1) Log into Ohi as "observer"
2) Launch a terminal
3) Run up the michelle DM screens if you want (you don't need to) by
typing "michelleMenu&" and choosing the mich_oper screen.
4) From a terminal, type "engMichelleSim &". You'll get a gaia display
and a little gui where you can enter an exec name, load it and run it.
5) In the gui, enter "readnoise" as the exec name (without the "s) and
hit the load button.
6) When you're ready, hit the "Run" button. This exec will set all the
relevant mechanisms and then take 20 bias frames. It will *not* open
the window cover! It will also enable and disable the array, so you
don't need to worry about that.
NB. You will need to know the number of the first and last frame you
took. Getting the last frame no. is easy, it will say so in the
terminal you launched engMichelleSim from. It will look like this:
DTK:OOS_Michelle:.. getHeaders end 130
DTK:OOS_Michelle:.. endObs 130
i.e., frame 130 was the last frame you took. To find the first frame
number, simply subtract 19 (e.g., in this case, the first frame was
You can also get the same info from the WFG serial console.
7) You can run the exec as many times as you want. When finished, hit
the exit button and then choose "Cleanup & Exit". Note that if someone
is running the OMP observing software in Hilo, this will crash their
system! You might have to close the gaia window yourself.
OK, that's how to take the data. They will appear in the directory
/ukirtdata/raw/eng/michelle/utdate where "utdate" is the current UT
date in the format 20040206 (year, month, day). Remember the UT date
changes at 2pm every day here! If the UT date changes, simply restart from
point 1 below.
To find the read noise, you will need to log onto ohi or kauwa as
observer and launch a terminal. Then:
1) In the terminal, type "oracdr_michelle_eng"
2) In the same terminal, type:
oracdr -list a:b -log sf -nodisplay DIFFERENCE_STATS
where a = the first frame number and b = the final frame number (111
and 130 from the example above). You must write DIFFERENCE_STATS in
Ignore all the error messages! The data reduction is set up to reduce
data taken at night with the OMP system, not the Michelle engineering
interface, but it still seems to give the correct result.
After a lot of scrolling, you will see something like the following:
"Average standard deviation for group is 5640.359 electrons."
This is the average read noise in electrons averaged over the 20
frames you took.
If you take more data, you don't have to do all setenv stuff again
(unless the UT date changes). All you have to do is run the "oracdr
-list a:b -log sf -nodisplay DIFFERENCE_STATS" command again and
change the first and last frame numbers.