There was a problem with one file in the downloaded zipped file (z186). I downloaded the compressed version (about 6 GB) of the UCAC4 star catalog from the Code Obsession web site (as mentioned in the manual), unzipped it, and then installed it in Observatory. There are only 2 or 3 Tycho-2 stars in that center 50%, which is why you need UCAC4 for this. There the distortions are small enough for Observatory to find a solution. A response came back quickly that they were able to plate solve the image I sent them but noted that I did need the UCAC4 star catalog: Observatory’s plate solver isn’t very tolerant with optical distortions, and by moving that slider you are telling it to only use the center 50% of your image for the plate solving. That equates to a pixel scale of approximately 0.38 arcsec/pixel. My D850 DSLR has an approximate field-of-view of 52' across its 8256 pixels horizontally at prime focus of my f/8 12' telescope. Before making those 'guesses' I tried increasing the 'search radius', but that didn't help. The error said that I should try the UCAC4 star catalog (which I had not downloaded yet) or adjust the frame size and pixel scale for the image (which were set at automatic).

I initially tried to 'Match' (plate solve) an image of NGC3628 (Sarah's Galaxy) using the installed Tycho-2 catalog. You can optionally download the UCAC4 star catalog (9 GB) and/or the USNO-A2.0 star catalog (7 GB). Observatory comes with the Tycho-2 star catalog. You first identify the object (i.e, M65) to Observatory, which can be as simple as having the object catalog number in the image file name. Plate SolvingĪ nice feature of Observatory, especially for reporting any discoveries, is 'Plate Solving'. Other image processing (levels, sharpening, etc.) will need to be done in another application. This is the final processed image from Observatory: I applied two adjustments for the M104 (Sombrero Galaxy) stacked, exported, and imported image: Backgound Neutralization and Flatten Background: Once you do that all the options in the 'Add' menu are enabled:

I had to export it and then import the saved image. I was surprised to find that I could not add adjustments for the just stacked image. Here I edited the resulted stacked image. You can also edit multiple images in bulk (such as before stacking). You can edit the resulting stacked image. Software Review - Observatory for macOS, page 2

Plate solving software for mac