BAS - Monthly Sky Guide

Transcription

1 BAS - Monthly Sky Guide April 2018 The Sun sets earlier now and so we can get some extra observing hours each evening. The outer arms of our Milky Way Galaxy now lie across the low southern sky and looking towards the north and Leo we will be looking into deep space so April perfect for distant galaxy hunting. 1

2 Dark Sky Best Observing Dates - April From April 10 th the New Moon the Moon sets after midnight, so evenings are dark. However, after New Moon you will need to wait later and later each evening for the Moon to set 2

3 Useful Telescope Alignment Stars Leo Gemini Alignment Stars: Alphard Regulus In April there are two stars that are worth learning to recognise and potentially use as alignment stars. The constellation Leo, the Lion, even though he is lying on his back for us in the southern hemisphere, is pretty easy to identify. Leo does actually look like a resting lion. Find the brightest star near the front foot of Leo, this is Regulus. But take care in the finderscope and eyepiece as there are many other white stars nearby. Alphard in Hydra is a little more difficult but it is a reasonably bright star in and fairly dark region of the sky. Just find Regulus first and then look even higher in the sky for Alphard. 3

4 Constellation of the month - Leo Leo is one of the zodiac constellations and one of the largest constellations in the sky. Leo represents the lion and was first catalogued by the Greek astronomer Ptolemy in the 2nd century, along with all the other constellations of the zodiac. Leo constellation is home to the bright stars Regulus and Denebola and to a number of famous deep sky objects, among them galaxies. Two big bright galaxies to start your Leo observing session with are Messier 66, a big spiral galaxy located 37 million light years away. And Messier 95, another big face-on spiral galaxy located 32 million light years away. These galaxies were observed and catalogued by French comet-hunter Charles Messier in 1780 and 1781 respectively. 4

5 The Planets Evening planet watching now starts to become possible. The first to rise each evening, shortly after dark, will be Jupiter, then followed much later by Saturn and then Mars rising around 10:00pm. But you will have to wait until late in April to get the chance to see all three bright planets in the eastern sky before midnight. 5

6 New Moon - 9 PM meridian constellations Vela Carina Vela means the sails in Latin and Carina means "the keel" of a ship. Both Vela and Carina were once part of the much larger constellation, Argo Navis, which represented the Argonauts ship that carried Jason and the Argonauts in search of the Golden Fleece. The Argo Navis constellation was first catalogued by the Greek astronomer Ptolemy in the 2nd century. The French astronomer Nicolas Louis de Lacaille divided it into three separate constellations in the 1750s - Vela (the sails), Carina (the keel) and Puppis (the stern) Vela contains a number of interesting stars and deep sky objects, among them the Eight-burst Nebula (NGC 3132), the Gum Nebula, the Vela Supernova Remnant, the Pencil Nebula (NGC 2736), and the Omicron Velorum Cluster (IC 2391). Carina contains the second brightest star in the night sky, Canopus, along with several other notable bright stars, among them Eta Carinae, surrounded by the famous Carina Nebula. Other famous deep sky objects in the constellation include the Theta Carinae Cluster (Southern Pleiades), the Wishing Well Cluster NGC 3532, the Diamond Cluster, and the open cluster NGC

7 Vela Planetary nebula and supernova remnant gas clouds are often low surface brightness and difficult to locate, however the planetary Eight-burst Nebula (NGC 3132) is worth a try in the less cluttered sky to the north of the main Vela constellation. The Vela Supernova Remnant, the Pencil Nebula (NGC 2736) is also a challenge a little to the south in the main body of the constellation. 7

8 Carina You could spend hours looking at countless star clusters and nebulae knots in the Carina Constellation. Two show-stopper objects not miss are the Wishing Well open cluster (NGC 3532) with its countless brilliant stars and one especially bright star X Carinae which is thousands of times brighter than our Sun. Then swing down to the wonderful Eta Carina Nebula (NGC 3372) and bask in the wonder of what many say is the greatest nebula of them all. It is amazing to think just how big this nebula must be as it is located 6,500 light years from our Sun. 8

9 Build your own observing list Click Find Objects Select object types Select constellation Search Make sure you take a look at the great observing planning tool DSO-Browser before the New Moon period. This is a fantastic tool to help you build a list of objects you can try and find each month. Just a few clicks on can generate a fantastic observing list of object types you are interested in. 9

10 Avoiding clouds More info: And the find the best cloud-free evenings for observing make sure you check CloudFreeNight and Skippysky as you plan your next observing evening. 10