Data gaps due to missing telemetry: ~ 18.8 h.

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

Problems with RESIK Primary Power Supply 

In weekly 02, 2003 we showed the long term variation of the "5V" voltage level  showing its dependence on the S/C temperature (as measured through RESIK internal temperature sensors). We followed the changes of this votage level carefully. Recently we noticed substantial drop of this voltage, as indicated by the on-board voltmeter (see the Figure 1). 

Figure 1. Plots showing recent variations of the temperature, as measured on the low voltage power supply unit (light brown) and the behavior of voltage readouts corresponding to "5V" level (dark blue). A sharp drop of this readouts has been observed recently.

In order to check whether this observed drop was caused by the degradation of power supply unit or the voltmeter itself, we have been looking also to the variations of the position of the PHA bin corresponding to the most prominent peak (fluorescence, E = 1.75 keV). Until quite recently, the peak position did not change, indicating that the HV level did not vary. However on March 10, we noticed that the peak began drifting towards the higher bins (as shown in Figure 2). 

Figure 2. Plot showing recent changes of the fluorescence peak position as observed for detectors A and B.
There are two anodes inside each detector. Each anode corresponds to individual spectral channel. The software notation of respective channel is used, as indicated on the vertical axis.

This last awarenessy prompted us to decide to switch to the redundant power supply unit. We did not test this activity before as this needs more elaborated use of the satellite telemetry system. We managed to prepare appropriate telemetry sequence by now. It will be send to the S/C today (March 14).


We hope the reduntant power supply unit will start providing RESIK with the right voltage soon.

Prepared by: Janusz Sylwester js@cbk.pan.wroc.pl and the RESIK engineering team: Mirek Kowalinski mk@cbk.pan.wroc.pl and Witold Trzebinski wt@cbk.pan.wroc.pl.