Quote:
Originally Posted by 209herschel
Thanks very much Matt. The pics have been a great help. I've got a book on the Messier Objects, so I'm really excited about trying to find a few of the large ones because I think the light pollution will be a bigger problem when the DSOs? One last question - I'm trying to answer is how best to understand the coordinates of objects in the constellation? So the book gives me the coordinates of the Orion Nebula but I'm not sure what's the best way of finding it. Is there a book that's useful for that type of thing? Thanks again for the assistance.
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Stellar coordinates on star charts use RA and Dec which is similar to longitude and latitude. What you also need to know is Local Sidereal Time. LST is approximately four minutes faster per day than standard clock time. You can get software or an app to tell you LST.
The LST equals the RA of any object crossing the north south meridian. In other words an object that has risen and reaches its highest point for the evening will have its RA equal the LST at that time. This gives you another way of determining LST if you know the RA of an object and it is just crossing, then that is the current LST at that time.
Dec is simply latitude. 90 degrees declination is equal to you location latitude up from the southern horizon. E.g. At 30 deg south of the Equator the south celestial pole (90 deg Dec) is located 30 deg up from the southern horizon. The celestial equator arcs from east to west and reaches 60 deg high from the northern horizon for an observer located 30 deg south of the Equator.
Orion is low in the west at sunset so you'll have to wait a couple of months before it reappears in the per dawn hours in the east.
At 19:43 Eastern Australian Standard Time the LST was 13:48. Use Stellarium and turn on equatorial grid and make sure cardinal points are showing and then look toward the N horizon.