What we work on, by question

MEGARA/GTC IFU spectroscopy of 26 local LCBGs shows that a kinematic correction for non-Gaussian line profiles reduces the scatter of the L(Hβ)–σ relation from 0.28 to 0.22 dex (Camazón-Pinilla, Guzmán & Chanchaiworawit, A&A submitted 2026).

H II galaxies are compact, gas-rich starbursts (EW(Hβ) ≳ 50 Å, R_eff ≲ 1 kpc) whose Hβ luminosity scales steeply with the velocity dispersion of the ionized gas, L(Hβ) ∝ σ⁵. That makes them standardizable candles that can bridge the distance-indicator desert at z ≈ 1.5–3, beyond the reach of Type Ia supernovae. The team observed H II galaxies with EMIR (near-infrared multi-object spectroscopy) and MEGARA on the GTC as part of the GOYA guaranteed-time survey between 2013 and 2019.

The limiting factor is the intrinsic scatter of the relation, up to ~0.3 dex in the local Universe. Current work uses the resolved kinematics from MEGARA to correct for non-Gaussian line profiles and second parameters — the same correction that reduces the scatter for local luminous compact blue galaxies from 0.65 to 0.37 dex — so that a corrected L–σ calibration is ready for application at z ≈ 1.5–3. Part of this is run as a SEASTAR student research project with Chulalongkorn University.

A 5-axis single-point diamond-turning machine in a temperature-controlled enclosure, 3D surface profilers, a cryo-cycling chamber, and an ultra-precision CMM. The production line Design → CNC → polishing → SPDT → metrology has reached TRL 6.

FY68 delivered the SPDT machine, profilers, cryo-chamber, and a TRL-4 production line; FY69 added the metrology upgrade (ultra-precision CMM, surface-quality tester, vacuum oven); FY70 proposes a surface-verification system (dual-mode laser interferometer, high-power microscope) and environmental control.

DARTS (Dual-beam Automatic Rapid Transient Spectrograph) is a fully robotic low-resolution spectrograph for classifying transients — supernovae, variable stars, active galaxies — in the era of large surveys such as the Vera C. Rubin Observatory. It covers 360–1,000 nm simultaneously in blue and red channels at R ≈ 1,000, with a K-mirror image derotator and an EMCCD slit-viewing camera. The optical design comes from UCO/Lick; most of the mechanical design, manufacturing, assembly, and alignment happens at NARIT. The first unit is bound for the Left Nasmyth port of the 2.4-m Automated Planet Finder at Lick Observatory, California, with a second planned for the Thai National Telescope.

SEAL Lab's contribution is the reflective optics: the slit-viewing mirrors were the first prototype on the lab's list in February 2024, were machined on the Freeform L and verified on the DynaFiz interferometer, and are now mounted on the DARTS bench. The slit masks are also cut by single-point diamond turning. Delivered as a FY2568 output.

Additive manufacturing lets a mirror be printed with a lightweight lattice behind its face — attractive for CubeSats and space telescopes — but only if the printed alloy can be diamond-turned to an optical finish. The team machined six substrates under identical conditions (2,000 rpm, 5 mm/min feed, 2 µm depth of cut, 21–23 °C): a cast RSA 6061 baseline, AlSi10Mg from two suppliers, and Scalmalloy, each with and without hot isostatic pressing (HIP). Stress-relieved AlSi10Mg reached a surface roughness Sq of 2.99–3.77 nm, close to the cast baseline of 2.23 nm, while HIP closed pores but coarsened the grains and roughly doubled the roughness (7.67 nm for AlSi10Mg + HIP, 12.53 nm for Scalmalloy + HIP). Specular reflectance over 400–900 nm matched cast aluminum for Scalmalloy and reached 70–80% for AlSi10Mg. The conclusion: printed mirror substrates are viable today with the right alloy and heat treatment.

The work grew out of the Newton Fund STFC–NARIT project on freeform-optics manufacturing (Durham University lead, 2020–2022) and a 2022 SPIE study of lightweight mirror design for conventional and additive manufacturing. It was published at SPIE Astronomical Telescopes + Instrumentation 2026 (Ruenarrom et al.) and continues with AM mirror prototypes for the ADOT 6U CubeSat with UK ATC. A PMU-B FY2570 proposal (F11) would take a CubeSat micro space-telescope prototype built from freeform 3D-printed parts and SPDT mirrors through a full space-qualification chain (outgassing, atomic oxygen, thermal vacuum, vibration, radiation) with TINT, UK ATC, and RAL Space, from TRL 3 to 4–5.

NARIT's CubeSat program is developing two Cassegrain space telescopes whose mirrors are made in Thailand for the first time: a 3U unit (about 6 kg, 100 × 100 × 340.5 mm, 4.7 m ground sampling distance from a 550-km sun-synchronous orbit) and a 6U unit (about 12 kg, 100 × 200 × 340.5 mm, 1.8 m ground sampling distance). SEAL Lab machines the M1 and M2 mirrors from GD&T-controlled shop drawings on the Freeform L, verifies their form on the DynaFiz interferometer, and aligns the optics in the lab; the 3U mirror is built on a lightweight lattice back.

The lab also delivered the retroreflectors for TSC-1 and a prototype tertiary mirror for TSC-1's hyperspectral imager among its FY2568 outputs, and the 6U optics were shown to the leadership of the Ministry of Higher Education, Science, Research and Innovation during its visit to the lab. The satellites are assembled in Thailand with a ground station at NARIT.

HARMONI is the first-light visible and near-infrared integral-field spectrograph of ESO's Extremely Large Telescope, led by the University of Oxford and now in its final design phase. Its optics — and those of other ELT instruments — call for large freeform mirrors in low-thermal-expansion glass. SEAL Lab's Freeform L currently handles workpieces up to 650 mm in metal. The N43 Frontier Research Infrastructure proposal submitted to PMU-B in August 2026 would raise the capacity to 700 mm, qualify ductile-regime machining of fused silica, ULE, and Zerodur, add a sub-micron defect-inspection microscope and coating and vacuum equipment, and produce at least three ELT-class demonstration optics with Ra ≤ 5 nm and PV ≤ 0.1 µm, reviewed and accepted by the Oxford HARMONI team and ESO. The plan takes the brittle-optics production line from TRL 4 to 6 in twelve months, trains six certified engineers, and targets entry into the ELT instrument supply chain.

Status: proposal under evaluation. Oxford and ESO have committed in-kind contributions (optical-design effort, interface specifications, instrument requirements, and facility access) matching NARIT's request.

Most AGN variability studies are dominated by bright quasars. This one targets the quiet majority: intrinsically low-luminosity AGN in SDSS DR17 at z < 0.84 with bolometric luminosities of 10⁴³–10⁴⁶ erg/s and Eddington ratios above 0.002, whose light is blended with their host galaxies. Principal-component decomposition of the spectra separates the AGN from the host, yielding black-hole masses (from the broad Hβ line, FWHM > 1,000 km/s) and Eddington ratios, and the AGN-only magnitudes in different epochs — photometric versus spectrophotometric — give the variability.

The ensemble structure functions rise with rest-frame time lag as power laws with slopes of about 0.20–0.22 in g, r, and i, and the amplitude maps out across the black-hole-mass–Eddington-ratio plane: variability is driven mainly by the accretion rate rather than by black-hole mass. Published as Chanchaiworawit & Sarajedini (2024, ApJ 969, 131); the same sample now feeds the AGN host-morphology project.

Does the shape of a galaxy tell us how its black hole grew? This project fits three-component models — an AGN point source plus inner and outer Sérsic profiles — to the SDSS images of about 16,000 low-luminosity Seyfert-1 AGN at z = 0–0.9 with black-hole masses of 10⁶–10⁹ solar masses, drawn from the sample of Chanchaiworawit & Sarajedini (2024). Black-hole masses come from multicomponent spectral decomposition; simulations set the reliability limits (S/N > 40, AGN fraction < 0.8, fitting error < 0.5 dex), and coefficients are bootstrapped in the g', r', and i' bands.

First results, presented by Thatchayuth Klipbua at APRIM 2026 in Hong Kong: the Sérsic index correlates positively with black-hole mass and with Eddington ratio, and negatively with redshift — hosts at higher redshift are less morphologically developed.

A 2020 ugriz monitoring campaign with ULTRASPEC on the 2.4-m Thai National Telescope. The analysis combines a PSF/aperture photometry pipeline with ICCF, JAVELIN, and Gaussian-process lag analysis, leading to a black-hole mass inference. Manuscript in preparation for ApJ.

NARIT's simulation-software development for ARRAKIHS began in 2018, and the institute is represented in the mission consortium by the team PI. NARIT's CHALAWAN cluster is one of four computing systems supporting mission simulations worldwide: the mock observations feed the mission's image-simulation pipeline and also yield cosmological dN/dz science from the background galaxies.

The mission was adopted by ESA's Science Programme Committee on 10–11 June 2026 as the second F-class mission (F2), with launch planned for late 2030. ARRAKIHS will image the faint outskirts of at least 80 Milky-Way-mass galaxies over 3–5 years with two binocular telescopes covering 280–1,600 nm in four bands, to count stellar streams and satellites and so test the nature of dark matter. The consortium spans nearly 48 institutions in 17 countries; Thailand is a contributing country through NARIT.

The idea is to teach a machine on real, well-understood data and then let it read the JWST era. Random-forest regressors are trained on SDSS galaxies to extract physical parameters from photometry; the low-redshift frames are then transformed to z > 3–10, the SDSS bandpasses are matched to the JWST/NIRCam wide filters, and the trained models are applied to JWST galaxies to predict properties that would otherwise need spectroscopy. Convolutional neural networks trained on imaging separate object types and redshift classes.

First results recover star-formation rates from photometry alone that follow a tight one-to-one relation with the SED-fitted values. The project is led by Gunmethus Cherdchoochavalit — it began as his BSc thesis at Chiang Mai University (2025), where he is now an MSc student — and has been presented at SPC 2025 and APRIM 2026.

About 45 h of OSIRIS imaging to 26.5 mag (AB) and 42 h of multi-object spectroscopy on the GTC (≈ 87 h in total) revealed an overdense region of Lyman-α emitters at z = 6.5, confirmed spectroscopically and characterized as a Coma-analog protocluster (MNRAS 2017; ApJ 2019; MNRAS 2019; MNRAS Letters 2020).

Protoclusters are the progenitors of today's galaxy clusters, and cosmic noon (z ≈ 1.5–3, roughly 2–6 billion years after the Big Bang) is when the cosmic star-formation rate peaked and about half of the stellar mass in the present-day Universe was assembled. Two JWST pure-parallel programs — PASSAGE (NIRISS imaging and slitless spectroscopy in 63 fields, 15 of them overlapping COSMOS) and SAPPHIRES (NIRCam imaging in 13 bands and wide-field slitless spectroscopy over 16.9 arcmin²) — now reach this epoch along many independent sightlines, but no unified protocluster catalog has been built from them.

This senior project does exactly that. HST and JWST images are retrieved from MAST, sources are extracted with SExtractor in dual-image mode on a common grid, single-band catalogs are merged and zero-point calibrated, and photometric redshifts are derived with EAZY (public redshift catalogs are used for the SAPPHIRES fields). Candidate structures are found with two complementary criteria: the galaxy overdensity δ = n/n̄ − 1 in comoving redshift slices, and a three-dimensional friends-of-friends algorithm on the (RA, Dec, z) distribution, followed by validation against earlier survey redshifts. The candidates are then fitted with Prospector using a non-parametric star-formation history to estimate mass-weighted ages, gas fractions, and quenched fractions.

Work plan: candidate search in PASSAGE (Jun–Sep 2026) and SAPPHIRES (Aug–Sep 2026), catalog validation and cross-matching with public data (Oct–Dec 2026), and SED fitting and characterization (Jan–Apr 2027).

Did the first overdensities make their galaxies grow faster, or just earlier? The team selected 1,169 galaxies at z = 2–8 in the JADES GOODS-North and GOODS-South fields with 19–22 HST/WFC3 and JWST/NIRCam bands, measured photometric redshifts with EAZY, and fitted every SED with CIGALE 2025.1 using a stochastic star-formation history (80 random-walk realizations per galaxy) plus an AGN component. Counting galaxies within 5 comoving Mpc and scaling by the galaxy bias turns the maps into matter-density contrasts, with cores of most-massive-progenitor scale (enclosed mass ~2 × 10¹³–10¹⁴ solar masses; 39 core members).

What comes out: most galaxies are metal-poor even in the cores; core members had stronger bursts in the last 30 Myr while the outskirts match the field; the star-forming main sequence sits 0.3–0.5 dex higher in overdense bins; stellar populations near the density peaks are younger than 200 Myr; and about 40% of z > 6 galaxies are caught between bursts. At the densest cores (δ_m > 20, z > 4) the dynamical time of ~0.5 Gyr is comparable to the time since the last burst — the environment appears to set the rhythm of star formation. A companion spectroscopic study uses the lensed z ≈ 7.87 protocluster behind Abell 2744 from the UNCOVER program. Presented at SPC 2025, EAMA11, and APRIM 2026; manuscript in preparation.

Why does star formation in the early Universe come in short, sharp bursts, and why do galaxies quench as they fall into clusters? The team's working hypothesis is spin-regulated star formation: gas with high angular momentum keeps a galaxy's spin parameter high and its fuel spread out; when the high-spin gas is removed — by ram-pressure stripping, harassment, strangulation, or mergers on the way into a dense environment — the rest funnels to the center and fuels a burst, after which the galaxy runs dry. Protocluster cores at z ≈ 2–4, with shallow potential wells and no hot intracluster medium yet, should therefore be bursty; assembled low-redshift clusters should be quenched; and the HI-rich field should show a clean spin–gas-mass relation.

The test is done in the nearby Universe, where spin, HI mass, and radial velocities can be measured directly: new MEGARA observations at the GTC (R = 5,000–20,000 in the optical) of galaxies selected by size, HI mass, and star-formation rate, alongside archival MaNGA and SAMI cubes, and Hector on the AAT. Twenty-six local luminous compact blue galaxies are already in hand. The first batch shows high specific star-formation rates in slow-rotating open-field H II galaxies from the GTC filler programs; more targets across HI fractions and environments are being added.

The LRS is the workhorse long-slit spectrograph for the 2.4-m Thai National Telescope: 400–800 nm with a 960 l/mm VPH grism, interchangeable slits of 4.5″, 2.7″, and 1.8″ giving R ≈ 300, 500, and 750, and an Andor Newton BEX2-DD CCD held at −100 °C by a thermoelectric cooler and a Thorlabs LK220 chiller. In its latest on-sky tests it reached r' = 20.8 AB at S/N 5 in one hour (21.5 in two hours). The prototype installed in December 2018 delivered R ≈ 800–1,300 over 440–740 nm (Paenoi et al. 2019).

The instrument was offered to the community as a shared-risk mode in Cycle 13 (December 2025 – May 2026) and enters full operations in Cycle 14 (October 2026 – May 2027). A user-friendly GUI and packaged reduction routines are in development; the guiding-camera mount, detector cooling, and upgraded mechanical components are described in Tharawan et al. (SPIE 2026), and the autoguiding and robotization software in Chomchuen et al. (SPIE 2026).

Commissioned on the 0.7-m Thai Robotic Telescope at NARIT AstroPark, with first light on Jan 27, 2025. CoLoRS covers 400–700 nm at R ≈ 100–200 in a 15.2-kg package with no moving parts; a dichroic at 805 nm sends the red light to the guider, so the same unit guides and takes spectra. It reaches S/N > 100 at r' ≈ 12 in under a minute and had logged nine nights on the TRT by March 2026. The optomechanical design, on-sky performance, upgraded mechanical components, and robotic control software were published at SPIE 2025 and 2026.

Next steps: science verification on the 0.8-m telescope at Phitsanulok in early 2027, and CoLoRS-NEX, which adds a C-RED 2 InGaAs short-wave-infrared imager (zyJH bands). The exposure-time calculator is developed by Plan Nitiwarangkul.