MosBot

Mosbot is a python program that tries to adjust our observing scripts to adapt to changing conditions through the night.

Run it by logging in to the *mzls@mayall-idl* machine and then running:

cd ~/obsbot
python mosbot.py <pass1.json> <pass2.json> <pass3.json>

You will need to keep that window open, because you want mosbot to keep running all night. "pass[123].json" are the 'plan' or 'JSON' files that Arjun should have given you; they contain lists of exposures we want to take depending on what the conditions are doing. It is probably most convenient to run mosbot from a Terminal window on the mayall-2 display. You don't need to read any of the output it produces, but you should check periodically that it is still running; the code is under development and some bugs remain.

Mosbot does two things:

• On startup, it reads the pass[123].json files, drops exposures that should happen before the current time, for each exposure writes two little shell scripts, and also writes a top-level script /mosaic3/exec/mosbot/tonight.sh
• It then starts waiting for new images to appear in the $MOS3_DATA directory. Whenever an image appears, it analyzes it and, based on the measured conditions (seeing, sky brightness, transparency), it decides which pass we should be running, and what our exposure times should be, and it overwrites the next few scripts.

Comments about how this works:

• mosbot by default starts with PASS 2 observations. And by default, we set all the exposure times to our minimum exposure time of 80 seconds.
• THEREFORE, if you kill mosbot after it has written out the tonight.sh script, you will run pass 2 with short exposures all night long. This is almost certainly not what we want to happen!!
• The tonight.sh script is not smart. Each exposure is written to a script, and the scripts are numbered. If you kill and re-start tonight.sh, you will start from the beginning of the night (or the last time mosbot was run). If you have to stop the tonight.sh script, PLEASE re-run mosbot to regenerate an appropriate tonight.sh script.
• The tonight.sh script writes to a file /mosaic3/exec/mosbot/seqnum.txt to indicate which exposure it is currently running. The mosbot.py script reads that file to figure out which upcoming exposures it should update. Mosbot by default writes 1, 2, and 3 exposures ahead of the current sequence number.
• Each exposure is split into two scripts. For example, exposure 3 happens in expose-3.sh, which takes the exposure, and then slewread-4.sh slews to exposure number 4 while reading out exposure 3. If the file quit is found in the directory in which tonight.sh is run, the script will quit after a readout (without slewing). This should ensure that we don't lose any data, so that is the way the tonight.sh script should be stopped. (It will delete the quit file just before it quits.)

About git:

• the ~/obsbot directory is a git checkout of the repository: ​https://github.com/legacysurvey/obsbot
• There is a "MzLS Observer" github account set up to log in with an ssh key, so you should be able to *git commit* and *git push* any code changes without having to know any passwords.