Short answer is yes, longer answer is that you can get a head start on the coordinates from a Bounding Box:
In the screenshot I have started from the “Your Observations” menu and then zoomed in on the general area in which I want the bounding box. Then I click on “Redo search in map” which generates the Bounding Box URL that I can then manually edit to better match the area I want inside the bounding box. Editing the URL is a real hit and miss operation of working with decimal places, although I suppose if I used a GPS I could pre-determine the coordinates that I want.
There are four coordinates to manually edit: those of the northeast corner of the box and those of the southeast corner of the box.