Re: Adjusting dial to new location
For complete generality: If your sundial was made for a latitude greater then yours by an amount called “DeltaLat” (which could be positive or negative), & if you want the dial to give LTST for a longitude 7 degrees west of yours (maybe because that’s your standard-meridian), then: After the tip, the initially-top-point of the sphere with a great-circle coinciding with the circumference of your circular dial-plate will have equatorial-coordinates of: (Lat+DeltaLat, 7). After that, it’s exactly as I said. On Sun, Apr 9, 2023 at 14:09 Steve Lelievre wrote: > > On 2023-04-08 8:52 p.m., Michael Ossipoff wrote: > > I know you said you wanted a link, not instructions, but people have been > suggesting how to achieve dial-autocorrection to Local True Solar Time > (LTST) at the standard-meridian, instead of one’s own meridian. So I felt > that it would be justified to comment about it. > > Michael, > > To me, your case seems to be a specific instance that is covered by the > general case - have I missed something? > > As things stand, I think I know the math involved because I have from the > article by Fred Sawyer that I mentioned in a previous email. It describes > the solution for the general case - we start with a dial at some latitude > and longitude that shows the solar time at some other longitude, which may > or may not be zero offset. We want to move it to a new latitude and > longitude and to show the solar time at some new 'other' longitude, which > may or may not have zero offset from the new location. As well, the article > by Fabio Savian, mentioned in his post, also discusses dial relocation. > (BTW, for NASS members, Fabio only mentioned his article in its Italian > version, but as well he kindly provided an English equivalent which was > included in the most recent issue of the Compendium) > Everyone, > > Since I'm writing this post, I'll take the opportunity to mention that I > have made a couple of small adjustments to my online wedge calculator, > gnomoni.ca/wedge . My thanks go to Roderick Wall for helping me make it > better for the southern hemisphere. Please let me know if you spot any > issues. > > > Steve > > > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Adjusting dial to new location
Yes, I spoke of a special-case in which you’re 7 degrees east of your standard-meridian. …for a concrete example. But the rest of what I said was for the general-case in which you want the dial to read in the LTST at your standard-meridian. But yes, I didn’t speak of when the dial is made for a different latitude *and* you want standard-meridian LTST. I thought that it was just about getting the standard- meridian LTST. …something I wouldn’t do anyway. On Sun, Apr 9, 2023 at 14:09 Steve Lelievre wrote: > > On 2023-04-08 8:52 p.m., Michael Ossipoff wrote: > > I know you said you wanted a link, not instructions, but people have been > suggesting how to achieve dial-autocorrection to Local True Solar Time > (LTST) at the standard-meridian, instead of one’s own meridian. So I felt > that it would be justified to comment about it. > > Michael, > > To me, your case seems to be a specific instance that is covered by the > general case - have I missed something? > > As things stand, I think I know the math involved because I have from the > article by Fred Sawyer that I mentioned in a previous email. It describes > the solution for the general case - we start with a dial at some latitude > and longitude that shows the solar time at some other longitude, which may > or may not be zero offset. We want to move it to a new latitude and > longitude and to show the solar time at some new 'other' longitude, which > may or may not have zero offset from the new location. As well, the article > by Fabio Savian, mentioned in his post, also discusses dial relocation. > (BTW, for NASS members, Fabio only mentioned his article in its Italian > version, but as well he kindly provided an English equivalent which was > included in the most recent issue of the Compendium) > Everyone, > > Since I'm writing this post, I'll take the opportunity to mention that I > have made a couple of small adjustments to my online wedge calculator, > gnomoni.ca/wedge . My thanks go to Roderick Wall for helping me make it > better for the southern hemisphere. Please let me know if you spot any > issues. > > > Steve > > > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Adjusting dial to new location
On 2023-04-08 8:52 p.m., Michael Ossipoff wrote: I know you said you wanted a link, not instructions, but people have been suggesting how to achieve dial-autocorrection to Local True Solar Time (LTST) at the standard-meridian, instead of one’s own meridian. So I felt that it would be justified to comment about it. Michael, To me, your case seems to be a specific instance that is covered by the general case - have I missed something? As things stand, I think I know the math involved because I have from the article by Fred Sawyer that I mentioned in a previous email. It describes the solution for the general case - we start with a dial at some latitude and longitude that shows the solar time at some other longitude, which may or may not be zero offset. We want to move it to a new latitude and longitude and to show the solar time at some new 'other' longitude, which may or may not have zero offset from the new location. As well, the article by Fabio Savian, mentioned in his post, also discusses dial relocation. (BTW, for NASS members, Fabio only mentioned his article in its Italian version, but as well he kindly provided an English equivalent which was included in the most recent issue of the Compendium) Everyone, Since I'm writing this post, I'll take the opportunity to mention that I have made a couple of small adjustments to my online wedge calculator, gnomoni.ca/wedge . My thanks go to Roderick Wall for helping me make it better for the southern hemisphere. Please let me know if you spot any issues. Steve --- https://lists.uni-koeln.de/mailman/listinfo/sundial
