Star Atlas

Post by **weixing** » Wed Sep 06, 2006 1:56 am

Hi,
To find an object in two dimension (the star chart is two dimension), you need two values, which is X and Y. RA is like the X and DEC is like the Y. To find an object on the star chart, you need both RA and DEC.

DEC represent North (+90 degree) to South (-90 degree), 0 degree is the equator of the sky.

RA represent East to West. The direction from smaller to bigger RA value (01h.. 02h... 03h... ) is toward the east and the direction from bigger to smaller RA (23h... 22h... 21h... ) is toward the west.

The DEC is the projection of earth latitude toward the sky. So, if you are at the earth equator (0 degree latitude), the sky over your head (perpendicular to the ground) is DEC 0 degree. Since Singapore is around +1 degree in latitude, the sky above us is actually +1 degree DEC.

Have a nice day.

Post by **weixing** » Wed Sep 06, 2006 2:02 am

Hi,
Check the website below for a better explaination of RA and DEC:
http://www.physics.hku.hk/~nature/CD/re ... hap03.html

Have a nice day.

wAi_kiT · Post by **wAi_kiT** » Wed Sep 06, 2006 2:09 am

Ok ok... Thanks Weixing. I think i understand it le. Well, now i have a totally different question, which i will start on a new thred! Thanks a lot!

Canopus Lim · Post by **Canopus Lim** » Wed Sep 06, 2006 10:18 am

Hi,

Actually the best way to know what you are looking at is to have someone who is experienced with you. That way you can confirm with what you see. Other ways to confirm is to compare the stars surrounding that star in which you are trying to identify. If these stars are in the correct orientation as in the map, that means you have identified the correct star. Sometimes when I hunt for Deep Sky Objects, though they are real fuzzy and dim, I can confirm if I am looking at the correct object or at the object at all by comparing the stars around it if it matches the map.

Post by **zong** » Sat Sep 09, 2006 8:11 am

Hi,

Yes i think a sky atlas would be mind boggling for a beginner. If you're living in near tampines, boon lay or toa payoh, you can join the 3 observation groups that are currently running, and there will be people there who are willing to teach you how to start stargazing. Look for weixing (tampines), rlow (boon lay) or me (toa payoh), and watch out at the observation sessions thread for other ad hoc groups to join. That way it's a lot easier to start learning. I didn't know how to use a sky atlas when i first started out too, and it took me a year without help to figure it out, so i know your worry ^^

rlow · Post by **rlow** » Sat Sep 09, 2006 2:17 pm

Yes, go look for Zong nearby at Toa Payoh on weekends. He would be happy to guide you in using a sky atlas.

Post by **zong** » Sun Sep 10, 2006 3:33 am

Oei rlow.. keep aiming me.. how can like that!! You come Toa Payoh very often also, can teach him mah

lol

rlow · Post by **rlow** » Mon Sep 11, 2006 1:37 pm

If you are talking about me, I still do refer to a sky atlas, specifically the Cambridge and Star Atlas 2000.0

kingkong · Post by **kingkong** » Mon Sep 11, 2006 3:54 pm

rlow wrote:If you are talking about me, I still do refer to a sky atlas, specifically the Cambridge and Star Atlas 2000.0

for mag.8 and dimmer objects only...

Clifford60 · Post by **Clifford60** » Mon Sep 11, 2006 9:06 pm

http://skychart.skytonight.com/observin ... ychart.asp
Use the above link to the interactive sky chart, select Ang Mo Kio as the city and Singapore as the country under "World By City" and submit, select the time zone and submit on the next screen. It will show you how the stars should look like from Singapore at a specific date and time (selectable). From there, compare to the atlas and learn how to use it.