MAXIM DL guide star selection

[multiweb]

How do you override MAXIM DL automatic selection for a guide star? I want to select the guide star explicitly but everytime I press start it defaults back to a hot pixel. :help:

[Tandum]

Just click on the star you want it to use and click start.

[avandonk]

You can select the calibrate star by left clicking when the calibrate thingy is ticked. Press start to calibrate. Then left click on your star of choice while the track thingy is ticked and then hit start!

Bert

[gregbradley]

In CCDsoft that would still fail as the software will automatically chose the brightest pixel in the image thinking it is the guide star. I have seen my autoguider go along nicely and then all of sudden hit 8 to 14 pixel guide errors due to selecting a hot pixel or camera artifact (Lodestar).

The best solution is a dark subtract. With an STi that is done simply by selecting autodark in the imaging menu and it takes a dark at the start and then reuses it continually through the session (it has shutter to be able to do this). It will not use a library dark though so you would have to be using Maxim that allows library darks for autoguiders.

So unless your guide camera is pretty clean and free of artifacts you need an STi or ST402ME or use Maxim.

Greg.

[RickS]

Or use ACP which picks the guide star for Maxim :thumbsup:

[troypiggo]

Yes, just click in on when you do the "expose". You should see the x and y coords change to the star you picked.

I also do as Greg suggested and do a full dark calibration of guide cam even for guiding.

[marki]

Just make sure it is a single click only, not double. Maxim will then use the star you have chosen to guide.

Mark

[multiweb]

I click the locate radio button in the AO setup window. MAXIM selects a star. I then click another one. Press start in the same window and MAXIM selects his own again.


:lol: You've confused the hell out of me there Bert. Calibrate thingy beign the radio button? Yeah I did that. Clicking start always defaults the star back to Maxim's choice.


Thanks Greg. I do darks and apply them to the lodestar. Then use full calibration in the camera setup windows.


Thanks Rick I read a little about ACP. I see that it has a line that disables MAXIM star selection: Camera.GuiderAutoSelectStar = False. Can you tell me the link to the latest version of this script. I'll check it out.




Thanks guys. Did that. The star selection in the AO defaults back to MAXIM selection as soon as any start button is clicked.

[Tandum]

Maybe you need a bad pixel map?

http://tech.groups.yahoo.com/group/MaxImDL/message/53252

http://tech.groups.yahoo.com/group/MaxImDL/message/53212

[multiweb]

Cool - thanks. Yeah that would be an easy fix. TBH I haven't used MAXIM DL in years. I did use the AO once but that was with the SX Lodestar utility. Will do a bit more reading. Looks like it's clear tonight again so I have another shot at it.

[RickS]

Marc,

Is it only during calibration that you Maxim is ignoring your choice of guide star? IIRC, I had the same problem and didn't find a solution. I worked around it with calibration frames so that I didn't have any hot pixels to guide on. Once calibrated I was able to choose a guide star when tracking.

Cheers,
Rick.

[multiweb]

Ok, so I've got this right. It's clear tonight so I'll give it another go.

1_ connect lodestar/AO etc...
2_ make a single dark frame then apply full calibration (or can you do a library of darks and combine to make a quality master dark?)
3_ in the AO set up window, click the locate radio button then start.
4_ one click on the star then start?

[naskies]

I use an SX AO with MaximDL and, like Rick, find the same thing. Clicking on the tracking image will set the tracking star correctly, though. From a user perspective, I'd definitely call it a bug.

I find that a dark library for my guider (Lodestar) is absolutely critical in order to calibrate the drive and AO correctly. In MaximDL's SX AO interface, you have to first set the dark frames in the calibration library, and then manually enable dark subtraction in the Setup pane. I almost tore my hair out in frustration until I figured that out :mad2: However, I track without calibration frames (as per the manual's recommendation) and find that it gives me about 2 Hz faster guiding.

Alternatively, I've sometimes found success by slewing to a bright star very close by and using that to calibrate.

[RobF]

Hi Marc

Remember you have full control of the manual parameters in Maxim too. From memory there is a public domain Maxim plug-in that will use plate solving to fill in the cal parameters, and works very well. Might be a way around your problems if AO is complicating things. Once you get a cal you should be able to use over and over.

[RobF]

There's ALWAYS something to learn in this hobby. Will have to check that out.

[naskies]

Yep...



I've just used the Autosave feature and shot a library of darks at various binnings and shutter speeds (0.05, 0.075, 0.1, 0.2 secs are what I usually use). I then go into Set Calibration (Process menu), auto generate, and replace with masters.



You need to first go into the Setup tab of the SX AO Control window, and ensure that Full Frame Image is checked in the Full Calibration section.

Once you've done that, click on the Locate radio button. I usually have the Contin. box checked to ensure that the star is reasonably steady first - then click on Abort.



Now click on the Calibrate Drive radio button, and then click Start. It should move the mount and calibrate itself.

You'll also need to do the Calibrate AO step if you haven't already. You need to re-do this if you change your imaging train (e.g. taking the camera out, and then putting it back in) - but not if you slew to a different part of the sky, or on successive nights with the same set up.

Step 5. Click on the Locate radio button again and re-acquire a guide star. (You have to do this before you can start tracking - even though MaximDL knows where the guide star is after the drive calibration step :screwy: )

Step 6. Click on the Track tab, and then click on Start. If all went well - you should see the guide star updating in the window and corrections being made.

Good luck! I find MaximDL's normal guiding set up fairly straightforward, but the AO set up is definitely convoluted.

[naskies]

One other thing - the SX AO units have a nasty habit of jamming. (In my case - it happens about 50% of the time after running Calibrate AO.) If this happens, you might find that MaximDL freezes for about 5-10 seconds before giving you a vague CCD camera error (3) (or something similar).

At this point, I usually disconnect both cameras from MaximDL, start the SXV-AO Utility, connect to the AO unit, click on Recovery, wait about 5 secs, disconnect from the AO unit (quit the program, or press Select Com Port), reconnect the cameras in MaximDL, and continue with the imaging run.

Sooo frustrating - if it didn't do such a good job when it works, I would have given up (or returned it) long ago.

[multiweb]

Thanks for the detailed post Dave. :thumbsup: I'm going to give it another go tonight again. Once I have it sorted out I'm sure it's just a matter of writing down the steps and following the right procedure. Will start by doing a library of darks as advised. I could see a lot of guide stars available in the lodestar viewport even at 1/20s so it's not the lack of guide stars that were the issue. I guess everything connects as well, so I can't complain too much. Got that far. :lol:

[naskies]

Aah yes - writing down the steps is a good idea! If I miss out on a month's worth of imaging due to bad weather, I usually come back and forget a critical step :lol:

By the way, I just found this very excellent article with step-by-step instructions and screen shots - in retrospect, it would have saved me much frustration:

http://astro.azurewebsites.net/Article/ArticleContent/5

The article reminds me of a couple of things that I forgot below:

* I use 2x2 by default with the Lodestar (SX recommends it in their manual too) - I get fewer image artefacts and faster update rates too.

* Dark frame scaling has never worked well for me on the Lodestar (even with a bias frame library) - so I prefer to take darks at lots of different exposure durations. Unlike a dark frame library for 30 min narrowband exposures, this doesn't take long :)

[multiweb]

Yeah I got Russel's great article. I used it originally 2yrs ago. I had it on the laptop last night again to refresh my memory while trying to figure things out. :) Good calibration should iron out most of the issues. Then some more will probably popup on the next step. :lol:

[multiweb]

Well thanks for all the tips and links guys. Got some pics on Sunday night and it all worked really good. Still not 100% sure what I did different from the night before but all the bits worked together. :lol: Just need to do some more reading now about the fine tweakiong and calibration grous in MAXIM as well. Not too clear on how this works. But I got some 5min cool subs in Ha. Just before the clouds and the moon. Thanks again. :thumbsup: Will post a pic of the rig (frankenstein noodle monster) and the test results here.

[multiweb]

Here's the bag of noodles as promised. Highly portable. ;)

[naskies]

Good stuff, Marc. What is your "AO 5V" for (the Jaycar transformer)?

I've started controlling my rig remotely recently too, and bundled up all the various cables running to the scope/cameras into one big cable. The one big cable is then firmly attached to the mount at such a point that I can slew anywhere in the sky and know that it won't snag on anything.

A little bit of peace of mind for when I'm remote controlling the mount and can't see what it's doing. (Though I have plans to set up an IR webcam to solve that too.)

[multiweb]

My AO is one of the first one that came out. There wasn't enough power through a laptop USB port so I have this box that I feed 5V to into the serial cable. Actually now I go through the hitecastro I might not need it anymore. Maybe there's enough voltage as it's a powered hub.


I used to tie things up but I use so many different configurations everytime I do something it wasn't practical anymore. Maybe one day if I have a permanent set up. Not for a long while though.

[naskies]

Aah, gotcha.



Very good point! I've started to settle on a single configuration to streamline things because it was taking me too long to re-configure for each set up.

[naskies]

In case anyone else is interested... here's a typical example of what my SX AO + Lodestar can do. The image is an 800% centre crop (i.e. 8 pixels here represents 1 pixel in the original image) from an unprocessed sub with only screen stretching applied.

The original image scale is 0.68''/pixel from a 30 minute Luminance sub, at 1625 mm focal length (GSO RC8) and 5.4 um pixels (SBIG STF-8300M), mounted on a black Skywatcher EQ6PRO. The big square blocks are warm pixels due to the dark current.

The uncorrected periodic error on that mount is about 40-45'', with a maximum error rate of 6.5'' in 1 second - i.e. the guide star dances around the screen between each exposure. I was getting eggy stars in *every* long exposure using standard guiding (anywhere from 0.2 - 3 sec guide exposures), hence the addition of the AO unit.

I usually run the AO unit with 0.1 sec exposures from the Lodestar at 2x2 binning, which results in an overall tracking and correction rate of about 6.5 Hz.

As you can see, the result gives me nice round stars even when heavily oversampling. It's also resistant to minor perturbations like small gusts of wind, vibration in the ground, etc.

It's very impressive tracking performance - akin to what you'd expect from a premium mount that costs 5x the price, for "only" 2x the price of the EQ6. The downside is that AO requires a bright guide star to be in the field of view, and it obviously doesn't help with pointing accuracy, backlash, reliable meridian flips, etc that you'd expect from a high end mount.