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you mean around 6:11 right? Yeah so that's from algebraic simplification, in (m1/m2)*F_s + F_s, both terms have F_s in them so you can pull that out and write (m1/m2+1)*F_s. Makes sense?

@@levitopher Oh I see it now. Thank you!

The plotting in AIJ can get a little buggy - are you sure you actually have the data? Check the measurements window to make sure there is actually data there. Also make sure the drop down menu in the Multi-plot window says something like "Source_AMag_T1" (for the target) or "AMag_C2" for the comparisons.

@@levitopher Hello! I solved the issue, somehow the X axis default option did not work but once I selected UTC for it and set Source_AMag T1 as the Y Axis, the plot option was then working and it showed the data properly! Thanks for the video and your response!

I think it's supposed to be -1 instead bc of newton's third law

In my notation, F^{1(2)}=F^{2(1)}, with the negative sign from Newton's third law being taken care in that previous line.

I don't know what "detrading" is - do you mean "detrailing"? In any case, AIJ is not often used for complex image modification, but it is based on ImageJ, which has a whole bunch of functionality I am not aware of. You might find an answer there. For the in-AIJ plot options, I'm quite sure you can do fluxes as well, but I often just pull stuff out to .csv for work in gnuplot or spreadsheets.

Hi! Do you mean wCs? That's the world coordinate system, and does not automatically come from iTelescope (you can force them to add it, but it costs telescope time!). You can add it by getting a free account at nova.astrometry.net and using the WCS function of AstroImageJ - I have a video on basic usage here: ruclips.net/video/-Y_apLDfvxE/видео.html .....but I have to say it's a little finicky, so be ready to spend some time on it!

@@levitopher sorry, I mean wcs. Thanks a lot, very helpful 😊

Well, "combine stacks" is really for single filter images, to improve SNR. Like you have 5 V filter images and you want to do combine them. Make Composite is used to take a 3-fiilter set (like RBV) and turn it into a color image. As for the align question - I think "image stabilizer" is an algorithm for making stacks look "less fuzzy", while stacking via WCS is just summing (or median, or ave...) the counts. I would say the first is for "nice images", and the second is for photometry.

@@levitopher You are awesome. Thank you, Christopher - your feedback/guidance is most helpful for a 'newbie' like me. My apologies for any inconvenience. May I ask you one final question? I have tried in both DSS and Astroimagej to produce a .tif file (after combining RBV images), and when I then import that .tif file into something like GIMP to do post-processing, there is NO colour information i.e. I am unable to get histograms for R, B or V to play around with the colour balance. I have am not having any success if I produce a .png or .jpg file. Thus, what should I do in Astroimagej or DSS to be able to export an image that I can then manipulate in GIMP?

* "I am also not having ...."

@@aneufield6564 Interesting, I would have tried the same thing! I don't actually think astroimagej is the best for color processing, but I would have expected your process to work. The only process I have for doing color images is loading the three filters separately as a stack, and then "make composite color image" and then "convert RGB stack to color image". Is that what you tried? I also kind of think you can save the stack directly as a png or whatever, but I'm not sure I've actually done that.

@@levitopher Hi Christopher! Once again, your feedback is very helpful and much appreciated. I will give your suggestions a try.

The ground is frictionless. The pushing force could be as small as possible (say, 0.5 N), and the system would accelerate (both blocks together) with some small acceleration. But in this problem, I'm trying to find the largest pushing force *before* the top block starts slipping off the bottom. That's the inequality I write around 6:45 - that's the condition for the top block to not slip. When I take the maximum value of that inequality, I'm taking the maximum pushing force before the top block starts to slip. Does that help? It's not "whatever force you apply to the bottom block", I can apply any force from 0 to F_max and the blocks will acceleration across the floor, but the top won't slip off the bottom.

​@@levitopherThank you for your response. I see how when I look at both blocks together as a system, even the smallest pushing force would cause acceleration. However, when I look at the equation for just the bottom block F-F_f_s = m_1a_1 and consider this from wiki on friction "Any force smaller than F_s_max attempting to slide one surface over the other is opposed by a frictional force of equal magnitude and opposite direction" I conclude that when looking at the bottom block, it will not accelerate if the pushing force is less that F_s_max and if the pushing force is more than that, it will accelerate but it will slip. Do you see my argument when looking at just the force equation for the bottom block? Where am I mistaken? thank you very much

I think that logical chain is not as simple as the application of Newton's 2nd law I use here, because it relies on your intuition about several different conditional forces and accelerations. But it's still correct of course!

VPHOT is available on the AAVSO website, but I believe you need to be a member to access it.

Yes I am!

Ha! Care to elaborate before I argue that notation doesn't matter?

You mean *between* your fingers and the nut, not *behind* the nut? That's a bit of a strange one, because the frets should be high enough to deaden any of those vibrations, unless they are very high frequency. Is your nut super high or something? Sometimes just cleaning the nut, where the string passes through, can help with random sounds.

@@levitopher there is no problem with the nut. I used the capo and it's still ringing between my finger and the capo.

Interesting comment - I would say sympathetic vibration is a quality of a particular instrument, and there shouldn't be any reason to mute strings to avoid it. When you play a low E, the high E vibrates in resonance, but that's not additional harmonic content (since they have the same overtones), it's just changing the relative amplitude of the various overtones. For sure, that might mean certain strings are louder then others, but these are acoustic instruments, that's absolutely part of the sound quality of them. Having said all that, muting strings while playing is certainly a possibility, but it doesn't match my aesthetic, so I personally wouldn't spend much time on that. I also assume are not talking about "Wolf Tones", in which interactions between the body and the strings actually change the quality of the sound. I don't know how common these are on guitars - they are something bowed string instrument players deal with all the time.

@@levitopher Thank you kindly for your thoughtful reply. I'm going to keep experimenting.

Hola Mariana! What do you mean by "example of power"? Constant wave motion (if it's ideal) will not lose energy, only transform energy from kinetic to potential and back. So the power in the entire system would be zero. Is that what you mean? Que quieres decir con "ejemplo de potencia"? Movimiento Ondulatorio constante (si ideal) no perder energia, solomente transformar kinetic a potential. El potencia in todo el sistema esta cero. Es eso lo que quieres decir? (assuming "potencia" actually means "power", as Google Translate tells me, not potential!!)

E!!!😒 Pero ya me estas hablando de un grafico de onda de funcion por el 0 e!!!!! Nada si eso mero T + E(Md)/F GRACIAS 😊👐

@@marianapenameza8218 I'm sorry, I don't think I understand, I don't actually know much Spanish, and I'm afraid Google Translate is not doing a good job with the technical words. But, I did not present a wave chart, right? For a spring, the zero of Energy is when the spring is not compressed. I'm afraid I don't know what "T + E(Md)/F" means! Can you clarify with words instead of letters? No pienso que te entienda - no se mucho espanol, lo siento. Pero - no presento un grafico de onda, verdad? Por una muelle, el cero de E es cuando ellas no estan comprimidas. Y no entienda tu Ecuacion - peudes escribes con pollabras en vez de letras?

I use both, and would advocate for learning both for different things. VPHOT is easier for most things (particularly related to AAVSO, as you say), but if you need to do particular image processing things, AIJ is better. Also, AIJ is just perfectly designed to spit out a light curve. It's very satisfying to open 100 images in AIJ, align them, click a target and comparison stars in one image, hit enter, and look at the light curve! VPHOTs built-in comparison stars are great...but what if you want to use a non-standard star? Back to AIJ!

@@levitopher Thank you for your swift answer :) as I was reading through the AIJ manual I saw that there is a builtin macro that can generate an AAVSO report in plugins > astronomy > multiplot then in the window that pops up File > Create AAVSO Exoplanet Database formatted report so that's nice :)

It would be nice if you could show this using a V filter, and show how to report the results to AAVSO. :-)

Translation "How come mine doesn't have MF focus mode? Give advice please please" Sorry, I don't specifically know why that mode might not be available for you. It could be the device you are using does not support it. The option is found on the left hand side, second button down. It might look like [AF]. Push that, and select [MF].

@@levitopher bang aku ngk ngerti bang bilang ap Coba pake bahasa indonesia dong

@@levitopher bang aku ngk ngerti bang bilang ap Coba pake bahasa indonesia dong

@@yusranofficial963 Silakan gunakan terjemahan Google, itulah yang saya lakukan. Saya berkata "Maaf, saya tidak tahu secara spesifik mengapa mode itu mungkin tidak tersedia untuk Anda. Mungkin perangkat yang Anda gunakan tidak mendukungnya. Opsi ada di sisi kiri, tombol kedua ke bawah. Mungkin terlihat seperti [AF]. Tekan itu, dan pilih [MF]. "

@@levitopher bang bleh mnta no WA nya?

Yeah this is what I'm advocating for in my other responses. It's part of the sound of the instrument. When you are purchasing an instrument, if it rings all over place and you hate it, don't get that one! Or switch strings, or change the position of the nut, or whatever. If I'm playing an acoustic instrument, I basically want as much organic sound coming from it as possible. As I mentioned above, there are so-called "wolf tones" that are considered to be negative aspects of resonance, but they can be fixed (or mitigated at least) in a couple of different ways if you think they actually do negative things to the sound of your instrument.

The one released by Vernier for use on the iPads. It's good for stuff like this but not quite good enough to do things like freefall.

@@levitopher Thank you!

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