SynScan HC - PAE (Pointing Accuracy Enhancement)
Posted 22 October 2013 - 02:24 AM
- "The SynScan hand control divides the sky into 85 small zones, and users can calibrate the pointing error for each of these zones. The next time that the SynScan controller tries to locate an object in the calibrated zone (or a zone nearby), it will automatically apply the recorded calibration data to compensate the pointing error. This function is useful for locating faint deep sky objects, and it is also helpful to obtain consistent pointing accuracy for a permanent observatory."
- "Whenever the SynScan hand control locates an object, it will automatically check whether a PAE calibration data is available, and apply the compensation accordingly. No manual intervention is required. If multiply PAE calibration is performed in the same zone, the previous calibration data will be overwritten."
Please see page 34 of SynScan manual here http://www.skywatche...ynScan 3.35.pdf
1) Does this mean that after a 2-3 star alignment, one can sync on no less than 85 stars with Synscan HC besides the initial alignment stars and Synscan will develop a sky model based on 85+2(or 3) stars simultaneously?
2) After you do a PAE (or syncing) on a star located in one of those 85 zones, the previous PAEs done on other stars located in other zones will be replaced with the last PAE or their sync data remains in HC sky model?
3) In other words, does SynScan PAE have the power of EQMOD N-Point alignment and step in front of Celestron 2+4 star alignment?
Posted 22 October 2013 - 12:42 PM
Posted 22 October 2013 - 02:43 PM
In your experience, after a PAE,does DSOs land in the middle of an eyepiece in that small part of the sky at >100x magnification?
Posted 22 October 2013 - 03:40 PM
Posted 22 October 2013 - 03:58 PM
I have found here http://stargazerslou...alignment-help/ a very nice explanation about how PAE works, as a user explained:
"First, if you use the ESC button multiple times you will get to the SETUP menu. Press enter, then scroll down through the choices until you get to Alignment (not Alignment Stars; that choice allows you to fiddle with how Synscan presents the alginment star menu), press Enter, and redo the star alignment. Whether you chose 1-, 2-, or 3-Star Alignment, SynScan will remember the previous alignment until you complete this alignment so that if you change your mind and use ESC to exit, you should still have your old alignment. In any event, this is how to redo an alignment if the results from the previous alignment are unsatisfactory.
But suppose you only want to enhance the alignment, not redo it? Synscan has an odd, quirky sort of adjustment called Pointing Alignment Enhancement, or PAE. This augments the previous alignment, but does NOT change the model of the sky. Synscan divides the sky into 88 zones. If you exercise PAE on an object, then any GOTO to a target within that zone will have an extra refinement made to it's pointing. The basic sky model from the initial alignment is not changed. So, for example, if you have done a 2-star alignment and then a GOTO to say, the Ring Nebula, and the GOTO does not place The Ring where you think it should, then you can recenter on The Ring and use the Utility menu, select PAE, and follow the instructions to accept the new location. From that point forward until you eitner delete all PAE with the Utility Menu, or until you redo a full alignment, the region around the physical sky where The Ring was when you used PAE will be adapted to your adjustment. If you then GOTO, say, The Swan in Sagittarius, Synscan will pay no attention to your previous PAE. If you like the results, fine; if you find the pointing to The Swan is also not to your liking, you can invoke PAE on this object. Then, GOTOs in that region (again, the actuall azimuth-elevation of the part of the sky where the object is at the moment) will be affected. Each PAE is independent, and only effective in a region around the invocation point. The purpose of PAE is to adjust the pointing for mechanical vagaries of the mount, such as less than perfect assembly, or looseness of some component(s), etc., that affect local pointing. PAE does not change the sky model developed in the alignment.
If you use a permanent setup, then over time, the entry of PAEs as you move around the sky (and note that PAE is not to an object, but to a region of your physical sky no matter what object is in that location), eventually you will have a refined space for your mount as long as you never redo an alignment of any kind. Once you redo an alignment, all PAE memory is erased. This includes power cycling effects; if you use Park before removing power, all alignment data is saved along with the PAE data. If power is removed without Park, all alignment data is lost. I wish Synscan had a feature to request alignment and PAE status to verify the condition, but we are blind to that.
If you relocate to a new site each night as I do (my Atlas is used for public outreaches at schools, parks, resorts, etc.), then PAE in the memory can provide mischief when doing the alignment on the next power up. It has saved the previous adjustments, so if you happen to choose an alignment star in a region where the previous use caused you to use a PAE, then the offset will be introduced to the pointing. You make your centering adjustment, then move on. But when your alignment process is complete, the PAE memory is erased. Oh, my, what a warped sky you might have! Luckily, all PAE can be erased without affecting the sky alignment data.
So, there you have it. Synscan does not have a feature to add stars to the alignment model as you go on after the alignment, but it does have PAE for local effects. But SCTs can play some mischief with this feature due to mirror "flop" when crossing the meridian, and mirror shift when changing focus. For serious pointing, such as for small CCD chips, then microfocus addons to the optical tube are almost essential to stop some of the mirror movements that can affect the alignment models or even PAEs."
Now, can anyone confirm if the above explanation is correct in practice?
Posted 22 October 2013 - 05:13 PM
Posted 23 October 2013 - 06:29 AM
Posted 23 October 2013 - 07:35 AM
So you confirm that one can do multiple PAEs in different parts of the sky during the same session and the HC will remember all and apply the correction everytime one returns to those parts of the sky.
To me PAE seems similar to EQMOD N-Point alignment.
The only problem I see with PAE is that if I want to center a DSO on my LodestarC sensor I have to discover a star close enough that DSO and know the name of it because the HC software doesn't suggest me the closest star to that DSO which is good for PAE.
And if there are no bright stars I can see through a Telrad near that DSO, how can I use PAE?
Because of this I think Celestron's Precise GOTO function is cleverer because you tell it the DSO you want to see in the middle of the chip/eyepiece and the HC will tell you the star to center closest to that DSO and this way you have to search for such a star.
With what telescope/ccd/eyepiece have you been using PAE and can you please quantify/explain somehow the improvement you saw after PAE in that situation? (e.g.: let's say with PAE the DSO lands in the middle of the chip/eyepiece at >100x and without PAE the DSO is completely outside the chip/eyepiece at >100x)
PS: You can delete all PAE data before you park your telescope to keep in memory only the initial 1-3 star alignment.
Posted 23 October 2013 - 01:07 PM
Posted 23 October 2013 - 02:00 PM
Your experience seems to sustain PAE description in the Synscan manual which is good news.
It's interesting that you didn't do PAEs on stars near the DSOs you wanted to land in the middle of the eyepiece but you did PAEs directly on those DSOs and it still worked.
I wonder what happens when the DSO don't land at all in the eyepiece. Than I suppose you have to find a star near the DSO and center it and than the mount will put the DSO in the eyepiece.
But how do you know which star to pick and center with PAE for that specific DSO if there aren't bright stars visible in that part of the sky?
Posted 25 October 2013 - 03:26 PM
I did 3 or 4 PAEs on the whole sky during the same sesion and it worked. I did PAEs on both stars and DSOs succesfully. I also observed two problems with PAE:
1) many times I couldn't find a star for doing PAE close enough to the DSO I wanted to see and which didn't land in the FOV of my eyepiece (~64x magnification) without PAE, but when I found such a star PAE worked well putting the DSO in the center of FOV
2) after a period of time (>30-60minutes) PAEs seemed to lose their efficiency in that part of the sky.
I also think that doing multiple PAEs in different parts of the sky during the same session will not have a negative impact on your inital star alignment.
The mount was aligned in EQ mode on 3 stars with Synscan HC: Cappela, Scheat and Vega ( as they were offered by the HC).
Posted 25 October 2013 - 05:08 PM
In the hand box, I had to go to the menu and clear the data. Then goto would work ok.
Posted 25 October 2013 - 09:44 PM
One problem I have had with PAE was that is saves the data from night to night. Since I am mobile a lot of the time, PAR data from a previous night would screw my alignment the next night.
In the hand box, I had to go to the menu and clear the data. Then goto would work ok.
I was under the impression that if you didn't choose "start from park" when you turn the mount on, all alignment data (including the PAE) is wiped, and you start from fresh.
Posted 26 October 2013 - 07:43 AM
Posted 26 October 2013 - 08:55 AM
It's possible I could have told it to start from park when I had my problem. Very possible! But something to keep in mind if you are having pointing problems. And to be fair I only recall that happening one time, most of the time my EQ-6 is fantastic at gotos.
A fresh star alignment will delete all PAE data, according to Synscan manual.
What do you mean by "fantastic gotos" with your Meade 10"+EQ6?