Let's assume I can travel in a space-time on Earth. Every time I jump I get to almost the same place, but in different past time relative to the first jump: it solves the problem of planet rotation, orbital moving, etc. Also if there is an obstacle in that place in another time, then I get softly pushed a little bit away, like if I appear in a collapsing invisible Zorb ball: it solves problem with survival in 99.9%.
There is one problem, I know the exact location before the first jump, but I don't know the exact time I jump in. To do my tasks I need to find out at least the Earth year I'm in - as fast as possible!
So what I can't:
- Most of my locations are uninhabited almost always (like desert islands), so I can't rely on a local population or artifacts all the time.
- I'm an average human, so I can't learn everything about every specific place I will travel - I can only memorize some common rules or heuristics, some limited simple or specific information.
- I can't take or drastically change anything in past.
What I can:
- I can get a backpack and take everything I need and can bear.
(I will update "can"s and "can't"s to clarify the question if required).
Some leading questions:
- What should I learn and take with me to determine the year almost everywhere?
- What are the locations, where I can detect the year in the fastest way?
- What is the most remote year in the past I can travel, so that I'm able to detect the year by any means at all?
Please, add some meaningful limitations to your answers: like, the average time for detection, the approximate area where your method works within declared detection-time, etc. Different answers may cover different areas or different historical periods.
Update #2: Time-traveler worker schedule example.
The time-traveler is a freelancer. He signs a contract to do something specific in the past with some specific people, events, items, etc. - in exact location. Different companies work with different locations. He has a limited series of time jumps - the last jump always brings him back. So, when he makes another jump he has to decide - can he do anything here and now, or may be he should wait a couple of years, or jump again for a better luck. That is why the known methods of detection of the year is a very valuable information for such freelancers.
Update #3: Time machine technology.
The technological level of some companies allows to program their time machines to visit some limited number of time periods in the past. The best machine has precision of ±15 years from a specified point. Also a single series of jumps (for all machines) is very-very costly - the more jumps machine can do in one series the better it is. But all machines unfortunately jumps to specified time periods in a random order. The list of time points is known to applicants beforehand, so they can decide if they possibly can distinguish at least epochs - not talking about the exact years.
P.S. Of course, the year detection is probabilistic - i.e. methods should work with at least 85% probability.