | |||
+ | help, ov | ||
+ | ;Get them all | ||
+ | |||
+ | v = ov->getdata(/dump) | ||
+ | help, v,/st | ||
+ | ;Manipulate them | ||
+ | vs = v[0:99] | ||
+ | |||
+ | ;Set them back | ||
+ | vnew = ptrarr(1) | ||
+ | vnew[0]= ptr_new(vs) | ||
+ | ov->setdata, vnew | ||
+ | |||
+ | ;Look at what we have now | ||
+ | |||
+ | help, ov->getdata(/dump) | ||
+ | |||
+ | </source> | ||
+ | |||
+ | == UV Smooth and Electron Visibilities by A. Massone == | ||
+ | |||
+ | == Amir Caspi == | ||
+ | |||
== Documentation == | == Documentation == |
Revision as of 21:42, 10 August 2010
Welcome to the visibility workshop!
Please take notes and submit them to steven.d.christe@nasa.gov!
Contents |
Introduction (by G. Hurford)
powerpoint presentation
Imaging with Visibility (by P. Saint-Hilaire)
powerpoint presentation
Visibilities on the Command Line (by P. Saint-Hilaire)
powerpoint presentation
;;CODE FOR DEMO: ;RESTORE, 'visibility_bag_20021126.sav',/V RESTORE, 'visibility_bag_20021126_5min.sav',/V RESTORE, 'srctrack_20021126.sav',/V vis00=vis0 ;ss=WHERE(vis00.isc GE 7) & vis0=vis00[ss] ss=WHERE(vis00.trange[0] GE anytim('2002/11/26 20:00') AND vis00.trange[0] LE anytim('2002/11/26 22:00')) & vis0=vis00[ss] nvis=N_ELEMENTS(vis0) phase_map_center=vis0[0].xyoffset ;; reference phase_map_center to fool software with .RUN vis1='bla' FOR i=0L, nvis-1 DO BEGIN IF i MOD 1000 EQ 0 THEN PRINT, i t=get_edges(vis0[i].trange,/MEAN) newx=INTERPOL(srctrack.X, srctrack.t, t) newy=INTERPOL(srctrack.Y, srctrack.t, t) tmp=hsi_vis_shift_mapcenter(vis0[i], [newx,newy]) ;;changing the phase so that each visibility is centered on source's exact centroid position IF datatype(vis1) EQ 'STR' THEN vis1=tmp ELSE vis1=[vis1,tmp] ENDFOR;i END;.RUN vis1.xyoffset=phase_map_center ;; makes the s/w believe all the visibilities are referenced to the same xyoffset (phase_map_center) ;RESTORE,'vis1.sav',/V !P.MULTI=[0,1,3] LOADCT,5 ERRWEIGHT=0 ss=WHERE(vis0.isc NE 6 AND vis0.isc GE 3) & vis0f=hsi_vis_combine(hsi_vis_edit(vis0[ss]), ERRWEIGHT=ERRWEIGHT) uv_smooth, vis0f, map, reconstructed_map_visibilities=rmv plot_map, /LIMB, map, /ISO ss=WHERE(vis1.isc NE 6 AND vis1.isc GE 3) & vis1f=hsi_vis_combine(hsi_vis_edit(vis1[ss]), ERRWEIGHT=ERRWEIGHT) uv_smooth, vis1f, map plot_map, /LIMB, map, /ISO ;; compare vis0 (rchi2: 9.5) and vis1 (rchi2:5.8) hsi_vis_fwdfit, vis0f, CIRCLE=0, srcout=srcout, fitstddev=fitstddev
Visibility Pitfalls by R. Schwartz
;Visibilities are a Data Compression Scheme ; ;1. Calib_eventlist is our first data compression - away from single events to time bins ; ;2. Stacked eventlist is a further compression - multiple rotations are epoch folded ; ;3. Visibilities are a further compression by a factor of 6 to 12, (half rotations) ; ;4. phase & amplitude fitting is inherently linear ; ;5. Inherent problem is tension between number of roll bins and minimum phase requirement ; in visibility determination. phase gap -> throw away varying fractions of otherwise good data ; ;6. Once it's in visibilities you have hidden your systematic errors ; ;7. Viz normalization is the default. We really need to study this ; ;8. For well separated sources with structure, the roll binning problem cannot be overcome for visibilities ; ;Let's play with visibilities hessi_data, im=im ov = im->get(/obj, class='hsi_visibility') HELP, ov ;Get them all v = ov->getdata(/dump) HELP, v,/st ;Manipulate them vs = v[0:99] ;Set them back vnew = PTRARR(1) vnew[0]= PTR_NEW(vs) ov->setdata, vnew ;Look at what we have now HELP, ov->getdata(/dump)
UV Smooth and Electron Visibilities by A. Massone
Amir Caspi
Documentation
The following is a list of currently available documentation on RHESSI visibilities.
- The Visibility Documentation Guide by G. Hurford (OUT OF DATE)
- User's guide to visibilities by G. Hurford
- Visibilities How to by Andre Csillaghy
- Visibility Object The object diagram for visibilities (OUT OF DATE)
- Choosing the number of roll bins for RHESSI visibilities by G. Hurford
- Measurement and Interpretation of X-ray Visibilities with RHESSI, a poster presented at SPD 2005.
- Normalization and Visibility Clean by G. Hurford