Sirius (being so bright) is often mistaken for an aircraft or spacecraft, especially when it is rising and the air is turbulent. It often appears to me to be flashing like a warning beacon or an ambulance light. This is a phenomenon called atmospheric prismatic dispersion and is natural, especially when the object is bright and near the horizon (as when rising). While it's in the same part of the sky as Betelgeuse, Procyon (also quite bright) is nearer, so that's another possibility.
Either of these bright stars will "be there" every morning, but they may not always "flash" since the air is sometimes much steadier.
These things lead me to the conclusion you're seeing Sirius through unsteady air:
- It's "below" Orion when rising.
- It rises about the time you report seeing the light.
- It rises every night.
- It rises in the same place.
- As it rises, it appears to move left/right relative to Orion (illusion caused by Orion moving westward).
- You can see it from both coasts of North America at roughly the same time (ignoring "artificial time zones").
One way to test this idea is to observe it on several consecutive mornings and take particular note of its location relative to Orion. If it matches the light you see, then that's probably it.
Or, as has been suggested, a photograph would prove or disprove it, since Sirius is bright enough to show on film or chip if the stars of Orion also show up.
Orion is the "home" of many satellites. Due to its location near the celestial equator, a good many satellites are stationed there, and others move through it quite frequently. However, these are not generally bright enough to be seen to twinkle and they don't have flashing beacons on them.
If you see this phenomenon repeatedly and frequently, and if it never appears to stray far from the horizon, then it most likely is one or more aircraft in the distance. It can't be the same one as seen from the opposite coast, but the same sort of thing may be occuring there.
Reports like this are difficult to assess since they're not coordinated (by experienced observers simultaneously) and are not quite specific enough to rule a particular cause in or out (see Centaur's questions).
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.