This morning's dawnflats script stopped, right at the start of the script (but I was sleeping), I think I know why. One of the reasons for this post is to alert other users of this problem.

The script output looks like this:
Initializing AcquireSupport V5.1.17
<snip>
Starting dawn flats. High Sun at 6:23:30 AM
This is AutoFlat version 5.1.15
Using flat plan defaultdawnflat.txt
Starting flat field acquisition.
Reducing slew settle time to 0 sec.
Doing 10 flats in Red at binning 2
Start slew to flat area...
Start rotate to PA 360.0 deg (raw rotator angle 359.8)
(wait for rotator)
(rotation complete)
TEST Red: 20 sec at bin 2
Testing with 64 x 64 sub-frame
Camera exposing
Exposure complete
Image downloaded
Failed to open image file for read access.
Extension doesn't start with SIMPLE or XTENSION keyword. (ffrhdu)
SIMPLE=TBITPIX=16/8unsignedint,16&32int,-32&-64realNAXIS=2/n
ffopen could not interpret primary array header of file:
C:\Program Files\ACP Obs Control\WebDocs\images\ebenson\AutoFlat\AutoFlat-201101
This does not look like a FITS file.
And there may be other problems, too

**Script Error (Tracking has been stopped)**
Source: PinPoint.Plate
Message: Failed to open image file for read access.
Extension doesn't start with SIMPLE or XTENSION keyword. (ffrhdu)
SIMPLE=TBITPIX=16/8unsignedint,16&32int,-32&-64realNAXIS=2/n
ffopen could not interpret primary array header of file:
C:\Program Files\ACP Obs Control\WebDocs\images\ebenson\AutoFlat\AutoFlat-201101
This does not look like a FITS file.
And there may be other problems, too
at line 620 column 17.


I had Maxim image compression turned on (see File...Settings...Files tab), this would have caused the ffopen call to fail. I had not realized that ACP was reading acquired files from disk (as opposed to transferring images from the Maxim.Document object). So lesson learned, perhaps an entry in the help file "Turn off Maxim compression" would be worthwhile?

So after this error occured like this the system just stopped (stopped tracking), what other safeguards are there to clean up after an oops? In my case the scope was sitting in the open looking at the zenith (I have no dome yet, the midday sun might have burned a hole in the shutter). Of course first thing I did when I woke up was check the scope and park it manually with the joystick since the Sun was pretty high already! So no dramas, but is some other system supposed to kick in when dawn flats fail?

EB