Measure the stack

Once you have saved the positions, you are ready to measure the stack.

1) Switch from aoa video 2 to hefi video 6.

2) On the Hefi GUI, move mirror In and light source to high. Also, in the center

column to the left of “In” and “Out” adjust the increment to about 30.

3) A bright array should be seen. Make sure it is still centered. Adjust the offset “In” and “Out” so that the array is a tight circle with as little fuzziness and “dancing” as possible.

4) When you’ve distinguished the best focus, move the light source down to “low.” Start in increments of 30 and move down to 10 and again, determine the best focus for the array. It should be close if you determined a good focus with the light source on high.

5) When the dot is at best focus, change exposure to 1/125 and click Focus on the bottom left of the GUI. A new GUI will appear titled “HEFI Focus Curve.” Toward the bottom left of this new window, under Focus Status click on Start. Another window will appear and will remain running for about 3-5 minutes. While the focal curve is being processed you will see your dot go in and out of focus.

6) While this focal curve is being calculated, note in the stack data on the night report the Outside Temp, Dome & Truss temps, and wind direction and speed. (All this info came be found on the HET weather gui)

7) Near the end of the 5 minutes, a plot should appear with a curve whose vertex should be near the center. If the curve appears you know you were really close in setting the focus. If no curve appears, hopefully the bad weather is to blame. If you get a straight line, make sure you did in fact the HEFI light on and the mirror deployed, or that HEFI did no crash while measuring the stack. When the focus curve says FINISHED, write down the ee50, ee80, Hefi focus and MARS FOCUS. There are two places to read these values. One is in the window that was calculating the focus curve and the other is in the Hefi Focus Curve GUI on the bottom. Take the better of the two. An ee50 below 0.65 is satisfactory. If that value is above 0.65 and the weather conditions were not binding, you should go back and do a few more iterations if there is time. NOTE this time as the FINISHED TIME. (If this is the first stack of the night, the end time should be before 18 degree).

8) Take out the HEFI mirror and turn off the light. The HEFI light is pretty expensive, so turning it off as soon as you do not need it is pretty important.

NOTE: If you are taking a post-observation, skip to step 10.

9) Go over to the wavescope terminal and perform the extra focal tests: EF ref and EF het.

After stacking, put in 'EF het' and wait for the pop-up to move the tracker over to the opposite side and realign the spots. Click 'OK' and wait until the test says it's done. Then you can tell the RA you're ready for a target.

EF ref can be done at anypoint in the night since it's internal to CCAS but preferably close to the beginning of every stack. Ideally during twilights for the first stack and before every restack. EF ref does not count towards stack time.

10) Close the CCAS shutter and select Video Channel 7, which displays the CCAM (Chevo-CAM) alongside the text version of the local weather on the large overhead video screen.

11) Inform the RA you are now ready for a science target.

Killing HEFI

If you have to kill via the terminal HEFI for any reason:

1) ssh to guider@mars

2) type in the command: ps -ef | grep HEFI

3) find the PID number for the gui

4) type in: kill -9 PID#

HEFI gui should immediately disappear and you can try relaunching it.