The Seestar S50 smart telescope comes with what’s called an alt-azimuth mount. It can move left to right and up and down and so track a point object as it moves across the sky. However, unless you want to take a picture of a point object, like a single star, this will only partly compensate for motion across the sky. Extended objects, which is just about everything, also appear to rotate as they move.

Here’s a timelapse movie that shows how an attempt to image M106 is hampered by this effect.

http://www.platitudes.org.uk/m106_edit.mkv

This makes it harder to stack frames. It also means that a lot of frames get rejected due to star trails and other unwanted artefacts.

As summer approaches, the amount of darkness is becoming less and less. Last night, the moon didn’t set until well after 1am. It starts to get light at 4am. With cloud coming and going, the window where images can be taken of deep sky objects is very slim.

However, between 2am and 3am this morning, the moon was gone and there was no cloud. I put the smart scope on an equatorial mount. This has one axis pointed at the celestial north pole. It allows the scope to track both the movement and the rotation of the night sky. This timelapse shows the difference when imaging the galaxy M51, the Whirlpool Galaxy.

http://www.platitudes.org.uk/m51eq.mkv

Not only is the rotation gone, nearly all of the frames, for the full hour of observing were kept. This is the result.