In parallel with Assembly, Integration and Validation (AIV) work on the TuRkish adaptive Optics system for Infrared Astronomy (TROIA) extreme-adaptive optics (XAO) system, PLACID optical alignment and commissioning with the internal calibration source started in February 2026.
At this time of year, accompanied by heavy snowfall, the adventure starts by using a chairlift and a snowcat to reach the summit! Once finally atop Karakaya Ridge at 3,200 m, the alignment tasks start by setting up the input beam with a fiber-coupled HeNe laser (visible light), a fiber launcher, an off-axis parabolic mirror (OAP), two fold mirrors and a pupil mask mimicking the aperture of the 4-m DAG telescope. Two alignments targets are used to align the beam towards the Australian DIRAC infrared camera (H1RG) and the PLACID on/off stage, that makes observations with or without PLACID possible. From there the process starts to step-by-step align the first pair of motorized fold mirrors (PUM1 and PUM2) to direct the beam into the instrument, before reaching the first parabolic mirror of the system (OAP1). Thereafter, the light path focuses onto to the Spatial Light Modulator (SLM). The alignment of OAPs is a little tricky at the beginning - shear plates and microscope objectives are used to confirm beam collimation or absence of astigmatism - but with time and experience even this step simplifies. Alignment on the PLACID instrument also proves to be less complicated than starting from scratch, as the optic mounts are already in place since Factory Assembly in Switzerland in 2023 (!) and only slight adjustments have to be undertaken.
After the SLM, the light continues on its path to OAP2 and another fold mirror before passing through the Lyot filter wheel, which contains PLACID's Lyot stops in the shape of the DAG pupil. Once adjustments for a straight path through the wheel are accomplished, a C-RED 3 near-infrared camera and a lens are positioned to re-image the Lyot pupil plane and the light source is switched from visible to near-infrared (1.6 µm, aka the astronomical H-band spectral window), in order to inspect the quality of the Lyot pupil plane (see photographs of laptops displaying pupil plane images).
Finally, OAP3, OAP4 and three fold mirrors (PBM 1, 2 and 3) bring the beam back towards a path to the DIRAC imager. For now DIRAC is not yet in use, and first PLACID performance tests were performed in H-band (narrow- and broadband) using the C-RED 3 engineering camera. The measured optical point-spread function (PSF) looks very similar to the theoretical DAG telescope PSF expected from simulations (see figure of PSFs side by side), and this is the point where we can declare a successful campaign!
The campaign at the observatory was finalized with coronagraphic images taken with a variety of focal plane masks on the SLM, that were easily implemented with a click of a button and with final adjustments of the GUI, in order to measure contrast performance numbers, required to pass the Preliminary Acceptance milestone for PLACID.
PLACID is now ready to launch, as soon as the DAG telescope and TROIA XAO system are on-sky! Stay tuned for a breaking news by this fall...
Owing to delays linked to the Acceptance of the DAG telescope, which was finally cleared by late May 2025 (meaning that the warranty period of the observatory has officially started!), the PLACID team was prevented to proceed with commissioning activities for a few months. But finally, green light to resume on-site instrumentation activities was given at the start of the summer season.
In early July 2025, the PLACID team traveled to the summit and started to cable up the instrument, its active motorized components, and its electronics. The server cabinet units were also installed on the Nasmyth rack, and a full rehearsal of live PLACID operation from the PC server - and from the telescope control room - was executed. We are glad to report that all critical active PLACID components are in good working condition and running smoothly from the graphical user interface (GUI)!
Our ATASAM and HEIG-VD colleagues can now proceed to install the TuRkish adaptive Optics system for Infrared Astronomy (TROIA) extreme-adaptive optics (XAO) system in front of PLACID over the coming summer and fall periods, followed by the Australian team from MacQuarie University, who will install the DAG InfRAed Camera (DIRAC) around late October. Hence we shall be back at the onset of the winter season to start optical commissioning of PLACID, followed by the first light: stay tuned!
At last, PLACID was unpacked and mechanically installed on the diffraction-limited Nasymth platform of the DAG telescope on January 29, 2025. The telescope dome crane successfully lifted the approx. 150 kg of the PLACID main optical breadboard (without the optics and electronics) all the way from the storage bay to the thermally-enclosed Nasmyth platform (with the enclosure roof panel removed to this purpose), through the dome floor crane opening. Pretty stressful minutes, but the "landing" on the Nasmyth optical table was ultimately very soft.
Now our Yverdon colleagues working on the adaptive optics (TROIA AO system) can start the precise alignment of their instrument with the PLACID weight at the right location on the table. Next step for PLACID: cabling campaign later this winter, and optical alignment this spring. We cannot wait to be back, look at the facility, the site and the landscape!
In November, the PLACID instrument (main crate and palettes) was successfully delivered to the summit, right before the heavy snowfall period when the road becomes unpractical for trucks. The last section of the road to the observatory and around the DAG itself was recently paved.
Furthermore, the KORAY image derotator from our HEIG-VD partners was internally aligned on-site and installed into the telescope flange leading to the diffraction-limited Nasmyth platform, the future home for PLACID. The delicate process of adjusting and inserting the derotator into the telescope flange can be seen on the images. This process has been successfully completed and the thermal enclosure for the diffraction-limited Nasmyth platform is currently being installed. Once this is completed, KORAY will be aligned to the telescope optical axis on-sky and we shall come to install PLACID, alongside our HEIG-VD colleage who will setup the TROIA XAO system. Exciting times ahead!
After quite a trip from Switzerland to Istanbul by air, then by truck to Eastern Anatolia, PLACID was delivered to the Erzurum ATASAM facilities at Atatürk University on March 9, 2024. The RACE-GO team conducted an on-site inspection visit and took the opportunity to visit the DAG observatory, ridding a snow cat, as the road to the summit at 3170 m is snow-covered in this season. All is looking good, and the long wait to be allowed to bring PLACID to the telescope summit facilities begins...