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′.

http://gsc.dc3.com/

The G-11 does not have a GOTO computer like the CG-5GT had, so I started out using manual setting circles.

Despite complaints that you’ll hear about setting circles, this is actually quite an effective method of pointing the telescope. With Veronica as the imaging scope, I could center up a single star, set the circles, and then point the scope to pretty much any target I wanted, and still get it in the field of view of the camera.

When I moved to Kate, the extra magnification started pushing objects just out of the FOV, which left me needing a more accurate method of pointing the telescope.

I found the Dave Ek Setting Circles Project online (thanks, Dave!) and I put together the parts to make myself a setting circles interface. These are all the parts, ready to be assembled and put into a project box. After finding out that one of the encoders on the mount was blown and getting a replacement from Losmandy, I got the setting circles interface up and running.

Still trying it out, but it seems good so far.

A first shot at the Autumn galaxies.

I was having a lot of trouble with astronomy lat night for some reason; My focuser motor is on the blink, I got my T-ring stuck to the MPCC (it’s still stuck), The clouds were rolling in and out, and it was a damp night even when it was clear.

In addition, I was having an unusual amount of trouble with my setting circles; usually, if I set up the circles on a star, I can get objects in the FOV every time by dialing the coordinates up. Last night, I tried The Helix Nebula (in Aquarius), and M74 (galaxy in Pisces), both to no avail. I even tried dialing up M31, and it wasn’t in the FOV, and I couldn’t find it by sweeping, but when I *did* find it, the setting circles were reading the coordinates I was expecting.
It was all very odd.

In any case, by the time I found M33, it was pretty late (already almost 2am), and somehow I didn’t get the galaxy centered very well. Yet another SNAFU in a very strange and not-too-easy night of attempted photography.

So, the target ended up not being within the “hot spot” that my too-small-for-photography secondary mirror puts in the center of the field (did I mention that my larger secondary is causing me no end of grief because its brand new coating rubbed off before it saw first light? My astronomy world is a little discombobulated at the moment…). What this means is that, since the target was in the upper right-hand corner of the frame, the right side of the image got a lot less light (due to vignetting) than the left side did.

After all that, it seems like a pretty OK image for a first attempt. I’ve got all autumn to get a better one.
M33 is the second-largest galaxy in the sky, as seen from Earth (measured in degrees of sky covered, on the order of 1 degree by 1/2 degree).

It’s a pretty big galaxy in its own right (measured in light years across, on the order of hundreds of thousands), but the fact that it’s also really close to The Milky Way and The Andromeda Galaxy (measured in light years distance, on the order of less than 10 million) means that we see it as a large object as well.

M33 is so large that various nebulae and clusters *in* M33 have separate NGC numbers (ie we originally thought they were separate objects). One such object is the large nebula at the lower right of the photo (it’s the red-and-definitely-not-a-star object on the edge of the badly vignetted area); that nebula is apparently almost 1500 light years across! (that’s the same distance as from Earth *to* the Orion Nebula; the Orion Nebula is only about 150 LY acress) Pretty big. No wonder it glows pink in hydrogen alpha light despite being millions of LY away…

Anyway, not a bad first shot of a galaxy I’m going to have to spend more time on, since it’s just about the perfect size and sky placement for the combination of Veronica and D70 that I’m shooting with these days.

Watch this space for updates.

Trying to round out the set of the largest galaxies visible from this latitude.

This is another galaxy that I would not have known about if not for “The List” (see M106 page).

The pairing of NGC4725 and its little buddy next door (ID?) could rival M81/M82 for prettiest galaxy pairing, but I was intrigued at the number of other background galaxies I also picked up in this shot.

Nearly 2 hours of exposure time (I lost 2 frames due to airplanes. grr.) was enough to bring out lots of detail, but I’m still fighting vignetting and, as always, a suburban location; I need to figure out how to get my backgrounds darker.

http://www.asahi-net.or.jp/~zs3t-tk/aim/aim.htm

Hi all,

My latest project is to see if I can build myself a set of Digital Setting
Circles for my new astronomy mount, which does not have an onboard pointing
computer. In short, I am trying to construct a device which will tell me
the Right Ascension and Declination at which the telescope is pointed.

The mount already has rotational encoders installed on both axes, so it’s

simply a matter of reading some initialization values from these encoders
(by pointing the telescope at two reference stars of known position, for
instance), and using those to create the basis for a “telescope coordinate
space”.

Then, it is a matter of doing a coordinate transform from “telescope
coordinates” (angle of deflection of the axes of the mount) to “equatorial

coordinates” (right ascension and declination).

Much searching on the ‘net revealed this URL:
http://www.asahi-net.or.jp/~zs3t-tk/index.htm, from which I got the
attached PDF. It details the matrix transformations necessary to do the
coordinate transformation needed (as well as some other useful transforms,
such as alt/az to RA/Dec, polar alignment error, and others).

My task, now, is to convert the formulae into code, and to build up the

circuit necessary to drive the sensors, display, clock, and whatever other
subsystems are needed.

As the two people I know who are most interested in both linear algebra and
astronomy, I thought you’d be interested in the paper and website.

Best,
Jimbo

Attachment Converted: “c:docume~1jharrisapplic~1qualcommeudoraattachmatrix_method_rev_e.pdf”

Attachment Converted: “c:docume~1jharrisapplic~1qualcommeudoraattachtaki.txt”

http://www.fer3.com/arc/m2.aspx?y=200210&i=007828
http://www.jgiesen.de/astro/solarday.htm
http://www.prairienet.org/cuas/faqcalc.html
http://star-www.st-and.ac.uk/~fv/webnotes/index.html

http://www.willbell.com/math/mc1.htm

http://www.nova-astro.com/

http://digicircles.eksfiles.net/dsc.html

http://www.fourmilab.ch/homeplanet/homeplanet.html

After a couple of days of being “closed for renovation”, the ad Astra Observatory at Newark, CA is back in business with the new Losmandy G-11 mount.

I had to modify the pier in order to get the mount to achieve polar alignment; It’s not the prettiest installation, but it works. Only 3 trips to the hardware store! By the way, did you know that hardware stores are open before 8am?! crazy, man. crazy.

The new mount is a real “grunt”er compared to the old mount (that is, when you lift it, you say “grunt“). The head is all aluminum, anodized black, and looks and feels just so much more solid than the CG-5. To my eye, it’s noticeably larger as well, which is nice, because I’m betting on it to carry pretty much any telescope I throw at it. I’ve seen G-11s with 14” scopes (in the 60-75# range) mounted. The G11 is a nice beefy object with a very precision feel to it. Fit and finish is top-flight. I had to call the manufacturer for some tech support, and actually got Scott Losmandy himself on the line! Good old made in the USA stuff (in L.A., in fact; the guy also builds rigs to hold lights and mikes and things for the movie industry, for what it’s worth).

There’s no GOTO on the new mount; it was a $1000 option that I couldn’t afford up front. It’ll cost extra to retrofit with GOTO later, but I may forgo GOTO in favor of Digital Setting Circles, which tell you where the mount is pointed, but doesn’t actually move the mount to the position of an object (call it a “push to” mount instead). The mount has encoders for DSCs, which are the gears that determine how much the mount has rotated, but I’d have to buy or build the decoder that can take this information and turn it into celestial coordinates. For now, I’m back to basics; just me, the stars, and “I think it’s around here somewhere…”. Which is strangely gratifying, as these things go.

The mount has a “polar alignment scope”, which is the first time I’ve had one of those. Basically, it’s a reticle that sits in the polar axis of the mount (which is normally the “hole” through which you sight Polaris in order to get a rough alignment), that shows the relative positions of the Big Dipper and Cassiopeia and Polaris; you rotate the reticle until the Big Dipper is in the correct orientation, then move the scope so that Polaris is in the correct spot, and bingo! a more or less “accurate” polar alignment. So I did this, and then decided to test the polar alignment of the telescope. I use a method that makes good use of my Nikon camera to get an accurate alignment (details are on my website), and so I decided to run a check. The longer you run the test, the more accurate the results, but I’ve found that even a 2 minute test is enough to show pretty granular amounts of error. So off I went, checking both axes for precision. I had to check my results several times, because under the 2 minute exposures I ran, I could detect *no* misalignment! What?! I mean, how accurate can a polar scope *be*?!

As a final test, I decided to run some unguided exposures; 30 seconds, 2 minutes, and then 5 minutes. This is all with Veronica and the whole imaging rig onboard ( I haven’t weighed the rig, but I’m betting it’s up near 30# ). So, no guide stars, just pointed at M13 (something that I knew I could find without GOTO), got it centered up and focused, and fired off a few shots. In short, I was floored. The 5 minute image showed some minor trailing. It would have been a “keeper” if I’d been shooting a set of them; the trailing was noticeable, but there was still enough data there to help the whole stack. In the 2 minute image, I could detect no trailing whatsoever. None. Perfectly round stars. This is after simply mounting, levelling, and using the polar alignment scope to align on Polaris. In contrast, with the same telescope/imaging rig, with a guide star, I’d lose about 70% of the images of 2 minutes or longer that I’d shot off of the CG-5. This is, simply, an entirely different class of mount.

I’ll have to check this to confirm, but I’ll bet that if I had done a 5 minute polar alignment test, I’d find that my polar alignment needed some small amount of tweaking. And that once I did that tweaking, I could probably get some 5 minute unguided images as well. What I’m saying is that I think that the trailing I saw in the 5 minute image was the fault of the polar alignment (ie “my fault”) rather than periodic error (ie “the mount’s fault”). In my test, I’d only asked it how accurate the polar alignment was over a 2-minute span…

I am amazed, astonished, stunned, proud… I can not say enough nice things about my experiences with the Losmandy G-11 so far.

sic itur ad astra, indeed.

galaxies:
ngc7331
M74 (too low?)
NGC253 (too low?)

(possibly too small, below):
IC342?
NGC772
NGC2403
NGC2841
NGC5905/5908
NGC5907
NGC5963/5965
Stephan’s Quintet

NGC7814

nebulae:
ngc281
ngc6334/6357 (just west of M6)
IC1805
IC1848
IC1396 (big. 3�. vdb142 nice part)
B72 (S oph bet Sco/Sag)

possibly too small, below:
M78
NGC7129
IC405
NGC7023
IC59/IC63
NGC7380
NGC7822
NGC6559 (just E of M8!)

M76
NGC6914