Image of M33 and the asteroid Eros

On the 4th January when it was still very cold and there was snow lying on the ground, we had a relatively clear night and so I thought I would have another go with my new Dwarf 3 smartscope. The moon (one day past full) rose about 17:15 UT but wouldn't interfere too much with my observing until later in the evening. So at about 6pm I set my tripod up with the Dwarf 3. I had been intending to observe some fainter targets but, as a bit of cloud began to roll in, I thought I would photograph something a bit more obvious, so opted for M33 (The Triangulum Galaxy). It was a very fortuitous choice! Here is the result of 216 x15s images:-

This is the virtually the full frame of the Dwarf 3. Auto parameters were used in the observation and in the post processing. I have binned the image x2 and cropped it slightly to remove field rotation effects. The first image was taken at 17:56 UT and the last at 19:05 UT. Midpoint 18:30 UT, approximately. This spiral galaxy is the third largest member of the Local Group of galaxies (after the M31 and our galaxy) and is perhaps just under 1 Mpc from us.

I have also marked a small streak of light to the right of the galaxy with a green line. Initially, I thought that this was some sort of remnant from the processing - the result of a bright satellite or plane being on a few of the frames. However, I learnt from the BAA that this was actually the asteroid 433 Eros and just happened to be in this field of view. The streak of light (40 pixels in length which corresponds to nearly 2 minutes of arc) was caused by the movement of Eros during the period of observation. Eros was about magnitude 10.8 at this time.

Below I include a cropped version of the above image which gives a closer look at the galaxy:-

The open spiral structure of the arms with blue regions of star formation are more easily seen. For comparison I include another image I took of M33 on the 23rd September 2016:-

This is based on 45x30s (22.5 minutes) of observation using a Celestron NexStar 102 SLT and a Nikon D90 camera at prime focus. I think the colour rendition in the Dwarf 3 image is so much better and more detail can be seen. To get the same exposure as this on the Dwarf 3 I would have needed (102/35)² x 1350 = 11466 seconds! I actually got a better image in 3240s on the Dwarf.

All text and images © Duncan Hale-Sutton 2026