INFO
Tool to view and calculate coordinates for astro image mosaics using Slooh telescopes.
Tool includes
- Visual view of target using Aladin Sky Atlas
- Target name resolution using Sesame interface
- Field of View (FoV) view of target with a chosen Slooh telescope
- View and calculate mosaics coordinates up to 10x10 size
- Target visibility during the night
- Moon altitude and distance from the target
- Target and moon altitude over next 12 months
- Slooh 500 list for selecting the target
- Filtering of Slooh 500 list based on altitude, time and distance from the moon
- Multiple target coordinate formats are supported:
- HH:MM:SS DD:MM:SS, HH MM SS DD MM SS
- HH:MM:SS/DD:MM:SS, HH MM SS/DD MM SS
- HHMMSS DDMMSS, HH.dec DD.dec
- A comma separated list can be given to show multiple targets
- Wiki interface to show target information
- Show Slooh 500 object names on a map (optional, enabled by default)
- NGC, IC, Sharpless and RCW object names on a map (optional, disabled by default)
- Object markers are clickable and print short info or a Wiki page
- Full screen control to show a bigger view of the map
- Control to change the map view
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 target input box, a query is sent to 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 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 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.
Map view with Slooh 500, NGC, IC, Sharpless and RCW catalogs
All Slooh 500 object names are added as a catalog layer to the map view. Each Slooh 500 object name is written next to that object on a map to make it is easier to identify major objects in a map. Slooh 500 catalog layer is enabled by default. Teide and Chile scopes have a different list of Slooh 500 objects.
NGC and IC catalog objects, Sharpless catalog objects and RCW catalog objects are available as layers to the map view. 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. These layers are not enabled by default.
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.
Two new controls are added to the map
- Catalog layer control button on the upper left corner can be used to enable or disable map layers. Also the base map can be changed there.
- A button to control full screen mode is at the upper right corner of the map. This makes it easier to see a bigger picture when browsing the map.
Filtering in Slooh 500 list
It is possible to filter Slooh 500 list in a few ways.
- First filter is altitude where you decide how high the target need to be during the night to be shown in the list.
- Then it is possible to filter by time. If there is for example only a specific time slot available the time filter c an use used to show what other filter conditions are met at that specific time.
- With a moon filter it is possible to show only those targets that have at least the given distance from the moon. If the moon is up it can be useful for example to pick only targets that are at least 90 degrees from the moon.
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.
Coloring of Slooh 500 list in the sky map
If there is some filtering on Slooh 500 targets, in the sky map target names that match the filter are printed in green color and targets that do not match the filter are written in red color. When browsing the sky map it is sometimes useful to see for example which targets are higher than 60 degrees on the sky.
Slooh Chile 2 Telescope
New Slooh Chile 2 telescope is added to AstroMosaic. It has a wide field of view of southern sky. It is a bit unclear if and when a focal reducer will be attached to the new Chile Two scope. AstroMosaic has both versions listed.
- C2 is without the focal reducer and 0° 43’ 00" Field-Of-View.
- C2FR is with the focal reducer installed and 0° 65’ 00" Field-Of-View.
Credits
- Interactive sky map is from Aladin Sky Atlas and Aladin Lite
- Name resolving by Sesame service
- Calculating position of sun and moon from Paul Schlyter How to compute planetary positions
- Slooh 500 list is from Slooh
- NGC and IC data from OpenNGC by Mattia Verga
- NGC and IC object distances are from Revised NGC/IC Data by Dr. Wolfgang Steinicke
- Sharpless data from The Best of Sharpless Catalog
- RCW data from Vizier
- RCW catalog B1950 coordines converted to J200 using info from Astronomical Coordinate Calculator version 0.31