X Virginis

Any information on this peculiar object, since the sequence team recently had a request for it. Originally designated "Nova Virginis 1871" it clearly isn't a nova in the accepted sense. Range is said to be about 7 - 11 visual but type is 'probably constant'! If it is some sort of DN then with a range of 4 mags one would expect outbursts roughly monthly - but in fact these outbursts are more like T CrB in terms of interval! To begin with I believed the 'cst:' designation and thought that this could have been one of those many 'novae' that occurred on or near the ecliptic. However I have since seen a LC that does indeed show a rise from 11m to 8m. What's going on here? What does the spectrum reveal?