Saturday, March 27, 2021

shared Stellarium searching tips

Had a very interesting conversation with John D today.

Reacting to my double stars bulletin in the RASC Toronto Centre forums, he said he was going to start trying double star observing, particularly given his bright urban skies. 

Woo hoo! Another double star disciple!

Then he asked me,

Can you give me a tip as to what search in Stellarium is best used to find the objects [you listed for us].  In other words, which catalog or catalogs and what level of objects need to be downloaded into Stellarium to find them.

I shared that I thought searching for doubles in Stellarium is straight-forward.

No download required. 

Step one is to get into the Search window in Stellarium. F3 or Ctrl-F or the magnifying glass button in the left toolbar. And let's simply use the "standard" way, the Object tab, in the Search window.

Then key in the "name."

I used the example HR 2174 Orionis also known as Σ855 (Struve, STF), SAO 113507, and HIP 29151.

If one searches for "HR 2174" (without the quotes), we will land at the correct double star system near Betelgeuse. And, in fact, Stellarium will show the alternate designations including the Struve number, the SAO code, and the HIP number.

I pointed out things are a little tricky with Greek letters. I show the double above with the common symbol, the upper case Greek letter Sigma: Σ855. That's the official double star designation according to the Washington Double Star (WDS) database. 

Sadly, I relayed, many software programs don't recognise Greek characters in search tools! That's why I show "Struve" (the discoverer name) and "STF" (the WDS discoverer code) as alternates. 

It is curious that Stellarium does not recognise "STF 855" or "Struve 855" while searching! That's disappointing to me, especially when it pings SIMBAD. I explained however that if one knows their Greek alphabet, they can click on the lower case sigma (σ) in the Stellarium search window and follow it with the numbers. It works!

Sidebar: Learn Greek.

All this showed we don't need to fiddle with anything. We don't need to load certain catalogues or search specific catalogues. The "normal" search process in Stellarium finds objects across different star and DSO and SSO catalogues.

searching for doubles in Stellarium

To John, I explained my reason for providing the alternate names for my double star suggestions. It allows for searching in case one method doesn't work. And it depends, in the end, on the specific software or hardware. Any of the designations I show above should work using SkySafari, SkyTools, TheSky, Cartes du Ciel, Starry Night, etc. But what about hand controllers at the telescope. The SAO and HIP numbers are there because hand controllers have (very) limited catalogues (compared to computers). My HC for example does not use HIP numbers.

John was happy. "This more than helps." Then he said, 

It's maybe just me, but if you don't regularly share out this nifty instruction, I would suggest you do that.  It would be a great resource to link to.

Good idea.

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