Question about Star Charts?

Okay, for my Astronomy class, I have to use equatorial and polar star charts to find the nearest star and constellation to certain right ascensions and declinations. My professor is very confusing, and although I asked him to repeat this twice, I still don't understand it.

I have the maps, and I'm looking at them, but I don't understand what I'm supposed to do. For example: It says that at 6 hour 25 min, at a declination of - 52 degrees 30', I can find Canopus (not sure if that's the right spelling, the copied star chart is really hard to read) in the Carina constellation. However, the next one says Right Ascension is at 9 hours and 27 minutes, and the declination is - 8 degrees, 30 '. There's nothing there! The right ascension is far left, and the declination is far right.

Am I reading this correctly?

Here is what the chart looks like. I couldnt find a bigger image, sorry.

here's a bigger one.


Thank you so much Richard. My professor flew through this on Thursday, and I've been struggling with it ever since. I sent him an email, but he hasn't responded yet. I'm still confused, but your explanation has helped clear a few things up.

2 Answers

  • 8 years ago
    Favorite Answer

    What you are supposed to do is to read your star chart rather as if it was a map of your neighbourhood here on earth. Instead of latitude, your chart has declination. Instead of longitude, it has right ascension. In the 'equatorial' charts, which actually extend well away from the celestial equator, right ascension runs along the top of your chart, and runs from zero to 24 hours. Declination runs up and down the chart, between -30 and +30 degrees (i.e. 30 south and 30 north).

    Now what you are being asked to do is to find the point on your chart which corresponds with 9 1/2 hrd RA, -8 1/2 degrees dec. You should find that spot towards the left of the top chart, a bit below centre. Near that point you will see that there is a rather bright star. You are next being asked to say which star it is - which shouldn't be hard, because it has a lable on the chart,a nd constellation boundaries are also shown on the chart - and those two things tell you which star in which constellation it is. End of exercise.

  • 8 years ago

    Move left from 9 degrees to about 9.5 degrees and up to -8 degrees, just above -10 - I see alpha Hydra at that location. Its just above and to the left of the r in the word hydra

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