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Posts Made By: Charles Hakes

March 31, 2009 09:46 PM Forum: CCD Imaging and Processing/Deep Sky

Back in action... M95 (preview?)

Posted By Charles Hakes
It has been a long time since I have posted anything from the FLC Observatory - mechanical problems, then computer problems, then buried in snow, then axle deep in mud... Now I hope things are ALMOST back to where they were in November. I just need to remind myself how anything works.

This is 12x3 minutes of M95 from Saturday night, mostly to check how things were working. (Actually PHD Guiding was acting a little flakey, but that is another story.) I did get a little color, and my plan was to get some more luminance and color data last night, but the wind was blowing like something else.

I am reasonably happy with the flatness here, and not too much done with processing - sigma beta combine, then arcsine stretch with a slight blur on the dim areas and slight unsharp mask on the bright areas. Comments and suggestions most welcome.

Charlie

May 7, 2009 11:59 AM Forum: CCD Imaging and Processing/Deep Sky

M51 re-start

Posted By Charles Hakes
Here is yet another start on M51. One of those objects I try to improve every year. This is 12x5min exposures, but it took well over 3 hours to get, with focusing, guiding, and other various set-up issues. The data is from last week before our weekend clouds and rain. There are some unprocessed color frames that I haven't looked at, but maybe today? I would really like to at least double the luminosity time whenever the seeing gets halfway OK, and then add color. Don't know about adding H-alpha, though, as that always seems to have limited returns for me, but maybe that is just my limited processing abilities.

We finally had a great, clear night last night, but it sure was bright out, and with evening activities I never made it out to observe. (Why do the clouds seem to follow the new moon?!) Anyway, even with the moon, tonight is supposed to be just as clear, so I may see what I can add. I sure hope to take advantage of the weather the next couple of weeks. Just as long as that doesn't lead to a too dry June.

Charlie


May 9, 2009 12:51 AM Forum: CCD Imaging and Processing/Deep Sky

data floor? (moon question)

Posted By Charles Hakes
Anyone ever do this?...

Since last night was about the most transparent night in the last several weeks, I took some RGB subs of M51, even with the moon. (Since M51 was the current project - M95 was WAY too close to the moon. Maybe I should have tried H-alpha, but that is another thread...)

Anyway, a colleague had taken a few 5 minute RGB subs a week ago. Seeing was ~3/10 both times. The background counts on the reduced "moon" subs are ~2-8x of the "non-moon" subs. Only a moderate amount in red, more in green, and quite a bit in blue. (It is as if the atmosphere scattered more blue light!) I have never tried this, but I am tempted to subtract a constant value from the reduced moonlit subs before combining them with the moon-free subs. It is easy to come up with a value, by subtracting the processed subs and getting an average pixel count. Anyone ever do this? What are the down sides? (Besides the moon versions being much noisier.) Thanks for any thoughts on this.

Charlie


May 10, 2009 03:05 AM Forum: CCD Imaging and Processing/Deep Sky

M51 re-start color

Posted By Charles Hakes
I re-stacked the luminance and added RGB, 50 minutes each. I did not subtract a constant from the RGB shot with the full moon (1/2 of it), as I asked about in another thread, but may go back and try that to see if it makes any difference. I'd still like to get some more L on a night with at least average, or maybe even above average seeing. And it should be dark for at least an hour tomorrow, so maybe then. Anything else to try?

Charlie


May 16, 2009 11:14 PM Forum: CCD Imaging and Processing/Deep Sky

M51 v2

Posted By Charles Hakes
Version 2 for this year. I added more data, so now there are 2:1:1:1 hours for LRGB, in 5 minute subs. I probably spent more time than that trying to balance the sharpness with the smoothness. I think there is more "stuff" in there, but I can't quite bring it out without it looking oversharpened (to me anyway). And after all that it seems like only a marginal improvement over the "quick analysis" image I had previously. I will likely keep working on it for a bit, so comments and suggestions are most welcome.

I still haven't gotten that night of better than just average seeing, so if that happens, I might keep adding data. In the mean time, I have been tweaking the azimuth adjustment on the wedge (overhead drift alignment). I think I can now track for about an hour without the declination autoguiding on PHD turned on. At least the graph in PHD shows less than a pixel drift.

Charlie


May 20, 2009 11:49 PM Forum: CCD Imaging and Processing/Deep Sky

PHD guiding question

Posted By Charles Hakes
Don't know if anyone has had this happen, but when using PHD guiding, I have recently experienced a net "drift". PHD says everything is just fine, but there is a noticeable long term steady drift of the image on the camera. Probably less than an arc minute over an hour, but that is still a lot of arc seconds. As the set-up gets more settled, this is just one more thing to track down. Could this be flexing in the mount between the main and the guide scope? I guess I could check how well they are aligned from one side of the sky to the other? Do I just need to re-calibrate? Any other ideas?

Thanks,
Charlie

May 24, 2009 12:44 PM Forum: CCD Imaging and Processing/Deep Sky

M51 final?

Posted By Charles Hakes
I am still spending too much time processing, so I should at least ask for feedback along the way. At least processing is something to do during all the recent rain. This may be the end of this M51 for a while, depending on your feedback to the following processing choices...

Fewer color subs - This version removed the "moon" RGB subs, and that appears to have fixed the weird gradients that I couldn't quite deal with in software. Still have 35 minutes each.

More contrast - Rather than continuing to fumble with curves, I just cranked the contrast slider over more than I normally would. Looking at other on-line shots, the ones with higher contrast seem to "jump out" more. Is this too much?

More sharpening - Again, more than I think looks "natural," but the result pops a bit more. Several iterations of unsharp mask here. I tried to be selective with stars, but I am sure I need more practice with that. Too much? (I have yet to do a "de-convolution" I like.)

More saturation - Once again more color than I personally like, but showing this to a few non-astro people, they like the vivid colors better. Again, too much?

Smoother background - With a Carboni action. I think it removes some of the faint background galaxies, but is the smoothness more visually pleasing?

Any comments and suggestions would be appreciated.

Thanks,
Charlie



June 9, 2009 04:33 AM Forum: CCD Imaging and Processing/Deep Sky

Drift NS - 7479

Posted By Charles Hakes
This galaxy happened to be rising a couple of mornings ago when I was doing some more wedge tweaks, so it got to be the target. This is unguided in declination - the first few 5 minute subs had some elongated stars, but by the end of the hour, it was drifting less than a pixel, as far as I could tell. Total of 10 subs. Started ~10 degrees above the horizon and seeing ~4". I may come back when it is higher and better seeing. Arcsine stretch, and background blur. Thought it was interesting enough to post.

Charlie


June 9, 2009 04:46 AM Forum: CCD Imaging and Processing/Deep Sky

Drift EW - 6543

Posted By Charles Hakes
This one is the Cat's Eye. Taken last night with the full moon. It was just over 90 degrees from the moon, so there shouldn't have been any direct light going in, but it was REALLY bright out there. 6nm Ha filter and 6 minute subs. (Rats - Turns out the core is still saturated.) Again, no declination guiding and good tracking by the end of the E-W tweaks on the wedge. There are 12 subs, and the flat was that of the luminance filter - wrong one, but that is what there was. Might be worth figuring out how to combine different exposures, since I think I could go much longer than 6 minutes now to get that outside part. Lots of smoothing in the dark areas.

Charlie

June 14, 2009 01:29 PM Forum: CCD Imaging and Processing/Deep Sky

NGC 4565 - more mount fiddling

Posted By Charles Hakes
So I thought I was totally done with one axis... but not so fast. I will likely have a few more nights of mount tweaking before I can say I am done, and I might only get to the "good enough" point. I am also tempted to open up the fork and work on the DEC gears to see if I can tighten the slop up a bit. At least it feels productive to get some sort of image out of these nights.

Anyway... 7x5minutes here (over a couple of hours). Still have DEC guiding off with this image. I was not familiar with this object, but it looks like it might be worth a return trip.

Charlie


Charlie

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