Saturday, February 16, 2013

First image with new setup: M44

As my very first image, I chose M44 - I figured that an open cluster is a good start object. Because I still couldn't figure out how to control the filter wheel from TheSkyX, I had to move it between series manually :-(

I took LRGB images. All images have a lot of noise - I wonder if it is because of our light pollution here. And I needed new darks, bias, flats and dark flats. I ended up with:
10 Luminescence 60 sec
5 RGB 240 sec
20 Darks
20 Flats
20 Dark Flats
20 Bias

Taking the Flats turned out to be quite the challenge. The flat panel that I use is too bright for the color filters and I had to use such a short exposure, that the vignetting did not come out. I ended up waiting for dawn and took them then. Also, they had lots and lots of artifacts:

But on further inspection (and after taking a second set of flats and processing them) it turned out that my scope (the camera and the corrector plate) are really this dirty...

I also used this as an opportunity to try out CCDStack. It's much more manual then Deep Sky Stacker, but I think it's worth the effort. I'll have a month or so before I have to decide if I want to buy it.

After a day of learning and playing, I finally had my first LRGB combined image. I did some basic processing in Photoshop and ended up with this:

Overall, I'm pretty happy with this, the star colors are good (but not too saturated). The only problem I had was that the background was very noisy. If you zoom in, you can see that the stars have a pretty strong halo, but that it then drops off. I wish I could have done this better.

This was also the first time, that I used the OAG instead of the guidescope. And I had the same drift during guiding that I had before. The good news is, that the guidescope seems to be OK. The not so good news is that there is this drift. I hope that this will improve when I hypertune my mount (everything arrived yesterday!) Unfortunately, I won't have time to do it this weekend and next weekend.

Thursday, February 14, 2013

Setting up the filter wheel and the off-axis guider

I finally received my filter wheel from Starlight Xpress!!! So, I could set that up and also finally use the off-axis guider from Starlight Xpress.

First, I reconfigured the scope: removed the 4 spacers (for correct backfocus) and replaced it with the filter wheel / OAG. And now, I can use the reticle eyepiece in the guidescope. And I had to do a bunch of recabling (and need a shorter USB cable for the filter wheel).

Then, I tested the filter wheel with the test software from Starlight Xpress - works!

Next, I connected the filter wheel to TheSkyX. Assigned names to the 7 filters. But then I couldn't control the filter wheel from the camera plug-in. It just didn't move at all. I checked the Bisque forums and a couple of folks mentioned issues with the Starlight Xpress filter wheel when they used a USB hub. So, I connected the filter wheel directly to the laptop - but same result. The weird thing is, when I connect TheSkyX to the filter wheel and use the Starlight Xpress program to move the filter wheel, TheSkyX shows status "Moving". I.e. there is some connectivity to the filter wheel.

Then I wanted to figure out the difference in focus. I used the Bahtinov mask for this and subframed stars in to get a very accurate focus. The 4 Baader filter (LRGB) have the same focus, while the Ha filter (from Orion) and the OIII and SII filter (from Astronomik) have an offset of +36. I could enter the offset into the Ascom driver, but not sure if and how that would be used from TheSkyX. It would certainly be helpful if TheSkyX automatically adjusts the focus when changing filters.

As the final step, I needed to focus the lodestar. But all lodestar images have a very strong glare in TheSkyX:

I don't see that effect in PHD or the lodestar program (from Starlight Xpress). Though in TheSkyX I see WAY more stars then in the other 2 programs. I asked on the Bisque forum about that.

And throughout the entire night, I had several connection problems. At some point the cables that run down the mount (USB, power) got loose when the mount slewed into an extreme position (I extend those cables a little bit). The serial ports needed some wiggling before they wanted to connect. And I had a power outage again - I can't seem to figure out where this comes from (I already replaced the 12V adapter and also the splitter).


I received a couple of answers:

Apparently, the image from the OAG is normal... I can try to use one of the stars - although there isn't much of a contrast. I could also try to take flats (and maybe darks and bias) to reduce the image properly. But wouldn't I need to take new flats every time I change the OAG (move it in or out - turn it).

Interestingly: when I started autoguiding with an image like the above, I got this picture in the subframe:
It seems as if subframing helps with the vignetting. So, that might work!

With this, I tried autoguiding in TheSkyX. Now, with the OAG, the movement should be much more sensitive. In x-direction, the default of 10seconds for the relay worked. But in y-direction I had to go higher then 100 seconds for the relay. In the +y direction it worked with much smaller values. But in the -y direction I needed the high value. I wonder if this is because of backlash in the mount. And if yes, if it will improve once I hypertune my mount (maybe this weekend?)
I started guiding with TheSkyX and could finally get it to work. But I had an image shift - like I had when I tried to guide with the guidescope. But the shift was very slow, good enough to try some imaging.

With regards to the filter wheel, I was (of course) asked to update to the latest version of TheSkyX - done.
I was also told, that TheSkyX only moves the filter wheel when I am taking an image (i.e. not when I just select a different filter in the drop down).
And finally, that I need the "driver in the ASCOM category that's installed along with the application."
I tried this, and the filter wheel indeed turns before taking an image. But after a few images, it timed out with the 209 error (as described in the Bisque forum).
I could not figure out what was meant with the ASCOM driver, will have to reply to the Bisque forum.

Monday, February 4, 2013

The distorted lodestar images are because of binning??!!

Tonight, I wanted to figure out why the lodestar images are so distorted.

First, I attached the lodestar to the main scope. There the image was perfect. So, it seems as if it is the guidescope. I moved it back, and ... no elongated stars at all! Strange. So, I focused the scope as good as possible (with the small Bahtinov mask).

Well, I then tried to work on autoguiding with TheSkyX. At some point, I had the elongated stars again. It took me a while to figure out, that this only happens when I'm 4x4 binning. Here are some images:

No binning:
The effect is easily noticeable. I wonder if this is a blooming effect?

Well, after that was cleared up, I tried to get autoguiding to work. But still no luck. I posted the guiding log file, the lodestar image and the autoguiding image to the Software Bisque forum - hopefully I will get some help.

And I also realized that I need to build a shield for the guidescope. Here is an image where some light reflects off the main scope:

And here is the same image with all lights turned off and some black paper on the scope:

And that was it.


Few days later: Yes, this is because of binning. Apparently, the lodestar only supports 2x2 binning. And if you choose a higher binning value, it only bins in one direction, i.e. 3x2 and 4x2 - that explains why everything looks so elongated. I can actually set the max binning in the ASCOM driver configuration. After I did that, TheSkyX only had 1x1 and 2x2 binning in the dropdown. Riddle solved!

Saturday, February 2, 2013

More Robofocus and Lodestar woes

Took out the scope and did the alignment and polar alignment. I wanted to use the lodestar for rough alignment and then the CCD camera for fine alignment. Plus I received the Bahtinov mask for my guidescope and wanted to fine focus the guidescope. But in the autoguide images, all stars we elongated! I never noticed that before. Interestingly, this is not noticeable in PHD! I have no idea if it's the Lodestar or the guidescope. I should put the lodestar into the main tube and check how images look there. But I didn't want to deal with this and rather move on.

First, I wanted to optimize the @focus2 parameters. I set the subframe to 400 - this captured almost all of the defocused star. I then reduced the focus range such that 2 measurement points are inside the v-curve and 3 outside. With that I did 3 focus runs. They resulted in focus position of 17081, 17044 and 17051. The distance here is 37 steps which equates for my focuser to 29 microns. Which is well within the focus range of 85 microns.. But I am surprised that they are so far apart. I would like to play more with these parameters, but that I have to cover/uncover the scope twice for each focus run makes it quite cumbersome.

Next I wanted to try the OIII filter. Took the Ha filter out, screwed the OIII filter in. First thing I realized is that this filter does not dim the stars at all. That should make focusing easier - so I thought. I used my optimized @focus2 parameters ... and didn't achieve any focus :-( Tried 2 more times - same result. I then checked the@focus2 log:

Seems as if the star that I selected was to bright - and as a result, the spike of the v-curve wasn't very high. I should try again with a dimmer star. But it was late and I called it a night...

I really need that filter wheel - or the hyperstar lens with the filter drawer. Then I can just focus with one filter and be done with it. Or maybe I'll get a filter drawer for my current setup...