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Re: M33 Deep (SVX152T, AP1100AE)
Roland Christen
Lotta good stuff there in your image.
My shot of NGC604 before modern CCDs: http://www.csun.edu/~rprovin/roland/ngc604.html
Rolando -----Original Message-----
From: ap@... <ap@...> To: main@ap-gto.groups.io Sent: Thu, Nov 3, 2022 3:19 pm Subject: [ap-gto] M33 Deep (SVX152T, AP1100AE) Least Roland think all I do is contemplate angels and pins...
This is an experimental image of sorts. It is my first light with the new OTA, fitting nicely on the AP1100AE, with the ASI6200MM and RGB data with a touch of Ha. My goal here was detail not lots of color, so I held down the blending of narrowband data. I also wanted to see how the corners looked, so this image is completely uncropped -- right to the edge of the stack is shown. https://www.astrobin.com/60o3yb/ If you drill down on astrobin it's a large image, about 80mb. Far larger than I would leave just for casual viewing, but what I found interesting is how deep you can drill. The data is about 45 hours of RGB and 4 or so of Ha, shot over consecutive nights in an unexpectedly clear period near the end of October. So if you feel like exploring, or interested in what an SV 152 can do, dive in. Once I get a Photon Cage and do a bit of fine tuning I'll do something similar with the QuadTCC as a reducer on it. Expecting good things, my preliminary look was very promising! Linwood -- Roland Christen Astro-Physics |
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Re: Custom Tracking Rates - Chandra Space Observatory
Roland Christen
Super-cool! 
Rolando -----Original Message-----
From: Brent Boshart <bboshart@...> To: main@ap-gto.groups.io Sent: Thu, Nov 3, 2022 3:15 pm Subject: [ap-gto] Custom Tracking Rates - Chandra Space Observatory This is the Chandra Xray Observatory using custom tracking rates derived from data from JPL Horizons. A 5 minute exposure with my Stowaway and my Mach2 tracked it perfectly. This mount continues to amaze me. I am using a 400 point all-sky model with Dec Arc Tracking enabled.
-- Roland Christen Astro-Physics |
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Re: Hand controller model for computer imaging.
Roland Christen
The keypad is used to help you produce the data that is sent to the mount. Once in the mount, the keypad has no further job except to turn the mount model on or off.
Rolando -----Original Message-----
From: Arvind <base16@...> To: main@ap-gto.groups.io Sent: Thu, Nov 3, 2022 2:29 pm Subject: [ap-gto] Hand controller model for computer imaging. I currently don't have the hand controller (HC) but wondering if it might be useful:
Given that the new HC has modeling capabilities, would such a model help improve tracking performance if the mount is controlled from a computer (go-to initiated from asiair or other programs)? Or is it somehow only limited to tracking performance for go-to initiated from the keypad?
Thanks.
-- Roland Christen Astro-Physics |
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Re: Custom Tracking Rates - Chandra Space Observatory
Thanks Dean! And Brent! Stuart On Thu, Nov 3, 2022 at 9:52 PM Dean Jacobsen <deanjacobsen@...> wrote: “I set up my new Mach2 tonight for the first time. Pretty stoked!” --
Stuart Heggie |
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Re: Just what is a Dec Arc model?
Ray Gralak
Hi Chris,
If the semantics are important then the nomenclature within the software should be amended.A model only exists inside APCC at runtime, not in the PNT file, which is just a bunch of data points. Loading the file "loads" (creates) the model. When I implement a "Dec Arc Tracking Algorithm" in APCC I do so in the Pointing Model tab.In order to view APCC's "Pointing Model" tab, you have to have APCC running, so a model exists then and is semantically accurate. BTW, there is no mention of a "Pointing Model" in APPM. The act of collecting data with APPM is just gathering data. As stated before, once a mapping file (.PNT) is loaded, then a model is created inside APCC and goes away when another set of data points is loaded or APCC is closed. The only place where the word Model is left out is where the check box is for enabling Dec arc tracking. I'mThe Dec Arc tracking algorithm is independent of the All-Sky model. They actually coexist with each other. The All-Sky model is used for pointing correction even when Dec Arc Tracking is enabled. And, the All-Sky model has a tracking rate correction algorithm of its own. Enabling Dec Arc Tracking simply tells APCC to use that tracking rate correction algorithm instead of the All-Sky tracking rate algorithm. -Ray |
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Re: Custom Tracking Rates - Chandra Space Observatory
“I set up my new Mach2 tonight for the first time. Pretty stoked!”
The Mach2 is the best thing since sliced bread. Enjoy. Dean Jacobsen Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/ |
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Re: Custom Tracking Rates - Chandra Space Observatory
Brent Boshart
Congratulations on the new mount, Stuart. I'll contact you soon to come over for a visit!
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Re: M33 Deep (SVX152T, AP1100AE)
Linwood, VERY nice image! For an image where "detail, not lots of colour" was the goal, the colour is beautiful! Stuart Heggie On Thu, 3 Nov 2022 at 21:19, ap@... <ap@...> wrote: Least Roland think all I do is contemplate angels and pins... |
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M33 Deep (SVX152T, AP1100AE)
ap@CaptivePhotons.com
Least Roland think all I do is contemplate angels and pins...
This is an experimental image of sorts. It is my first light with the new OTA, fitting nicely on the AP1100AE, with the ASI6200MM and RGB data with a touch of Ha. My goal here was detail not lots of color, so I held down the blending of narrowband data. I also wanted to see how the corners looked, so this image is completely uncropped -- right to the edge of the stack is shown. https://www.astrobin.com/60o3yb/ If you drill down on astrobin it's a large image, about 80mb. Far larger than I would leave just for casual viewing, but what I found interesting is how deep you can drill. The data is about 45 hours of RGB and 4 or so of Ha, shot over consecutive nights in an unexpectedly clear period near the end of October. So if you feel like exploring, or interested in what an SV 152 can do, dive in. Once I get a Photon Cage and do a bit of fine tuning I'll do something similar with the QuadTCC as a reducer on it. Expecting good things, my preliminary look was very promising! Linwood |
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Re: Custom Tracking Rates - Chandra Space Observatory
Wow! Nice demonstration! I set up my new Mach2 tonight for the first time. Pretty stoked! Stuart Heggie On Thu, 3 Nov 2022 at 21:15, Brent Boshart <bboshart@...> wrote: This is the Chandra Xray Observatory using custom tracking rates derived from data from JPL Horizons. A 5 minute exposure with my Stowaway and my Mach2 tracked it perfectly. This mount continues to amaze me. I am using a 400 point all-sky model with Dec Arc Tracking enabled. |
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Custom Tracking Rates - Chandra Space Observatory
Brent Boshart
This is the Chandra Xray Observatory using custom tracking rates derived from data from JPL Horizons. A 5 minute exposure with my Stowaway and my Mach2 tracked it perfectly. This mount continues to amaze me. I am using a 400 point all-sky model with Dec Arc Tracking enabled.
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Re: APPM Platesolver Comparison
ap@CaptivePhotons.com
On Thu, Nov 3, 2022 at 03:37 PM, Roland Christen wrote:
How many angels can dance on the head of a pin. That's what you're pursuing here.Bear in mind around the time ASTAP was being added to APPM Ray was the one who raised the issue of its accuracy. I also maintain with my refractor I get a very usable DEC Arc model at 1/4 frame but not at full frame; by usable I mean the model improves a guide assistant run rather than degrading it or having no real impact. It could well be operator error, and frankly it is not impacting my real use. But it's intriguing. FWIW. Linwood |
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Hand controller model for computer imaging.
Arvind
I currently don't have the hand controller (HC) but wondering if it might be useful:
Given that the new HC has modeling capabilities, would such a model help improve tracking performance if the mount is controlled from a computer (go-to initiated from asiair or other programs)? Or is it somehow only limited to tracking performance for go-to initiated from the keypad? Thanks. |
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Re: Just what is a Dec Arc model?
Hi Mark >>>2. What happens if the Dec-Arc box is checked in the Tracking Correction Status section (and also the other Pointing and Tracking boxes on that screen are checked) but the target will NOT travel through the mapped area ? Does that cause worse tracking for that target, or does APCC suspend the model adjustments? I can offer a couple clarifications First, the pointing corrections are always done using the all sky "algorithm" (which is there and active, but you don't see it). Tracking outside of the points would also revert to the all sky model. However - as you may point out and rightly so - there are no points outside of your dec arc model, so if you anticipate imaging outside of the dec arc, you may want to use an all sky model, or at least have one ready and available (even something simple like a 20 point model) I can't speak if it produces indifferent, better or worse results. I think some experimentation would probably give you a good answer here On Thu, Nov 3, 2022 at 1:56 PM Mark Tenboer <mtenboer@...> wrote: Thanks Brian. I'm hoping Ray or Howard can pipe in and answer #2 --
Brian Brian Valente astro portfolio https://www.brianvalentephotography.com/astrophotography/ portfolio brianvalentephotography.com |
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Re: APPM Platesolver Comparison
Patrick Sparkman
Yep, totally there with you Roland. I guess that I just needed to prove it to myself that using ASTAP as a solver was not causing me issues as it is much faster and more reliable than PinPoint. Now I feel confident that any issues with an ASTAP generated point model are either the way APPM is using the ASTAP data and/or some other mechanical issue.
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Re: Just what is a Dec Arc model?
Mark Tenboer
Thanks Brian. I'm hoping Ray or Howard can pipe in and answer #2
2. What happens if the Dec-Arc box is checked in the Tracking Correction Status section (and also the other Pointing and Tracking boxes on that screen are checked) but the target will NOT travel through the mapped area ? Does that cause worse tracking for that target, or does APCC suspend the model adjustments? The reason I ask is that once you make a Dec-Arc map/model for a target, the model stays in place in APCC indefinitely until it is replaced with another. For the next target that night, I might decide there isn't enough time left to make a new Dec Arc map and so I will track without it. However, the model for target 1 is still active in APCC and the check boxes are checked. Does APCC disregard the model in place if and when the target travels through an area outside the map? Mark |
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Re: APPM Platesolver Comparison
Roland Christen
How many angels can dance on the head of a pin. That's what you're pursuing here.
Let's say that you take two measurements of star position that are separated by 1 hour of RA. The first measurement is dead nuts zero error, the second measurement has an error of 1 arc second. If the model is based on the first measurement, you would have a star drift of zero in a 1 hour exposure. If your model is based on the second measurement, then you might expect a slight drift of 1 arc second in your second image. How many people take 1 hour unguided images?
In other words, the tiny differences in star position measurements are meaningless. You get far more error from simple mechanical random errors than you do from these plate solve errors. Just the other day I was monitoring the exact axis position of my encoder mount by reading the encoder output to an accuracy of 0.15 arc sec, and looking at where a focus star was on the crosshair. Then I moved the focuser position back and forth by a tiny amount. That star moved sideways away from the crosshair due to lateral motion of the focuser drawtube, even though the encoder reading of the mount axis did not move at all. Since plate solve uses star positions on the chip rather than actual axis position of the mount, then tiny mechanical errors of the optical train can introduce much larger errors than those of a particular plate solve software.
Rolando -----Original Message-----
From: ap@... <ap@...> To: main@ap-gto.groups.io Sent: Thu, Nov 3, 2022 4:49 am Subject: Re: [ap-gto] APPM Platesolver Comparison On Thu, Nov 3, 2022 at 12:31 AM, Patrick Sparkman wrote:
With ASTAP, the main variable to adjust was the downsampling value from 1 - 2 -3 along with the solver speed. One thing worth noting is many (most?) use of ASTAP now is with downsample set to zero, which means that ASTAP decides on the fly which to use. I do not know its criteria - it may simply go by pixel size, or it may calculate image scale and change based on that (one could look I guess), but it is interesting this shows a variation of almost half an arc second based on what is for many a hidden decision they may not even know is happening. I would presume for a given camera/optics it uses the same value all the time, but do not know.
Now that said, if I did the math right, your image scale is about half an arc second per pixel, so I guess I am unsurprised if downsampling to 1" and 1.5" changes the result in the < 0.5" range. Here's what is vexing about this question in general, as I did something much the same. Two things really: The first is that we talk about errors and what we are talking about really is differences in two measurements. We really have no idea, I think, which is "right". Do we? Now if we had (say) 5 different plate solves, actually independent (not the same engine under the covers) and got 4 answers that are basically the same and one outlier, we may feel more confident in discarding that one (though remember Galileo was an outlier also). That ASTAP variation seems more in line with the mount's movement (I assume that's a proper interpretation of the above?) lends some credence to ASTAP being more consistent. I think. But "correct" remains elusive.
The more practical question aimed at answering "more correct" is which yield the better results when the points solved are used in a model (all sky or dec-arc). That is more difficult to measure. I have done one cut at that with testing subframe sampling and ASTAP, and am fairly confident at least in wider fields that a subframe (not bin) yields a much better model based on running a guide assistant run afterwards. But admittedly only at one point in the sky, and very limited trials as it takes so long. But the analog to this aspect is one that is often called "sensitivity testing". How sensitive is the model (i.e. algorithm) to changes in individual plate solving solutions? How much does an error in plate solving impact tracking rate, in particular. If the answer is "hardly at all" this is mostly moot. If it has a big impact then this is more worth pursuing. This would likely vary a lot by the nature of the error -- if the errors are purely random, one would expect in Ray's secret sauce that the errors tend to cancel out, yielding a smoothing (for want of a better word) of those errors that would center around the real value. On the other hand, if they are biased (like your pinpoint ones are above, though one could also argue the ASTAP are biased the other way)... then potentially the model this yields is also biased and at least pointing would be off. But is tracking rate (the more important thing I think) affected much? What would be quite interesting, I think, is if we could take a dataset much like yours, and produce a .pnt file with it, and feed it back into APCC and then slew to a given location in the sky, or on the arc (as the case my be) and see what the corrections calculated look like. Then do it again with a different solver's data. Repeat. This might not tell us which is right, but it might tell us how sensitive the tracking corrections (which is what I think everyone is really interested in) are to slight variations in plate solving. That file format would be tedious to replace by hand (though possible), but I wonder if Ray would find this question interesting and might either do it, or allow the offline batch solver to produce a .pnt file. While I get that the algorithms are proprietary, determining the sensitivity of the algorithms to different plate solvers is a good thing for everyone and I don't think give away APCC secrets, whether the result is "doesn't much matter" or "oh my god, stop using XXXX". Or in my pet case - full frame subframe usage. Personally, because someone will point it out... I guide, and this is all relatively unimportant to me achieving good results. But the mathematician (or aged, desiccated remains that are left of one) finds the whole question fascinating, which is why I keep digging. Thanks for grabbing a shovel and helping, Patrick! Linwood -- Roland Christen Astro-Physics |
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Re: Mach 2 is as effective as the leading statin drug?
where is this maple syrup available? On Thu, Nov 3, 2022 at 10:43 AM Samir Patel <samir111275@...> wrote: I can vouch for the maple syrup candies form him. They were gone in a day. Seriously GOOD STUFF. --
Brian Brian Valente astro portfolio https://www.brianvalentephotography.com/astrophotography/ portfolio brianvalentephotography.com |
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Mach 2 is as effective as the leading statin drug?
Samir Patel
I can vouch for the maple syrup candies form him. They were gone in a day. Seriously GOOD STUFF.
toggle quoted message
Show quoted text
On Thursday, November 3, 2022, Bill Long <bill@...> wrote:
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Re: Just what is a Dec Arc model?
DFisch
Chris, well said and thanks for identifying the likely root of my misunderstanding. Tom Fischer On Thu, Nov 3, 2022 at 09:56 Chris White <chris.white@...> wrote: On Mon, Oct 31, 2022 at 10:50 AM, Ray Gralak wrote: --
TJF MOBILE |
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