Procedure for obtaining SDO cutouts for an EIS data-set#

SDO cutouts (both AIA and HMI) can be obtained very quickly through the JSOC. In this article I illustrate how cutouts corresponding to a specific EIS raster can be obtained.

I consider an EIS active region observation that began at 02:30 UT on 15-Apr-2011. The raster took 62 mins to complete. We would like AIA 193 cutouts at 1 min cadence for the period 02:30 to 03:32, and HMI magnetograms at 45s cadence for the same period.

Get EIS pointing and FOV size#

The wiki page ... explains how to obtain the center and FOV of an EIS raster, so you can follow the instructions there. You should get values of (xcen,ycen)=(199,305), and (fovx,fovy)=(120,160).

Get AIA 193 cutouts#

Go the JSOC exportdata webpage. In the 'RecordSet' box, type:

aia.lev1_euv_12s[2011.04.15_02:30/62m@1m][193]

Click on the 'Recount' button and make sure a non-zero number of Records are found.

For 'Method', choose 'url-tar' from the drop down list. You will see a new option called 'Processing' that appears. Tick the box.

Within the processing options, select 'im-patch - Extract sub-frame'. A new box appears with various input widgets, some of which will be automatically filled in. For the others, type:

LocUnits: 'arcsec from center'
T_Ref: '2011-04-15T03:01:02Z' (choose time from middle of raster)
X: 199
Y: 305
BoxUnits: pixels
Width: 300 (some contingency has been factored in here)
Height: 400 (some contingency has been factored in here)

For 'Protocol' leave it as 'FITS'. I suggest using '**NONE**' for compression as the cutout files generally don't take up much space. Type in your name and e-mail, and then click on 'Submit Export Request'. After a couple of minutes wait, click on 'Submit status request' and you should see a link to a tar file containing your data (it may not longer for large data-sets).

Get HMI cutouts#

Repeat the above procedure, except that in the RecordSet box you should do:

hmi.M_45s[2011.04.15_02:30/62m@45s]

For the field of view, you need to account for the difference in plate scale between AIA and HMI, so multiply by 1.2:

Width: 360
Height: 480

Comments#

Why use pixels instead of arcsec for the FOV size?
I found erratic results when using arcsec - the HMI FOV would end up with a different size to AIA.

Why use the register option?
This performs sub-pixel interpolations so that when you make a movie from the cutouts you do not see the occasional pixel jumps that otherwise would be seen.

What if I want multiple AIA filters?
Instead of giving '[193]' in the RecordSet box, give e.g. '171,304,335'.

How do I get AIA UV images?
For these you need to give 'aia.lev1_uv_24s' in the RecordSet box.

How do I get HMI 45s intensitygrams, or HMI 720s magnetograms?
In the RecordSet box, use 'hmi.Ic_45s' and 'hmi.M_720s'.

Why not download Rice-compressed files?
When read_sdo reads these files there's a small delay as each file gets uncompressed. This can be irritating if you're reading a large number of files in one go. Reading the uncompressed files is much quicker.