GeorgeCarey

You can make a pointing file without using Sequence but it is so much easier and quicker if you use Sequence. To start with you could do 5 stars in each hemisphere and make a bigger pointing file when you have figured it all out. You will need Pinpoint which is quite expensive, but you can download it for free and use it for a month or two before you need a license. I use an exposure of about 5 seconds for each image and it works perfectly.

A pointing file usually only needs about a 5 second exposure for each frame. Are you using Sequence to make the pointing file?

I am confused. Are these errors happening when you are making a pointing file? You say the image exposures are 600 seconds which does not sound like a pointing file.

The log file settings are in menu Control.... Misc settings At the bottom of the list is 'Enable Log File'. The log is written in Program Data/ASA/Autoslew/AutoslewLogs

I cannot remember which menu it is in, but there is an option to write a log file. I will look for it when I next get to my observatory computer.

You are right that it cannot be dithering. I still think you should check the motor currents in the log.

Sorry, I don't understand.

Set Autoslew to log the motor currents and see what the currents are doing. When there is a current error Autoslew moves the mount to try and correct the error. The deviations in your graph look exactly the same which does not usually happen with dithering.

I thought the serial numbers told you the magnetic angles?

I wonder if Autoslew will recognise the absolute encoders and remove the Homefind button?

Thanks people. Apparently there are at least 20 novae in M31 each year, so it is worth a few images.

As Mark says, the drift method may be your best option. It takes a long time, but as you have a permanent setup in an observatory, will only have to do it once. What altitude can you get to in the South direction? Even if you cannot go much past the zenith, drift alignment should work.

Thanks Bernard. This is the first bit of serious work I have done that has got somewhere. I was encouraged by the fact that M31 has about 50 novae a year, which puts a discovery within reach of the amateur. George

My mount did its job well on Sunday: http://www.astronomerstelegram.org/?read=8327

Very nice! How many subs for each object?

Have you done a 'find home position' routine when you switch on the mount? I don't think the problem has anything to do with the number of stars in the pointing model. The ini file should have the correct values for your encoders - it is worth checking this with ASA? Contact Support and send them the ini file. George

Good to hear it is going well!

Hi Daniel, how did the imaging session go?

A small amount of humming sound when passing through the meridian is quite common. If it is only during slews it does not really matter. If the sound occurs when the mount is tracking then you need to reduce the D parameter a little. I do not know why you are losing USB contact. I have never experienced that.

Great to hear you are all set now! Happy imaging.

As far as I know, Save parameters is different from save to INI. I always sync in Cartes du Ciel. It works. You don't need a new pointing file to do a sync. From what you say it looks like you are making more pointing files than you need. A 40 star pointing file should be good enough. When you start Autoslew it will tell you in the information window if it has found your pointing file. If it has, centre a star, sync in CdC, set new home position and you are ready to image. No further pointing files until you change the telescope setup.

That should work. Remember to Save Parameters before you switch off. When you shut down Autoslew you may get a message to save to INI. That only needs to be done if you have altered the motor PID settings. I have turned that off so it does not come up each time, but I can't remember where that option is in the menus. Setting magnetic angle, Homefind, Home position is very confusing at first. I had no idea what I was doing at first!

There is no preferred place to set the new home position. I sync on a bright star like Arcturus or Vega, and then set new Home Position. I suppose the position should not be too low in the sky because then atmospheric refraction might come into play.

Set home position is not the same as Homefind. The pointing model will only calculate the relative positions of all the stars, in other words, the angular distances between them. When you switch on Autoslew it does not know where it is pointing. (My system does not have absolute encoders). The Homefind looks for reference marks and when found it knows the altitude and azimuth that it is pointing relative to the Earth, but has no idea where the stars are. When you sync on a star then Autoslew knows where it is pointing, but it will forget if you switch it off. Setting a new Homeposition will link Autoslew with a synced position, your observatory position and, most important, the time in your PC clock. Save the parameters and then when you next switch on you only need a Homefind. You won't need to set a new Homeposition unless you change the pointing model. Perhaps it is best to think of Set New Homeposition as "Remember the latest Sync".

Did you clear old configuration before calculating the 40 star pointing model? Did you then tell autoslew to save the model and use it at next switch on? The next operation is to centre on a known star and sync in Cartes du Ciel. Then go to this menu and set a new home position: Then tell Autoslew to Save parameters with this menu: If you don't save parameters I have found that Autoslew can forget the Homeposition. With my setup I have gone for nearly a year without resynching and the object was always close to the centre of the frame.