I was asked by someone contacting me through AstroMart how to use the SBIG AO (older AO-7, or newer small-format AO-8, or larger-format AO-L) with MaximDL camera control software.
This is not entirely obvious from just looking at the windows, tabs, and settings; for example, there is both a Guide tab on the Camera window and Track and Drive tabs on the AO window, which
seem to overlap. Basically, one can use SBIG cameras with AO in either non-AO guiding mode or AO mode, depending on which camera is slected in the Set-Up tab. For non-AO use,
SBIG Unversal should be selected; for AO use, SBIG w/AO should be selected. Then, when the camera is connected, the AO Window appears (which I put below the Camera window).
Following are basic instructions for using AO (attached to an SBIG camera) with MaximDL camera control software.
ASSUMPTIONS:
- Although I have MaximDL v.5, I am still using MaximDL v.4, so the following instructions refer to the windows and tabs on MaximDL v.4. The basic procedure is the same in MaximDL v.5
- I have assumed that you already have the system set-up for normal (non-AO) guiding - i.e., the guide cable is connected, and the various guiding parameters have been set
PROCEDURE:
1) Make sure that in the MaximCCD (camera) window, you go to Setup and choose "SBIG w/AO" (not "SBIG Universal")
2) Connect the camera; a window comes up called "SBIG AO Control" - I usually position that directly below the camera (MaximCCD) window
3) Get a guide star focused on the guide chip (you can go to the Locate tab, and press Start to make a single image from the guide chip; make sure you get a Brightness of at least 2000-3000
(the star should be fairly well centered at this stage, as we will need to do a calibration)
4) Go to the Drive tab (of the SBIG AO Control window) and set the Calibration Time; mine is set to 10sec with my 12" LX200
(basically, you want a long enough time so that the star moves at least 10-20 pixels, but not so long that it goes off the guide chip)
5) Go back to the Locate tab, and click "Calibrate Drive" - this will set the bump directions
(when the AO hits the limit you set, it will bump the mount to bring the star back to the center of the AO)
6) Once the Drive (bumping the mount) is calibrated, you need to click Calibrate AO
(this only has to be done once, unless you change angle between the AO and the camera - which probably won't happen; this calibrates the adaptive optics, based on the camera directions)
7) Now that you have everything calibrated, find a nice guide star and put it on the guide chip
(doesn't have to be near the center, but also can't be right at the edge of the chip, or MaximDL will complain that it is too close to the edge)
8) Go to the Drive tab (still in the SBIG AO Control window) and set the Activation Level - I have mine at 19%
(which means the mount will bump, if the AO gets to 30% or 70%, where 50% is center; don't set less than 10% or more than 40%)
9) Set the Bump Time, depending on what Activation Level you have chosen
(my Bump Time at 19% activation level is 60 (1/100sec - actually it's 600mS); if my activation level were 30%, I'd set the Bump Time to 80 - this will bump enough to bring the star back to center)
10) You DON'T need to worry about the "Drive Calibration", as these will be filled-in correctly after you have calibrated the AO - which you have to do for every position angle
(i.e., if you have a rotator, and rotate the camera, you need to re-calibrate the Drive (mount bumping), but NOT the AO)
(FYI - you can also figure out all the calibrations for different angles, and just click the boxes as needed, without doing a Drive calibration; but you need to know if East or West if on a GEM)
11) There should be nothing to set on the Setup tab (mine has Manual Settings checked, and Reverse X checked - I'm not sure I know why that is checked !?!!?) Track Box is 16x16.
(the tracking speed is set for 100 on each axis - but I'm not sure I ever touched that, so it may be the default setting)
12) FINALLY, you can now go to the Track tab, and set the exposure time (as low as possible, but still getting at least 1000 in the Brightness box (on the Locate tab)
13) Aggressiveness is usually set around 7, but you may want to experiment with this
(too low, and not enough correction is made each time; too much, and it can oscillate or way over-correct, which is bad for guiding)
14) Maxi Move is set to 8 - not sure how to set this, but wanted moves to be within the 16x16 pixel guide box
(but, if you have very high winds hitting the scope, you may need to set Max Move to 16 or higher, so that if one gust knocks the scope, it only takes a 1-2 corrective moves to bring the star back)
15) Binning is almost always set to 3 - there is not much advantage to lower binning, as our pixel scale is about 0.5 arcsec/pixel, so binning 3x3 is still 1.5 arcsec/pixel, which is less than usual seeing
(the only time I might try binning of 2 is if I have a really bright guidestar (like magnitude 5 or 6), so I have wasted light, so I decrease the binning - but I'm not sure it helps more accurate guiding)
16) LAST STEP: Hit "Start" - you should see the guide star in the window moving around slightly, but staying near the center