MVM: Skycell sky value offsets

[stscijgbot-hstdp]

trafficstars

Issue HLA-782 was created on JIRA by Michele De La Pena:

Issue found by Jenn and documented on 25 May in team-burgundy Slack channel. For hst_skycell_p1091x13y11_acs_wfc_f606w_all, there is a problem with the matching of the background sky intensity. This may be an issue in CALACS in that ACS bias jumps are not properly accommodated.

[stscijgbot-hstdp]

Comment by Robert Swaters on JIRA:

The goal is to confirm the cause of the jump in background