by Robert Vanderbei, Assistant Director

I’ve been having lots of fun with my Seestar S30 smart telescope. Over the last week or so I took pictures of the Andromeda galaxy, the Orion Nebula, and the Pleiades. As I’m sure many/most of you know, I have for about 8 years been teaching a Freshman Seminar here at Princeton University called “Sizing Up The Universe”. The course is all about how we can measure distances to things using data/pictures acquired using cameras and telescopes that are affordable to amateur astronomers. We start by measuring the size of Earth, then the size of and distance to the Moon, followed by the Sun and other planets in our solar system. After that we use pictures I’ve taken over multiple years of Barnard’s star to measure its parallax and hence its distance. Then toward the end of the semester, we study RR-Lyrae stars and use them to measure the distance to some globular clusters near our Milky Way galaxy and from those distances we estimate roughly how big our Milky Way galaxy is. Then, we notice that there are some globular clusters that can be imaged in nearby galaxies and comparing the angular size of those far away globulars to the angular size of our nearby globulars we are able to estimate the distance to some of our nearby galaxies. Lastly, we study some pictures I’ve taken of Quasar 3C-273 using a diffraction grating that I bought. From those pictures we are able to measure the red-shift of that quasar. These things are all very fun to do and in previous years I’ve mostly used pictures taken with my 10″ Ritchey-Chretien telescope together with cameras I’ve bought from StarlightXpress.

This year, we are doing things a little differently. The Freshman Seminar program has bought eight ZWO Seestar-S30 smart telescopes so that the students in the class (there are 15 of them) can take their own pictures of things. My hope is that maybe we’ll use some of those pictures for our analysis. With those goals in mind, I have started taking pics with my own Seestar-S30. I’m having lots of fun. It’s both easy to do and the images captured are amazingly good for such a small telescope. Shown here are three of the pictures I took recently.

The first picture is of the Andromeda galaxy (aka M31). It was taken in the evening on September 19. The image is a stack of 480 10-second exposures, i.e., 80 minutes. I used the Seestar app in “Mosaic” mode. As I recall, I enlarged the image to be about 70% larger than the base size of the camera. When doing mosaic mode, there is a significant temporal gap between exposures because the app moves from one position to another position after every exposure. So, the 80 minute total exposure time took about twice that long to get.

The second picture was taken of the Orion nebula (aka M42) in the early morning hours of September 22. The image is a stack of 210 10-second exposures, i.e., 35 minutes. This picture was also taken in “Mosaic” mode but the size was not upscaled. I only used mosaic mode so that I could orient the picture so that we can see Orion’s sword in a vertical orientation. The nebulosity we see around those few bright stars near the top is called the Running Man nebula, aka NGC 1977. Those stars are the “top” of Orion’s sword. And, of course, Orion’s nebula is the large interesting nebula at the center of Orion’s sword. And, lastly the few bright stars similarly far down below the Orion nebula form the bottom of Orion’s sword. Visually, the top, middle, and bottom of Orion’s sword just looks like three stars but here we see that it’s actually more than three stars.

The third picture is of the Pleiades (aka M45). It was taken in the earlier morning hours of September 22. It’s a stack of 105 10-second exposures, i.e., 17 minutes. And, it too was taken in “Mosaic” mode so that I could orient the picture with north at the top, east at the left, etc.