The ArTéMiS wide-field sub-millimeter camera: preliminary on-sky performance at 350 microns

Abstract

ArTeMiS is a wide-field submillimeter camera operating at three wavelengths simultaneously (200, 350 and 450 µm). A preliminary version of the instrument equipped with the 350 µm focal plane, has been successfully installed and tested on APEX telescope in Chile during the 2013 and 2014 austral winters. This instrument is developed by CEA (Saclay and Grenoble, France), IAS (France) and University of Manchester (UK) in collaboration with ESO.We introduce the mechanical and optical design, as well as the cryogenics and electronics of the ArTéMiS camera. ArTeMiS detectors consist in Si:P:B bolometers arranged in 16×18 sub-arrays operating at 300 mK. These detectors are similar to the ones developed for the Herschel PACS photometer but they are adapted to the high optical load encountered at APEX site. Ultimately, ArTeMiS will contain 4 sub-arrays at 200 µm and 2×8 sub-arrays at 350 and 450 µm. We show preliminary lab measurements like the responsivity of the instrument to hot and cold loads illumination and NEP calculation.Details on the on-sky commissioning runs made in 2013 and 2014 at APEX are shown. We used planets (Mars, Saturn, Uranus) to determine the flat-field and to get the flux calibration. A pointing model was established in the first days of the runs. The average relative pointing accuracy is 3 arcsec. The beam at 350 µm has been estimated to be 8.5 arcsec, which is in good agreement with the beam of the 12 m APEX dish. Several observing modes have been tested, like "On-The-Fly" for beam-maps or large maps, spirals or raster of spirals for compact sources. With this preliminary version of ArTeMiS, we concluded that the mapping speed is already more than 5 times better than the previous 350 µm instrument at APEX. The median NEFD at 350 µm is 600 mJy.s 1/2 , with best values at 300 mJy.s 1/2 . The complete instrument with 5760 pixels and optimized settings will be installed during the first half of 2015.

MKID Large Format Array Testbed

“…The increased availability of large format arrays of ultrasensitive detectors fulfills the need for maximizing science output through high on-sky scanning speed. In the last decade, microwave kinetic inductance detectors (MKIDs) [1] are emerging as an excellent choice due to their intrinsic multiplexing capability, which makes the readout of kilopixel arrays relatively simple and cheap compared to other technologies [2], [3]. Instruments like MUSIC [4] or NIKA [5] and NIKA 2 [6] are showing the potential of this approach in the astronomical field.…”

Antenna Coupled MKID Performance Verification at 850 GHz for Large Format Astrophysics Arrays

“…Such imaging instruments require kilo-pixel arrays populated by sensors with the background limited sensitivity and high optical efficiency to maximize science output and on sky scanning speed and sensitivity. There are several proven technologies used in these frequency bands [3], [4]. However, later microwave kinetic inductance detectors (MKIDs) [5] are an excellent choice, due to their intrinsic multiplexing capability which makes reading-out large detector arrays relatively simple and cost effective.…”

Optical design for the 450, 350, and 200 µm ArTeMiS camera

“…In Figure 13 we give the values corresponding to the run of July 2013 for the 350 µm band, a cold stop of 44 mm in diameter and the center of the field of view. For the other bands, see [1]. …”

“…The nominal optical design of ArTeMiS is described here, as it will be achieved in 2015, with its full set of bolometric modules and its set of submillimeter filters for the 200 µm band. Its global performances are described in another paper 1 .…”