han59

Without an image an advice is difficult. Comets are faint and the image will be noisy. To get a good image you will need at least 30 minutes exposure time for a short focal length (500 mm) telescope and long focal length a few times longer exposure. If your sky is not very dark it becomes even more difficult to image and comet. Han

ASTAP has a new feature to align and stack images of asteroids. The alignment is called "Emphemeris alignment" and allows to align the images using the calculated position. As a test, I made in April 57 images of M95 & M96 using 200 seconds exposure. So total a little more than three hours exposure time. M95 & M96 are fairly close to the ecliptic making the images both useful for a galaxy image as for the asteroids. The images where made with my 100mm F/5.8 APO and an ASI1600 MMC camera. The SQM value in my garden reaches about 20.4 maximum. First I made a normal stack and annotated asteroids in the image. The number of asteroids in the ASTAP annotation database was set at 200,000 and the limiting magnitude at 20. Quite a few asteroids are annotated. However, they are not visible due to the self-movement. ASTAP has the ability to align and stack the images based on the calculated position. The program will show in a drop down menu the asteroids within the range of the image. Then it is just a matter of selecting one of the asteroids and then to re-stack the image. Eventually I can see that the limiting magnitude for my 100mm telescope (after 3 hours exposure) is about magnitude 19.5. See selection below. Han Asteroid 5741 with magnitude 17.9 8383 with magnitude 18.4 25232 with magnitude 18.9 and 25799 with magnitude 18.8 Asteroid 12601 with magnitude 19.4 barely visible:

They have had plenty of clear skies moments to test there first assembly. Makes you wonder.

I have made 5 minute video demonstrating how to measure the magnitude of comet C/2019 Y4 (Atlas). It's an almost fully automated process. The comet flux is measured and converted to a magnitude using the imaged stars as reference. Calculating the star magnitude/flux relation is fully automatic using Gaia DR2 catalogue as reference (calculated Johnson-V). The only manual operation is selecting the area and removing the stars near the comet. Video: https://youtu.be/BEjcSm_cZx8 Feedback about this new method is appreciated Han

You better solve the tilt in X (between left and right). That reduces the quality. Most likely the stars are on one side a little larger. Assuming the average FWHM is about 10, the difference is 2.9/10 is 29% Sometimes just remove and replace the camera could help. Or turn it 180 degrees and look to the difference. Han

You probably are better off by stretching in APP or ASTAP. In GIMP you could stretch using curves, but most likely like in Photoshop you will loose colour of the faint objects: See e.g.: http://allthesky.com/articles/colorpreserve.html or here https://www.markshelley.co.uk/Astronomy/Processing/Colour_Preserving_Stretch/colour_preserving_stretch.html And explained in this little graph: Input: blue=5 red=10 The input colour ratio is then 10/2 is 2. The curve gives these values after stretching: Output: blue=0.26 red= 0.38 De output colour ratio is then 0.38/0.26, about 1.5. De result is less colorful. A better method is colour preserved stretching as implemented in ASTAP: in de range of 0..1: luminance:=(red+green+blue)/3 luminance_stretched:=gamma_curve(luminance) red_output :=luminance_stretched * red greenn_output:=luminance_stretched * green blue_output:=luminance_stretched * blue The ratio between red, green and blue so the colour stays the same. Only the luminance is stretched. Han

Just as a test, screenshot solved in nova.astrometry.net, annotation in ASTAP: Han

Syncing near Polaris could be rejected by EQMOD/HEQ5/6. A small offset will result in a huge RA offset. If the offset is too large, the mount will refuse to sync. You better slew first to an east, south, west or zenith location before you try to sync the mount. Han

I wasn't aware of the X-Trans CFA pattern, but this post triggered me to add experimental X-Trans support to ASTAP (v0.9.351). Maybe useful for Fujifilm camera owners. Han

This difference can be explained If the image is vertical flipped somewhere in the process. There are only four Bayer patterns possible so it doesn't matter so much: Normally RGGB: R G G B Vertical flipped GBRG: G B R G For correct colours, use ASTAP auto colour correction. See tab Stack method "Auto Level and colour smooth" or after stacking go to tab pixel math 1 "Colour correction". It will adjust R, G, B such that background is gray and average star colour is white. But it looks like you already have a nice image. Han p.s. why is this UK site suggesting to change colour to the American color?

Would it help to have a program to convert batchwise all available FITS files to 16 or 32 bit TIFF? No loss of quality. Then there is no need for a plugin. All stack programs can export to TIFF or PNG so the need for Photoshop to read FITS files only exists if you want to stack with Photoshop. Han

Automation makes it possible to use any brief clear sky moment. Imaging an object is not restricted to a single night. You could have 90 minutes of clear sky, take a series of images and continue imaging the same object next clear night. My only setbacks are occasional bad USB connection and computer freeze. The computer freeze is mainly caused by the memory module connector of my old 2009 desktop. The old desktop is permanently placed in my astro shed. It was never designed for the cold and occasional high humidity environment with continuous ventilation. But it has survived already 5 year in the shed. Making the connection a few times normally fixes the problem. One of the two old harddisk doesn't like temperatures below zero so it is used as secondary disk. Han

Thanks again Don. The new ASTAP version 3.19 with asteroid annotation is available to play with. Han

Hello Don, The last image is also fine for me. The two are spot on. Thanks again for providing. I have now enough images for testing and can finish the interface. Will be released in one or two days. Han

No binned 2x2 is fine. Yes please some more for testing. No need for applying darks or flats. It is very stormy here but the sky is now partly clear. But very risky with my flap-open roof. And still some rain is coming.... Han

Now it becomes clear, CCDstack has modified the DATE in the header. The comments by CCDCiel are removed by CCDStack. Okay no problem. Always use DATE-OBS Han

Hello Don, This one matches also well. Took some time to prove but looks all good! I'm only a little puzzled by the two dates in the FITS header: DATE = '2020-02-11T19:45:42' DATE-OBS= '2020-02-11T19:10:42' What is the Windows file time of the original file? Thanks for providing the image! Han

First the one of Michael. This are the result I get at 17:32 UTC and 20:37 UTC. Looks very good. Thanks! Magnitude is 13.1: UTC 17:32 UTC 20:37:

No, but if possible try to set it correct

Hello Don, More then 3 month back will most likely give a too large offset. The program uses the MPCORB.dat file from the minor planet center. Unfortunately you can only download the latest MPCORB.dat version, not one from 3 months ago. My intention is to check the rather complex calculation. The annotation should be spot on. You can just load a FITS file (or raw) in the program (astap) , press solve button, press annotate asteroids en it should work. The UTC observation time and location on Earth is read from the FITS header or has to be entered manually. Yes a new image Vesta or Metis will do. 😀 If you can make a second one some time later then the movement will prove which object is an asteroid. Han

For the testing new software to annotate asteroids on images, I'm looking for recent images containing asteroid(s) tracks. Preferably in FITS format (with start exposure date) or with the original file time. Is there anybody who can assist? Han

Thanks for the feedback. I'm just waiting for a Sun spot & clear day for further testing. Han

Yes it will work with any camera including OSC sensors as found in a DSLR. The basic principle it pretty simple. It analyses the image on higher frequencies. How sharper the image the more higher frequencies (faster changes in grey) can be found. For practical reasons the focus curve is displayed upside down to make it compatible with a V-curve based on HFD or FWHM. By default the algorithm groups the pixels in 2x2 so a bayer matrix as found in OSC doesn't have any influence. Han

Today I have uploaded on Youtube a live demonstration of autofocus on the Moon: https://youtu.be/8eWxTQTmYBk Han

That could be an option but will require some significant amount of work. Interface should be INDI. There is already an existing INDI sky simulator using the GSC star catalog, but I have never tried it. Is there something to improve? Note that I just fixed a small problem with the "go default" button and it is just uploaded as Sky simulator 1.9. Han