Barnard's Star
May 21, 2017

While at Batsto for the May 20, 2017, WAS Public Star Watch, Barnard's Star was observed. Located in Ophiuchus, near the obsolete constellation Taurus Poniatovii, this red dwarf is interesting because it has the greatest proper motion of any star at 10.3″/year, in large measure because it's just 6 light years away. This picture was captured at 1:19 am EDT on May 21, 2017, with a Canon 7D Mark II digital SLR camera and a Canon 70 to 200 mm f/2.8L zoom lens (on a fixed tripod) set to 135 mm focal length, then mildly cropped. It was exposed 4 seconds at f/2.8, ISO 3200 and 3600K white balance. Mouseover for labels.

The position of Barnard's Star matches well with the position indicated on charts generated with SkyTools and Stellarium, but I found that the position generated with SkySafari Pro (versions 4 & 5) on my iPhone did not match the telescopic eyepiece view (but see the note at the bottom of the page). In brief, SkyTools and Stellarium (and perhaps other planetarium programs that I do not have) update the position based on the date of the chart, which can result in a significant movement because of the high proper motion of Barnard's Star. Since the year 2000, it has moved almost 3 arc minutes north, but the Sky Safari chart shows no indication of that movement. In the set of images below, compare the magnified crop of the original picture above with screen captures from SkyTools and SkySafari, both set for the summer of 2017. Mouseover for labels.


Magnifying Crop from the Original Image Above (taken in 2017)


Screen Capture from SkyTools 3 Pro (set to 2017)
The position of Barnard's Star matches the image above.
Screen Capture from SkySafari Pro 5 (set to 2017)
Barnard's Star is in the year 2000 position, but see the note below.


Update, 14-March-2020: While searching for some settings related to precession in Sky Safari 6, I checked the "Precession" tab under "Settings" and found an on/off button for "Proper Motion." It was turned off, presumably the default setting since I never made any changes to it before (and didn't even realize it was there). I clicked it to the "on" setting, then checked Barnard's Star against an image taken on March 12, 2019 (setting SkySafari to the same date) and it then displayed the correct position. In any case, the two planetarium program clips show the nominal 3 arc minute movement in 17 years, but more obvious is the large change in position angle relative to TYC 00425-0262-1.


Barnard's Star, June 2021 (proper motion measured)