Jared May: What's Up August 26-September 4, 2021
This upcoming week may be a load of disappointment for stargazers and amateur astronomers since the forecast is looking very rainy and cloudy. We can always hope that there will be a clear night that sneaks its way in. Nighttime temperatures are hovering around the low 70s. Sunset is around 8:12 PM, so expect the faintest stars and Milky Way to reveal themselves by around 9:15 PM. In the event of a sporadic clear night, be on the lookout this week for the third-quarter moon, a faint eclipse on Jupiter, a recent nova, exercise your star-hopping abilities, and prepare to take a star-trail image.
Monday, August 30 the moon will pass through its third-quarter phase. During this phase, the moon stays out of the sky until much later into the night. This means that stargazing and astrophotography benefit greatly from the moon-free dark skies. If you are up to 1 AM you will be able to catch the third-quarter rising over the eastern horizon.
The third quarter moon near the Haydes cluster in Taurus on Monday, August 30.
During the early-morning hours of September 1st between 12:30 AM and 5 AM one of the four Galilean moons, Calisto, will be casting a shadow across the surface of Jupiter. You will need a higher-power telescope to see this, and even then it will be difficult. This shadow will appear to be a tiny black dot near the lower red stripe on Jupiter.
A shadow transit of Callisto, on the Morning of September 1
If you missed all the excitement in March of this year about the nova that suddenly brightened in Cassiopeia, you can still observe this star! Plotted in the image is a light curve of this nova. You can see that it brightened in March and then randomly throughout the year. This nova, officially named V1405 Cas, still shines at magnitude 8 or so. This makes it a great telescope and binocular target. V1405 can be found by hopping off of the “steep” leg of the Cassiopeia constellation.
The Nova 1405 CAS is still visible in binoculars after many months.
The light curve of Nova 1405 CAS. In this plot, up is brighter.
Star hopping is a skill that is great for manually aligning a telescope, using binoculars to hunt for deep-sky objects like clusters, galaxies, and nebulae, and it is a great skill to have at any star party. Star hopping to find a deep-sky object may involve starting by finding a bright star, then hopping to a nearby fainter one, and getting progressively closer to your deep-sky target. Moving north to south, here are a few bright stars that you can try hopping between: Dubhe, Arcturus, Polaris, Caph, Vega, Rasalhague, Altair, and Nunki. Most of these stars are also in familiar constellations, can you figure out which stars belong to which constellation?
If you are new to astrophotography or a veteran, star-trail images are always fun, easy, and artistic. Star-trail images look like someone took all of the stars in the sky and smeared them out. If you are observant you may notice that these “dragged out” stars all appear to rotate around one point in the sky – this point is Polaris, the North Star. All you need is a DSLR, a tripod, a shutter remote or intervalometer, and 90 minutes. Set up your camera on the tripod with the north star in the field of view using a relatively wide-angle lens and frame up your shot. Ensure the stars are sharply focused. Set the ISO to 800 or 1600 (depending on your light situation), your exposure to 10-30 seconds, and open your aperture all the way to f/4 or so. Shoot your images in JPG mode to save some memory card space. Loop these 10-30 second exposures for 90 minutes using your intervalometer and making sure not to bump your tripod and camera. Take your files and import them into a free software called StarStaX. This software will take care of everything and you will have a beautiful star-trail image. Try using Photoshop or GIMP to make some final edits on your image and voila!
One of the most striking, but easiest, forms of astrophotography is the “Star Trail” image.
The forecast is usually pretty reliable up to a few days in advance, but hopefully some nights over the next few days turn out to be clear. Enjoy the warm nights and the sunset that will progressively get earlier through the seasons. This week be on the lookout for the third-quarter moon, an eclipse on Jupiter, the still-visible nova near Cassiopeia, all while using your star-hopping skills and taking a star-trail image.
Clear Skies!