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BAA Observing calendar

Conjunction between Mars and NGC 6530

Tuesday, 2018, March 20 - 02:15

Dominic Ford – originally published on

Mars and NGC6530 will make a close approach, passing within 0°49' of each other.

From London (click to change), the pair will be difficult to observe as they will appear no higher than 13° above the horizon. They will be visible in the dawn sky. They will rise at 02:28 (BST), 3 hours and 35 minutes before the Sun, and attain an altitude of 13° above the southern horizon before fading from view as dawn breaks at around 05:27.

At the moment of closest approach, Mars will be at mag 0.1, and NGC6530 at mag 4.6, both in the constellation Sagittarius.

The pair will be a little too widely separated to fit comfortably within the field of view of a telescope, but will be visible to the naked eye or a through pair of binoculars.

The precise positions of Mars and NGC6530 at the moment of closest approach will be as follows:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 18h04m50s -23°30' Sagittarius 0.1 7"6
NGC6530 18h04m40s -24°19' Sagittarius 4.6 15"0

The coordinates above are given in J2000.0. The pair will be at an angular separation of 88° from the Sun, which is in Pisces at this time of year.

The details of this observing event were provided courtesy of