I am evaluating CCDAP and have some questions:

1. In shooting flats with a rotator (Pyxis 3"), is there a way to have flats taken at say dawn with both position angles used in a sequence? For example, say I shoot M1 with an initial PA of 90...it goes on its merry way and then does a meridian flip, and rotates to a PA of 270 and shoots a few more L frames and then color frames...so I need flats for both PAs, is there a way to do this automatically?

2. I shot a series last night, M76 (first use of this program) and it went along, shot the L frames guided, did a meridian flip and continued on its way, everything fine, shot several more L frames after the flip. It seemed to be unable to find the guide star for the R, G, and 2 of the 3 B frames but the last blue frame was OK...Looking at the log showed nothing amiss as far as I could tell (no difference between the frames that worked and those that didn't, file included).

3. Anyone have any ideas or experience as to what the best meridian flip settings are for a Paramount ME MKS4000 system using Maxim5.07 for guiding with a rotator? A bit worried about Maxim's ability to accurately activate "pier flip" after a meridian flip and guide correctly. My thoughts are that it ought to pause a bit before the meridian and then wait until the object is a bit past it but not sure of exactly how to set that up.

4. In shutting tracking off in the options-data acquisition, if this is checked does thie mean that after all frames are taken LRGB, tracking is turned off until dawn flats are taken? Again, Paramount ME mount?

5. What do people feel a good guiding ADU target value is? ST10XE 12.5" RC at f/9, binned 2x2 for guiding, Astrodon filters?

Thanks, Mike

ccdap20091008_213050.log (90 KB, 7 downloads) Log file

Hi Mike,

To answer your questions:
1. Sure. Simply set the desired PA on two series on the Flats page. For best efficiency, select series order and start with the PA West and then rotate to the PA East. Select the Position Angle from the Utility window at the west, which will give the PA for your target. In your sample log, you will see m76: PA 252. For more details, see Help/Command Summary/Flat Frames along with Imaging Strategies/Calibration Frames.

2. You should check Precision Slew To Target on the Targets page so that the target is precisely centered, especially after a meridian flip. It is also required to get accurate guiding.

3. Your meridian flip settings are fine. In fact, with the ME you can set set the Meridian Tracking to 10 minutes comfortably. There is no need to worry about Maxim settings. They are all handled by CCDAP. In many cases, the Maxim UI doesn't reflect the status of the automation interface. This is by Maxim design intent.

4. While you can set tracking off between light frames and dawn flats, you can also simply select Park. Selecting both is redundant since you can not turn off tracking when the ME is parked - tracking is turned off in that case by definition.

Some other observations on your log
1. I would allow 10 cycles to get to within your guide tolerance of 1 pixel. 3 cycles may trigger AGSR unnecessarily.
2. Your plate solve settings are not reliable. See log entries a4 21:34 and following. You can example the SyncImages to see why they didn't solve - unsolved SyncImages are not deleted. You may have better luck using the GSC and/or use longer plate solve exposures. Examining the images should tell you a lot.
3. Unless your OTA has a seriously curved focus field, you do not need to set the focus star centering to 5 arc-sec. This wastes time and is most likely unnecessary. Most likely a 100 arc-sec. tolerance is sufficient.
4. I would set a higher guide star ADU target - suggest 3000. If you set it too low, you may lose guiding due to passing clouds, changes in transmission, etc.
5. Your minimum flat field exposure is too short. The effect of the moving shutter will bias your flat fields. Suggest a good minimum is 2 sec. and a reasonable maximum is 30 sec. By keeping the max. to 30 sec., you should be able to comfortably calibrate your sky flats with a simple bias subtraction.

OK, I am still a bit confused about this flat thing, even after reading the help sections...lets suppose that I am going to shoot M1, PA to start is 90 degrees, after a meridian flip it will be 270 degrees. But let's also suppose that I am also going to shoot M42, initial PA 180 degrees, after the meridian flip 0 degrees. Is there a way to do the flats for both of these with dawn flats for example? Sometimes, because of temperature differences, I prefer to shoot flats at dawn if possible. What I did for M76 last night was make it for both PAs manually. In other words is there a way to have the program do, automatically flats for the L filter at a PA of 90 and 270 with one entry (would this be the dawn/dusk setting)? Or would sseries 1 be for 90 and series 2 be for 270 for L and then 270 each for RGB? Sorry to sound thick on this, my previous experience has been with another program with a different way of doing things.

Mike

The position angle (PA) is the same whether east or west of the meridian. However, the rotator position is 180 degrees different from one side to the other. That is why the flats page has an entry for angle and a selection for PA East and PA West. Thus, if your target is at PA of 77 degrees and you need flats for both sides of the meridian and you want to take them all at dawn, you will need 2 series with the same filter and the 77 angle but one will have PA West selected from the pulldown and the other will have PA East selected. There is no need to enter a rotator position - CCDAP calculates the necessary rotator position based on your initialization and the specified PA.

Now, if you do both dawn and dusk flats, you can enter one series, check Dusk Order and With Rotation since you have a rotator and get all the flats you need for up to 8 series with east and west flats. See the help file for details on this option.

Unless you have extreme changes in focal length due to temperature, there is no reason not to take both dusk and dawn flats. Focus is not an issue for flats.