How to align AZ-EQ6 in daylight

[seedy (Chris)]

Hi all
I would like to be able to track the sun through the day using my AZ-EQ6.
I can guess south close enough in EQ mode to be close but I ain't having a lot of luck making it work in AZ mode.

Any ideas that might point me in the right direction would be appreciated.

Cheers
Chris

[redbeard (Damien)]

Hi Chris,

Not sure if this will help but with my scope a Meade lx200 when in alt/az mode, there is a align process that is normally done with stars. So what I do, is set the mount up and do a automatic align , (it's in the menu), and all I do is after the normal level/north auto stuff, the scope slews to where it thinks the first star should be and I simply select yep OK, same on the second star. The scope then thinks all is good and then I select the sun as an object to track, after it slews to where it thinks the sun is, I then use the hand controller to point to the sun, do a synch, and tracking seems to work. A bit rough, but it works. So if your mount has similar alignment menus, might work.

Cheers,

Damien.

[frolinmod]

Originally Posted by redbeard

So if your mount has similar alignment menus, might work.

Alas it doesn't. You can indeed lie to the hand controller about alignment stars, but that doesn't help any. It doesn't have a Sun object to slew to nor can a user defined object be used to define a solar system object, only fixed ra/dec objects, hence you can't even fake up a Sun object. For Sync, you have to slew to an alignment star and sync on the alignment star. Not too useful during the daytime.

[Wavytone]

Assuming you can set up your mount in the same spot each night, I would create two fake stars, as follows. There are two methods.

A. Artificial Star at the zenith and second star on the horizon, due east or west.

This first method involves some maths to work out sidereal time - or use an app such as Emerald Chronometer that will show this.

Define a "star" at the zenith by pointing the telescope directly vertical, using a spirit level to check it is vertical in the east-west plane and again in the north-south plane. This corresponds to a "star" with declination equal to your latitude, and the RA equals the Local Apparent Siderial Time (see definition halfway down this page http://en.wikipedia.org/wiki/Sidereal_time).

Define a second "star" due east or west by pointing the scope horizontally east or west (use a spirit level to get it horizontal). For the azimuth, a compass will give you a rough idea but not very accurate. The best way would be to se the mount up one night and use the digital circles to point the scope due east/west and put a marker on a wall or fence. This corresponds to a star on the celestial equator (declination = 0°) with RA = the Local Apparent Siderial Time - 6 hours (west) or + 6 hours (east).

B. Use two reference marks visible in daylight and also at night, say a distant streetlight, a sign or the top of a building, whatever.

This second method is more complex and involves trigonometry, to get this right you must be reasonably proficient at maths.

Basically:

a) Set the scope up one night and use it to determine the altitude and azimuth of these marks, by measuring their equatorial coordinates from the mount, and doing the maths to get altitude and azimuth.

b) Use this information to define two "stars" at any other state/time (in daylight) corresponding to these marks, noting that you can calculate their RA and dec for any date/time in the future.


1. Set up one evening as per usual and do a really good two-star alignment - testing GOTO's on some stars to be sure. Once you are sure, point it at one of these terrestrial marks and see what it thinks the RA and Dec are - you must also note the date and time to the nearest second.

Now, doing some maths, work out the altazimuth coordinates for this mark - altitude and azimuth. I'll leave it to you to do this, Google is your friend, alternatively you can consult any number of astronomy textbooks.

2. Repeat for the second terrestrial mark.

Now that you have the altitude and azimuth bearings for these points.

To set up again in daylight on any other date/time, you can calculate the equatorial coordinates for these marks. It will help immensely if you have a programmable calculator with a realtime clock - or the i41CX app on an iPhone or iPad - to calculate the RA and dec of these marks when you need it.

Note the dec should be constant, only the RA should be different.

[OICURMT]

I do a one-star alignment with my Celestron U2K... (it has the Sun in the DB).

You should be able to do something similar by using the following steps.

1) Enter in a user configued star that is co-incident with the Sun (i.e. look up a star that is currently in the same location as the sun.
2) Use that star for a one-star alignment (i.e. center the sun)
3) Wait 15 minutes and then re-align against that star (i.e. Sun).

This should get you close enough for government work.

You obviously MUST have a solar filter on your scope prior to doing this...

OIC!