It has been a tough few weeks for the tea-leaf readers and rumor-sifters of Moscow - a timely reminder of how tortuously uncertain the process of ''news'' gathering in the Soviet Union can be.
A week ago, for instance, just about any Kremlinologist in town would have told you that the political career of one Geidar Aliyev might be in trouble.
Then on Nov. 22 an odd thing happened: Geidar Aliyev was promoted to full, voting membership of the Communist Party Politburo. And on Nov. 24, Mr. Aliyev, until then party leader in the Azerbaijan Republic, was named a first deputy prime minister in the national government.
Among the more tantalizing but, alas, erroneous reports gaining credence or publication in the transition period from the rule of Leonid Brezhnev are these:
* Andrei Kirilenko, longtime member of the leadership, had also passed on.
So sure seemed this bit of ''news'' that a prominent Soviet journalist ''confirmed'' it to a European reporter. A senior foreign diplomat told a colleague: ''I can't in good conscience reveal my source. But we are 100 percent certain that Kirilenko is dead.''
Mr. Kirilenko did, in fact, retire ''for reasons of health,'' a move announced Nov. 22. He was also, however, alive.
* Then there was Arvid Pelshe, at 83 the oldest member of the Politburo. He, too, was said two weeks ago to have passed on. So certain appeared the report, so firm were its ''sources,'' that some Western news organizations reported it not as rumor, which it was, but as fact, which it turned out not to be. Mr. Pelshe showed up at a Nov. 23 session of the Soviet Parliament looking definitely alive.
The Aliyev saga is of a slightly different ilk, being rooted not in rumor but in the esoteric craft called Kremlinology.
Mr. Aliyev, the Kremlinological signs said, was a ''Chernenko man.'' In more or less plain English, he was said to have picked a losing horse in the Brezhnev succession sweepstakes, his presumed candidate having been longtime Brezhnev protege Konstantin Chernenko rather than new party leader Yuri Andropov.
There are various quite believable explanations for Mr. Aliyev's subsequent promotion, even if he really was a ''Chernenko man'' and even if there really was, as some foreign analysts assume, something of a ''power struggle'' between Messrs. Andropov and Chernenko when Leonid Brezhnev passed on.
As it happens, however, one Krem-linological explanation of Mr. Aliyev's good fortune currently making the rounds is that he was not really a Chernenko man after all, but an ''Andropov man.''
The telltale is said to be Mr. Aliyev's stint as head of the KGB security organization in his native Azerbaijan Republic. Mr. Andropov was longtime head of the national KGB.
The problem lies not so much with Kremlinologists - as a rule they are among the most serious, dedicated, and thoroughly trained foreign observers of Soviet politics - as with Kremlinology. The ''signs'' on which its practitioners are forced to rely can be woefully iffy.
In the case of Mr. Aliyev, one main argument for the assumption he was a ''Chernenko man'' was that he had seemed to be a ''Brezhnev man.'' And one perceived ''sign'' of close ties to Mr. Brezhnev was simply that Geidar Aliyev outdid all but a few Soviet political figures in his lavish public praise for the late party leader.
A recently revised edition of a book by Mr. Chernenko was said to have differed from the original largely by addition of a portion lauding Aliyev's home republic.
A good example of the limits of Kremlinology, related good-naturedly by a Moscow diplomat, is said to have come in a tea-leaf-reading session a few days back among Western diplomats here. It seems Leningrad's Grigori Romanov, a Politburo member, recently gave a speech on his home turf for which even his handpicked lieutenants withheld customary applause.
''This,'' said a Western diplomat, ''was deemed to mean one of two things. It may mean Mr. Romanov is in a very weak political position. Or it may mean that he is in a strong position, because he is strong enough to make a speech that even his lieutenants disagree with.''