Re: String representations of numeric values

From: Thomas McGlynn <tam-at-lheapop.gsfc.nasa.gov>
Date: Fri, 21 Apr 2006 08:48:00 -0400

Clive Page wrote:

> On Thu, 20 Apr 2006, Roy Williams wrote:
>

>> Who is writing VOTables with sexagesimal in them? Surely the best 
>> thing is to convert to decimal as soon as possible, and convert back 
>> to sexagesimal (if wanted) at the last possible moment before the 
>> human eyes see it.

>
>
> Roy (et al)
>
> I agree with you for newly created VOTables, but I suspect that for some
> time converted FITS tables will be encountered quite frequently.
> Unfortunately this is an issue with which the FITS community has failed
> to deal, and it is a serious one. If you look at the thousands of
> tables in the Vizier collection, for example, you will find a
> substantial number (perhaps 30%) have celestial coordinates not in
> decimal but in sexagesimal, and in an amazing variety of formats (with
> minutes and decimals or minutes and seconds, with colons or spaces as
> separators, etc).
>

Hi Clive,

Right now is the only opportunity we will have to fix this problem. All VOTables have been created within the past few years. We have a chance to establish a standard (and I confess I had thought we had done so at least for the cone search and SIA services). If we allow a variety of formats for the times and positions then we will be saddled with them forever. The 'failure' of the FITS community should inspire us to do better! Providers have to build software to create VOTables, and they are the ones who know best how to convert the data to a standard format. Vizier's approach of adding a new column which gives the positions in the standard format while retaining a string to ensure historical continuity is great, but software that uses coordinates should find them in a standard format.

        Tom Received on 2006-04-21Z14:49:04