Detector Array

Detector characteristics are given in this section. Note that the GMOS-South and GMOS-North detectors have been upgraded to Hamamatsu CCDs in 14B and 17A, respectively. Note also that the telescope optics are currently silver-coated, reducing the system throughput in the blue.

The GMOS-S detectors were upgraded to the new Hamamatsu CCDs in June/July 2014, improving red sensitivity, and including an upgraded detector controller. The GMOS-North original EEV detectors were replaced with e2v deep depletion devices in October 2011, improving sensitivity in the blue and greatly improving / extending sensitivity to longer wavelengths. A new focal plane array populated with Hamamatsu devices was installed in GMOS-N in February/March 2017, so that both GMOS instruments are currently operated with Hamamatsu devices.

For updates on status of the GMOS-N and GMOS-S detector arrays, see the Status and Availability webpage. Additional information on the current GMOS-N detector status is available here.

For the Hamamatsu detectors, the default detector read-out configuration is

• slow read
• low gain
• 12 amplifiers

The six-amplifier mode is not supported (three-amplifier mode is not available for these CCDs). Fast read-out speed is available for time resolved observations and high gain for observations of very bright objects. 

For the e2v DD detectors used in GMOS-N until February 2017, the recommended detector read-out configuration was

• slow read
• low gain
• 6 amplifiers

The original intent for the e2v DD detectors was to use the three best amplifiers, giving the lowest read-noise. (This was the case for the original EEV detectors.) However, a recabling enacted to reduce spurious noise yielded the 3 amplifiers mode unavailable, so that all GMOS-N data taken with the e2v DD detectors utilized 6-amp mode.  

• New GMOS-North Array Characteristics (Hamamatsu)
• GMOS-N Hamamatsu Array Current Status (Updated March 2022)
• GMOS-North Array Characteristics (e2v DD)
• GMOS-North Array Gain and Read Noise (e2v DD)
• Old GMOS-North Array Characteristics (EEV) 
• Old GMOS-North Array Gain and Read Noise (EEV)


• New GMOS-South Array Characteristics (Hamamatsu)
• GMOS-South Array Characteristics (E2V) 
• GMOS-South Array Gain and Read Noise (Hamamatsu)
• GMOS-South Array Gain and Read Noise (Older)