Jim:
Your brief message has created several questions.

1. 1. Texas Heavy Artillery Regiment was from the Galveston area. Served mostly on the coast as coastal artillery. An element of the regiment served in the Red River Louisiana area for awhile.

2. 15th Texas Battery was known as Nichol's Texas Battery, commanded by Capt. William H. Nichols. Raised in December, 1862, served at Galveston and in Spring 1864, sent to the Trans-Mississippi. Fought against Banks in the Red River campaign. Surrender on June 2, 1865.

3. A. E. Dege, 8.Texas Battery raised in Bexar County summer 1861. Served in Texas throughout the war. Served in SW Texas, sent to Galveston, surrendered June 2, 1865. It was commanded by Captains P. Fox, Sackfield Maclin and A. E. DEGE.

I am not familiar with the Texas counties so cannot link them to Austin or Travis County. This incomplete information may help to direct your inquiries.
Regards
Ron