With the observatory down for another week or so, I have been considering re-trying the Mac Mini out as an observatory server.

I started researching Mac astrophotography software, with disappointing results.

Here is a list of things that I am coming to depend upon from my astronomy software:

- DSLR control
- webcam control
- autoguider control
- motor focus control (including autofocus)
- telescope control (parameter setting/getting, plus slewing)
- image naming and storage
- guiding data
- polar alignment
- periodic error analysis
.
.
.
the list goes on. These are just the heavy hitters that I thought of while sitting here. Note I didn’t even touch image processing (stacking, deconvolution, etc).

Put simply, the tools on PC can get all this done for me, with a lot of fuss and nonsense. Essentially, MaxIM does the heavy lifting, and with a couple of “plug ins” (because really that’s what FocusMax and PemPro are), I can do the rest. If I upgrade to the “pro” version of MaxIM, I can even do planetarium style telescope control from MaxIM. Neat. I haven’t even gone to the really complicated level, with plate solving and scripting/automation.

The tools for Mac just aren’t there. Yes, there are lots of planetarium programs. Yes, there are a handful of camera control programs (still difficult to find ones that work with particular cameras though). Yes, there are a couple of telescope control programs. But to do all of what I can do in Windows? I can’t find a setup that is fewer than 3 programs (Equinox + iAstrophoto + PHD Guiding and there’s no PE analysis or autofocus, period). And there is a lot of stuff (like CdC) that “only sort of works” on Mac (CdC has no scope control for Mac for instance).

In short, pains me to say it, but I can’t but see running Windows as my observatory box for the foreseeable.

I just don’t see the Mac Mini being a useful platform for astronomy. Not when I have a native Windows laptop out there already. Built-in screen and keyboard, same number of USB ports, no need to dual boot or fight a VM.

I wouldn’t mind being able to offload the processing to a different box. But I guess I am pretty happy with how the PC is running the observatory at the moment.

Another task checked off the list, at least for now.

As I said in my last post, I learned about “Configurations” in MaxIM today. Very nice feature.

I also a focusing tutorial for DSLRs in the Max 5 online manual. It’s a great tutorial, and has a key piece of information on it that is not immediately obvious:

“The two text panels [on the Expose tab of the Camera window] can be set show image statistics, including the location and value of the brightest pixel. When focus is sharp the pixel value will be maximized. To select the display mode, simply right-click on the panel. ” (emphasis mine)

I should have gotten a free copy of this manual while I was under warranty and upgraded from MaxDSLR. It’s not cool that I’ve had this software for 2 years and didn’t know about this feature.

Anyway, MaxIM, for all its faults (the list of which is long and distinguished), does have some nice features, and it sure does consolidate my astrophotography workflow into one package (for the most part).

MaxIM also seems to be one of the most-compatible pieces of software relative to other outside packages. PemPro, FocusMax, and PoleAlignMax all work with MaxIM by default (although PoleAlignmax also requires PinPoint/MaxPoint, which I don’t have).

I don’t see any reason to change my “astro-OS” at the moment.

I had a bunch of stuff on my TODO list after last night.

So I took care of some of it while the sun was up today.

I recharged the deep-cycle battery.

I figured out how to get the FocusMax windows back (thanks to some help from a friend).

I got the COM ports for the ST-4 and G-11 figured out, so both can connect to MaxIM.

I upgraded to the latest version of ASCOM (5.5.1) and the latest Gemini ASCOM driver (Gemini .NET).

I moved the laptop into the docking station and the ST-4 on top of the docking station.

I re-soldered the flat box and the polar scope illuminator (which I also wrapped in heatshrink, which will hopefully make it stronger).

I hooked up a 12v power supply near the flat box so it won’t overvolt (and has a nice power switch).

I found the Gizmo (still need to make sure it’s working).

I worked on Velcroing the cables a bit (still needs work).

I cleaned up the observatory somewhat.

In short, with the focusing that happened yesterday, I am just about ready to get shooting as soon as the sun goes down. w00t!

Clear Sky Clock said it would be cloudy all night, so of course it stayed 90% clear until about midnight, when it socked in. But I’m getting ahead of myself…

I decided to get the autoguider up and running tonight. I wanted everything focused and aligned so that I can get started shooting again for real.

On top of this desire, my new clip-in Ha filter showed up today, and I really wanted to try it out!

So I hooked up the autoguider, got it all focused and balanced the rig. I booted up the scope, which wanted to cold-start again. No problem. Quick slew to Betelgeuse… and that’s where the problems started.

For some reason, the main scope and its finder (which were aligned as recently as 2 days ago, and have not been touched) are no longer in alignment. No problem; I see the star in the finder, I’ll just sweep the scope around until I find it.

No dice.

I don’t know what my problem was, but I tried everything I could think of, including sweeping the scope by hand, and I could not find *anything*. It took me 40 minutes to finally stumble over Rigel and then get the finder and scope aligned. While that was in the vicinity, I set up the guide scope to be roughly aligned, too.

As part of this fun, I figured out that the reticle is not centered in the guiding eyepiece. Again. That is a silly feature. But I figured out how to get it centered, so now the guide finder, guide scope, and reticle eyepiece all agree about the center of the field. Which is nice.

So after losing about 45 minutes of clear sky, I got the scope turned on and started an alignment run… the deep cycle battery died. argh. OK, set up the 15v power supply — deal with the battery later. Now I’m working the alignment (oh, I had mis-calculated GMT earlier in the evening, too — I was having a bit of a day), and the polar alignment is way off compared to a few days ago. Pulled out the polar alignment scope illuminator, and it’s got a busted power cable. Again. That is the worst design ever. I decided to just go forward with it; I’ll deal with polar alignment later. I need to be using my Gizmo anyway. Where is that thing? hmm…

OK, so I’m aligned. I boot up the computer, and shoot a test image of Betelgeuse through the Ha filter. It is of course not in focus. No problem. Fire up FocusMax (nothing can go wrong with the focuser — it’s on COM1), and …

all of the FocusMax windows show up offscreen. I have no idea why. I even tried to Regedit them into place; no dice. Meanwhile, tick, tick, tick, clear sky still, but I can see clouds moving in. Also, Orion is now well past meridian. grr!

Fine. I fire up the focuser in MaxIM (I tried to get the ST-4 and mount working in MaxIM, too, but needed to reinstall the USB-to-Serial drivers for reasons passing understanding, and never got that working right — you guessed it, deal with it later), did an autofocus run in MaxIM for the first time ever.

Let me say at this point that I really like the new MaxIM focus routine. It brings up a V-curve just like FocusMax, and while it seems to converge on a solution a little more slowly, it does seem to get there pretty well, as evidenced by the fact that in just a few minutes, I had autofocused the Ha filter on Betelgeuse! (FWHM of ~5.5, high winds and encroaching clouds and sketchy collimation, so give me a break, this is about what I usually get)

So I fired a 40sec exposure of Betelgeuse, so I could see some diffraction spikes, and got a bright fuzzy ball with lots of stars in the background. I looked up, and couldn’t even see the star through the cloud cover. OK, I get it. So I slewed over to M42 anyway, because I was going to make sure I was in focus.

A couple of 40sec and then 2min frames of M42 looked pretty good given they were clearly destroyed by clouds.

I tried to set up the ST-4, but it spent a lot of time losing the star and giving me “E E” followed by “-E -E” type corrections, so I turned it off. I only like guiding in MaxIM if I can help it.

At this point, it was about midnight, and we get to where I started this post… socked in solid with clouds, and no images to show for it.

And a longer todo list.

But a few more things are set up again, including of all things, the autofocus routine in MaxIM! Cool.

Fingers crossed for a clear night this weekend. Next one won’t be wasted.

I sent my Gemini north for Art to look at. He let me know that it arrived OK today.

The G-11 that’s here is ready to go; I think it’s polar aligned. I also spent some time figuring out how to use the Canon (which will require using a new software package, either DSLRFocus or DSLRShutter, to run, since MaxIM doesn’t support 300D with DSUSB).

So of course it’s been cloudy for 2 days straight.

http://docs.sdaa.org/AISIG/CCD_Imaging_Primer.pdf

lots of basic information about equipment and software selection, and a really nice section on image processing.

I saved off one of my larger tracking logs last night, and decided to analyze it for Periodic Error in the mount. To help the data, I downloaded PECPrep from SourceForge. After an initial problem, I realized that I had to get the 1.5.3 full package, not the 1.5.3 exe-only upgrade. 1.5.3 knows how to parse track logs from MaxIM DL v5.

I read in the tracking log, with the following settings:

focal length 400 (Pumpkin)
pixel size 13.75 x 16 um (ST-4)
everything else default (bin 1×1, 0, 0, no check)

I set the mount to “G11”.

The verdict:

Peak PE+ : 12.42 arcsec

Peak PE- : -12.89 arcsec
RMS PE : 1.88 arcsec (wow)
Avg PE+ : 1.60 arcsec
Avg PE- : -1.30 arcsec
Max rate: 7.82 arcsec/sec (ouch)
Max Delta + : 16.88 arcsec
Max Delta – : -10.66 arcsec

Avg. Noise : 0.02 arcsec

Trend Y = 0.0000X + 0.3

Those last two (if I’m reading them right) indicates that the data is relatively good; a linear trend in Y means (to me) that I should have turned on Dec compensation in the settings. The noise figure means (to me) that the data is relatively clean wrt wind, people tapping on the OTA, etc.

So the overall feeling I’m getting here is that the mount is generally good; an average of <+/-2” of PE = 4” to 5” peak-to-peak (from the RMS = 1.88” figure) is excellent. The mount is totally worthy of doing astrophotography, which we knew already; it shows flashes of greatness.

Quite troubling, however, is the Peak PE (25” peak to peak) coupled with the high max rate ~8”. This means that the PE is not smooth; that things will be going along fine and then all of a sudden, a 1-pixel jump can happen (ST-4 = ~8”/px). This is also something I’ve noticed.

Looking at the Frequency spectrum, I’m getting spikes in the graph exactly where I was expecting and hoping: at integer divisions of the worm period (and not, for instance, in the bearings, races, or motors). This means to me that I should be able to tune the PE down a little bit by adjusting the worm.

I need to spend more time analyzing the data.

My autoguiding isn’t as straightforward as it used to be. I have a lot of new gear that I’m trying to figure out; G-11, Gemini, ASCOM, ST-4, MaxIM. Each of these adds a little bit of uncertainty to the mix.

Of them, the ST-4 (which guides the mount via 4-way relay switches) is the equipment I’m most used to and comfortable with, so all other things being equal, I try to stick to using the ST-4 relays to do the guiding job; they’ve done great for me for years.

However, I’ve noticed that when I’m using the ST-4 standalone with the Gemini, I get long strings of 0 and 1 corrections (that’s as much as 1/5 of a pixel, or ~1.5”), followed by a 5, then a -5, then more 0/1s. So it feels like there is some overcorrection that is happening. To help with this, I set the ST-4 to average about 3 frames, so a 5 usually turns into a a 1 or 2, but I maybe do a couple of them.

When I added MaxIM into the mix, it handles this with “aggressiveness”, which essentially sends a percentage of the asked-for correction. I never really found that aggressiveness and the ST-4 relays worked all that well together; it seemed like the aggro settings were not having much effect.

So I switched over to using ASCOM; ie the ST-4 takes the photo, MaxIM parses it and decides on the correction, and then MaxIM sends the correction directly to the mount via a RS232 connection. After some initial hiccups, I think I have this working pretty well. I set the aggressiveness to 3, and that seems to be enough to keep things more or less in check. I’m not sure why. I think that the ASCOM control might be able to tell the mount “just slow down” or “just speed up”, rather than “go left” or “go right”. I’m not sure about that, but … shrug.

One problem that I’ve been seeing is that tracking works great for 45m or so and then starts getting worse and worse. I have no idea why.

I tried turning on the relays the other night, to see if the 45m problem was related to the ASCOM stuff, but that was a mistake. The relays made things go haywire. At this point, the ASCOM settings are tuned, so I am going to stick with them.

Here’s last night’s result. Not too bad.

I really like NGC 4725. It’s one of those galaxies that I never hear about, but it’s very photogenic and has a really cute companion nearby. There is another “buddy” in the upper left corner, too.

I need to ply my trade in Leo some more (4725 is up near the Dipper), but a lot of the galaxies in Leo/Virgo are small. I don’t think I’ve done a good M65/66 yet, though, so maybe that’s next.

I’m also noticing that galaxies which are dimmer than mag 9 are a little disappointing.

Processing notes:
I did remember to use Median stacking this time (which tightens up the stars).

I also tried out the “quality” filter (a new thing in Max 5 I think), using “roundness” of “0.2” (the default for roundness), which ate about 5 of the later images, which is consistent with I thought I noticed later ones with tracking problems.

There’s something wrong with the flats. I turned off boxcar this time, but there is still a bad color gradient from center to edge. I’ll reshoot the flats and see if I can fix it. The good thing is, the dust bunnies seem to have stayed put; all of these calibration frames were from almost a month ago, and in particular the flats are still flattening the image very well, if throwing the color off a bit. I could probably do some tweaking to the master flat (ie throw it into PS and grayscale it) to make it work a little better. But I think I’m just going to shoot more flats and see what happens.

The 900×600 image is my normal treatment; I select a 1500×1000 section of the image that contains my object, do all the processing on that, and then resize down to 900×600 to tighten everything up once I’m finished.

The FOV in this image is around 40′x27′.

Doug (author of MaxIM DL) suggests shooting everything RAW Monochrome. This has never worked correctly for me, but whatever.

IMPORTANT POINT: If (and only if) flats are shot in RAW Monochrome, then “boxcar” filter needs to be turned on.

Since I shoot in RAW Color, *no* boxcar filter is needed for flats.