The 2026 edition (6th edition) of the Imm Deep Sky Compendium is now finished and available for free download. The 36 MB download link is here.

This 6th edition includes additional object images, Astrobin links and error corrections, but does not include any feature additions.

While I was tempted to add new objects and new features to this edition, I did not for two reasons:
1. The spreadsheet is so complex that it pushes Excel hard and starts to crash more often when expanded.
2. Many of you have adopted previous versions of the Compendium spreadsheet for your own use, adding your own data and notes to the My Section columns. Keeping the number of columns and rows unchanged makes copying your data to this version easier.

Description
The Compendium is a free, detailed Excel spreadsheet that provides the astrophotographer with a useful tool for finding interesting deep sky targets to image, specific to the current time and user location. The spreadsheet contains a database of 3145 deep sky objects and 26 cross-referenced catalogues. Each object has an image, a description, an imaging rating, a SIMBAD link, an ALADIN link, and 20 pieces of technical data. The spreadsheet runs on both Windows and Mac.

This update is only available for the English language version. If you are a new user looking to download one of the other 6 language versions, please see the 4th edition post here.

Before You Begin

Once you download the spreadsheet you must enable the macros, which are disabled by default in all downloaded Excel documents. To enable the macros in Windows, right click on the downloaded file in Windows File Explorer, select Properties, and select the Unblock checkbox on the bottom of the General tab. To enable the macros in Mac, simply click on Enable Macros when opening the file.
Depending upon your computer settings, you may see formula warnings (green triangles in cells) throughout the sheet which are visually annoying and which slow down the refresh time. Disable these warnings by clicking on one of those cells, then clicking on the exclamation point which appears, then clicking on Error Checking Options, then (under Error Checking Rules) deselecting the boxes for "Unlocked cells containing formulas" and "Formulas referring to empty cells".

Excel Access
The program requires Excel - it cannot be run on free spreadsheet programs. I have not found a free program which is able to run the 2300 lines of macros (VBA programming code) that is used for the calculations for each of the 3145 DSO objects (with 64 pieces of data for each object) together with sun and moon calculations. Similarly, because of the macros, the spreadsheet only runs on the desktop versions of Excel for Windows and MacOS. The use of macros is not supported on Excel for iPhone, iPad and Android phones, nor in the online (browser) version of Excel.

For those of you without Excel, or who prefer using written materials instead, I have published a 750 Best Deep Sky Objects book on Amazon to assist you with imaging target selection. All proceeds from all of my books go towards astronomy college scholarships.

Best regards and clear skies!
Gary