RESIK & Diogeness NEWS

Data gaps due to missing/bad telemetry: -

Note, that the link to the catalogue page  is now: http://www.cbk.pan.wroc.pl/resik_catalogue.htm.

Recent  Spectra Observed in Third Order Reflection

In one of the previous news (see Weekly 49, 2002) we have mentioned about the possibility of the RESIK operation in third order reflection and showed corresponding raw spectra. At those time we did not work out the corrections for instrumental effects. Here we present results of our first attempt to correct the spectra obtained in 3^rd order for the notch  effect. Presence of notch introduces artificial spikes into the spectrum measured also in the third order reflection mode.  The opportunity to see 3^rd  order spectra arises when stronger flares are being observed by RESIK. The threshold to switch to this mode is set presently at the M1 class level as seen by GOES. Last April (from 21 to 27) some moderate (M class) flares were produced. RESIK recorded some of them in the third order. Below we present example of the spectra recorded for this event, also in 3^rd order reflection.  

Figure 1. A part of RESIK catalogue page for the discussed flare on 26 April 2003 at 03:06 UT. In the lowest panel one can see the times of switch on/off  of the first/third mode operation (arrows).

Figure 2. RESIK spectra integrated over 15 min. preflare period (upper panel) and during 7 min. of late decay phase. It is clearly seen that the decay phase spectra are much more noisy. It is also seen that on the  decay phase spectra substantial non solar (auroral?) X-ray signal contributed to the spectrum which is especially well pronounced in channel #2. By looking to the catalogue page, one can find that the collection of the decay phase spectra took place when CORONAS was within the auroral oval i.e. region of  increased non-solar contamination.

Figure 3. The RESIK spectra obtained in the third order of reflection from the crystals. They were measured over the maximum of the double flare. In Channels #1 and #2 some residual continuum contribution is only seen. However in channel #3 groups of lines belonging possibly to H- and He-like ions of Ni could be seen. In channel #4 group of Fe XXV/Fe XXIV ions lines is evident as well as other lines still awaiting for the identification.

For the presentation we have chosen  the short event on 26 April (start at ~ 03:01:00 UT, max. at 03:06 UT, end at 03:16:00 UT), in our catalogue see 09716_0. This flare  has reached M2.1 GOES class and was SN in Hα. It occurred  within the active region  located at N19W66. The flare was interesting because of its peculiar GOES light curve shape.  It was double peak event, with two maxima of similar importance and nearly identical e-folding rise and decay (see Figure 1). RESIK well observed the whole rise phase, both maxima and late decay phase. In Figure 2 we show the first order spectra observed during the 15 min. of preflare phase (top panel) and during the late decay. In Figure 3 the third order spectra measured during the phase of double maximum are presented. Statistically significant features (lines) can be seen on #3 and #4 spectra. They correspond in wavelength with resonance/satellite transition in Ni and Fe (H- and He-like) ions. Note that most of the istrumental notch is now removed.

Prepared by:  Barbara Sylwester bs@cbk.pan.wroc.pl and Janusz Sylwester js@cbk.pan.wroc.pl  

Page made on 7 Jun 2003 by:  Anna Kepa ak@cbk.pan.wroc.pl and Jarek Bakala jb@cbk.pan.wroc.pl