The asteroid Vesta (known as a minor planet as it is one of the largest ones) has been at opposition recently. From an article in the BBC “Sky at Night” magazine (online version here) I was inspired to take some photos. I have superimposed them, and the result shows the movement of Vesta over 5 nights as a line of little dots. Fun!
The stacked image without annotation is here:
Because the images are added, the stars appear brighter relative to the asteroid, so in binoculars it was a bit brighter than it appears here. I did have another image from two nights prior to the sequence, but I was only able to take an image with the sky quite bright due to clouds, so I have excluded it from the sequence.
Here is an example of a completely unprocessed image, from May 12:
The area of the stacked image is in the lower half of this photo; the star pattern should be recognisable, though it is at a different angle.
The images were taken using a Nikon D3100 with a manual zoom lens set at 70mm and focussed at infinity (to avoid the faff of using a modern autofocus lens). The image quality is not fantastic but is OK for this purpose. The images were 4 second exposures at f/3.5, ISO1600, with the camera mounted on a tripod and a cable release used to fire the shutter.
The images were first processed using the Gimp software to adjust the “dark” sky level to about the same value (since the night sky in Scotland is so bright at this time of the year). They were then stacked using the freeware program DeepSkyStacker, without any dark or flat frames. Even though the images were at different orientations (up to about 10 degrees) and different centres, the stacking software worked well. The images presented here have been further processed to enhance the brightness of the stars, and to add the annotations indicating star names in Libra and Virgo.