Availability of Prime Focus Imaging at the INT for Semester 98A

• Further commissioning of the INT Wide Field Prime Focus Camera (INT-WFC) occured during May 1997 resulting in a system with three usable Loral CCD's, all subject to certain flaws. Further infomation can be found at http://www.ing.iac.es/Onhelp/INT/wfc_notes.html.
• Some WFC ommissioning will occur in October 1997 when the new TCS is installed and further tidying up of the observing system and autoguider software is carried out.
• The ING has continued to experience problems in the delivery of the complete package of 4 science grade Loral CCDs.
• Hence it has been decided to replace the Lorals in favour of three 4k x 2k EEV thinned CCDs (pixel size of 13.5um) (NB: the autoguider CCD will remain a Loral CCD).
• This upgrade will be implemented during a commisioning period in March 1998. Thus the WFC will be available with a 6k x 4k pixel array for the second half of semester 1998A.
• Please check with naw@ing.iac.es or mike@ast.cam.ac.uk for the latest information.
• The Service-Queue scheme will operate for the WFC in Semester 1998A.
• The INT-WFC filter set is primarily broad band imaging (UBVRIZ). A H-alpha filter (FWHM of 100A) and a [O III]5007A (FWHM of 100A), and Strombren U,B,V,Y are also available. A Kitt Peak B filter is on order and should be available for Semester 1998A.

Estimated Characteristics of the INT-WFC with EEV CCD's

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

Table 1. Example exposure times for INT + thinned EEV 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       23.6   24.8   25.0   24.5   24.0       

Dark Sky/pixel (counts)           1k     3k     4k    11k     7k 

(c.f.Exposure time(secs) EEV5   3600   3600   1800   1200   1200) 
( - a thick EEV!                                                )

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 EEV chips

Pixel Size(µm)                                        13.5    
       
INT Scale(arcsec per pixel)                           0.333   
          
Pixel Format                                          4096 x 2048  
  
Physical size of imaging area per chip(mm)            55.3 x 27.6
                                      (arc min)       22.53 x 11.26 
  
Imaging area produced by 3x1 chips(arc min)           22.53 x 33.78
                                  (deg²)              0.211    

Physical size of mosaic including 0.1mm gaps (mm)     55.3 x 83.0
 
Readout time for whole array                          < 100s  

Target readout noise (rms)                            < 4e-