Question

part (c) which set(s) of equatorial coordinates is not possible for a star to have? (please note: select all that apply.) (ra, dec) = (-3.5h, +27.5°) (ra, dec) = (23.5h, -89.9°) (ra, dec) = (25h, -69.2°) (ra, dec) = (0.2h, +81.0°) (ra, dec) = (12.8h, -0.2°)

Explanation:

Step1: Recall right - ascension (RA) range

Right - ascension ranges from 0h to 24h.

Step2: Recall declination (dec) range

Declination ranges from - 90° to + 90°.

Step3: Check each option

• For (RA, dec)=(-3.5h, + 27.5°), RA cannot be negative, so this is not possible.
• For (RA, dec)=(23.5h, - 89.9°), both RA and dec are within range.
• For (RA, dec)=(25h, - 69.2°), RA exceeds 24h, so this is not possible.
• For (RA, dec)=(0.2h, + 81.0°), both RA and dec are within range.
• For (RA, dec)=(12.8h, - 0.2°), both RA and dec are within range.

Answer:

(RA, dec)=(-3.5h, + 27.5°), (RA, dec)=(25h, - 69.2°)