[Tool] SkyCompendium: The field assistant for Gary Imm's catalog

20 replies•425 views
Francis Moreau avatar

Hello, astro enthusiasts!

I would like to share with you an exciting project called SkyCompendium, designed to facilitate the preparation of your observation and astrophotography sessions. This tool is based on Gary Imm's famous “Compendium of Astrophotography Targets,” a database of over 3,000 carefully selected objects (rare nebulae, galaxy clusters, IFN zones, etc.).

The idea is to transform the old Excel file, which can sometimes be complex to use in the field, into a smooth, interactive web app.

Key features:

Real-time planning: The app uses your GPS location to instantly calculate which objects are visible above your local horizon at a given moment.

Offline mode: Once loaded, the app works without a network connection (local cache), ideal for isolated areas without 4G coverage.

Comprehensive object data sheets:

Field of view visualization via Aladin/DSS2 (framed at 120% of the target size).

Height graph for the current night.

Annual visibility graph to anticipate the seasonality of targets.

Detailed ephemeris: astronomical night times, sunrises/sunsets, and moon impact.

In-depth search: Direct links to Simbad and Aladin are integrated for each object.

100% free and community-based: This is a non-commercial project designed to help you think outside the box.

The application is available here: https://skycompendium-online.web.app

The tool is still being refined, particularly in terms of mobile usability, so feel free to test it and give us your feedback!

Clear skies to all!

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Rainer Ehlert avatar

Hi,

Great and thanks a lot, as I never know what to image, it will help me choose an adequate object and see what will come up in future days.

So far I like it and at the moment no questions. Maybe later when I have looked deeper into it.

Very well done 👍️

John Hayes avatar

WOW! This is absolutely fantastic and it looks super useful. Thanks for putting this together. I’ve only played with it a little but I can see that you did a really great job with this app!! It is super easy to use and it has all the information that I want to see.

- John

Rainer Ehlert avatar

Hi Francis,

As I have two piers in my Observatory and at certain positions the telescopes collide, I know I know, but this developed like this because when I planned the Observatory I did not expect to grow that much with the telescopes.

I would like to suggest, if possible, to be able to order the objects by RA and so I know if they will collide or not.

Thanks for this great job.

lunohodov avatar

Francis,

I spent some time with the tool and while there are some small issues with translations, it’s already awesome! I’ve added it to my list of awesome resources. Thank you!

Be well, stay safe

Well Written Respectful Supportive
Francis Moreau avatar

Rainer Ehlert · Feb 6, 2026, 01:36 AM

Hi Francis,

As I have two piers in my Observatory and at certain positions the telescopes collide, I know I know, but this developed like this because when I planned the Observatory I did not expect to grow that much with the telescopes.

I would like to suggest, if possible, to be able to order the objects by RA and so I know if they will collide or not.

Thanks for this great job.

That's an interesting suggestion, I'll add it to my to-do list.

Well Written
Francis Moreau avatar

lunohodov · Feb 6, 2026, 04:19 AM

Francis,

I spent some time with the tool and while there are some small issues with translations, it’s already awesome! I’ve added it to my list of awesome resources. Thank you!

Be well, stay safe

I would be interested in knowing about any translation errors you have noticed.

Please let me know via private message.

Well Written Respectful
Rainer Ehlert avatar

Hi,

One more suggestion.

It would be good if I could change the time format to HH:mm:ss instead of AM and PM. Thanks

Gordon Pegue avatar

Would be useful to specify my location with Lat Long coordinates.

Rainer Ehlert avatar

Gordon Pegue · Feb 6, 2026, 11:44 PM

Would be useful to specify my location with Lat Long coordinates.

Well, I opened the map in Sky Compendium, zoomed in as max. as possible and was able to set my coordinates quite accurate.

JBNZ avatar

MATE!!!! I’ve been thinking of doing this with Gary’s awesome data for ages - I’m a web app dev by day. Your implementation looks great - will be using it heaps.

Thank you so much!

Francis Moreau avatar

Rainer Ehlert · Feb 6, 2026, 10:28 PM

Hi,

One more suggestion.

It would be good if I could change the time format to HH:mm:ss instead of AM and PM. Thanks

I'm not sure I understand, all times are in 24-hour format.

Dominik Weinbrenner avatar

Fabulous work! The spreadsheet really became a bit too swamped with amazing data.

I was wondering: Is there a way to display images ofn the targets right away in the dashboard? I think selecting a target by looks is an intuitive way of choosing.

Supportive
Rainer Ehlert avatar

Francis Moreau · Feb 9, 2026, 08:17 AM

Rainer Ehlert · Feb 6, 2026, 10:28 PM

Hi,

One more suggestion.

It would be good if I could change the time format to HH:mm:ss instead of AM and PM. Thanks

I'm not sure I understand, all times are in 24-hour format.

Hi Francis,
Look at the screenshot.
BTW, here it is a bit difficult to choose the values with the mouse pointer. Maybe a bit wider field for easier selecting? Thanks Rainer

đź“· image.pngimage.png

Francis Moreau avatar

Rainer Ehlert · Feb 6, 2026, 01:36 AM

Hi Francis,

As I have two piers in my Observatory and at certain positions the telescopes collide, I know I know, but this developed like this because when I planned the Observatory I did not expect to grow that much with the telescopes.

I would like to suggest, if possible, to be able to order the objects by RA and so I know if they will collide or not.

Thanks for this great job.

Done

Rainer Ehlert · Feb 9, 2026, 06:29 PM

Francis Moreau · Feb 9, 2026, 08:17 AM

Rainer Ehlert · Feb 6, 2026, 10:28 PM

Hi,

One more suggestion.

It would be good if I could change the time format to HH:mm:ss instead of AM and PM. Thanks

I'm not sure I understand, all times are in 24-hour format.

Hi Francis,
Look at the screenshot.
BTW, here it is a bit difficult to choose the values with the mouse pointer. Maybe a bit wider field for easier selecting? Thanks Rainer

đź“· image.pngimage.png

Done

Francis Moreau avatar

lunohodov · Feb 6, 2026, 04:19 AM

Francis,

I spent some time with the tool and while there are some small issues with translations, it’s already awesome! I’ve added it to my list of awesome resources. Thank you!

Be well, stay safe

Corrected

Rainer Ehlert avatar

Francis Moreau · Feb 9, 2026, 08:57 PM

Rainer Ehlert · Feb 6, 2026, 01:36 AM

Hi Francis,

As I have two piers in my Observatory and at certain positions the telescopes collide, I know I know, but this developed like this because when I planned the Observatory I did not expect to grow that much with the telescopes.

I would like to suggest, if possible, to be able to order the objects by RA and so I know if they will collide or not.

Thanks for this great job.

Done

Rainer Ehlert · Feb 9, 2026, 06:29 PM

Francis Moreau · Feb 9, 2026, 08:17 AM

Rainer Ehlert · Feb 6, 2026, 10:28 PM

Hi,

One more suggestion.

It would be good if I could change the time format to HH:mm:ss instead of AM and PM. Thanks

I'm not sure I understand, all times are in 24-hour format.

Hi Francis,
Look at the screenshot.
BTW, here it is a bit difficult to choose the values with the mouse pointer. Maybe a bit wider field for easier selecting? Thanks Rainer

đź“· image.pngimage.png

Done

Hi Francis,
Thanks. Looks great now and now one can see the values immediately.

Beautiful done.

This app has helped me a lot and now I can quickly see what arises in my Sky. Much better then trying to find something in my planetarium software. Also the ability to set ones horizon or limits, makes it a lot easier.

Some people say they need to see the object in their FOV but knowing ones FOV I think this is really not necessary. Maybe for big nebula? OK, I specielized on the Arp galaxies.

Great job

EchoTango avatar

Rainer Ehlert · Feb 7, 2026 at 01:12 AM

Gordon Pegue · Feb 6, 2026, 11:44 PM

Would be useful to specify my location with Lat Long coordinates.

Well, I opened the map in Sky Compendium, zoomed in as max. as possible and was able to set my coordinates quite accurate.

I am not able to change the location from my iPad. Seems to be a problem with “double-click to move pointer”.

Rainer Ehlert avatar

Hi Francis,

Just noticed that now I can sort also by Coordinates.

Thank you very much.

What I like most is that this application is not overloaded like Telescopius.com

The saying “Less is More” is completely true here

AndBergAstro avatar

Bonjour Francis

Je connais bien le compendium de Gary, et j’ai fait un fichier similaire pour chez moi selon mes différents équipements.

Ma situation est particulière car mon ciel azimutal visible n’est que de 0 à 180 degrés.

Serait-ce possible d’ajouter un filtre azimutal? Merci

André

Well Written
Sean Jackson avatar

This is superb. Thank you!