Flatangle Charts - High quality charts

jventura · Joined: 04 Jan 2011 Posts: 294 Location: Portugal

Hello everyone,

I'm happy to announce a new update to the Charts web app! It features a redesigned interface and some minor error corrections. Smile

Find it at http://apps.flatangle.com/Charts/

Enjoy,
Jo�o Ventura

Astraea · Joined: 04 Oct 2004 Posts: 358 Location: Colorado, USA

I just want to thank you again for this lovely, much-needed web app. Having the terms present on the chart is so helpful, and the form and fonts are beautiful.

Martin Gansten · Posted: Thu Mar 19, 2015 6:05 pm Post subject:

Indeed, it looks great. I'd love to use it, and so, I'm sure, would many others who use a sidereal zodiac (which, incidentally, is the zodiac in which the terms first appeared). Any chance of an ayanamsha feature, Jo�o?
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pankajdubey · Joined: 17 Nov 2006 Posts: 1229 Location: Delhi

jventura · Joined: 04 Jan 2011 Posts: 294 Location: Portugal

Martin Gansten · Posted: Fri Mar 20, 2015 9:00 am Post subject:

jventura · Joined: 04 Jan 2011 Posts: 294 Location: Portugal

skyrack · Joined: 02 Aug 2012 Posts: 192 Location: Thailand

Jo�o and Zoidsoft,

I have recently been working with Paul Schlyter's algorithms for calculating planetary positions.
This is, I believe, based on Jean Meeus's Astronomical Algorithms which zoidsoft has mentioned using.

And I have been using Michael P. Munkasey's House Formulary for calculating MC and ASC.

The algorithms for calculating planetary positions are producing good results, but when comparing my calculated MC and ASC to those produced by Astrodienst there is a difference that cannot be ignored.

I note that flatangle also produces MCs and ASCs slightly different from Astrodienst (about half of a degree in the one chart I have compared).

This may be only a slight discrepancy but these are important angles and given the same data of time and place I would expect results to be the same to within 1 arc second.

Adding the Local Sidereal Time to the flatangle chart would be useful.

Any help anyone can offer on calculating the MC and ASC would be more than welcome.

Jo�o please don't take my criticism the wrong way. What you have done is quite illuminating especially with the terms and decans included.

jventura · Joined: 04 Jan 2011 Posts: 294 Location: Portugal

zoidsoft · Joined: 10 Feb 2006 Posts: 1037 Location: Pulaski, NY

Time zone being off by 1 hour usually produces an ascendant difference of 10-20 degrees. I'd check the location data next to make sure that latitude and longitude are correct. One factor that affects the ascendant is delta time which is estimated differently depending upon the source and the era. In the Swiss Ephemeris this is calculated automatically in the conversion from UTC to ephemeris time and the function used to calculate house cusps can use either ephemeris time or universal time. A possible error here is using one time standard when another is called for. A difference of 1/2 degree is about 2 minutes of clock time.
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Curtis Manwaring
Zoidiasoft Technologies, LLC

jventura · Joined: 04 Jan 2011 Posts: 294 Location: Portugal

Hi Curtis,

in this case it was simply a problem with the location data..

Jo�o Ventura

skyrack · Joined: 02 Aug 2012 Posts: 192 Location: Thailand

Yes, I had made a small error in the location coordinates which caused the discrepancy. Thanks to Jo�o for looking into it.

Zoidsoft,

Delta time - is that the same as the Equation of Time?

Skyrack

zoidsoft · Joined: 10 Feb 2006 Posts: 1037 Location: Pulaski, NY

skyrack · Joined: 02 Aug 2012 Posts: 192 Location: Thailand

Thanks a lot!.

That degree of technicality was just what I wanted.
Thanks again for clarifying that.

Skyrack