On the present release, the YLA includes Level 0 (raw), Level 1 (corrected and assembled) and Level 2 (corrected and composited) data products for the SXT. The Level 1 and 2 data products have been corrected as fully as possible for instrumental effects such as dark signal and visible straylight. Level 1 includes both full frame (FFI) and assembled partial frame (PFI) data in floating point format. Level 1 products include every usable image, even if most of the frame may be missing due to TLM dropout. Level 2 data products include only FFIs taken with the SXT thin (1200 A aluminum (Al.1) and Al/Mg/Mn composite (AlMg) filters. Level 2 FFI images have been de-scattered by deconvolution of the SXT point spread function and have been corrected for telescope vignetting. SXT Level 1 and 2 data products are in instrument units (DN/sec/pixel). Conversion to physical units requires knowledge or assumption about the solar differential emission measure and the use of software such as, e.g., sxt_teem.pro.
We have created SXT data products in both YOHKOH-specific (XDA) and FITS formats. The XDA format is convenient for analysis with existing SSW/YOHKOH software that runs under IDL. The more general FITS format enables use of advanced SSW applications including the SSW mapping software by Zarro et. al. FITS products do not specifically require IDL to read and view images.
Level 0 data for all Yohkoh instruments and Level 1 full-frame images for SXT are also available via the Virtual Solar Observatory. For Level 2 browse images, the SXT movie maker service is available to create the customized movies of 2-composite FFIs, of your own!
Service of data searching, quick-looking, or custom archiving is not available in this beta-release. For the purpose of helping to find suitable datasets, the SXT Observing Logs Inquiry Form is available.
Here is a list of data products available in the YLA at this time.
XDA Format:
Level 0 (One file per YOHKOH orbit)
Complete raw, reformatted data for all YOHKOH instruments.
Level 1 (One file per calendar day)
All usable PFIs, observing regions assembled.
All usable FFIs.
Level 2 (One file per calendar day)
Two-exposure composite FFIs.
Two-exposure uncertainty arrays.
Three-exposure composite FFIs (longer exposures).
Three-exposure uncertainty arrays.
FITS Format (One file per image):
Level 0 Not applicable.
Level 1
All usable PFIs, observing regions assembled.
All usable FFIs.
Level 2
Two-exposure composite FFIs.
Two-exposure uncertainty arrays.
Three-exposure composite FFIs (longer exposures).
Three-exposure uncertainty arrays.
Two-exposure browse FFIs.
Three-exposure browse FFIs.
Cautions and disclaimers:
0. Exposures comprising Level 2 composite images may be taken up to +/- 11
minutes apart. Beware of solar changes between exposures. For study of
specific events or periods it is advisable to examine the Level 1 data
which often include many images that, for one reason or another, didn't
make it to level 2.
1. Correction for CCD saturation in Level 2 products is not perfect in
many highly saturated images. Flare and eclipse images are not well
corrected because of caution 0.
2. This a beta release, please be alert for and report problems with the
data products. Screening to remove bad images isn't complete.
3. There are uncorrected problems with the YOHKOH attitude database late
in the mission, particularly in 2001.
4. After 14-Nov-1992 straylight correction of the thin Aluminum images
isn't perfect. This has a minor effect for the analysis of bright
features but causes intensity uncertainty of faint regions -- which is not
reflected in the uncertainty arrays. The best looking movies will be made
from the AlMg filter, half-resolution, images.
An example of the file name: sfr920720.1502
sfr: A prefix for SXT Full Frame (whole sun) Images.
Other prefixes --- spr : SXT Partial Frame Images
hda : HXT data
bda : BCS data
wda : WBS data
ada, cba : for calibration purpose.
920720.1502 : date and approximate time (yymmdd.hhmm) at which
the satellite started observation in the orbit.
Files are organized by date, and each contain all level 1 images obtained
during the orbits started in the day. Note, therefore, that the data for
the first 1 hour of a day might be found in the file of the day before.
Large PFI images (larger than 512 pixel in x- or y-direction), which are
occasionally obtained by special operation or for a campaign observation,
are collected in separate files to reduce the total file size of the day.
Those files are maked with '_large' at the end of the file name.
(e.g. spr930428_large).
(for FFI)
http://solar.physics.montana.edu/ylegacy/level1_xda/sfr/
ftp://solar.physics.montana.edu/pub/yoarch/level1_xda/sfr/
(for PFI)
http://solar.physics.montana.edu/ylegacy/level1_xda/spr/
ftp://solar.physics.montana.edu/pub/yoarch/level1_xda/spr/
Each file contains one solar image, and is organized in the daily directories locating under the tree structure of the type, year/month/day/. (e.g. to reach the images obtained on 20-Jul-1993, go stepping down the directory to 1993/07/20/.) The file name of the level 1 FITS products is defined in this document.
An example of the file name: sxtf_19930720_214131_231.fts
sxtf : A prefix for SXT Full Frame Images. (cf: sxtp is for Partial Frames)
_19930720_214131 : date (_yyyymmdd) and approximate time (_hhmmss)
at which the image was taken.
_231 : Stands for spatial resolution (0:full, 1:half, 2:quarter) and the
filter pair (in the order of the filter wheel B and A).
This example shows that the image was taken with the quarter
resolution and with the filter pair, B/A=3/1=AlMg/Open.
.fts : The suffix for the FITS format.
SXT composite images combine 2 or 3 long and short exposures to increase dynamic range and remove detector saturation. Each composite image has a related uncertainty image which provides the statistical error for each pixel. SXT browse images are made from the composites and are comparable to the now-familiar SXT movies. They are logarithmic(safe_log10) and byte(8-bit) scaled, cleaned of SAA and cosmic ray spikes, and adjusted so that images from the 2 SXT thin filters look similar. Browse images are cosmetically appealing but are not appropriate for quantitative analysis. Level 2 data products only use complete or nearly-complete images. Only the SXT browse images have been co-aligned. Other SXT images may be readily co-aligned with existing SSW mapping tools.
Files are organized by date. The file name of the 2-images composites starts with 'ssc', while that of the 3-composites starts with 'sst'. The uncertainty arrays have the same file name as the corresponding composites except having '_unc' in the last part.
Examples: ssc19930720_0014_1110110.2 <-- 2-image composites for 20-july-1993. ssc19930720_0014_1110110.2_unc <-- the uncertain array of the above. sst19930720_0014_1110110.2 <-- 3-image composites for 20-july-1993. sst19930720_0014_1110110.2_unc <-- the uncertain array of the above.
As from 24-May-2007, the level_2 XDA archives are
rearranged.
The composites made with 2 and 3 images (previously called SSC and SST,
respectively) are now stored in the same directory.
The file name prefix are kept as before.
(for the new SSCs, e.g. old SSC+SST)
http://solar.physics.montana.edu/ylegacy/ssc/
ftp://solar.physics.montana.edu/pub/yoarch/ssc/
Each file contains one solar image, is organized in the daily directories locating under the tree structure of the type, year/month/day/. (e.g. to reach the images obtained on 20-Jul-1993, go stepping down the directory to 1993/07/20/.) Their file name is defined similarly to the Level 1 products except the prefix (see examples in below).
Examples: sx2c_19930720_214131_231.fts <-- a composite image (2-image-composite) sx2cu_19930720_214131_231.fts <-- the uncertainty array of the above sx3c_19930720_035753_121.fts <-- a composite image (3-image-composite) sx3cu_19930720_035753_121.fts <-- the uncertainty array of the above sx2m_19930720_214131_131.fts <-- a browse image (made from 2 images) sx3m_19930720_035753_121.fts <-- a browse image (made from 3 images)
As from 18-May-2007, the level_2 FITS archives are
rearranged.
The composites made with 2 and 3 images (previously called SSC and SST,
respectively) are now stored in the same directory.
The file name prefix are kept as before.
(for new SSCs e.g. old SSC+SST)
http://solar.physics.montana.edu/ylegacy/ssc_fits/
ftp://solar.physics.montana.edu/pub/yoarch/ssc_fits/
(for new browse images e.g. old sx2mov + sx3mov)
http://solar.physics.montana.edu/ylegacy/sxtmov9/
ftp://solar.physics.montana.edu/pub/yoarch/sxtmov9/