Slrn is a news reader that can obtain news from NNTP servers or local spools.
When the text of an article is displayed, slrn divides the screen into two windows: the upper window shows the list of articles in the current newsgroup, sorted by thread. The lower window is the article pager, which displays the text of the article (including headers). Use the z (zoom) command to maximize the article pager. In this mode, the list of articles is hidden and the pager starts on the second line of the screen. Repeating the z command will restore the article index. Whether the article pager is maximized or not, it can be hidden using the h (hide) command, which ensures that the article index is displayed in the upper window, and leaves the lower window blank.
You may also find it helpful to adjust the size of the article pager permanently in your ~/.slrnrc configuration file. Section 2.3 of the slrn FAQ explains how to do this by creating a macro that will be activated whenever the article pager is displayed.