Using infrared photometric data extracted from the 2MASS, IRAS and MSX databases, 142 suspected young stellar objects (YSOs) are selected from about 2 million stars in the Camelopardalis segment of the Milky Way limited by Galactic coordinates, b=132-158{deg},+/-12{deg}.
Canadian Galactic Plane Survey (CGPS) 1420-MHz Compact Source Catalog
Short Name:
CGPSNGPCAT
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains a catalog of compact sources of radio emission at 1420 MHz in the northern Galactic plane from the Canadian Galactic Plane Survey (CGPS). The catalog contains 72,758 compact sources with an angular size less than 3 arcminutes within the Galactic longitude range 52 < l<sub>II</sub> < 192 degrees down to a 5-sigma detection level of ~1.2 mJy. Linear polarization properties are included for 12,368 sources with signals greater than 4 x sigma<sub>QU</sub> in the CGPS Stokes Q and U images at the position of the total intensity peak. In the reference paper, the authors compare the CGPS flux densities with the catalogued flux densities in the Northern VLA Sky Survey (NVSS) catalog for 10,897 isolated unresolved sources with CGPS flux density greater than 4 mJy in order to search for sources that show variable flux density on timescales of several years. They identify 146 candidate variables that exhibit high fractional variations between the two surveys. In addition, they identify 13 candidate transient sources that have CGPS flux density above 10 mJy but that are not detected in the NVSS. In the CGPS, the Synthesis Telescope at the Dominion Radio Astrophysical Observatory (the DRAO ST) provided arcminute-resolution images of the radio continuum and atomic-hydrogen line emission of the northern Galactic Plane. The CGPS DRAO radio continuum observations provided images of Stokes I, Q, and U in four 7.5-MHz sub-bands spanning 35 MHz, centered on 1420 MHz. The observations were carried out in three phases beginning in 1995 and ending in 2009. The sky coverage of each phase and the observing dates are listed in Table 1 of the reference paper. The Galactic plane was covered with a width in Galactic latitude of 9 degrees, centered at b<sub>II</sub> = 1 degree to accommodate the warp of the Galactic disk. The longitude coverage was constrained by the southern Declination limit of ~20 degrees, the range that could be effectively imaged by a linear east-west synthesis telescope array. The Phase II observations included an extension to higher latitudes (b<sub>II</sub> = 17.5 degrees) over a restricted range of longitude. In this table, we present the CGPS 1420-MHz compact source catalog covering 1,464 square degrees and spanning a range of 140 degrees of Galactic longitude between 52 and 192 degrees. This table was created by the HEASARC in June 2017 based upon a machine-readable version of Table 2 from the reference paper that was obtained from the AJ web site. This is a service provided by NASA HEASARC .
Laser Guide Stars (LGS) allow Adaptive Optics (AO) systems to reach higher sky coverage and correct the atmospheric turbulence on wider field of views. However LGS suffer from limitations, among which is their apparent elongation which can reach 20 arcseconds when observed with large aperture telescopes such as the European Southern Observatory's 39m telescope. The consequences of these extreme elongations have been studied in simulations and lab experiments, but never on-sky. Yet understanding and mitigating those effects is key to taking full advantage of the Extremely Large Telescope (ELT) six LGS. In this paper, we study the impact of wavefront sensing with an ELT-scale elongated LGS using data obtained on-sky with the AO demonstrator CANARY on the William Herschel telescope (WHT) and ESO's Wendelstein LGS unit. CANARY observed simultaneously a natural guide star and a superimposed LGS launched from a telescope placed 40 m away from the WHT pupil. Comparison of the wavefronts measured with each guide star allows to build an error breakdown of the elongated LGS wavefront sensing. With this error breakdown, we isolate the contribution of the LGS elongation and study its impact. We also investigate the effects of truncating or undersampling the LGS spots. We successfully used the elongated LGS wavefront sensor (WFS) to drive the AO loop during on-sky operations, but it necessitated regular calibrations of the non-common path aberrations on the LGS WFS arm. In the off-line processing of the data collected on-sky, we separate the error term encapsulating the impact of LGS elongation in a dynamic and quasi-static component. We measure errors varying from 0 to 160nm rms for the dynamic error and are able to link it with turbulence strength and spot elongation. The quasi-static errors are significant and vary between 20 to 200nm rms depending on the conditions. They also increase by as much as 70nm in the course of 10 min. We do not observe any impact when undersampling the spots with pixel scales as large as 1.95 arcseconds but significant errors appear when truncating the spots. These errors appear for field of views smaller than 10.4 to 15.6 arcseconds, depending on the spots elongations. Translated to the ELT observing at zenith, elongations as long as 23.5 arcseconds must be accommodated, corresponding to a field of view of 16.3 arcseconds if the most elongated spots are put in the diagonal of the subaperture.
