NICMOS focus during the Second NIC3 campaign (started June 4, 1998)
On June 4th, 1998, the HST Secondary Mirror (SM) was reset to place NIC3
in focus for the second NIC3 campaign. The commanded SM move of 16.6
microns away from the Primary Mirror was expected to result in NIC3 best
focus at the nominal NIC3 setting of -9.5 mm in PAM space. The post-move
focus results (see the focus history
table and plot ) showed that the
NIC3 focus moved in the desired direction, although a slight offset from
the targeted PAM position remained. The subsequent analysis which
involved the attitude breathing model revealed however that the focus
measurements were probably impacted by an unusually large breathing
anomaly which occured during the post-move focus sweep. This anomaly may
account for the offset seen in the latest focus results.
|
 |
|