Instrumentation for the La Silla Observatory                                  
                                                                              
                                                                              
The IRSPEC at the NTT was upgraded at the beginning of the 1991 season by     
replacing its linear detector with a 2D SBRC 58x62 pixel InSb array which     
exhibits good cosmetic quality and high quantum efficiency from 1 to 5 micro- 
meters. In order to optimize the performance of this array, a multiple non-   
destructive sampling mode was included within the new VME-based acquisition   
system developed at ESO. Together with measures to reduce the instrumental    
background, an improvement in sensitivity of about 20 has been achieved in the
1-2.5-micrometer region. The resolving power now ranges from 1500 to 3000 for 
two pixel sampling with a 4-arcsec slit, and the slit length is 2 arcmin.  For
the individual IRSPEC files the only index table (IRSPINDX) is located in the 
INDEX directory. For the IRSPEC files, the emission feature (H2(1), H2(2), or 
H3+) is given in the NOTE field.   In addition, a shorthand notation is used  
for target designations, as given by the following list:                      
NH - Northern Hemisphere                                                      
NH SWS - Northern Hemisphere South West Side                                  
N1,N2,N3,N4 CE (center), S1,S2,S3,S4 - offsets given in Schulz, et al. (1995)