APEX SEPIA receiver:as a test bed for ALMA development

SEPIA (Swedish ESO PI receiver for APEX) was introduced at the APEX telescope in early 2015, installed in the Nasmyth cabin A at the guest position and commissioned as a PI instrument. The design of the SEPIA was driven by the idea of using ALMA receiver cartridges on the APEX telescope and in particular a new (that time) ALMA Band 5 receiver cartridge. The SEPIA cryostat was designed from scratch and can accommodate up to 3 ALMA cartridges. In February 2016, the second receiver cartridge, ALMA Band 9 (DSB) was installed and in the summer 2018 it was replaced with an experimental Band 9 receiver with 2SB mixers. In March 2019, SEPIA got all-new tertiary optics and was moved to the facility instrument position in the Cabin A. In our talk, we will present the SEPIA design, latest results on the development of the third experimental receiver channel corresponding to the ALMA Band 7, commissioning results for the new facility heterodyne instrument for the APEX tele scope.