Atacama Pathfinder EXperiment APEX
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SEPIA instrument

SEPIA contains three channels called SEPIA180 (ESO-OSO PI), SEPIA345 (facility) and SEPIA660 (facility). The receiver shares the backend with FLASH+ receiver, XFFTS, (PI instrument built by MPIfR, Bonn).

The SEPIA180 frequency channel is a dual polarization 2SB receiver built to the specifications of ALMA band 5 with the RF band 159-211 GHz. The receiver is based on the pre-production ALMA Band 5 receiver cartridge, more technical details can be found in [1].

The receiver has two IF outputs per polarization, USB and LSB, 4-8 GHz, for a total of 16 GHz IF band. The sideband rejection ratio is >10 dB and 18.5 dB average. The single-sideband noise temperature of the Band 5 frequency channel is below 55K at all frequencies within the RF band.

The SEPIA345 band intends to cover the frequency range between 272 and 376 GHz. Installation and commissioning are still pending and are expected for 2019 Q3.

The SEPIA660 frequency channel is a dual polarization 2SB receiver installed and commissioned during the second half of 2018. It replaces the previous DSB receiver built to the specifications of ALMA band 9, based on a pre-production ALMA Band 9 receiver cartridge. See complete technical description in [2].

In the current incarnation (2SB), the receiver covers the RF frequency range 581-727 GHz. The receiver has one IF output per polarization, 4-12 GHz, but currently only 4-8 GHz IF is recorded by the APEX backend. For 2019 this is expected to record all full 4-12 GHz. The receiver temperature of the SEPIA660 frequency channel is below 350K at all frequencies within the RF band, and below 250K in the frequency range 600-700K.

Observing time estimators

[1] Publications resulting from using the data obtained with the Band 5 receiver shall refer to the following publication: Billade, B., Nystrom, O. ; Meledin, D. ; Sundin, E. ; Lapkin, I. ; Fredrixon, M. ; Desmaris, V. ; Rashid, H. ; Strandberg, M. ; Ferm, S.-E. ; Pavolotsky, A. ; Belitsky, V., "Performance of the First ALMA Band 5 Production Cartridge", IEEE Trans. Terahertz Science and Technology, Vol. 2, No. 2, March 2012, pp.208-214.

[2] For a technical description of the Band 9 receiver, please see the following publication: Baryshev, A. M.; Hesper, R.; Mena, F. P.; Klapwijk, T. M.; van Kempen, T. A.; Hogerheijde, M. R.; Jackson, B. D.; Adema, J.; Gerlofsma, G. J.; Bekema, M. E.; Barkhof, J.; de Haan-Stijkel, L. H. R.; van den Bemt, M.; Koops, A.; Keizer, K.; Pieters, C.; Koops van het Jagt, J.; Schaeffer, H. H. A.; Zijlstra, T.; Kroug, M.; Lodewijk, C. F. J.; Wielinga, K.; Boland, W.; de Graauw, M. W. M.; van Dishoeck, E. F.; Jager, H.; Wild, W., "The ALMA Band 9 receiver. Design, construction, characterization and first light", Astronomy & Astrophysics, Vol 577, A12 (February 2015).