With a clear weekend in the forecast and some cottage time coming up I finally got a chance for some imaging time. Skies at the cottage in Marion Bridge are reasonably dark with the Milky Way clearly visible. I’ve been itching to get out for the final testing of my Esprit 120. After SkyWatcher shipped me a replacement Esprit to replace a unit with pinched optics, I noticed a strange distortion in some of the stars in several of my images. The distortion only showed up after saturation boosts so I wanted to do some more testing to figure out what was causing the problem. After shooting several star fields at varying altitudes I very pleased with the results. It turns out that the distorted stars were due to atmospheric dispersion and saturation boosting during processing. Aligning the three colour channels before any other processing completely solves the problem and the scope produces stunning images as advertised.
First up is a shot of M13. I was imaging the cluster as one of my test shots to verify the atmospheric dispersion problem. The shot was taken from our cottage and the cluster was almost directly overhead.
The image is a 50 minute exposure with round stars right to the corners. Several field galaxies are visible in the full res version of the shot with NGC 6207 in the upper right of the image.
Since the night was supposed to be clear until morning the next target up was M57. This was a chance to check how much true resolution I was going to loose by moving from an eight inch reflector to a 4.7 inch refractor as I have an image of this target taken with my reflector.
The shot is a 69 minute exposure made from a stack of 23, three minute subs. The 15’th magnitude galaxy PGC62532 is easily visible to the upper left of M57 and there are galaxies down to 17’th magnitude in the field.
Over several nights I managed to capture over five hours on Ngc7497. This is an unimpressive nearby galaxy about 60 million light years distant. The interesting part about imaging this galaxy is the gas and dust that fills the field. The dust is much closer than the galaxy being inside the Milky Way. The shot could use over ten hours to really bring out the detail in the very faint dust field, but all in all it turned out quite well given that is was shot with a DSLR.
Once vacation ended it was back to the work day grind, but with another clear weekend I couldn’t resist a little more imaging time. This time several members of the local RASC Centre headed out to the St. Croix Observatory (SCO), the Centre’s roll off observatory in some dark skies about 40 minutes outside the city. Since I had to get into work at a reasonable time the next morning I had to image something bright in the limited time I had so I decided to give M8 a try. The seeing was not the best with PHD showing around two arcseconds guide errors so I wasn’t sure how the stars in the field would turn out, but the software did a great job and the stars were very tight and circular all the way to the corners of the image.
With the weather here in Nova Scotia this has been a productive summer of imaging and the Esprit 120 seems to be a great imaging platform, performing as advertised.