European Southern Observatory
New Technology Telescope

General :
Observations :
Operations :

SOFI Calibration Plan: Flat Fields

Flats are take for SOFI in two ways for the imaging mode (templates SOFI_img_cal_DomeFlats and SOFI_img_cal_SpecialDomeFlats) and in one way for the spectroscopic mode (template SOFI_spec_cal_DomeFlats).

Move the telescope to the Flat Field position. The Nasmyth A has to be open and M4 positioned to SOFI. Make sure that all the lights in the building are off.

Load the requested template from /data/SOFI/SYSTEM/COMMON/OBD into Bob and run it. After a few minutes you will be prompted to switch on the flat-field ligh. Use the control of the SOFI calibration unit in the OS of SOFI - lamp 2 - for the broad band imaging flats and the manual control on the back wall of the control room for the narrow band imaging and spectroscopic flats. Set the level to produce an average of about 4000 ADU on the image. This can be checked with the Statistics Option from the View menu of the RTD.

It takes about 20 minutes per filter to run the SOFI_img_cal_SpecialDomeFlats template and about 10 minutes per filter or mode to run the SOFI_img_cal_DomeFlats or SOFI_spec_cal_DomeFlats template with DIT = 1.2 sec and NDIT = 60.

When the Special Flat are aqcuired it is important to double check in the RTD that the position of the mask is correct

Send comments to: NTT Webmasters <nttweb@eso.org>
Last Update: 2 March 2001(Leo Vanzi)