Astro Mosaic Telescope Planner


Link to AstroMosaic page.


Source code in GitHub.



Astro Mosaic is a tool for planning telescope observations. It shows a visual view of the target using a selected telescope, visibility during the night and it can calculate mosaic coordinates.

Tool includes

Multiple telescope services

Currently Astro Mosaic supports Slooh and Telescope Live telescopes. You can also add your own telescope (see below).

Telescope field of view

AstroMosaic can show telescope field of view and mosaic grid view.

Night and year visibility

AstroMosaic can show target visibility for a given night and also visibility for next 12 months. Also moon altitude, phase and distance from the target is shown.

Sky map view with multiple catalogs

Astro Mosaic supports Messier, NGC, IC, Sharpless, RCW and Slooh 500 catalogs. All catalog object names are added as a catalog layer to the map view. Each catalog object name is written next to that object on a map to make it easier to identify major objects in a map. Catalog map layers are disabled by default.

There are a total of 13959 NGC and IC objects that can be shown on the map. Sharpless catalog has 313 objects listed mostly from the northern hemisphere. RCW catalog has 182 objects listed mostly from the southern hemisphere. RCW catalog includes also objects from the Gum catalog.

Catalog object markers are clickable. When you click on a marker a short info is written on the panel to the right side of the map. If the Wiki check box is checked then the Wikipedia page of that object is shown when possible.

Additional controls on the map

Filtering in catalog list

It is possible to filter catalog lists in a few ways.

Filtering points are calculated at midnight and then two and four hours before and after midnight. So in some cases it is possible that a target is not listed if it will match the filter only between those calculated points.

Configuring and embedding Astro Mosaic

Configuring Astro Mosaic using URL parameters or embedding it to a page is described in a separate document Astro Mosaic Configuration. It is possible for example to add your own camera and lens or telescope to Astro Mosaic.

Aladin API for visual view of target

Astro Mosaic would not be possible without Aladin Sky Atlas and Aladin Lite. Aladin Sky Atlas is a great interactive map created from digitized astronomical images. It is simply amazing that such a great resource is available. And it is totally free!

Aladin Lite provides HTML5 and programmable Javascript API interface to Aladin Sky Atlas. It makes it very easy to integrate into a web page. There are great examples and documentation to get started very quickly.

For displaying images Aladin Lite uses preprocessed data from HiPS. HiPS (Hierarchical Progressive Surveys) is the hierarchical tiling mechanism which allows users to access, visualize and browse seamlessly image, catalogue and cube data. There are 250TB of data available from different HiPS surveys.

Sesame Name Resolver

Astro Mosaic uses Sesame service for resolving names. When a name like m101 is written into the target input box, a query is sent to the Sesame server to resolve the name. As a result Sesame server will return an XML page that contains target RA/DEC coordinates among other things. Sesame is actually an interface to other name resolvers: Simbad, NED and VizierR.

Calculating position of sun, moon and planets

There are very good resources available to calculate sun, moon and planet positions at a certain time and place. In Astro Mosaic that information is used to calculate for example moon position and altitude during the night, sun rise and set times and moon phase.

Perhaps the best resource is a page How to compute planetary positions written by Paul Schlyter. It has a lot of good and practical information. He has also another page Computing planetary positions - a tutorial with worked examples that has similar information. Those pages have all required information on orbital elements, coordinate transformations and such.

Moon phase

Moon phase shown in Astro Mosaic is based on it's own calculations so it may not be exactly correct. It was very difficult to find a good example on that so Astro Mosaic just calculates the angle between sun and moon as seen from earth. That angle is then used to calculate moon phase.

When the moon and sun are on the same side angle is zero degrees and moon phase is 0%, when they are on opposite sides the moon phase is 100% and when angle is 90 degrees phase is 50%. And other vales are between those.

Wiki interface

Astro Mosaic can optionally show a Wiki page of the target. Wikipedia has an API that can be used to find a page id based on a search text. A surprisingly large number of Messier, NGC and IC targets has its own page at Wikipedia. If a page id is found then a mobile version of that page is shown in an own frame.

Astro Mosaic does some basic parsing on names before they are sent to Wikipedia search. For example messier objects can be written as m101 but they are translated to Messier 101. Also NGC and IC objects are formatted slightly before sending to Wikipedia.