Current Background Estimates

The background estimates that are currently included with Calnic C and NICMOSlook were obtained empirically by medianing several sparse images together. These new estimates of the G096 and G141 grisms backgrounds, when scaled appropriately, were observed to be significantly better background estimates than the pre-launch models. However, in the case of the G206 grism, the Interpolated background method better accounts for the relatively large variations of the G206 background.

 

Figure 3.2: Example of grism image and an image showing the pixels used to calculate a background estimate. The highlighted areas on the right panel are the pixels actually used to estimate the background.