• Frame Type SCIENCE_SDI
• DPR.TYPE OBJECT; SKY
• DPR.TECH IMAGE,DIFFERENTIAL,JITTER; IMAGE,DIFFERENTIAL,JITTER,CUBE; IMAGE,DIFFERENTIAL,JITTER,PT; IMAGE,DIFFERENTIAL,JITTER,CUBE,PT

description: The SDI+, or SDI, mode of NACO consists of four images through three narrow band filters which are simultaneously recorded on the detector. Two images are taken outside the ~ 1.6 um methane feature (at 1.575 um and 1.600 um) and two images taken inside the feature (both at 1.625 um). All filters have a FWHM of 25 nm. The plate scale of the SDI+ camera is 17.32 mas/pixel. This mode was designed to detect methane rich objects near very bright stars.

This is an example of the SDI+ lamp flat raw frame. The transmitted wavelengths are 1.6 um (top left), 1.575 um (top right), and 1.625 um (bottom left and right). Note that the vertical misalignment of the mask varies with time and cannot be corrected for.

In P82, the SDI+ permanently replaced the "old SDI", now decommissioned.

For further details please consult the NACO User Manual.