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Astronomy Mathematica Wolfram|Alpha Curated Data

Altitude of Polaris in Mathematica 10 and W|A

Hans Milton

Posted 11 years ago

For horizontal coordinates of stars, I have noted that StarData in Mathematica 10 returns values I don't expect. Taking a simple example, the altitude of Polaris. Regardless of date or time of day it will be close to the observers latitude. My home is near the 64th parallel. For latitude 64N, v9 gives a reasonable value: But not so in v10: And a query directly in W\|A gives the same, wrong, answer: Changing $GeoLocation has no effect

POSTED BY: Hans Milton

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Jeffrey Bryant

Jeffrey Bryant, Wolfram|Alpha, LLC

Posted 11 years ago

With this week's push to production, these inputs should now work with the "Location" qualifier specified: StarData["Polaris", EntityProperty["Star", "Altitude", {"Date" -> DateObject[{2014, 7, 31, 22, 30, 0}], "Location" -> GeoPosition[{64, 20}]}]] PlanetData["Mars", EntityProperty["Planet", "Altitude", {"Location" -> Entity["City", {"NewYork", "NewYork", "UnitedStates"}]}]]

With this week's push to production, these inputs should now work with the "Location" qualifier specified:

StarData["Polaris", 
 EntityProperty["Star", 
  "Altitude", {"Date" -> DateObject[{2014, 7, 31, 22, 30, 0}], 
   "Location" -> GeoPosition[{64, 20}]}]]

PlanetData["Mars", 
 EntityProperty["Planet", 
  "Altitude", {"Location" -> 
    Entity["City", {"NewYork", "NewYork", "UnitedStates"}]}]]

POSTED BY: Jeffrey Bryant

Jeffrey Bryant

Jeffrey Bryant, Wolfram|Alpha, LLC

Posted 11 years ago

`AstronomicalData[]` used `$GeoLocation` to determine your location. Wolfram\|Alpha as well as `StarData[]`, etc. don't use `$GeoLocation`, they make use of what the Alpha server thinks your location is based on GeoIP. It would be useful to know what you get when you go to Alpha and enter "where am I" to see what latitude/longitude it thinks you are at. Your input for StarData has an extra set of curly brackets so the location qualifier is being ignored as a result. It should be part of the list that contains the "Date", so {"Date" -> <blah>, "Location" -> <blah>} instead of {"Date" -> <blah>}, {"Location" -> <blah>} however, even when using the correct form, this results in an unknown Qualifier message that is being investigated.

POSTED BY: Jeffrey Bryant

Hans Milton

Posted 11 years ago

This is what I get from "where am I" on my home PC: My internet provider is registered in Stockholm, but I live 500 km more to the North. If I make the "where am I" query on my PC at work, I get the IP address only. Nothing else. On both PC's, the Polaris altitude W\|A query gives values close to the latitude of Stockholm. In Mathematica: FindGeoLocation[ ] returns {63.83, 20.25} on my home PC. And that is about right. But on my PC at work I get {62, 15} from FindGeoLocation[ ].

POSTED BY: Hans Milton

Jeffrey Bryant

Jeffrey Bryant, Wolfram|Alpha, LLC

Posted 11 years ago

If you want to get your Alpha query to support a different observation location than where it thinks you are, you need to modify the input string to include a hard coded date and location such as here: http://www.wolframalpha.com/input/?i=altitude+polaris+on+July+31+2014+22%3A30+from+lat+64+long+20 time zone isn't specified so it should default to your time zone. As for getting the StarData query to work with the "Location" qualifier, it's being looked into.

POSTED BY: Jeffrey Bryant

Hans Milton

Posted 11 years ago

Jeff, thanks a lot for quick answers. My interest is in applications of Mathematica. Not W\|A as such. So for for the moment I will use v9's AstronomicalData. When I need a stars horizontal coordinates. Practically, it works just fine. But to me this appears as a regression. From v9 to v10. Horizontal coordinates are referenced to a particular position on the globe. So its meaningless to ask for the coordinates. If you are not able to clearly specify your location.