*** Note - On Dec. 3, 2023, I gave an overview of the Compendium on the YouTube Astro Imaging Channel which can be seen here. ***The 2023 edition (4th edition) of the free Compendium is now finished and available for free download.
Since I released the Compendium last year with a Windows-only Excel version of the spreadsheet, I have received many requests for a Mac version. This year, I am happy to now release a program which works on both Mac and Windows versions of Excel.
What is the Compendium?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 location. The 30 MB file is available in 7 different languages and may be freely downloaded at these links:
The spreadsheet contains a database of 3135 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.
A Compendium Companion is also available, at this link:
eBook download link (45 MB size) - The eBook has over 100 compilation posters of deep sky objects, including complete catalogues such as Messier, Caldwell, Abell, Arp and Hickson, to give you examples of imaging targets. The eBook is only available in English at this time.
4th Edition ChangesThe 4th edition contains the following changes:
- Spreadsheet (Excel) now runs on both Windows and Mac. The look of the spreadsheet is a bit different because of the need to move on from ActiveX controls.
- 6 foreign language versions of the spreadsheet are now available.
- In response to requests of users of the 3rd edition, the number of filters for screening and sorting of objects in the spreadsheet has been increased by 50%, to 110 filters. This includes filters for all 26 object catalogues. To save space, a dropdown system of filter selection has been added.
- A number of new objects and collections have been added. The total number of objects has not changed because I have cleaned up duplicates and eliminated a few obscure entries.
- Additions and corrections have been implemented in the 188,000 cells of object data.
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".
Limitations- 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 3135 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 numerous reasons, I have not protected the spreadsheet from editing. Please be careful not to delete any of the columns, or the top 9 header rows (which contain formulas).
Astronomy Scholarship FundThe Compendium is provided free for your use. If you find it useful, I would appreciate a small donation to the
Imm Astronomy Scholarship Fund, a tax-deductible donation account established to provide financial assistance to college students with an interest in astronomy. The scholarship will be open for applications in January and will be awarded in June, hopefully on an annual basis if funding allows. All U.S. and international students attending college in the United States may apply for the scholarship. For those of us who love astronomy as a hobby, this is a small way for us to encourage and reward students who take up this challenging career.
Feel free to ask me any questions and to provide feedback in term of error corrections and additional feature requests.
Best regards and clear skies!
Gary
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