Download of Observatory 2.1 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program is categorized as Audio & Video Tools. We recommend checking the downloaded files with any free antivirus.
From the developer:
Collect and curate your astronomical images. Search 10+ professional image archives simultaneously. Create master bias, dark and flat frames. Calibrate, register, stack and adjust your FITS, XISF (PixInsight), SBIG and RAW images, all nondestructively.
FEATURES
• Quick Look & Spotlight: display thumbnails, previews and metadata of FITS, XISF and SBIG images in Finder and other applications.
You may want to check out more software for Mac, such as Mitaka Plus, which might be similar to Observatory.
Science Tools