RamaSpaceShip

Hi Mike, As the PC clock drift is about 1 second per day, which meens a RA error of 15 arc seconds (so about 15 pixels!!!) on a slew if you don't sync on a star, it seems to me that synchronising once a day is sufficient. Don't forget that a sync on a star is able to compensate the time drift very precisely (the star movement is a very good clock ), and it is wise to do it after each clock sync. Best regards. Bernard

Hi Jay, The GPS is not a clock, it only provides time reference from time to time. Getting time from a USB GPS takes several milliseconds while the loop that controls the ASA mount has a 5 milliseconds period or less. The accuracy of the GPS time cannot be easily better that a few milliseconds when Autoslew requires less than a millisecond. So no, it is not possible to use the GPS as a real time clock with a sub-millisecond resolution. This is a fact. In addition GPS time has some jitter effects and needs several time values from satelites to be accurate: see http://catb.org/gpsd/gpsd-time-service-howto.html The PC real time clock is accurate. Its deviation is about 1 second per day, which is good enough for astro-photography (it means 0.2 arc second RA error after a 20 minutes exposure). Getting time from the PC clock takes less than a microsecond. But as any device, it may (very rarely) be broken. Autoslew needs to know what time it is before a slew, in order to determine the target position, and it uses the GPS for that purpose. Once this position is reached, it needs a real time clock to stay on the target, and it uses the PC real time clock for that. They are the best available devices for these different goals. Best regards. Bernard

Hi Max, Much clearer now. Due to variations in temperature and humidity, and to usage of the telescope, some slight changes in the configuration occur and there is no way to avoid that. This means that PA is to be redone from time to time, and, as I wrote above, as soon as you move the mount on the pier to improve the PA, every previous pointing model becomes unusable. The only solution I see is to make a new pointing model, as you have no way to know what the changes are with a sufficient precision. Don't forget that the changes are not only on PA but also on all the other errors that a pointing model is trying to compensate. So, if your pointing model becomes not so accurate, it can only be fixed by redoing it from scratch. Best regards. Bernard

Hi Max, I understood that it is the other way round: you build a (simple) model to calculate PA error only. When you get star positions to make a model, the calculations on that data solve a multi-variable equation set to get the value of the different pointing errors of your telescope: PA, collimation, flexure, etc... These values are then used by the mount to adjust the pointing and give much better accuracy. When you want to only improve PA, Autoslew simplifies the equation set to resolve only PA error variables. You can also do the equation resolution by yourself, by using the appropriate math. Once you move the mount on the pier to make better PA, every previous pointing model becomes wrong. Best regards. Bernard P.S. As I am not sure I correctly understand your question, the answer above may not correspond to your issue.

Hi all, The GPS (nor NTP) cannot do anything in this situation as it only allows for a one shot synchronisation (say before each slew), and not for continuous time getting during the exposures. Autoslew uses the system clock to keep the mount on target, and if the clock deviates significantly, then you have a big trouble that needs to be fixed. You can setup a NTP server on your lan to determine the deviation of your PC clock after one hour. The choice of the GPS or NTP is up to you. Even on high latency internet lines (like satellite ones), the accurracy is sufficient, as a shift of a few seconds is completely corrected once a star is synched (it is a deterministic error). Best regards. Bernard

Hi Mike, "Atomic Clock Sync" is just a configuration utility to set hidden values for the Windows time service. The Windows time service uses NTP (Network Time Protocol) to adjust the system clock from a NTP time server. You need to choose a time server close to you like "uk.pool.ntp.org". NTP is used worldwide since decades, time servers are in sync with atomic clocks, and the protocol is robust and accurate. You have to sync before your astronomic operations begin, and not in the middle as this can confuse Autoslew. Best regards. Bernard

Hi Daniel, When doing PA or a new pointing model, I always verify that the error associated with each star (displayed on the bottom line of Autoslew) is in reasonable limits (say less than 400 in each axis), if not I discard the star. I do that because I noticed that such values fool the resulting pointing file such that its calculations are wrong. Why is there such error, I don't know. I suspect that the pier side value is misinterpreted causing the initial error. Please do the same checks and tell me if you have similar behaviour. Best regards. Bernard

Hi George, You should'nt, unless you promoted the Brexit. But the story is not finished yet. You will have to drink this cup of bitterness to the dregs. Next step, Scotland will soon vote to leave UK, and return to EU. Its currency will become the euro... Second shake... Well, future of England appears a bit dark. The real shame is on those politicians who lied about the real consequences of this vote. I did not imagine that you could have worse politicians than what we have here in France, but they proved they can do it!!! Don't expect anything better in France!!! Europe is a great help in this area (and in some others). Europe needs to be changed to better serve it citizens, but leaving it means just going backwards, with a huge work and a little chance to get back on par. Anyway, good luck. British people demonstrated that they can come to the end of such adversity. Bernard

Hi Dirk, You can copy the following folder "C:\ProgramData\ASA\Autoslew" as a whole (and keep a backup somewhere that you can restore at any time). This folder contains all the configuration files you need. This is the best and safest way to recover all your settings in Autoslew. That's also the reason why maintaining an up-to-date backup of this folder is a very good idea. For those who did not do such a backup, you can do it NOW. Regards. Bernard

Hi Luis, Just amazing!!! It's a so wonderful picture. The technique is impressive also! Very good job. Bernard

Hi Dale, There is a support email address: support@astrosysteme.at. Or you can use their support web page: http://www.astrosysteme.com/asa-support/ Best regards. Bernard

Hi Michael, Put these optical surfaces in warm water (50°C) added with dishwashing liquid. Move them in the liquid until the crud disappears. Then use isopropyl alcohol to rinse these surfaces, and a hair dryer on cold position to remove the alcohol.. Then you can put them back, cleaned!!! (This works also for the main mirror.) Best regards. Bernard

Hi Thomas, What are the bound values for the focuser position? As far as I can see in the log, it seems to repeat focus position:11,95. I wonder why. It probably stops because the result is bad after 5 tries at this position. But I don't know what is wrong as I don't use MaximDL yet. Best regards. Bernard

Hi Lukas, I have a similar position. But I would be happy to participate if they open their software as that would be a win-win approach. Best regards. Bernard

Hi George, Do you have a working backup of your Autoslew configuration directory? I had a similar problem some time ago, and the solution was to wipe out the Autoslew configuration directory and to replace it by a known working backup. It was corrupted for an unknown reason. By the way, to all ASA mount users, it is wise to make a backup of your Autoslew configuration directory once you think it is working correctly. Accidents or corruptions are something that happens, in particular with Windows. Best regards. Bernard

Hi Thomas, This is a really wonderful image. I love the colors, I love the 3D effect. Thanks a lot for sharing. Best regards. Bernard

Hi John, Yes, the new absolute encoders have a better precision than the current incremental ones. But this additional precision will have nearly no effect on the performance of the mount. The only case where it may help is when the mount is used for some special professionnal operations. For amateurs like us, the current mount performance is already optimal in terms of precision: do you need more than 20 minutes subs? I don't think so. Best regards. Bernard

Hi Nigel, Using absolute encoders in place of incremental ones is only a simplification of the system. Once the "homefind" is done, incremental encoders provide the exact same service. So I don't think it is worth to change as it is not a real upgrade of the system. Best regards. Bernard

Hi Nigel, You just had a dream. The ASA2 software that was shown is just a in-house demo, with some ASA promisses that we all know how to interpret. Today, this software is still "to be made". Ian, I think ASA is afraid to be too successful, so they need to limit the customer interest to their products. They found a solution to this issue that works. Best regards. Bernard

Hi Michael, The width is important, it must be bigger than the tube ring width. A thickness of 1mm is ok for me, as it needs to be strong enough. Best regards. Bernard

Thanks, Christer, I was able to get the pdf file using the new link. Bernard.

Hi Waldemar, I got the exact same message. Any forum administrator to fix this? Bernard

Hi Pavel, It's really a great, great one. I have the same feeling than Robert regarding the 3D effect. The red eyes of the dark beast in the top right corner are impressive. And the tiny blue background makes this image crystal clear. Good job. Bernard

Hi Pelle, If you have some flexure, then it could be very hard to get 20 minutes exposures, in particular if not all cables go through the mount. You need to identify the source of the flexure. And to solve it, or at least reduce it. You need to try other USB cables to find one that is usable through the mount hub, or to manage such that the cabling has a very little torque on the OTA, else it can be a good source for your issue. Good luck. Bernard

Hi John, This picture gives an impression of 3D vision that is absolutely amazing. Very good job. Bernard.