2.2 Summary of STIS Performance Changes Since 2004

The performance of STIS after its repair during SM4 is similar in most respects to its performance prior to the 2004 failure, but there are some important differences. While most of the changes in performance represent the continuation of previous trends (and were anticipated), some of the changes (e.g., in the behavior of the NUV-MAMA dark current) were not expected. All of these changes need to be taken into account when planning new STIS observations.  Detailed descriptions of the differences are given in the appropriate sections of this Handbook, but for the convenience of users familiar with the previous performance of STIS we list the most important of the changes below, linked to the appropriate sections of the Handbook:

• Changes in CCD Read Noise (7.2.3)
• CCD Dark Current (7.3.1)
• Charge Transfer Efficiency (7.3.7)
• Figure 7.1: Relative Sensitivity vs. Time for First-Order CCD L-Modes G230LB, G430L, and G750L (7.2.5)
  
• NUV-MAMA Dark Current after SM4 (7.5.2; see Figure 7.20)

For the most up-to-date values of some of the more frequently monitored quantities, users should consult the Performance section of the STIS web pages. The STIS ETCs are regularly updated to reflect the current/anticipated detector characteristics.