At the Start of the Night

You can start observations when the Sun is 10 degrees below the horizon (you can check the Sun altitude in the Tololo Environment Page - VPN needed). The telescope operator will let you know when you can start.

The first thing to do is to turn on Vsub (within the System Control Tab at the Observer Console). All buttons in the System Status should be green. If that is the case, you are ready to go.

It is always recommended to take a bias or test image after turning Vsub on. The general procedure is to take 2 zero images. This can be done simply by taking a zero image from the Exposure Control Tab.

To correct the pointing of the telescope, take a short exposure at the position of the telescope using the Exposure Control Tab in the Observers Console (for example, 5s in the r filter). In observer2, find a terminal an load Kent's Tools (more details in the next section) by typing:

> observer

Once the image is delivered, type:

> center

This command will perform the astrometry of the field just observed and it will calculate the offsets in RA and DEC from the coordinates of the telescope. Give these offsets to the telescope operator. He will apply the corrections. After that it is recommended to take again another exposure of 30s to recheck the pointing and setup the focus and guider.

An easy way to do all this is to load the script start.json (which is in the directory ~/ExposuresScripts/User_scripts/) that will do the following exposures:

• two bias 
• a break
• one 5s exposure in r for pointing
• a break
• one 30s exposure in r for pointing/focus/guider

Now you are ready to start your science program. Load your scripts and go.

Focusing will be performed automatically for every image and thus there is no need to run any focus sequence.