dan_adi

I wasn't paying attention on the guiding RMS conversion to FWHM. Now it makes sense. I found a formula for estimating final FWHM on the ESO website, can't remember how they dealt with autoguiding RMS, but I'll check and report back. Thank you Vlaiv

Do you guys find meteoblue seeing forecast accurate? For my location they seem to optimistic, between 1 and 2 arcsec. I use Prism astro software that reports seeing and star FWHM in my subs and the best FWHM I got was 1.9. Usually I have values between 2-3 arcsec. In Prism the difference between reported seeing and median star FWHM is 0.2 arcsec, this tells me the scope is focused ok. The autoguiding RMS with Mesu 200 is usually 0.2-0.3 arcsec. So my guess is meteoblue is way to optimistic for my location. I doubt I should get bellow 2 arc sec seeing at sea level.. What is your experience?

I've searched for some time for something easy, and I came across the Streamlit library for python. It was way easier than using tkinter. For filter simulation I used the synphot library published by Space Telescope Institute. These are the guys that look after Hubble and JWST. Also the astropy library came in handy for automatic conversion of units. This reduces the chance of an error creeping in when working with flux density units, correcting for airmass-extinction etc. The main equation is fairly simple, you can find different variations of it in the references tab. By far the hardest part was simulating the filters and fluxes, but we are grateful that the pros make their tools freely available. Astropy is also very cool to work with. For example I made a small bit of code that reads my fits files header, extracts the focuser position and focuser temperature. Then I make a liniar fit between those 2 and get the temperature coefficient. This way I can average the results from a few nights, enter the coefficient in my focuser software and then I only need to focus 1 time during the night with temperature compensation enabled. Cool stuff

Hello, I don't have a git hub repository. I wrote it in python, and used streamlit to make it an web app. Afterwards I used docker to contain the applications and it's dependencies into one place and deployed it. Streamlit is nice and fast for making WebApps, but the code is re run after a user action, so it took me a couple of days to figure out how to retain the user input values into variables, otherwise every variable is reset and nothing is stored. I had to use their session_state method to retain values. A little bit weird, but it works. If you want I can see if I can push the app docker image to their repository, and then you can download the docker image on your PC, and run it locally. Or I can send you the individual .py files so you can compile it on your own.

Hello, in order to reasonably detect some object you will need a SNR of at least 10. The higher the SNR you want, the higher the exposure time you will need. The target mag and sky mag will also influence the exposure time. If you have 21.78 mag skies that is really nice. I have 20.4 measured with a sky quality meter. You choose whatever SNR you want. The higher the SNR the better the detection will be but this also translates into more imaging time. The project came to be, because I want to detect the gravitational arcs in Abell 2218 with an 8 inch scope and I didn't know how much time I will need on this target. The faintest arc, arc 362 located at 10 billion light years has a mag of 24.5. For a SNR of 20 I will need around 80 hours for Luminance filter with my setup. If I aim for a higher SNR it becomes unpractical... because I have a small aperture scope. The good news is that I am at 40 ish hours down the road, and if I do an agresive stretch on the image I am beginning to see the faint arc. I will probably finish next summer, but at least I know it's doable.

Hello, the app can be accessed here: http://clearskies.go.ro:8501/ To use the Dark theme, go to the menu option on the upper right corner (the 3 horizontal lines), then click on it, then choose Theme->Dark Hope you find it useful

Hello guys, It was pretty hard for me to make an individual app for Windows/MAC/Linux, so I rewrote the whole thing as a web application, that I will put on a little Intel Nuc webserver I have at home. This way anyone will be able to access it regardless of operating system. The best part is that it was easier to make the web app than the standalone application. Once I have everything in order I will publish the web site address. Below are some print screens.

Sorry for the delayed response, haven't checked in for a while. It's good that mr. Mesu will take the mount and service it. No doubt someone messed with it. The mount autoguides very well, as well as more expensive mounts, but they are small cut-corners if you will, in order to make the mount more accessible-price wise. For example I didn't like the wire connections and the servos exposed to the elements, a nice aluminium case to cover them would be nice and also protect the sensitive electronics. Other than that the mount is really good for the high payload. The only time I see the autoguiding deteriorate to 0.5 " RMS or 0.7" is in windy conditions. But in windy conditions I also have worse seeing, so I don't image anyway in such a night. In my routine I unpark the mount, so it starts tracking, I focus, then do a platesolve - offset init, then a goto to my target. The target is usually less than 1 arcminute away. I do another platesolve-offset init, goto target, and start autoguiding - imaging. So it would not take more than 2-3 platesolves to get things going. With regard to remote use, I wrote a little tutorial you can find here on the forum, in order to control the mount through a local area network. It is not hard but it takes a little DIY to make a serial cable and a small investment in a serial server dongle. This is how I control my mount now, and it works reliably, something I cannot say about using USB cables in general .. I am confident mr. Mesu will get your mount in order.

Friction drive mounts do slip, you can not eliminate it. Well u can but with Renishaw absoulte encoders on RA and DEC... I usually run my mesu mount with the acceleration and speed at the lowest setting to reduce the slip possibility. Overall, my guiding RMS is between 0.15" and 0.3" in seeing conditions of about 1.8-3 ". For gotos I use platesolving. Did you do your tests with a ccd/cmos camera attached to the scope? Do you initialize the mount before gotos?

I see from your signature that you use a MI250 mount with Sitech controller? I thought it was a Mesu mount ... my mistake. Did mr.Mesu fit the controller to the mount? Otherwise I don't see how he should have a dat file for that mount. Did you contact Mathis Instruments? Maybe they can help

Have you tried asking mr. Mesu if he has your dat file?

Never mind, problem solved .... but nobody uses Prism?? It's a wonderful piece of software for observatory control

Hello, anybody using Prism v.10? Have some questions about guiding... The Prism english forum is very silent ..

Small update: If you use Prism v.10 with a Mesu mount, in the Misc tab, Nutate coords and Aberration coords should be unchecked, to avoid correcting twice. Don't know about other software, but the sitech manual states the for TheSkyx these options should also be unchecked. So better to ask SGP, NINA, Stellarium developers how their software report the coordinates, because this will affect pointing. Since I had the mount I've been running with those options checked. Talk about live and learn 😁 Clear skies

Then I am missing something. So you are saying if I get large guiding errors my eccentricity won't be affected but only FWHM?

Professionals use exposure time calculators based on theory. The equations are not that hard to compute and give a better estimate than just guessing or practice.

It's simple really, if one can guide at 1" RMS error with an image scale of 0.2 "/pixel and get good results (round stars), then 10 micron, AP, ASA, Astelco, Planewave etc. would have never existed as mount manufactures.

300 sec per sub, - 10 degrees C. Don't worry, it took me 3-4 years to have a setup that works with minimal effort. By the time I was finished the new gen CMOS sensors came out :))

Small pixels are not really a problem, as you can bin your camera and make larger pixels and optimize you image scale. I guess the new ASI 6200 or 2600 series don't have amp glow. But given your top notch skies the cameras you have will do a great job as is. I use a CCD KAF 16200 sensor and it's ok in Bortle 4. Bellow is a work in progress, about 20 hours worth of subs in luminance with a CCD. I'm ok with it. MasterLightAbell2218_ABE.tif

Given the prices in astro gear this 60 ish pounds is nothing 😄. I did try the cheaper stuff, but as mentioned above, I also found the variation was too great to make precise balance. From the video the gadget seems pretty stable when measuring, also it has a metal case and good cables.

For example galaxy M33, surface brightness 23 mag/arcsec^2, and a desired SNR of 20 in each band: Luminance: 1.55 hours R: 5.38 hours G:5.72 hours B: 6.3 hours For a SNR of 40 in each band: Luminance: 5.98 hours R: 21.7 hours G: 22.6 hours B: 24.9 hours As a side note I don't know how the SNR adds in each band, I've had a conversation with Vlaiv some time ago about this, but I could not find some equations in this regard. The conclusion beeing the SNR in each band is not additive, like the final SNR is not the sum of SNR in L + RGB. In your case I would aim for a SNR of 40 in Luminance, and a SNR of 20 in each RGB, so I would expose for 5.98 hours in Luminance, 5.38, 5.72,6.3 in RGB. Round that to 6 hours in each band, so 24 hours in total exposure time. Hope this gives you an idea about your setup and imaging time. Another note, for extended objects like galaxies and nebulae, you need the surface brightness for computation, not the simple magnitude. Here is a simple explanation: https://rasc-vancouver.com/2020/08/23/surface-brightness-vs-magnitude/ Clear skies!

When I get to my computer I will input your parameters. Don't worry so much about noise, with stacking the signal will "grow" faster than the noise, that is why we stack multiple photos. I also have a CCD with 10 electron read noise and 300 sec exposure for LRGB, in Bortle 4 zone, is a good compromise. If you have such dark skies you can expose for longer, but one limitation would be your mount and guiding performance, wind gust, and also satellite trails and such.

It could be run on windows too, with python and the dependencies installed. But first I must run it on my windows machine to check. As a side note the calculator computes the total integration time needed for a desired SNR. The individual subexposure length is not computed. The thing to remember is that the total SNR and total integration time is important. You can reach the desired SNR with lots of small subexposures or fewer longer exposures. What dictates this, is the type of camera you use, CMoS or CCD, your light pollution and read noise. Clear skies

I had to write my own software for this. Install python, synphot and astropy, then run ETC.py. All files should be in the same folder. Didn't get a chance to make a standalone app. I'll get to it some time. Tested on IOS and Ubuntu, windows not yet. If you can't compile and run it, PM me and I'll calculate the total exposure time for your target. Clear skies! CCD.csv compute.py device.py ETC.py utility.py

Yes the 8 inch f 6.5 one, oiled spaced triplet. Wonderful scope, but now I need some way to disperse clouds all year round:))