IMACS – Calibrations

Numbers below correspond to new configuration - after the dewar swap 

Since the end of June, we are experiences issues with the power supply of the Variable Lamp, thus the tabulated voltages might not give the expected level of counts. To get sufficient counts for the various configurations it is suggested that you use a voltage in the range of 3.0-4.7V.

Imaging

In the table below we provide some reference numbers of imaging flat counts obtained in the various filters and suggested lamp intensities (Ql and Qh refer to the Quartz lamps in the DCU). These frames were obtained with the dome closed at night. 

Note: During daytime the dome is not completely light tight and the exposure times should be kept <10sec in order to minimise fluctuations due to stray light:

Camera f/2 :

Camera f/4 :

 
Flats of the sloan-u are not possible with current lamps (120sec with Ql+Qh give ~4500counts with f2 and ~2500counts with f4). For this filter twilight flats should be obtained. 

A new sloan-u filter has been purchased that is more efficient than the previous one. Dome flat calibrations are possible using available lamps.

Spectroscopy 

Camera f/2 :

The following exposure times will give between 20000-25000 counts using the Qh lamp in the DCU and the Spectroscopic2 filter 

Camera f/4 :

The following exposure times will give between 20000-22000 counts using the Qh + Ql lamps in the DCU