han59

FYI, the ASCOM Sky simulator version 1.8 has been released. The default star database goes now up to magnitude 14. Improved artificial stars. Deepsky labels can be switched off. The image dimensions are now set at one place in the program. Han

Doesn't help you but note that the free alternative GIMP can read FITS file. Han

It is possible to plot in an spreadsheet both the measured V-curve and the hyperbola fit as found: Here an early report of my setup 13:22:39 median Focus=35972 a=1,23909 b=143,37264 _____________ lowest error=0,01187 iteration_cycles=4 13:22:39 center Focus=35925 a=1,87688 b=212,46136 _____________ lowest error=0,00540 iteration_cycles=4 13:22:39 outer ring Focus=36028 a=0,30912 b= 37,90557 offset= 103 lowest error=0,02590 iteration_cycles=6 13:22:39 bottom left Focus=36000 a=1,47225 b=169,40969 offset= 75 lowest error=0,01023 iteration_cycles=2 13:22:39 bottom right Focus=35825 a=1,52325 b=167,86880 offset= -100 lowest error=0,00695 iteration_cycles=2 13:22:40 top left Focus=36094 a=1,39523 b=159,90826 offset= 169 lowest error=0,00958 iteration_cycles=4 13:22:40 top right Focus=35934 a=1,74906 b=200,38594 offset= 9 lowest error=0,00777 iteration_cycles=4 My focuser makes about 1500 steps per mm, so the found differences up to 169 steps are very small a little more then 0.1 mm or 0.004 inch. The measured curve and the hyperbola fit of the INNER area The measured curve and the hyperbola fit of the OUTER area: The spreadsheet used is attached hfd_center.zip

With this post, I want to introduce a new method for measuring tilt and curvature and it is a request for some test data. Thanks, Han The program CCDinspecter measures the tilt and curvature by the difference in FHWM (~hfd) values between the center and outer areas of an image. I have tried to indicate it in a sketch below: I assume CCDinspecter calculates the curvature by ((A/B)-1)*100%. Where B is the average fwhm/hfd of the center and A of the outer areas. This will not work if the image is not in focus. There is even a focuser position where A=B. It would be better if the curvature would be measured as C expressed in focuser steps. So ideally you should measure the best focus position for each area. This can be realised by taking several images like for focusing and find the best focus point of each image area by curve fitting the V-curve of the hfd values measured in each area of the images. This idea is implemented in the free program ASTAP, tab "inspector". You can feed it with several images at different focus points and it will report the best focus point for each area of the image. It is also possible to copy paste the data into a spreadsheet. Then you create graphs like these: Graph of the focus curves of 100mm APO astrograph, focal length 580 mm. Plotted are hfd values of median=all, the center of the image, outer area and the image split in four parts: In the program, the data is presented as a table which can be selected and copied to the clipboard: The usage is as follows: Prepare a series of short exposure images with different focuser positions and a lot of stars. Exposure time a few seconds. Move for each image the focuser a small step but only in one way to prevent backlash problems. Images with stars having an hfd above 12-14 will not be analysed correctly since this was historically not implemented. Browse with ASTAP to the images. Press analyse Optional: Select all rows by ctrl+a, copy with ctrl+c and copy to your favorite spreadsheet. Press curve fitting for report on best focus point for each image area. This is experimental. I'm interested in more test images. If anybody can assist, make them as indicated below. Han

That's an interesting option we haven't consired. Note that the sharpeness is also depending on the seeing. The autofocus routine is building a curve where sharpness is a function of focuser position. The program will find the best focus position using curve fitting. The curve fitting will cope with the seeing effects. Manually finding the best focus with the sharpness value will be more difficult. You will get litte unstable sharpness values near the best focus position due to the seeing. Nevertheless this could be an interesting option which is easy to implement. In setting tab FILES there is currently an option "Automatic HFD measurement for every sequence capture" Something simular could be done if "Planet" autofocus is selected and without sequence. So report the sharpness in the log after each exposure. I will propose it to Patrick. later, proposed. See https://www.ap-i.net/mantis/view.php?id=2264

Yes it will work for terrestrial objects. If measures the intensity slope between dark and light areas. This slope will be less when de-focused. It has been tested successfully on the Moon without seeing the rim, but for testing it terrestrial objects, select a target with some sudden intensity differences. Focusing on the Sun rim worked also fine, but unfortunately Sun spots are still missing. One focus test on Venus was also successful. Testing on Jupiter or Saturn has to wait till they show up in the night sky. Han

For info: The latest version of CCDCiel (freeware) introduces autofocus for the Moon, Sun and planets. The principle is the same as with autofocus for stars. For planets however, it measures the sharpness of the image instead of the half flux diameter of the stars. Feedback is appreciated. Han

Very nice image. The image details of NGC4216 are amazing! There are more galaxies to see. I can't help you with the PI annotation, but here an alternative annotation by ASTAP of your jpeg file. (but I'm a little puzzled by the SDSS entries around NGC4216):

Unfortunately, I have no other filters then H-alpha. Maybe I will expose a few hour longer for a better SNR value. Correction, the location is NNW of the star Meissa. The light areas are part of SH2-264 which center is at the star Meissa. Below the image plotted in a map:

This image is de result of four nights in December/January. The weather was not very good. I wished I could have exposed longer. The dark nebula are B30, B31, B32 not very often imaged. Nevertheless they are nice objects to image. There is some similarity with the horse-head nebula more south. These dark nebula are at three degrees NNE of the star Meissa in Orion. Han Telescope 100 mm APO astrograph APO100Q, F5,8 ASI1600MM-Cool Camera Filter H-alpha 7 nm 66x200 sec four nights in December 2019 and January 2020 CCDciel and ASTAP stack program

In the latest beta version v3.85.1 of APT, you can select ASTAP as astrometric (plate) solver.

I'm surprised you need more then single precision. In my program I define the arrays as single precision by purpose since memory requirements quickly increase if you have a few images in memory. If your looking for a new challenge, develop and document a de-mosaic routine for astro OSC images. Especially when stars are saturated in the center and the stars are small, HFD/FWHM value 2 to 3 pixels. For me it is just simple statistics, average value, standard deviation....

I'm sorry for you loosing your job. Python is an interpreter. For speed a compiler solution would be better. But if your comfortable with Python at least it is muli-platform. What are the ideas? Han

Your using the V-curve option to focus. This is the oldest method. I have used V-curve option in the past till dynamic was introduced. The Start focus HFD (2) default setting is 20 but for me 15 or even 10 was required to get good snr values. The Near focus HFD position (3) setting I had set at 6 or 7. It uses point 2) and 3) to find the focus at 4) So V-curve focusing only works if 3) still lies in the linear area. I think you can select for 3) a value twice the mininum so the HFD at focus. The problem with this method is that you have to calibrate the V-curve in advance and in most case you have to slew to a bright calibration star for a good SNR value. Too much saturation could also be a problem at focus. So the star should bright but not too bright. Later the hyperbolic curve fitting (=dynamic) was developed and since this is implemented, I haven't used the V-curve focusing anymore. I would suggest to try this dynamic focusing + stay in place. In the dynamic method there is less need to de-focus and therefore it is better suited to "stay in place" for focusing: I have tried to describe the performances with plus and minus signs in the table below: To change focusing, you have to select "dynamic" and "stay in place". (For sequences "stay in place" is also an option you should set). The minimum snr in this screen shot is probably too low. I would set it at 6 : It tries find the best hyperbola fit on the measured points. Below a quick sketch I made to illustrate the principle. Hyperbola fitting can work in the non-linear area of the curve. Therefore less defocusing is required. The inputs are focuser positions and the corresponding HFD values, the seven stars in the sketch. The curve is the best fit it can find and the routine knows the bottom position so the best focus position. The minimum HFD is about 2.5. For focusing you don't have to defocus to a HFD value more then two or three times the minimum value. So in this setup to HFD 5 or 6. This is how it looks in reality: -- Han

For narrow band you often need longer exposure times to get stars above the noise. You can speedup focusing by using 1) "stay at position" and 2) dynamic focusing. 3) Limit the number of step to 7 or 8 or 9 steps . Furthermore you can reduce the exposure time if you 4) limit the focuser steps such that your focus if going not far off. For my setup the HFD value at focus is around 2.5. I tune the focuser steps such that the maximum HFD is around 5 maximum. Example for H-alpha 7 nm, I'm using 4 or 5 seconds exposure for focusing. Going to a dedicated bright star for focusing takes more time then "stay at position" If this is abracadabra for you, ask me for more information. Han

Installing libraw is the intention. That message should also popup if you try to open raw files. This shouldn't effect Astroberry in anyway. The program using the following file: /usr/lib/libraw/unprocessed_raw I switched to libraw only a few weeks ago. Older versions call dcraw. -- Han

@dannybgoodewhat are the indications showing in your setup? You can see in my last screenshot what to expect. That will identify where the problem lies. So specific the RA,DEC solution in APT, the RA, DEC position of the mount after sync and the RA, DEC position (J2000 or Jnow or both) of the frame in Stellarium.

I run a simulation in APT and got in the same problem. However there is a APT button "Jnow" near "connect /disconnect telescope" which fixed the problem. Does this work for dannybgoode? This test can be done in simulation. Just load an image in APT, solve it and sync the (real) mount. Then check the results. Han Before: Activate the button Jnow With the button Jnow activated:

Stash remind of an other problem, modeling of eqascom (eqmod). If you use eqascom, the eqascom model could be wrong. The number of APT retries (goto++ attempts default two times) will indicate this. Reset the eqascom align and sync data for the alignment. It could have collected wrong alignment points from telescope sync command. You can switch this add alignment points behaviour off:

Solvers can fail but it is very very very rare. In all other cases the error is less then one pixel. If your telescope is not perfectly polar aligned, you could need two syncs rather then one. So check your number of tries, the acceptable error as indicated above and equinox setting(s) J2000 or Jnow. A J2000 vs Jnow error is the most likely cause.

Poor connectors could be a problem. As Blinky indicated maybe the hub is spoiling the serial communication. It's only 9600 baud serial but the timing of the bits is very critical. A club member here is also using a 5 meter USB cable without problems. So I assume a 5 meter usb cable is preferably to a hub connection. Moving the usb->serial dongle closer to the computer is an other option. The serial cable is possibly less sensitive to long lengths then USB.

Could be a communication error due to cable quality/length. How long are the USB cable and the serial cable? If the USB cable is a few meters long, maybe it helps if you use a shorter USB cable.

If it is a "sync across meridian" problem and you using Eqmod, note that Eqmod version prior to 2.00n doesn't give a error message: "ASCOM Sync reject exception" Using Eqmod 2.0.0n or higher will give a this error and if SGP is programmed well it should pass on this messsage. See https://groups.io/g/EQMOD/topic/56626302#49214 This will only help with error reporting. To bypass the problem see my previous remarks.

A solve problem would be difficult to explain. The meridian is not a boundary for a solver. But note that a HEQ5/6 mount (and maybe others) can't sync across the meridian. This could occur if you flip exactly at the meridian. The mount could think your just past the meridian but your solver tells it is just a few minutes before the meridian and sync will fail. You can avoid this by flipping 20 minutes after the meridian crossing if your software allows this or just wait 10 minutes or slew to an object further away from the meridian and sync. Han

I missed your message. Yes now I have looked to the image. The image has two problems. The resolution is too low and the stars are elongated. - ASTAP likes minimum resolution of around 1.5 mp so something like 1500x1000 pixels. Your image is 965x635, so close to 0.6 MP - Stars are too much elongated. Something like ratio 3x1. They are recognised as galaxies. ASTAP will ignore any bright object which is more then 30% elongated/oval. You can see the if you activate the CCD inspector or use test button "Show tetrahedrons". The exposure duration is more then enough. You can easily expose less, 5 or 10 seconds is sufficient. Lets continue this on the ASTAP forum. Somehow I didn't get your reply in the email box, but will have look more regulary. Han Han