Документ взят из кэша поисковой машины. Адрес оригинального документа : http://star.arm.ac.uk/summerschool2012/workshop_arm.pdf Дата изменения: Thu Sep 20 19:03:01 2012 Дата индексирования: Tue Oct 2 01:37:32 2012 Кодировка: Поисковые слова: voyager

Welcome to the workshop on Downloading and Reducing Solar Remote Sensing Data
Maria Madjarska (Armagh Observatory) Your task is a study on "Multi-temperature analysis of an active region from AIA/SDO and EIS/Hinode" We will work out step by step how to proceed in your study. Step 1: Search for the Atmospheric Imaging Assembly (AIA) and EUV imaging spectrometer (EIS) data

AIA data
The possible sources for obtaining AIA data are:

1. The AIA cutout service at Lockheed http://lmsal.com/get_aia_data/ This service allows a small region from a full disk image to be extracted and downloaded.
2. From the Virtual Solar Observatory (VSO - http://sdac.virtualsolar.org/cgi/search ) We will test here the first option: Go to the link: http://lmsal.com/get_aia_data/ and enter:


Start Date: 2010-09-29 Start Time: 22:35 End Date: 2010-09-29 End Time: 22:36 Select the channels you want to have: e.g. 171 е, 211 е, 193 е, 304 е Select the region of interest or a full disk image. We will analyse data from AR 11109 in the north-west region as shown here.

Enter your name, address etc and click order (because ordering takes time, we have already downloaded the data for you). The data are in your working directory. The downloaded images are full disk images in the 171 е, 211 е and 193 е channels.

Do: IDL>$ls ; lists the content of the current directory


Wavelength and temperature response functions of the AIA telescopes
only for information
The filter response for the EUV channels can be viewed using the aia_get_response.pro procedure. The default return is a response curve as a function of wavelength: Copy and paste these commands into your SSWIDL session: chanlw_resp=aia_get_response() help,chanlw_resp,/str help, chanlw_resp.a171, /str The response function for each channel can be plotted the following way: plot, chanlw_resp.a171.wave, chanlw_resp.a171.ea, xrange=[150,200],ytitle='Effective area [cm!E2!N]', title='AIA 171 ' +STRING("305B),xtitle='wavelength ('+STRING("305B)+') plot, chanlw_resp.a193.wave, chanlw_resp.a193.ea, xrange=[160,240],ytitle='Effective area [cm!E2!N]', title='AIA 171 ' +STRING("305B),xtitle='wavelength ('+STRING("305B)+') plot, chanlw_resp.a211.wave, chanlw_resp.a211.ea, xrange=[180,240],ytitle='Effective area [cm!E2!N]', title='AIA 171 ' +STRING("305B),xtitle='wavelength ('+STRING("305B)+') You can repeat the same line for each of the other EUV channels. The temperature response can be obtained with: temp_resp = aia_get_response(/temp) help, temp_resp, /str help, temp_resp.a171, /str plot, temp_resp.a171.logte, temp_resp.a171.tresp, title='AIA 171 ' +STRING("305B) Warning: You will notice that the filters cover a wide range of temperatures and the interpretation of these images should be made with caution.


EIS data
You can obtain EIS data from: 1. The Hinode SDC Europe (Norway) http://sdc.uio.no/search/API 2. The MSSL/UCL (UK) EIS website is: http://msslxr.mssl.ucl.ac.uk:8080/SolarB/ The first website permits to view data from all instruments on Hinode at any given time which is useful for multi-instrumental studies. We will test now the data link: http://sdc.uio.no/search/API Give the date: 2010-09-29 Click on the EIS instrument as shown here if you want to view only the EIS data Click on Search The file you need is: eis_l0_20100929_223226.fits Select and retrieve Note that there are simultaneous XRT data taken of this region. We have already retrieved the file to save you time so you don't need to download the data.

You now have the data you need! We proceed towards the data reduction and analysis.


Step 2

Data reduction

s

and visualization

Step 2.1 AIA data reduction and viewing
First open a terminal and start an idl session with sswidl . Note that you need to have installed the Solarsoft (http://sohowww.nascom.nasa.gov/solarsoft/ ) on your computer with the appropriate settings. The AIA data have to be reduced: see the SDO guide for more details ( http://heawww.harvard.edu/trace/SSXG/ynsu/Ji/SDO_Data_Analysis_guide.pdf ) To make it easy, copy and paste each instruction given in red into idl: IDL> The following steps are to read, reduce and visualize an AIA image of AR 11109 in the 171 е channel. read_sdo,'ssw_cutout_20100929_223749_AIA_171_.fts',index,data ; reads the file into data array ( data) and header structure (index). You can also read a list of files in the following way: files=findfile('*ssw_cutout*.fits') then read_sdo, files, index, data Note that AIA data can be very large. If you have many full disk images you can apply this procedure: read_sdo, afiles, aindex, adata, llx, lly, nx, ny ; where (llx, lly) are the pixel positions of the lower-left corner of the required cutout and (nx, ny) is the size of the sub-field. This will reduce the size of the read area. aia_prep,index,data,index_171,data_171 ; Reduces the data and saves the output into index_171 and data_171


index2map,index_171,data_171,map_171 ; Produces from index_171 and data_171 a map_171 structure sub_map,map_171,smap_171,xr=[0,600],yr=[0,500] ; cuts the region of interest aia_lct, rr, gg, bb, wavelnth=171, /load ; loads the color table for the AIA 171 е channel plot_map,smap_171,dmin=2.,dmax=1500. ; plots the image; Change dmin and dmax to get the optimal intensity scaling of your image. You can instead of dmin and dmax, plot your image in logarithmic scale adding the keyword /log . To produce a ps and a png image do: set_plot,'ps' ; sets the output device to a poscript device device,filename='map_171.ps', /color,bits=8,/encapsulate,xs=18,ys=18 plot_map,smap_171,/log device,/close ; closes the device set_plot,'x' ; sets the output device to your screen $convert -density 160x160 map_171.ps map_171.png to convert your postcript image into png format If you have done all correct, you should get this image: Repeat this step for an image in the 211 е and 193 е channels The following step are to read, reduce and plot an AIA image of AR 11109 in the 211 е channel. read_sdo,'ssw_cutout_20100929_223726_AIA_211_.fts', index,data ; reads the file into data array ( data) and header structure (index) aia_prep,index,data,index_211,data_211 ; Reduces the data and save the output into index_211 and data_211 index2map,index_211,data_211,map_211 ; Produces from index_211 and data_211 a map_211 structure


sub_map,map_211,smap_211,xr=[0,600],yr=[0,500] aia_lct, rr, gg, bb, wavelnth=211, /load plot_map,smap_211,dmin=2.,dmax=1500. set_plot,'ps' device,filename='map_211.ps', /color,bits=8,/encapsulate,xs=18,ys=18 plot_map,smap_211,/log device,/close set_plot,'x' $convert -density 160x160 map_211.ps map_211.png If you have done all correct, you should get this image:

The following step are to read, reduce and plot an AIA image of AR 11109 in the 193 е channel: read_sdo,'ssw_cutout_20100929_223732_AIA_193_.fts',index,data aia_prep,index,data,index_193,data_193 index2map,index_193,data_193,map_193 sub_map,map_193,smap_193,xr=[0,600],yr=[0,500] aia_lct, rr, gg, bb, wavelnth=193, /load ;


plot_map,smap_193,dmin=2.,dmax=4500. set_plot,'ps' device,filename='map_193.ps', /color,bits=8,/encapsulate,xs=18,ys=18 plot_map,smap_193,/log device,/close set_plot,'x' $convert -density 160x160 map_193.ps map_193.png If you have done all correct, you should get this image:

How to produce composite image from three AIA channels?
Follow the next few steps: sz=size(smap_171.data) ; gets the size of the data array nx=sz(1) ; the size of the X axis ny=sz(2) ; the size of the Y axis


truecolorimage = bytarr(nx,ny,3) ; creates a 3-dimensional array truecolorimage[*,*,0] = bytscl(alog10(smap_171.data), max=3.9, min=1.8) ; adds the 171 channel image truecolorimage[*,*,1] = bytscl(alog10(smap_193.data), max=3.9, min=1.8) ; adds the 193 channel image truecolorimage[*,*,2] = bytscl(alog10(smap_211.data), max=3.9, min=1.8) ; adds the 211 channel image

plot_image,truecolorimage ; plots the resulting composite image The resulting image should look like this image You can experiment by changing the intensity scaling of each individual image.


Step 2.2 EIS data reduction and visualization

file_eis='eis_l0_20100929_223226.fits.gz' ; reads the file which contains the EIS data into a string array eis_prep, file_eis,/save, /quiet,/def ; data reduction and radiometric calibration in units ergs cm -2 s-1 sr-1 е
-1

The above step will produce two files: eis_ er_20100929_223226.fits (error file) and eis_ l1_20100929_223226.fits (reduced data file) Now we will produce intensity images in various spectral lines (temperatures): file='eis_l1_20100929_223226.fits' ; reads the data file dd = eis_getwindata(file) ; reads the data into an idl data structure That will open a list of the observed spectral lines you have to choose from. Each line is numbered. Type the number of the chosen line. Choose the first line 1, Fe X 184.54 е (logTmax = 6.0 K). plot,average(average(dd.int,2),2) ; plots the spectral window of the line You will notice that in some cases the spectral window contains more than one spectral line, i.e not only the line at this wavelength. Warning: The spectral window can contain a readout of the whole detector. Consult the spectral atlas (paper by P. Young et al., PASJ, 2007, v. 59, p. 857), which is on your desk. Identify the spectral line of interest and cut the spectral window from pixel lam0 to pixel lamn:


lam0=20 lamn=30 dd_fe10_184=dd.int[lam0:lamn,*,*] plot_image,average(dd_fe10_184,1),min=100,max=2500 im_fe10=average(dd_fe10_184,1) map_eis_fe10=make_map(im_fe10,xcen=dd.xcen,ycen=dd.ycen,dx=1,dy=1) ; creates a data structure using the real x-center, y-center of the image, the pixel scale in arcseconds. That helps to align with images from other instruments, e.g. AIA. plot_map,map_eis_fe10,/log ; plots the Fe X image in logarithmic scale. You can also define you own scale.

You can also use the AIA color table for the 171 е channel and later compare with an AIA 171 е image. Do to so type: aia_lct, rr, gg, bb, wavelnth=171, /load plot_map,map_eis_fe10,/log


Repeat the same steps for Fe XI 188.23+188.30 е (logTmax = 6.1 K).) (the two lines blend each other) and Fe XII 195.12 е (logTmax = 6.1 K). Repeat the same for other lines (temperatures). file='eis_l1_20100929_223226.fits' ; reads the data file dd = eis_getwindata(file) ; select the Fe XI 188.40 line, number 3 plot,average(average(dd.int,2),2) ; You see that the window contains 3 lines, 2 Fe XI and one Fe XII. Cross check with the spectral atlas. Select only the Fe XI lines. lam0=0 lamn=16 dd_fe11_188=dd.int[lam0:lamn,*,*] plot_image,average(dd_fe11_188,1),min=100,max=4500 loadct, 3 ; loads the red-temperature color table; You can also choose some of the AIA color tables like for instance the 211. im_fe11=average(dd_fe11_188,1) map_eis_fe11=make_map(im_fe11,xcen=dd.xcen,ycen=dd.ycen,dx=1,dy=1) plot_map,map_eis_fe11,dmin=100,dmax=4500 You should see this on your screen:


file='eis_l1_20100929_223226.fits' ; reads the data file dd = eis_getwindata(file) ; Fe XII 195.12 е plot,average(average(dd.int,2),2) ; there is no other line in the spectral window as you can see im_fe12=average(dd.int,1) plot_image,im_fe12,min=100,max=4500 map_eis_fe12=make_map(im_fe12,xcen=dd.xcen,ycen=dd.ycen,dx=1,dy=1) plot_map,map_eis_fe12,dmin=100,dmax=4500 You should see this on your screen:

You can try to produce a multi-color (line) image the same way as with the AIA images.

More guidance how to analyse EIS data can be found here: http://msslxr.mssl.ucl.ac.uk:8080/eiswiki/Wiki.jsp?page=EISAnalysisGuide . Feel free to contact me at madj@arm.ac.uk if you have any questions from software installation to data analysis. If I do not know the answer, I know who you can ask to help you.

Well done and enjoy the solar physics research!!!