Glint Masks in PS1 / GPC1

(Back up to IPP for PS1)

I've added the ability to psastro to generate glint mask features based on the locations of stars just outside the field of view of the camera. The psastro recipe file now includes options for glint 'regions', which describe areas in focal plane coordinates where stars responsible for glints may be found. Each glint region describes a type of glint; at the moment, the only known types are TOP, BOTTOM, LEFT, RIGHT, which represent glints starting on one of those four sides and moving from that side toward the camera center, along either the camera X or camera Y axis. The type of glint defines the direction of the glint. The current parameters for glints in GPC1 are determined empirically, and represent rectangular regions that run along the entire side of the camera, starting about 40mm (4000 pixels) from the edge and ending 180mm (18000 pixels) from the edge. The length of the glint is also crudely set based on the glint star's instrumental magnitude. Currently, an instrumental magnitude of -20 corresponds to a zero-length glint, and every magnitude increase in brightness extends the glint by 2500 pixels. For a Medium Deep 240 second i-band exposure, a 6th magnitude star yields a glint with a length of roughly 10000 pixels.

Sample Images

Below are two images showing the glint masking. The first image shows the binned greyscale image of a portion of an MD08 exposure. The glints are seen at the top and right side of this image. The next image shows the mask generated for this image. The glints are mostly masked.