2. Finding and downloading IRIS-SDO-Hinode co-aligned data cubes

2.1. Using the IRIS Webpage (HCR)

Co-aligned IRIS, SDO and Hinode data cubes can be found using the IRIS search webpage (http://iris.lmsal.com/search). The detailed description of the search engine and how to use it is provided in ITN 26. Briefly, it consists of several selection widgets that allow the user to specify the time range of interest, and filter the results returned by the search engine. Among other options, the filter options include the cadence, target region, exposure time, type of rasters and slit-jaw images. The latest version of the search engine introduces the option to find all IRIS observations for which co-aligned SDO or Hinode data cubes are available by simply checking the appropriate option buttons. These buttons are shown below, highlighted with the red box and the magnified region. They are normally hidden under the “More” button, which opens up to provide more options when clicked. After the user set up the search parameters, clicking on the search button will populate the right panel with observations that match the search criteria, which for this tutorial we restricted to IRIS observations with co-aligned data cubes. Finally, selecting the observation of interest in the right panel, the bottom table is updated. In the right column of that table are links to the co-aligned data cubes.


The IRIS search webpage where search options for SDO and Hinode co-aligned data cubes are selected (red box).

2.2. Using SSWIDL

SDO/AIA and Hinode/SOT level 2 data co-aligned with a given IRIS observational sequence can be retrieved using IRIS SolarSoft package. Before we request the data cubes, we should check their availability using the following SSW IDL command (this requires IDL 8.2 or greater):

IDL> hcr=iris_time2hcr('1-jul-2015','1-sep-2015',/expand_eventid,limit=2000,/struct)

The first two arguments in the upper command define the time range within which we want to search for data cubes. In this particular case, the search is performed for a period of two months, between 2015 July 1 and 2015 September 1. The optional keyword /struct implies that the resulting variable hcr will be returned as an IDL structure of 2000 return elements as defined by the keywords /expand_eventid and limit=2000. The most important tag names contained in hcr are:

  • PARENTURL - gives the urls for the IRIS level 2 FITS files;
  • SDO_SSW_JOBID - provides job IDs of SDO cutouts, also used as input parameter in various IRIS SolarSoft routines;
  • URL_SOTSP_CUBES - the urls for the Hinode/SOT SP level 2 data cubes (when available);
  • URL_SOT_CUBES - the urls for other available SOT level 2 data;
  • MARTINAIA_COMPURL - the urls for SDO data sets;
  • STARTTIME - starting time of IRIS observational sequence;
  • STOPTIME - ending time of IRIS observation;
  • OBSID - OBS ID for IRIS observational sequence;
  • SCIOBJECTIVES - Scientific goals defined by the corresponding HOP and/or IHOP;
  • EVENTID - contains event ID, also used to create link to HCR Event web page;
  • UMODES - IRIS unique observational modes executed for a given OBS ID;
  • TARGET - target region on the Sun.

Using the standard IDL routine where, one can now select observations that contain only SDO/AIA or Hinode/SOT data cubes overlapping with IRIS measurements. Let us, for example, find only SDO/AIA and IRIS co-aligned data. The IDL command would look like this:

IDL> fg=where(hcr.martinaia_compurl ne '!NULL')

In case we want to extract observations that also have Hinode/SOT measurements, we can obtain it this way:

IDL> fg=where(hcr.martinaia_compurl ne '!NULL' and hcr.url_sot_cubes ne '!NULL')

here fg contains the subscripts of the hcr structure corresponding to the selected observations:

IDL> print, hcr[fg].full_obsid

This gives us all data cubes from July 1 to September 1 of 2015 that have coordinated and co-aligned IRIS, SDO/AIA, and Hinode/SOT observations. For demonstration purpose, we will proceed using the observational sequence whit an index of 85 and full IRIS OBSID = 20150805_110921_3860109380.


Since new data sets are regularly being generated and/or updated, the OBSID list and indices may change.

More information on this particular dataset, such as start time, scientific objective or target for example, can be extracted using the following command:

IDL> info=get_infox(hcr[fg[85]], 'starttime, sciobjectives, target', /more)
2015-08-05 11:09:21 AR12394 tracking, with Hinode AR

Before we explain how to obtain links to the data and download them, we can get more familiar with the measurements visiting its HCR web page. The URL can easily be obtained using:

IDL> print,ssw_hcr_make_query(eventid=hcr[fg[85]].eventid)

The link points to a web page where we can see details of the corresponding IRIS observational run. On the right side of the page, there is a section called “Co-aligned data” which contains links to the SOT/FG and AIA data cubes (red box). Clicking the links automatically initiates downloading of the corresponding co-aligned datasets.


Upper part of the HCR web page for IRIS observation with OBSID 20150805_110921_3860109380. The red box on the right side shows the link to SOT/FG and AIA FITS files.

In addition, there are four AIA thumbnails at the bottom of the same page. They link to their associated quick-look movies (QLM) giving insights on AIA co-aligned filtergrams.


Bottom part of the HCR web page for IRIS observation with OBSID 20150805_110921_3860109380. The red box indicates the link to all AIA quick-look movies.

The rest of the AIA QLMs can be accessed following the link “SSW page” enclosed by the red box. Some of these AIA QLMs are presented here:


Examples of AIA quick-look movies located at SSW web page for SDO cutouts co-aligned with IRIS OBSID 20150805_110921_3860109380 measurements. The figure shows four of seven available movies.

After getting familiar with the IRIS and SDO/AIA datasets, we can proceed with the download. As already mentioned, the data can be downloaded directly from the associated HCR pages. However, there are two more alternatives. One of them is using SolarSoft commands through which we can obtain URLs to the IRIS, SDO and Hinode index web pages. From there we can download the data using a web browser. To get the parent folder of IRIS level2 data we can type:

IDL> irisl2url=str_replace(hcr[fg[85]].url,'/level2/','/level2_compressed/')
IDL> print, irisl2url

Similarly, the co-aligned SDO/AIA and Hinode/SOT data cubes can also be obtained by:

;SDO/AIA data
IDL> sdol2url=hcr[fg[85]].martinaia_compurl
IDL> print, sdol2url


;Hinode/SOTSP data
IDL> sotspl2url=str_replace(hcr[fg[85]].martinaia_compurl,'SDO','SOTSP')
IDL> print, sotspl2url
;Hinode/SOTFG data
IDL> sotfgl2url=str_replace(hcr[fg[85]].martinaia_compurl,'SDO','SOTFG')
IDL> print, sotfgl2url

The second alternative way to get AIA and/or Hinode data cubes is to use IRIS SolarSoft routines. The files will be downloaded to the current local folder as *.tar.gz files. The command to do it would look like this:

;download AIA data
IDL> l2sdo=iris_time2files(hcr[fg[85]].starttime,hcr[fg[85]].stoptime, level=2,/compressed,/urls,/aia)
IDL> sock_copy,l2sdo

;download Hinode/SOT data
IDL> l2sot=iris_time2files(hcr[fg[85]].starttime,hcr[fg[85]].stoptime, level=2,/compressed,/urls,/sot)
IDL> sock_copy,l2sot

For IDL 8.5 and higher it is possible to download the files using the wget function:

IDL> result=wget(URL)

where URL represents a scalar string or string array containing the URL(s) of the file(s) to be downloaded.

In the next Chapter, we will demonstrate how to read the downloaded co-aligned SDO/AIA and Hinode/SOT datasets and visualize them.