Project Overview of the Beijing-Arizona Sky Survey

TL;DR

<3-5 sentence high-level summary>

Abstract

The Beijing-Arizona Sky Survey (BASS) is a wide-field two-band photometric survey of the Northern Galactic Cap using the 90Prime imager on the 2.3 m Bok telescope at Kitt Peak. It is a four-year collaboration between the National Astronomical Observatory of China and Steward Observatory, the University of Arizona, serving as one of the three imaging surveys to provide photometric input catalogs for target selection of the Dark Energy Spectroscopic Instrument (DESI) project. BASS will take up to 240 dark/grey nights to cover an area of about 5400 deg$^2$ in the $g$ and $r$ bands. The 5$σ$ limiting AB magnitudes for point sources in the two bands, corrected for the Galactic extinction, are 24.0 and 23.4 mag, respectively. BASS, together with other DESI imaging surveys, will provide unique science opportunities that cover a wide range of topics in both Galactic and extragalactic astronomy.

Figures (5)

• Figure 1: Filter responses for the BASS $g$ (blue) and $r$ (red) bands. The red solid curve is the CCD QE and the cyan curve presents the atmospheric transmission on Kitt Peak. The dashed profiles are the transmission curves of these two filters. The solid profiles are the total responses, including the CCD QE and atmospheric extinction. The dash-dotted curves show the $g$ and $r$-band responses used by the SDSS.
• Figure 2: The footprint of the DESI imaging surveys in the Aitoff projection centered at ($\alpha=120\arcdeg$, $\delta = 0\arcdeg$). The blue region shows the DECaLS coverage, and the red one shows the coverage of BASS and MzLS. The red curve represents the Galactic plane. The green points with labels show the positions of the Galactic center (GC), Galactic anticenter (GAC), north Galactic pole (NGP) and south Galactic pole (SGP).
• Figure 3: An updated image taken by the all-sky camera installed on Kitt Peak. The green envelope shows the BASS footprint. The points (blue for $g$ band and red for $r$ band) are the tiles to be observed during the night. The telescope pointing is over-plotted in cyan. The yellow dashed lines display the Equatorial grid.
• Figure 4: The telescope pointing error and image quality varying with time during a whole night. From top to bottom, the panels show the parameter variations for R.A. (red) and decl. (blue) errors in arcsec of the telescope pointing, real-time exposure time (red) and exposure time in second given by the ETC (blue), sky brightness in mag/arcsec$^2$, zero point in mag for 1e/s, full depth in mag, and seeing in arcsec. The number shown in each panel gives the parameter value of the last point. The top x axis is the Mountain Standard Time in hour, and the bottom one gives the Beijing time. Different passes are shown in the third panel with different symbols. The dashed line in the first panel gives the upper limit of 20. The one in the second panel indicates the typical single exposure time of 100 s. The blue and red dashed lines in the fifth panel show the defined depths of $g$ and r bands, respectively. The dashed line in the last panel gives the seeing cut of 1.7.
• Figure 5: The observation progress in the past two years of 2015 and 2016. From left to right, the panels are progresses for Pass 1, Pass 2, and Pass 3. The bad-quality data taken in 2015 are removed. The black point shows the BASS tiles of one pass. The blue and red points present the tiles that have been observed for only $g$ band and only $r$ band, while the green points show the tiles observed with both filters. The percentages in the legends show the fractions of tiles that have been observed.