In the Astronomer’s Telegram #11448 [1] it is announced that a very bright (almost 1st magnitude) transient object is found between the Lagoon and the Trifid nebulae. No other object has been found in the region and the source itself was not visible some days earlier.
Within less than an hour later a second follow up telegram (#11449) informs the community that the transient object is … Mars !
It goes without saying that errors are for humans. But this one shows that every astronomer has to have a basic grasp of the night sky at least.
[1] http://www.astronomerstelegram.org/?read=11448
[2] http://www.astronomerstelegram.org/?read=11449