class jwst.transforms.models.GrismObject(sid=None, order_bounding={}, sky_centroid=None, partial_order={}, waverange=None, sky_bbox_ll=None, sky_bbox_lr=None, sky_bbox_ur=None, sky_bbox_ul=None, xcentroid=None, ycentroid=None, is_star=None)[source]

Bases: jwst.transforms.models.GrismObject

Grism Objects identified from a direct image catalog and segment map.

  • sid (int) – source identifed

  • xcentroid (float) – x center of object in pixels

  • ycentroid (float) – y center of object in pixels

  • order_bounding (dict{order: tuple}) – Contains the object x,y bounding locations on the image keyed on spectral order

  • partial_order (bool) – True if the order is only partially contained on the image

  • waverange (list) – wavelength range for the order

  • sky_centroid (SkyCoord) – ra and dec of the center of the object

  • sky_bbox_ll (SkyCoord) – Lower left corner of the minimum bounding box

  • sky_bbox_lr (SkyCoord) – Lower right corder of the minimum bounding box

  • sky_bbox_ul (SkyCoord) – Upper left corner of the minimum bounding box

  • sky_bbox_ur (SkyCoord) – Upper right corner of the minimum bounding box


The object bounding box is computed from the segementation map, using the min and max wavelegnth for each of the orders that are available. The order_bounding member is a dictionary of bounding boxes for the object keyed by order

ra and dec are the sky ra and dec of the center of the object as measured from the non-dispersed image.

order_bounding is stored as a lookup dictionary per order and contains the object x,y bounding location on the grism image GrismObject(order_bounding={“+1”:((xmin,xmax),(ymin,ymax)),”+2”:((2,3),(2,3))})

Create new instance of GrismObject(sid, order_bounding, sky_centroid, partial_order, waverange, sky_bbox_ll, sky_bbox_lr, sky_bbox_ur, sky_bbox_ul, xcentroid, ycentroid, is_star)