Has anyone ever used Jerry Wahl's Excel Spreadsheet that helps plan Polaris shots? He apparently updated the data file for 2015, but it says it's a zipped file, but downloads as an "EP", which I haven't been able to import into the spreadsheet at all, let alone properly formatted.
I've sent him a few emails, but he must be away on vacation or something (can't blame him). The file is here, in the "CEFB" link.on the www.cadastral.com web site. (( http://www.cadastral.com/2015ephs.htm).
Any clues as to what I'm doing wrong are appreciated.
If you change 2015.EP to 2015_EP, you can open the file with Notepad. It is legible in Excel, but not separated properly into cells.
Cheers,
Henry
2015 Polaris Ephemeris problem
I'm not familiar with CEFB. But here's that file reformatted as a csv. I hope Jerry doesn't mind. Note that the angle data is in packed degrees/hours minutes seconds format and not decimal values. That means more work if using it in Excel.
https://dl.dropboxusercontent.com/u/25124076/2015_EP.csv
If you prefer the minutes and seconds in separate columns,
https://dl.dropboxusercontent.com/u/25124076/2015_EP_unpack.csv
You can get the headings on the columns from the web format link, which is easier to read, although only a month at a time.
Pssst...
...the plural of ephemeris is ephemerides, not ephemerii, which isn't a word.
Pssst...
> ...the plural of ephemeris is ephemerides, not ephemerii, which isn't a word.
Want to hear something funny? I wrote the title of the thread ephemerides...then uploaded the link and saw that the "word" ephemerii was used. I hesitated a moment because I didn't think it was right, but hey, it's on the WEB, right?, and changed it to that, lol.
2015 Polaris Ephemeris problem
> I'm not familiar with CEFB. But here's that file reformatted as a csv. I hope Jerry doesn't mind. Note that the angle data is in packed degrees/hours minutes seconds format and not decimal values. That means more work if using it in Excel.
> https://dl.dropboxusercontent.com/u/25124076/2015_EP.csv
>
> If you prefer the minutes and seconds in separate columns,
> https://dl.dropboxusercontent.com/u/25124076/2015_EP_unpack.csv
>
> You can get the headings on the columns from the web format link, which is easier to read, although only a month at a time.
That's a start. At least I know now it can be mushed about and gotten into Excel. Now I can't figure out how to strip out all the Sun columns. All I'm looking for at the moment is Polaris, as in this screen shot from the data tab in Jerry's workbook:
I know I can probably cut the data out on each of 365 lines and paste the rest in, bu Is there an automated way I can do it?
2015 Polaris Ephemeris problem
Maybe I don't understand the question, but if it reads into Excel satisfactorily you can just select columns you don't want and delete them.
2015 Polaris Ephemeris problem
> Maybe I don't understand the question, but if it reads into Excel satisfactorily you can just select columns you don't want and delete them.
Oops. My bad. I clicked the link and it opened "in line" rather than download the file. It looked like just rows of data.
Once I downloaded the file as a .csv, I'm good to go (for the moment, at least:-/ ). Thanks for your help!
Excel DDMMSS to Decimal DD.xxxxxx
> I'm not familiar with CEFB. But here's that file reformatted as a csv. I hope Jerry doesn't mind. Note that the angle data is in packed degrees/hours minutes seconds format and not decimal values. That means more work if using it in Excel.
> https://dl.dropboxusercontent.com/u/25124076/2015_EP.csv
>
> If you prefer the minutes and seconds in separate columns,
> https://dl.dropboxusercontent.com/u/25124076/2015_EP_unpack.csv
>
Well, this sure turned out to be an endeavor. I tried using an excel formula someone here linked me to (can't remember who), but it's rounding the numbers or something. The results don't match.
Does anyone have a known, good Excel degrees-minutes-seconds to decimal degrees formula? (Or, a 2015 Polaris GHA and Declination Ephemeris in Decimal format)? I've tried to output the info in the right format using MICA, but that's not working.
Excel DDMMSS to Decimal DD.xxxxxx
Can't you use the unpacked version of the csv file in my second link?
for decimal degrees
=L3+M3/60+N3/3600
Excel DDMMSS to Decimal DD.xxxxxx
I tried to compare results from MICA to Wahl's results, but I MICA offers a choice of several reference frames (apparent or astrometric, geocentric or topocentric, etc.) and I couldn't figure out what reference frame Wahl used.
Excel DDMMSS to Decimal DD.xxxxxx
> I tried to compare results from MICA to Wahl's results, but I MICA offers a choice of several reference frames (apparent or astrometric, geocentric or topocentric, etc.) and I couldn't figure out what reference frame Wahl used.
I used "Apparent Topocentric Local Horizon". Last fall when I did this using Wahl's spreadsheet, the numbers matched nicely. Now, I used Bill93's formula to convert GHA and Dec to decimal, then cut and paste the two columns of data into Wahl's spreadsheet, but the numbers don't match. I used 1/1/2015 at 1600 hrs. I get 48' and change in Wahl's sheet, but 39' in MICA.
Not quite sure what the problem is yet. Did you get the data for 2015 into his sheet?
Excel DDMMSS to Decimal DD.xxxxxx
My initial reply is that I think the appropriate frame of reference to use is apparent geocentric. I wouldn't use topocentric because a paper ephemeris, or an electronic ephemeris that isn't custom-calculated for a particular place on the surface of the earth, does not take into account the location of the observer. I would not use the astrometric frame of reference, because I believe that is computed with respect to the equator and equinox in January of 2000, which wouldn't be appropriate. I'll try a few things and add to my reply.
Excel DDMMSS to Decimal DD.xxxxxx
> My initial reply is that I think the appropriate frame of reference to use is apparent geocentric. I wouldn't use topocentric because a paper ephemeris, or an electronic ephemeris that isn't custom-calculated for a particular place on the surface of the earth, does not take into account the location of the observer. I would not use the astrometric frame of reference, because I believe that is computed with respect to the equator and equinox in January of 2000, which wouldn't be appropriate. I'll try a few things and add to my reply.
If I'm not mistaken, both MICA and Wahl's spreadsheet allow for input of local position (in LAT and LONG). That said, would not "Geocentric" be referenced from the center of the earth, and Topocentric be referenced from you local position?
The whole point of Wahl's spreadsheet is to pre-calculate pointing angles to the star from where you are. If I have "Topo" and "Geo" mixed up, please slap me side the head.
Excel DDMMSS to Decimal DD.xxxxxx
I've made an Excel spreadsheet attempting to compare results from MICA and Wahl for 5 dates in 2015, spaced 90 days apart (which is easy in MICA; MICA doesn't like monthly or quarterly intervals).
Numbers still don't match
> I've made an Excel spreadsheet attempting to compare results from MICA and Wahl for 5 dates in 2015, spaced 90 days apart (which is easy in MICA; MICA doesn't like monthly or quarterly intervals).
That's very curious.
Are you sure the MICA numbers are in DDMMSS as are Wahl's (in your spreadsheet).
I'd *really really* like to get the sheet set up properly. You'd think that with something as known and stable as astronomical observations, there wouldn't be much disagreement. Maybe this area falls into that general idea that if you ask 10 surveyors the same question, you'll get..."It depends" 6 out of the 10, 2 "yes's" and 2 "no's":-D
Numbers still don't match
I forgot that Wahl's csv file used packed degrees, minutes, and seconds. Also, I had a wrong date in my spreadsheet. After I made the appropriate corrections, there is good agreement between MICA and Wahl's results.
I haven't found Wahl's spreadsheet that allows input of the observer's coordinates. The csv file is designed for any user anywhere, so must present results for an imaginary observer at the center of the earth. Also, the surveyor ultimately wants results elevation relative to the horizon and azimuth measured from the north pole along the horizon, but this isn't possible when the observer's location isn't known, so the north pole and equator are used in the csv file.
Excel DDMMSS to Decimal DD.xxxxxx
>1/1/2015 at 1600 hrs. I get 48' and change in Wahl's sheet, but 39' in MICA.
I tried SPADE, another (old) DOS program. I wouldn't trust it this many years later for solar without some checking, but it ought to be good for Polaris.
1/1/2015 16:00 UT
location 43 40 30 N 072 35 03 W (somewhere near rfc) azimuth 000 39 11
Wahl's spreadsheet
> I haven't found Wahl's spreadsheet that allows input of the observer's coordinates.
It's very cool (when all the tables are set up properly, lol). I'd post it, but I can't really remember if he sent it to me personally, or someone here linked to the file. If he surfaces, he can weigh in on whether we can post it.
It allows you to "pre-calculate" the location of the star at the time of the expected observation, then, in another section, you can input your actual measurements and it will do the math. All that's left is the Convergence and LaPlace.
Check your email.
Excel DDMMSS to Decimal DD.xxxxxx
> 1/1/2015 16:00 UT
> location 43 40 30 N 072 35 03 W (somewhere near rfc) azimuth 000 39 11
Thanks! We'll go with two out of three. I'll keep mushing the data until I get the right angle. I have probably a month to figure it out (when the average temperatures get back up to a reasonable level for Polaris observations.:-)