SWIMS open use observations at the Subaru Telescope completed

The Simultaneous-color Wide-field Infrared Multi-object Spectrograph (SWIMS), the first-generation instrument for the TAO 6.5-m telescope, has completed its open use operation at the Subaru Telescope (NAOJ, in Hawaii), which had lasted 2 years since 2021.

We began designing and manufacturing SWIMS in 2009, conducted various functional tests and improvements in Japan, and made performance evaluations and adjustments at the Subaru Telescope since 2018, for preparation and training for full operation at the TAO telescope. We confirmed that SWIMS performed observations as designed, and open use of SWIMS at the Subaru Telescope from April 2021 was approved.

▲Fig. 1: SWIMS under open use as a PI instrument at the Subaru Telescope

There are two types of instruments operated on the Subaru Telescope. One is the facility instrument which is developed mainly by the observatory (collaborating with other institutes such as universities), and the other is called "PI instrument" which is developed independently by other institutes. SWIMS is a PI instrument.

When SWIMS was opened as a PI instrument in the first half of 2021, a lot of observation proposals were submitted by domestic and international researchers, taking advantage of SWIMS' unique capability of simultaneous observations at two wavelengths. It clearly indicated the high expectations to SWIMS. Some proposals were to make a pilot observation preparing for full-scale observations at the TAO telescope, and some proposals were to observe celestial objects in the Northern Hemisphere which wouldn't be visible from the TAO telescope in the Southern Hemisphere.

From April 2021 to the time of writing this article, various open use observations have been made targeting various objects from intragalactic objects to distant galaxies. Total observation time is about 600 hours, and the total amount of acquired observation data is nearly 2 TB. Some results have already been published as referred papers. During the open use operation at the Subaru Telescope, SWIMS operated stably without any major problems except for the replacement of a cryocooler in November 2021 due to a decline in cooling capacity. Researchers who have conducted imaging and spectroscopic observations using SWIMS have praised the simultaneous observation of two wavelength ranges as highly efficient and excellent for acquiring a large amount of data rapidly.

• Asano, T. et al. 2020, ApJ 899, 64
• Bouy, H. et al. 2022, A&A 664, A111
• Matsumoto, A. et al. 2022, ApJ, 941, 167M
• Terao, Y. et al. 2022, ApJ 941, 70
• Uno, K. et al. 2022, ApJ in press (arXiv:2301.09901)

▲Fig. 2: observation at the summit with help of Subaru staff (right)

In addition to the imaging and MOS modes, the integral-field spectroscopy unit (IFU) mode which had been developed with RIKEN from 2010, succeeded in its first light in March 2022, and started open use in the second half of 2022. The SWIMS IFU mode has a wider field of view than conventional near-infrared IFU instruments, enabling the simultaneous observation of spectral information from a large spatial extent of a celestial body. Unfortunately, due to the eruption of Mauna Loa, we were unable to obtain most of the open use data using IFU. But we were able to obtain sufficient results as a technical demonstration for observations at the TAO telescope.

SWIMS open use operation at the Subaru Telescope ended in the second half of 2022. SWIMS will be transported to the institute of Astronomy (IoA, in Mitaka, Tokyo), and final adjustment for the TAO telescope will be made. It will be transported from Mitaka to Chile in the first half of 2024, full-scale science operations are expected to start in the second half of 2024 in early cases. We will do our best to meet your expectations toward full-scale observations at the TAO telescope.

Please stay tuned for SWIMS results at the Subaru Telescope and future activities at the TAO telescope.

▲Fig. 3: SWIMS and its team leader, Motohara

Related link

• SWIMS Subaru Telescope Observations Completed (Subaru Telescope webrelease, April 26, 2023)