SUMER Study #2230: Flare Watch 25.Oct.00

date, time: 25.Oct.00, 00:00 - 26.Oct.00, 00:49 UT
field of view: 1000 arcsec E, 450 - 150 arcsec S
slit: 4.0 arcsec x 300 arcsec (number 1)
raster step size: 0.0 arcsec (0 elementary steps)
exposure time: 162.5 seconds
telemetry: 48 images of 1024 spectral x 360 spatial pixels (format 2)
237 images of 512 spectral x 360 spatial pixels (format 38)
237 images of 512 spectral x 360 spatial pixels (format 38)
compression: quasilog-min-max (method 5)
wavelengths:
1108.26 Å on reference pixel 731 of Detector A (48x)
1126.10 Å on reference pixel 327 of Detector A (237x)
1108.26 Å on reference pixel 731 of Detector A (237x)
rotation compensation: no
binning: no spectral, no spatial
on-board flat field correction: no

The sequence W,R,L,R,L,R,L,R,L,R,L is repeated approx. 47 times, where W refers to the whole spectral window (1098-1138 Å, format 2), while L and R refer to the left and right part of this window - with a small overlap containing the Ca X 1115/2 and the Fe XIX 1118 line - which are repeated five times, alternating (both in format 38).

In a first approach, 229 "left" windows (format 38, 1108.26 Å on pixel 731) of 25.Oct.00 were analysed. This leads to a sequence of images approx. 6 minutes apart. - In a second approach, all formats were used; the 2D images are accordingly updated. - Meanwhile, EIT took images of the whole Sun approx. every 12 minutes. The SUMER slit points to a coronal loop system above an active region at the south east limb. During the time of the study, according to the events page, several events occured, but it is not easy to assign them to the data observed by SUMER. In two cases, significant intensity reactions in both "hot" and "cool" plasmas combined with significant reactions in line shifts and widths can be observed.

Representative lines were selected for analysis: One relatively cool transition region line, S III + Si III 1113.22 (30 000 - 63 000 K), one coronal line, Ca X 1115.51/2 (740 000 K), and one "hot" coronal line, that only shows up in flare situations, Fe XIX 1118.073 (7 700 000 K). The images below show the SUMER slit with time moving from left to right for approx. 25 hours. Shifts were determined relative to the (not very dynamic) Ca X line. - In the "right" window, which does not contain S III 1113.22, the comparable line S IV 1122.52 was used as a substitute to fill in the gaps.

SUMER slit position in EIT image

The small interval shows the position where 10" were averaged for the figures of intensity, shift and width vs. time (see below). Within this interval, the main intensity increases of both reactions (approx. 01:45 and 13:30 UT) take place; px 162-172 were selected, corresponding to 169"-180" above 450"S.

Spectral window "L"

Cont 1112 / 1122 (10 000 K)

S III 1113.22 (63 000 K) / S IV 1122.52 (138 000 K)

Ca X 1115.51/2 (740 000 K)

Fe XIX 1118.073 (7 700 000 K)

The observation time of this study runs from 25.Oct.00, 00:00:50 UT (= start of first exposure), to 26.Oct.00, 00:49:27 (= start of last exposure). It is not quite equidistant; ther are some gaps of which the longest is approx. 14 min, shortly after 12 UT. The exact starting times (in seconds after 25.Oct.00, 00:00:00 UT) of the 522 exposures can be found in the IDL/XDR restore file TIME_S179001_XDR.RST

To decide about potential flares, three subsets of 45 exposures each (covering approx. 2 hours each) have been selected: "Flare 1", starting 01:00 UT, "Flare 2", starting 13:00 UT, and a "Control" interval without visible flares, starting 03:01 UT:

"Flare 1"

"Flare 2"

"Control"

These intervals (here shown averaged) around Fe XIX 1118 can be seen as animations by downloading the IDL/XDR restore file CONTROL_S179001_XDR.RST and the IDL programme CONTROL_S179001.PRO and starting it in the same subdirectory.

Fe XIX Events in SUMER Study Starting 25.Oct.00, 00:00 UT

Time  Solar X Solar Y    Intensity    Size   Shift   Width
/UT   /arcsec /arcsec   /count s-1 /arcsec /km s-1 /km s-1
----- ------- ------- ------------ ------- ------- -------
01:47    -999    -283     0.986750      42      41      64
08:20    -999    -399      1.02115      29      52      66
08:20    -999    -369     0.351756      21      44      62
08:26    -999    -348     0.349493      39      29      60
11:04    -999    -266     0.414759      36      35      66
12:07    -999    -375     0.262258      18      21      52
12:24    -999    -326     0.429511      30      23      59
13:36    -999    -336     0.709704      40      39      65
13:38    -999    -307     0.645596      18      46      70
13:38    -999    -281      1.59230      86      38      85
18:30    -999    -270     0.460268      59      38      55
20:34    -999    -333      3.83168      46      38      78
20:46    -999    -376     0.579333      22      27      59
20:46    -999    -284      6.53613      50      64      87
22:59    -999    -266      1.75918      30      39      61
23:07    -999    -294      1.44996      28      27      70
23:16    -999    -325      1.05011      39      28      68
23:18    -999    -384     0.930046      46      26      67

Line intensity, shift and width vs. time

Original data are in the (4 MB) IDL/XDR restore file s179001_xdr.rst. It contains the following vectors and arrays:

goes-time    in h after 25 Oct 2000, 00:00 UT
sumer_time   in h after 25 Oct 2000, 00:00 UT
intens_goes  GOES XS 0.5-4 in W / m²
intens_s3    in SUMER count / (line * 162.5 s * px)
intens_ca10
intens_fe19
intens_cont  Cont 1116 in count / (Å * 162.5 s * px)
shift_s3     in km/s
shift_ca10
shift_fe19
width_s3     in km/s
width_ca10
width_fe19
1 px corresponds to 4.0" x (300/287)".

IED, 19.Mar.02