Deep J-band imaging of high redshift QSO candidates with the Himalayan Chandra Telescope

High redshift QSOs (redshift >5.7) are highly important ob jects. If such QSOs may be found, their spectra will reveal the onset of reionization of the intergalactic medium (Gunn-Peterson trough), and provide precious in sights into the re-ionization epoch in the very early universe. Here we report our pilot attempt to follow-up high redshift QSOs with the Himalayan Chandra Telescope. Deep J-band imaging was performed on three high redshift QSO candidates colour-selected from the SDSS, using the near-infrared imager. Although none of the targets turned out to be likely high redshift QSOs, careful data reduction shows that the data reach the required depth, proving that the Himalayan Chandra Telescope is a powerful tool to follow-up high redshift QSO candidates

Luminosity functions of YSO clusters in Sh-2 255, W3 main and NGC 7538 star forming regions

We have conducted deep near-infrared surveys of the Sh-2 255, W3 Main and NGC 7538 massive star forming regions using simultaneous observations of the J H Ks-band with the near-infrared camera SIRIUS on the UH 88-inch telescope. The near-infrared surveys cover a total area of ∼ 72 square arcmin of three regions with 10-σ limiting magnitudes of ∼ 19.5, 18.4 and 17.3 in J, H and Ks-band, respectively. Based on the colour-colour and colourmagnitude diagrams and their clustering properties, the candidate young stellar objects are identified and their luminosity functions are constructed in Sh-2 255, W3 Main and NGC 7538. A large number of previously unreported red sources (H − K > 2) have also been detected around these regions. We argue that these red stars are most probably pre-main sequence stars with intrinsic colour excesses. The detected young stellar objects show a clear clustering pattern in each region: the Class I-like sources are mostly clustered in molecular cloud region, while the Class II-like sources in or around more evolved optical H II regions. We find that the slopes of the Ks-band luminosity functions of Sh-2 255, W3 Main and NGC 7538 are lower than the typical values reported for the young embedded clusters and their stellar populations are primarily composed of low mass pre-main sequence stars. From the slopes of the Ks-band luminosity functions, we infer that Sh-2 255, W3 Main and NGC 7538 star forming regions are rather young (age ≤ 1 Myr)

pyTANSPEC: A Data Reduction Package for TANSPEC

The TIFR-ARIES Near Infrared Spectrometer (TANSPEC) instrument provides simultaneous wavelength coverage from 0.55 to 2.5 micron, mounted on India's largest ground-based telescope, 3.6-m Devasthal Optical Telescope at Nainital, India. The TANSPEC offers three modes of observations, imaging with various filters, spectroscopy in the low-resolution prism mode with derived R~ 100-400 and the high-resolution cross-dispersed mode (XD-mode) with derived median R~ 2750 for a slit of width 0.5 arcsec. In the XD-mode, ten cross-dispersed orders are packed in the 2048 x 2048 pixels detector to cover the full wavelength regime. As the XD-mode is most utilized as well as for consistent data reduction for all orders and to reduce data reduction time, a dedicated pipeline is at the need. In this paper, we present the code for the TANSPEC XD-mode data reduction, its workflow, input/output files, and a showcase of its implementation on a particular dataset. This publicly available pipeline pyTANSPEC is fully developed in Python and includes nominal human intervention only for the quality assurance of the reduced data. Two customized configuration files are used to guide the data reduction. The pipeline creates a log file for all the fits files in a given data directory from its header, identifies correct frames (science, continuum and calibration lamps) based on the user input, and offers an option to the user for eyeballing and accepting/removing of the frames, does the cleaning of raw science frames and yields final wavelength calibrated spectra of all orders simultaneously.Comment: 10 pages, 6 figures, accepted for publication in the Special Issue of Journal of Astrophysics & Astronomy, 2022, Star formation studies in context of NIR instruments on 3.6m DOT, held at ARIES, Nainital during 4-7, May, 202