How do I add ancient Greek accents in Ubuntu?

I am taking a course in ancient Greek, and there are various accents that go above the vowels. I want to be able to type these on Ubuntu.

For example, if I hit ;, then a (while in the modern Greek keyboard layout), I get this character: ά. However, I can't figure out how to add the other accents (`` and^`, for example).

See if this helps: How to type Greek, Greek Polytonic in Linux

Excerpt:

Result                Key combination                      Works for…
Tonos/Acute ΄         Dead key (;) + vowel                 All vowels: ά έ ή ί ύ ό ώ
Dialytika ¨           Dead key (:) + vowel                 These vowels: ϊ ϋ
Dialytika with Tonos  Dead key (;) + Dead key (:) + vowel  These vowels: ΐ ΰ
Dialytika with Tonos  Dead key (:) + Dead key (;) + vowel  These vowels ΐ ΰ
Περισπωμένη ῀         AltGr + Dead key ([) + vowel         ᾶ ῆ ῖ ῦ ῶ
Υπογεγραμμένη         AltGr + Dead key (]) + vowel         ᾳ ῃ ῳ
Ψιλή ᾿                AltGr+ Dead key (:) + vowel or       ἀ ἐ ἠ ἰ ὐ ὀ ὠ ῤ
                      the letter ρ
Δασεία ῾              AltGr+ Dead key (”) + vowel or       ἁ ἑ ἡ ἱ ὑ ὁ ὡ ῥ
                      the letter ρ
Βαρεία `              AltGr+ Dead key (’) + vowel          ὰ ὲ ὴ ὶ ὺ ὸ ὼ
Μακρόν ¯              AltGr+ Dead key ({) + vowel          ᾱ ῑ ῡ
Βραχύ ˘               AltGr+ Dead key (}) + vowel          ᾰ ῐ ῠ

If you use the "Ubuntu" font, then you get a circumflex from the [ key on the Greek polytonic keyboard. If you use other fonts, then you get a tilde above the vowel in stead.

For anything you can't type, you can atleast find it in the charmap, run the program Character Map (gucharmap), it is an awesome Unicode browser, searchable by name or secion (look for polytonic greek).

I found this one there: ᾰ (U+1FB0 GREEK SMALL LETTER ALPHA WITH VRACHY)

Edit: Now I realize this is the same (looked different at different size) and you wanted it with the curve opening downwards. I Looked through the Character Map with all hits for "alpha" and it does not seem to have any character like that.

Is this more like it? α̑

that is normal Alpha together with ‍̑ U+0311 COMBINING INVERTED BREVE