RHESSI QUICKLOOK IMAGES

RHESSI quicklook images are now available, and are being generated automatically. You can view plots of the images by going to the Rhessidatacenter web page

http://hesperia.gsfc.nasa.gov/rhessidatacenter/

and clicking on RHESSI Quicklook Images. This will send you directly to the qlook image browser.

New routines to access qlook image FITS files.

The images are also saved in FITS files and can be accessed using the RHESSI software package.

Command Line:

From the command line, type

data = hsi_qlook_image(time_range) 
or
data = hsi_qlook_image(flare_id=[n1,n2,...])

The variable data will contain an array of images for that time range or those flares. You can also request an array of objects or map structures by using the /object or /map keywords, or request specific energy band images by using the energy_band=[elo,ehi] keyword. For example:

maps = hsi_qlook_image(flare_id=2042101, /map)

will return an array of map structures, one for each energy band.

If you want the full-sun image for a flare, set the /full_sun keyword.

Widget Interface:

From RHESSI GUI:

click File / Retrieve/Process Data / Quicklook images.

At IDL command line: type hsi_ui_ql (or hsi_ui_ql, flare=n)

If you don't have the RHESSI data archive mounted, setting search_network,/enable will work as usual (will copy the file from the archive to $HSI_DATA_USER on your computer). Or alternatively, you can manually copy the files from the appropriate subdirectory of

http://hesperia.gsfc.nasa.gov/hessidata/metadata/qlook_image/

to your location of $HSI_DATA_ARCHIVE, $HSI_DATA_USER, or a new environment variable $HSI_QLOOK_IMAGE_FILE_ARCHIVE. If you use the new variable, be sure to define it in your local site-specific setup.hessi_env. The software will automatically find the files in any of those locations.

Contents of the image files

Note that this description is only valid for images for flares after 1-nov-2003. Images for the previous flares are currently being reprocessed.

For each flare, there is one full sun back-projection image, in the 6 to 25 keV energy band, with 128X128 16 arcsec pixels. On the plotted image, values for the spin axis and flare positions are printed in the lower left and right corners, respectively.

Higher resolution images are created, using the CLEAN algorithm, for the 3 - 6, 6 - 12, 12 - 25, and 25 - 50 keV energy bands. If it is determined that there are enough higher energy photons available, then images for the 50 - 100 and 100 - 300 keV bands are created. These images are 64X64 pixel (3 arcsec pixels) images made using detectors 4, 5, 6, 7, and 8.

For a given flare, the image accumulation time is the same for each energy band, typically two minutes centered on the peak of the flare (the peak is determined using the 12-25 keV count rate).

Comments to: jimm@ssl.berkeley.edu

22-jan-2004, jmm