Availability of Prime Focus Imaging at the INT for Semester 97A

• Preliminary commissioning of the INT Wide Field Prime Focus Camera (INT-WFC) will take place during January 1997. Full Commissioning will occur in May 1997.
• Present expectations are that the INT-WFC will may be available in semeseter 97A (after MAY 1997) with configuration consisting of two or three 2048*2048 Loral CCD's plus one 2048*2048 Loral CCD for the autoguider system. Please check with naw@ing.iac.es or psb@ast.cam.ac.uk for the latest information.

• Assuming that the January and May commissioning is successful, the INT-WFC will be offered during Semester 97A (May - July 1997) on a shared risks basis. Consequently the existing INT Prime Focus unit will be unavailable for use in Semester 97A.
• The INT-WFC offers primarily broad band imaging (UBVRIZ). A H-alpha filter (FWHM of 100A) and a [O III]5007A (FWHM of 100A) will also be available.
• Applications requiring narrow band imaging (except with H-alpha or [O III]) are discouraged for semester 97A due to the uncertain availability of the existing INT PF camera.

Characteristics of the INT-WFC with Loral CCD's

Predicted performance values for the INT-WFC with the Loral CCD's are given:

Table 1. Example exposure times for INT + thinned Loral CCDs

Waveband                          U      B      V      R      I      

Sky Brightness (no moon)        22.0   22.7   21.8   20.9   19.9   
               (7 day old moon) 19.9   21.6   21.4   20.6   19.7  

Exposure time(seconds)           600    600    600    600    600        
    
Limiting magnitude(S/N)=5       24.0   25.0   25.0   24.5   24.0       

Dark Sky/pixel (counts)           1k     3k     4k    12k     8k 

(c.f.Exposure time(secs) EEV5   3600   3600   1800   1200   1200) 

1. Sky brightness estimates are from CTIO observers guide.
2. S/N estimates assumes 1 arc second seeing and profile fitting.
3. Limiting magnitudes are rounded to nearest 0.5 magnitude and assume dark sky.
4. For sky 1 magnitude brighter exposures would need to be increased by a factor of 2.5 to reach the same limiting magnitude.
5. To go 1 magnitude fainter than the limit in the table exposure times would need to be a factor of 6.25 longer.

Table 2. Physical Properties of a CCD System based on Loral chips

Pixel Size(µm)                                        15.0    
       
INT Scale(arcsec per pixel)                           0.37   
          
Pixel Format                                          2048 x 2048  
  
Physical size of imaging area per chip(mm)            30.7 x 30.7 
                                      (arc min)       12.8 x 12.8 
  
Imaging area produced by 2x2 chips(arc min)           25.6 x 25.6 
                                  (deg²)              0.18   

Physical size of mosaic including 1mm gaps (mm)       62.4 x 62.4 
 
Target readout time for whole array                   < 120s  

Target readout noise (rms)                            < 10e-