Image of the Week

27 November 2019: Transit image with a twist (and a turn!) About 13 times per century, fleeting Mercury can be seen passing directly in front of the Sun in what is called a transit. The most recent Mercury transit occurred on 11 November 11, 2019. Teams on Cerro Tololo Inter-American Observatory (CTIO) and Kitt Peak National Observatory (KPNO) developed observing plans in an effort to recreate an experiment to calculate the Earth-Sun distance. CTIO’s Daniel Munizaga obtained this image of the transit with a 6-inch Celestron Nexstar telescope and a Nikon D750 camera by taking images every five minutes. While the path of Mercury across the Sun in fact traced a straight line, in this image the path appears to loop backwards due to an effect called field rotation as the telescope and camera track across the sky. Juan Seguel also imaged the transit of Mercury from CTIO, accompanied by students from the …

20 November 2019: International Gemini Observatory follows a comet from beyond: NOIRLab’s International Gemini Observatory continues tracking a visiting comet from beyond our Solar System. Gemini’s second image release of the comet, discovered by Russian amateur astronomer Gennady Borisov in August of this year, reveals the evolution of the comet as it approaches its closest approach to our sun in December. The image also features the distant background galaxy (going by the catchy designation: 2dFGRS TGN363Z174) that happened to appear adjacent to the comet when the image was captured on the night of November 11–12 2019. “The comet is doing what we would expect a comet to do as it approaches the Sun,” according to Meg Schwamb of Queen’s University Belfast who led the observations. “Gas is being vaporized and the gas cloud, or coma, is expanding and being blown away from the Sun. It’s reassuring that comets from beyond our Solar System …

13 November 2019: Earlier this week, while observing with DECam on the Víctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF NOIRLab, astronomers Clara Martínez-Vázquez and Cliff Johnson noticed something interesting. One of their images, the 333 seconds-exposure seen here, contained at least 19 streaks that they quickly surmised were due to the second batch of Starlink satellites launched last week. The gaps in the satellite tracks are due to the gaps between the DECam CCD chips in the 2.2-degree field. At the same time, the CTIO all-sky camera recorded the satellites which were even visible with the unaided eye. Several frames from that camera can be seen in this timelapse video from CTIO. Links Gemini North Cloud Camera timelapse video of the passage of the Starlink satellite cluster over Maunakea. This sequence was obtained on the night of 12-13 November. CTIO all-sky camera