----- Original Message ---- > From: luzius.thuerlemann <[email protected]> > > Thanks very much! Everything is working fine. But I have still one question. > Do > you have an idea how I could accurately measure the altitude of my horizon? I > own a small Alt-Az-Telescope, but how do I make sure that the > Azimut-direction > is the right one? I mean, I only can estimate it visually with a compass. But > I'd like to look up in CdC when (in clearly-sub-minute accuracy) e.g. a > planet > or a star appears behind a mountain to be able to prepare for events that > might > happen. Any idea? Maybe something with GoogleEarth?
Using Google earth would be tricky since the I think the altitude (height, not angle) numbers reported are probably not very precise, and have limited spatial (lat, long) resolution. If some of your limiting horizon is close, it would not be very accurate. And if that horizon includes growing trees, the height (and angle) will vary over time. As Sander and Chris suggested, just use the equipment you have - your scope and CdC. I haven't used the app they mentioned, but done manually, it would work like this: If your scope is computerized, you can read out alt-az numbers directly from the keypad as you point to the "limiting points" on your horizon (one catch here: many computerized scopes use alignment methods that can correct for a tilted tripod, but in some cases the alt/az numbers they report are "relative to the mount", not true alt-az. In that case, taking a few minutes to level your tripod with a carpenter's level when setting up would help make sure the reported alt-az numbers are accurate (for other purposes, levelling is _normally_ not critical for most computerized mounts, despite the persistent online urban legend). If your scope is not computerized, you could still look at the parts of the sky near your "horizon points" with your scope, and find them on the CdC screen, to find the alt-az numbers for those points. -John > --- In [email protected], John Mahony wrote: > > > > ----- Original Message ---- > > > > > From: luzius.thuerlemann > > > > > > Hi John > > > > > > You write that the chart must be in Alt-Az to be able to show the local > horizon. > > > > Yes. The display has two modes, either alt-az (zenith is up, and either > alt-az or eq grid or both can be displayed, and the horizon is shown) or > equatorial (celestial north is up, and only the eq grid can be displayed, and > the horizon is not shown). Patrick used various names for these modes, but > click the icon with the two curved blue arrows, normally in the middle of the > right toolbar. > > > > > I now tried to alter the Alt-numbers in the horizon_Geneve-file and saved > > > it > > > > under another file-name...so the Geneve-file isn't overwritten. But for > > > some > > > > reason, neither my own trial-horizon nor the Geneve-horizon is displayed > > > on > the > > > chart. > > > Also, I can only display the Equatorial grid but not the Azimutal one, > although > > > both are activated under "lines". > > > > That means the chart is in eq display mode. You need to switch to alt-az > mode. > > > > -John > > > > > > > About my trial-horizon-file: starting Azimut is 0, ending one 359. > > > > > > Thanks > > > > > > Luzius > > > > > > > > > > > > --- In [email protected], John Mahony wrote: > > > > > > > > That looks like the same format as for v2.76. It's a text file with > > > > the > > > alt-az numbers. See the help file. > > > > > > > > But even without this, there is a "default" horizon at alt=0, when you > have > > > CdC set to show an alt-az view. So this much should work even without > making > > > your own horizon file. This (or a custom horizon, if you make your own > file) > > > will only show in alt-az display mode. > > > > > > > > In the "chart appearance" window, check the horizon details shown at > > > > the > > > bottom. The "invisible" checkbox doesn't mean what it sounds like. It > makes > > > the sky (below the horizon) invisible, so you just see the (normally) > > > green > > > ground below alt=0. But if you uncheck it, it makes the ground > > > semi-transparent, so you can see stars through the colored ground. > > > > > > > > -John > > > > > > > > > > > > > > > > > > > > ----- Original Message ---- > > > > > From: Graham > > > > > To: [email protected] > > > > > Sent: Wed, December 23, 2009 7:03:26 AM > > > > > Subject: Re: [skychart-discussion] local horizon creation > > > > > > > > > > Hi Luziuz, > > > > > I managed to do it in version 3 not sure about 2.76c, it like doing a > html > > > image > > > > > map, below is the part from the help file, the contents of my horizon > file > > > is > > > > > this: > > > > > > > > > > # Horizon description file for Carte du Ciel > > > > > # > > > > > # File format : > > > > > # Azimuth(integer) Altitude > > > > > # > > > > > # Be sure to begin at the North horizon (azimuth 0) > > > > > # Intermediate missing value are interpolated > > > > > > > > > > 0 25 > > > > > 5 24 > > > > > 10 20 > > > > > 15 16 > > > > > 20 15 > > > > > 25 20 > > > > > 30 15 > > > > > 35 10 > > > > > 40 24 > > > > > 45 24 > > > > > 50 24 > > > > > 55 24 > > > > > 60 24 > > > > > 65 24 > > > > > 70 19 > > > > > 75 5 > > > > > 80 7 > > > > > 85 5 > > > > > 90 15 > > > > > 95 15 > > > > > 100 10 > > > > > 105 10 > > > > > 110 8 > > > > > 115 8 > > > > > 120 8 > > > > > 125 10 > > > > > 130 50 > > > > > 135 50 > > > > > 140 50 > > > > > 145 50 > > > > > 150 55 > > > > > 155 60 > > > > > 160 80 > > > > > 165 80 > > > > > 170 80 > > > > > 175 80 > > > > > 180 80 > > > > > 185 80 > > > > > 190 80 > > > > > 195 80 > > > > > 200 80 > > > > > 205 80 > > > > > 210 80 > > > > > 215 80 > > > > > 220 80 > > > > > 225 80 > > > > > 230 80 > > > > > 235 80 > > > > > 240 80 > > > > > 245 80 > > > > > 250 80 > > > > > 255 80 > > > > > 260 80 > > > > > 265 80 > > > > > 270 70 > > > > > 275 64 > > > > > 280 55 > > > > > 285 45 > > > > > 290 45 > > > > > 295 45 > > > > > 300 35 > > > > > 305 40 > > > > > 310 40 > > > > > 315 34 > > > > > 320 30 > > > > > 325 35 > > > > > 330 35 > > > > > 335 35 > > > > > 340 30 > > > > > 345 30 > > > > > 350 27 > > > > > 355 27 > > > > > The first number is how many degrees to the right you are looking and > the > > > second > > > > > figure is how many degrees up do you have to look to clear your > obstruction, > > > > > > > > hope that makes sense, its a handy tool, saves you going out to see > > > something > > > > > that is behind a building or mountain in your way! > > > > > > > > > > Graham > > > > > > > > > > > > > > > "Write your own horizon file > > > > > You can write a file with a simple ASCII-editor like Wordpad or Vi to > define > > > > > > > > your local horizon. As an example, you can open the file > > > > > [installation > > > > > directory]/data/horizon/horizon_Geneve.txt. As you can see from the > file, > > > the > > > > > horizon is defined by a serie of records. Every line contains a pair > > > > > of > two > > > > > values. The first value is the ‘azimuth’, the second is > > > > > the > > > > ‘altitude’. The > > > > > units are degrees, where azimuth 0° is North and 90° is the > Zenith. A dot > > > (.) > > > > > can be used as a decimal separator. You can put comment in your > > > > > horizon > file > > > by > > > > > lines that start with a mesh (#) character." > > > > > > > > > > > > > > > > > > > > > > > > > ________________________________ > > > > > From: luzius.thuerlemann > > > > > To: [email protected] > > > > > Sent: Wed, 23 December, 2009 11:33:44 > > > > > Subject: [skychart-discussion] local horizon creation > > > > > > > > > > > > > > > Hi there, > > > > > > > > > > I'd like to create my own local horizon visible from my home with > mountains > > > and > > > > > valleys. Version 2.76c . Is that possible? I'd be happy also with a > simple > > > > > horizon line just that I see where my horizon lies. > > > > > > > > > > Thanks and CS > > > > > > > > > > Luzius > > > > > > > > > > > > > > > > > > > > > > > > > Send instant messages to your online friends > http://uk.messenger.yahoo.com > > > > > > > > > > [Non-text portions of this message have been removed] > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > ------------------------------------ > > Yahoo! Groups Links > > >
