Shwetha Prakash | Searcharxiv

arXiv2026

TIME Commissioning Observations: II. On-sky Characterization and the 2D Map Data Processing Pipeline

The Tomographic Ionized-carbon Mapping Experiment (TIME) is a line intensity mapping (LIM) instrument that is designed to observe the power spectrum of the [CII] $158$~$\mu$m emission line during the Epoch of Reionization. TIME completed a commissioning run in 2022 at the Arizona Radio Observatory onboard the 12-M Radio Telescope at Kitt Peak, where it observed galactic sources for the first time. In this paper we report on an analysis of observations of the Orion Molecular Cloud (OMC) and G49.5 (a local HII region). The OMC observations were taken at least once a day to assess the stability of the instrument and demonstrate its on-sky performance. We describe a spectral image processing pipeline to make calibrated maps of raster scans of these sources, incorporating planet observations for gain calibration. We show with G49.5 that, when compared to the Bolocam Galactic Plane Survey, we are able to achieve a $< 3\%$ calibration difference. Based on the outcomes from this commissioning phase of TIME, we have demonstrated preliminary performance, and identified sources of improvement necessary for pursuing a LIM measurement.

astro-ph.IM↗

arXiv2025

TIME Commissioning Observations: I. Mapping Dust and Molecular Gas in the Sgr A Molecular Cloud Complex at the Galactic Center

We present the processing of an observation of Sagittarius A (Sgr A) with the Tomographic Ionized-carbon Mapping Experiment (TIME), part of the 2021-2022 commissioning run to verify TIME's hyperspectral imaging capabilities for future line-intensity mapping. Using an observation of Jupiter to calibrate detector gains and pointing offsets, we process the Sgr A observation in a purpose-built pipeline that removes correlated noise through common-mode subtraction with correlation-weighted scaling, and uses map-domain principal component analysis to identify further systematic errors. The resulting frequency-resolved maps recover strong 12CO(2-1) and 13CO(2-1) emission, and a continuum component whose spectral index discriminates free-free emission in the circumnuclear disk (CND) versus thermal dust emission in the 20 km s$^{-1}$ and 50 km s$^{-1}$ molecular clouds. Broadband continuum flux comparisons with the Bolocam Galactic Plane Survey (BGPS) show agreement to within $\sim$5% in high-SNR molecular clouds in the Sgr A region. From the CO line detections, we estimate a molecular hydrogen mass of between $5.4 \times 10^5 M_\odot$ and $5.7 \times 10^5 M_\odot$, consistent with prior studies. These results demonstrate TIME's ability to recover both continuum and spectral-line signals in complex Galactic fields, validating its readiness for upcoming extragalactic CO and [C II] surveys.

astro-ph.IM↗