Friday, April 22, 2011

Lunar Images Video Clip 04/22/11

Just a test vid I made with a sampling of lunar images. I'm working on a more inclusive one but wanted to see how this turned out first. Had to compress it to half resolution to upload it. Looking for a location to place a higher resolution version.

Some high res pics to go with it:

Lunar Images

Sunday, April 17, 2011

Old data!

Since the Moon is full, I've been taking the time to work out kinks in my new imaging rig, and clean up my image archives.  I stumbled upon a few in my files that I apparently stacked but never processed for whatever reason.  Here's M13 - 20x30sec with my old Hyperstar setup, and M81/M82 - 20x30sec.  No darks, no flats.  These had to have been some of my original test shots with the Hyperstar prior to adding a wedge and autoguiding.  There's no other reason I would have shot for that short of an exposure time.  None of these are top notch obviously, but it was fun to see how much I could pull out of these early shots.  I also have M17, but can't seem to get it uploaded without serious degradation.  Still working on it.

Click the images to maximize - lots of jpg compression artifacts in the small-scale versions that go away in full scale...

Friday, April 15, 2011

Fighting with Flats on the QHY-9

I've yet to figure out the issue with my Flats.  I take them with the same methodology as I did with my QHY-8 OSC in which, I had no issues.  I use either the "white tshirt" method, or the "dusk/dawn sky" method.  My color channels are not aligned at all regardless of what I do.  I can crank the gain to 100, 50, 0, no change.  Amp on, Amp off, no change.  Offset adjustments don't affect the seperation.  Exposure time changes nothing but where the three peaks show up in the histogram but they are always seperated.  I'll add that the optimal exposure times to land around 25K ADU/Max readout is at least several seconds in dim or strong light so the time is high enough that I'm thinking the shutter is not a factor here, I think?  I've checked for light leaks in the imaging train, and just to be sure I've wrapped everything up, except the fan on the camera of course.  I've had TEC on and off, no difference there.  I can't think of what the issue is.  However, I've yet to apply Flats with this camera that didn't worsen my light frames significantly.  Usually creating a nasty color gradient across the image - an effect that isn't present without the Flats.  Unfortunately, vignetting and dust motes are left behind of course.  I just don't get the problem here.  The IR filter is perfectly clean.  It's not in an extreme hot or cold environment right now.  I don't know what to do here.  I've attached a screenshot of my bias frames and data around it, along with a sample Flat, and the same Flat debayered as well so that I can show the color value readout.  One thing I'll note - when I debayer, then auto color balance, the flat looks like a proper flat.  Ideas?  I'm out of them.

Thursday, April 14, 2011

A quick first light with the flattener / reducer issues worked out...

Finally have all of the right parts in place, added a 40mm spacer between the W.O. 0.8x FF/FR II and the QHY-9.  The field looks much sharper now.  Instead of 20-30% of the field showing visible curvature, I figure maybe 5-10% of the field has any worth note, and even that portion has improvement so it's not terrible.  We're really only talking the extreme corners at this point.  Plus with the FOV I get anyway, cropping it out isn't a terrible loss.  A compromise I'm willing to accept.

Unfortunately I only squeezed out 9 subs x 150sec before I had to end my session.  Note that the moon was blazing away in the sky so between not having many subs and having the glowing orb of death making an impact, there's a pretty bad gradient in the background so I didn't push this image too hard.  I also was dealing with rediculously strong winds again so there's a slight elongation on the stars, but again it's minimal and should be a testament to how rigid the new rig is to be able to stand up to 40mph gusts.  I still have some issue with my flats that I don't have fully sorted out and plan to spend the weekend working on.  More to come on that topic.

Monday, April 11, 2011

An Evening of Lunar Imaging and Observing

Just finished setting up for an evening of Lunar imaging and observing.  QHY-5 primed in the ED80SF APO, and the XT6i is cooling down.  I plan to attempt an LRGB composite of the moon tonight with my QHY-5 - something I've never done before with lunar shots.  I took a snap of the gear, poised and ready to go, and snapped a quick digicam shot of the moon by hand through the XT6i just at sunset, blue filter installed.

Sunday, April 10, 2011

25 Hours exposure time on Orion

I took my old data -18.5 hours worth (, and supplemented in another ~8 hours.  This was the outcome, and my last pass of the season.  Inverted luminance data attached as well just to show the dynamics of what's going on in this region.

Dry Spell? Reprocess old data!

Still working on fully assembling my new imaging rig and of course, the moon is back.  So, I decided to go back and reprocess my 1st light image from my Hyperstar almost 1 year ago.  This was M20 and M8 shot in Alt-Az mode as I didn't have a wedge at this point.  This image was completely unguided.  25 subs x 25 sec.  I didn't take flats or bias as I had zero experience with them at that point in the game since I had always owned small chip CCDs prior and there was no need for them.  Below is the reprocessed version versus the original pass.  You can see I was able to "flatten" it out and remove the vignetting with a few software tricks. 

Friday, April 8, 2011

Lunar Imaging Manually with "Push-to" Dobsonian

Got home this evening to see clear skies and the moon declining in the west.  I set the XT6i outside and let it cool for 5 minutes while I grabbed a laptop and my QHY-5.  I manually tracked on the moon @ 1200mm FL and shot 6 seperate mosaic panels.  Total time was 10 minutes from setup, to tear down, and 5 minutes to process the AVIs and manually stitch the mosaic, and post process.  I'd say that's absolutely the fastest imaging session I've ever had by far.  I'll add that this is the first manual Dob I've had experience with, and only 2nd light with it.

High Res versions available here - Josh's Astrophotogallery - Moon Mosaic w/Dob

Sunday, April 3, 2011

More Focal Reducer/Flattener, and general imaging woes...

I made an aggressive pass at NGC 2264 and Markarian's chain the last two nights with the new William Optics 0.8x Focal Reducer/Field Flattener II.  After an analysis of the results, I came to realize the reduction isn't where it should be and I still have significant curvature in the far corners.  First indicator was that I saw no minimal signal and depth increase per exposure, and the scaling was not much different.  As it stands, my reducer is acting more like a .096 FF/FR instead of .8 as intended.

Second issue - I've yet to take functional flats with the QHY-9.  Now this one is confusing to me and I still do not have an answer.  When I apply flats with or without bias frames, I have a HARD color gradient from bottom right corner, going to the top left.  I have hardly any gradient without the flats, but then I have the dust motes, and vignetting to contend with.

On the first issue, it seems spacing is the problem all together.  My QHY-9 has 15mm of spacing from the sensor to the end of the nosepiece.  There's another couple of mm from the Reducer threads to the glass.  However, optimal spacing is somewhere between 50mm and 56mm.  I'm nowhere near that.  So now I have to hunt down the appropriate extension.  Agena has spacer sets available.  I've also talked to a member of Cloudy Nights who has his own machinery and can custom fabricate an adapter/extension for me and color match it to my equipment.  This is probably the way I'll end up going.  For now, my reduction is nil.

Ok so the flats issue is going to take a bit to explain.  I use the same methods I've always used with my QHY-8 but they don't seem to work on the QHY-9.  White T-shirt stretched over the objective, point the objective at a diffuse light source, and adjust the exposure times to get the ADUs between 25K and 35K as recommended by other QHY-9 users.  I've already done a bias calibration and an offset of 100 has been established with a gain between 40% and 50%.  I've tried my T-shirt method, and I've tried the dusk/dawn sky method, simply aiming in a clear part of the sky and snapping away.

On the preview screen the flats look just fine.  However, the histogram indicates severe misalignment of the individual RGB channels.  You can clearly see three peaks with seperatation.  This is more prominent with the T-shirt method.  I've tried adjusting the exposure length, doubling, and quadrupling the tshirt fold, same thing with the sky method with and without a T-shirt.  What I've found is if I do flats with an exposure shorter than .5 sec, the color channels are in alignment but I have a sweeping gradient which I believe is a result of the mechanical shutter shadowing the flat.  When I run an exposure of 1 second or greater, the channel seperation begins to grow, fast.   At 2 seconds or greater, the channels are seperated, sometimes peak to trough on the histogram.  I've tried every mixture and combination of stacked flats and applying them to my lights.  After applying, I have a very prominent color gradient starting from one corner and working across the entire image.  A hard stretch of the data shows a "hypercolor" gradient effect.  If I don't apply the flats, I have a gradient, but not hypercolor, and it's not as prominent.

If I had to guess, I think part of the problem is not having the CCD fully orthogonal.  You can see this dark shadowing in the same pattern as the gradient in lights and flats, stretched or otherwise.  It just dawned on me that after getting the WO FF/FR, I don't need the Orion 2" extension tube I bought.  After doing some diagnosis, it would seem this tube was allowing a slight bit of imager sag.  Unfortunately it clouded up last night and I cannot confirm I've eliminated the issue.  However, it would seem I still have a misunderstanding on the purpose of flats.  I assumed it would see this as a "curvature" problem in the image and aid in rectifying it just like it would with normal vignetting.  Apparently I'm incorrect?

Here's a few images to show what I'm referring to.  I've been "ugooglizing" the web heavily to look for examples of similar issues but am yielding no results just yet.  Maybe someone on the forums wiser than I am (not hard to accomplish) will have some ideas.

Here's what I think is the flexure/orthogonal issue culprit (Orion 2" extension tube).  There's only 2 tensioner screws and the FF/FR + QHY-9+Cables is causing some sag.
 Here I've removed the extension tube.  After adding the WO FF/FR I had to rack the focus way in anyway.  Extension is no longer needed.  I'm able to tighten it down much better now and I can't sense any flexure by feel as I could before.
The culprit on it's own.  I think the lack of a third set screw is design problematic.  I suppose I could tap another one in, but no need since I no longer need the part.

5 sec flat indoors with tshirt method pointed at diffuse light source.

0.5 sec flat taken outside with no T-shirt.

0.5 sec flat taken outside with T-shirt.

Markarian's chain - flats applied, hard stretch to emphasize gradient (doesn't matter which, they all do this).

Markarian's chain - no flats applied, hard stretch.

Again, it doesn't seem to matter on the flats, although the color gradient is a bit more wild with the flats that have seperate peaks/troughs for the color channels.  Either way, the hard gradient is there from bottom right to top left.  Without the flats, my images always look like that last one where it shows the vignetting/field curvature and dust motes, etc.  I have tried flats ranging from the top end of the histogram down to the bottom.  Every variety of exposure times, t-shirt thickness, with/without sky, indoors at an ambient light, etc etc.  I know it shouldn't matter but I even temp match it with the regulated cooling.  I'm at a loss.  I've used every method described above with my QHY-8 on my prior rig and I would always get good flats that improved the images. 

For reference, I don't have an LP problem, my skies are dark.  I could run rediculously long exposures on the QHY-8 unfiltered with tremendous results.  Yet with the QHY-9 it's providing that mustard yellowish tint as if it were LP induced.

For now, I process without flats, and just crop the image by about 20% which really sucks since I'm losing all of that image real estate.

Saturday, April 2, 2011

More on the XT6i

Aurora, finally over her initial thrill of getting a new toy, slowed down long enough for me to educate her on finding objects.  Once she realized how easy it is with the Intelliscope object locator, I was shoved away and she went ape on the sky.  In a matter of minutes she had perused M42, M45, NGC2024, and then for grins was star hopping!  I didn't even teach her that yet!  We had spent the last several days looking at constellation charts, naming major stars, having her draw the constellations out, and point out object locations.  So far we've covered Leo, Orion, Taurus, Scorpius, and Ursa Major.  I didn't think she was paying attention fully, but apparently I was very wrong.  What was even more amazing was now that she had connected the constellation drawings with what was in the sky, she was able to identify what I had done on her walls a year ago (I mapped her whole room accurately with the constellations, using a special kit of glowing stars that illuminate the room at night).  We must have spent another 15 minutes with the lights off, and her talking me through the constellations.  And not just constellations - she was pointing out where in the conestellations the nebulas were!  She's going to have star hopping down better than I ever have.  She's starting to relate the objects in the eyepiece with what I've shown her on my live "preview" screen on my CCD output since the short exposures are comperable to a live view through a scope.  I think she finally caught the astronomy bug.

Friday, April 1, 2011

Aurora's XT6i

Bought Aurora an XT6i to replace her ETX-80 with.  Impressions so far are good.  The instructions for assembly could have been better (parts better labled).  It took a while to get it together.  Optics are great, and the object locator is spot on.  We took it for a test run last night and it zeros in on the objects just fine.  Orion looked magnificent.  I am going to replace the 30mm finder with a new 50mm finder that I have.

Good timing on its arrival as I'm doing a public outreach for her school in a few weeks.  Going to need the extra scope!

Test run with new flattener/reducer

NGC2264.  I overslept and didn't pull the trigger until 2 hours later than planned so I only had time for 10 subexposures so it's not very smooth - lots of gradient artifacts.  This was taken in sustained 30mph winds and 40mph gusts.  Image scaled down 50%, cropped 20%.  I plan to get several more hours over the weekend.