Last night was clear again, but with a measured sky brightness of sqml=21.44. This is not quite as dark as previous nights. The primary goal was to capture an image of asteroid (285) Regina. However, that quest was unsuccessful. The asteroid was just too dim (mag 16) and too low in the sky (11°) where the airglow is strong. Instead, here are some images obtained while waiting for the asteroid to emerge from behind the mountain ridgeline. No sense wasting a clear dark night.
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| Corona Borealis. Sony A7iii + Rokinon 85mm f/1.4 + softon filter. |
The constellation Corona Borealis is worth monitoring because of an expected eruption of a recurrent nova sometime this summer. When (if) it happens the new star will be comparable in brightness to Alphecca, which is the brightest star in this constellation.
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| Omega Centauri skimming the distant mountains. Rokinon 85mm. |
Near the top edge of the above image is a fuzzy blob that is the galaxy known as Centaurus A. This is a strong radio galaxy that is also the 5th brightest visually. It is thought to be the product of a long-ago collision between an elliptical galaxy and a smaller spiral galaxy. It contains a supermassive black hole with a mass of about 55 million suns.
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| Antares (left), M4 (right), and NGC 6144 (top edge). |
This image was obtained with an Astro-Tech 80mm ED f/6 triplet refractor with a 0.8x reducer and a 0.71x reducer for a final focal length of 273mm f/3.4. The camera was an Olympus E-M5iii at ISO 1600, 60 s. A ZWO AM3 mount was used for tracking.
The three objects of interest in this frame are at vastly different distances. Antares is a red giant star 550 ly distant. The globular cluster M4 is 7200 ly away and is the closest of this type to earth. The globular NGC 6144 near the top edge of the frame is more than four times farther away at 29,000 ly.
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