Titan mount adjustments & Number of exposures calculation using SNR

OK, I made some finetuning of the mount few days ago and acquisition are much easier now. I still have few "motor stalled" so I need to work on this again but now the pointing model is great and I can point my targets within the field of the guiding camera. If I resync on a target and go to another one close by, usually it points very close to the fiber hole!

Tonight's session is done remotely from the house. It works great and I can watch Star Trek Into Darkness on TV tonight! :-)


I have also improved my procedure by measuring the SNR of the first spectrum (or using the first two spectra, dividing them and calculating single exposure SNR = measured SNR / 1.4). I then use the single exposure SNR to calculate the number of exposure to reach 100 of signal to noise ratio:

Nb Exp = (100/[single exposure SNR])^2

My first exposure time is set so I reach maximum ADU around 40000. This means that once I know the number of exposure, I can reuse the same number for all my acquisition of the same target no matter what sky conditions are, I just adjust the exposure time to reach 40000 max ADU...