Quickest way to slew from target to target - EQTour - Alignment

[SniffTheGlove]

Previously just been doing a few manual alignments in EQMod and thought that it would be good if I could automate the alignment process a bit quicker, so went through Chris's Youtube site and read up on a few things and found I could use EQTour as there is an Alignment Tour List there (AlignmentStars.lst). I loaded up EQTour and configured my gamepad to issue a slew command (So I can slew directly to the next target without having to issue the slew from EQTour) on an unused key. So now I once I have checked my Polar Alignment and I then run the Alignment Tour to build up the multiple 3 point alignments in EQMod.

So last night I loaded the tour and selected stars Mag 2 and brighter and then ran it.

This is when I noticed that the mount was going all over the place to each target and thought this is long winded process.

So today I have just looked at the AlignmentStars.lst file and noticed that it was in alphabetical constellation order, so no wonder my mount was going all over the place and doing multiple meridian flips.

So looking at the file I wondered what would be a better sort order so that the alignment tour can be run in the shorted time possible. ie short slews.

So is it best to sort it in....

RA followed by Dec ?

Dec followed by RA ?

I think the better one will be RA followed by Dec so that there should only be one meridian flip. Would this be right?

eg of AlignmentStars.lst

# Alignment Stars - J2000 positions taken from The Bright Star Catalogue 5th Revised Ed.
# use !J2000 keyword to allow tell EQTour to apply procession.
!J2000
!FORMAT=R;D;C;O;M
0.139805556;29.09055556; Peg; Alpheratz;2.06
0.220611111;15.18361111; Peg; Algenib;2.83
0.438055556;-42.30611111; Pho; Ankaa;2.4
0.675138889;56.53722222; Cas; Shedir;2.23
0.7265;-17.98666667; Cet; Diphda Beta Ceti;2.04
1.162194444;35.62055556; And; Mirach;2.06
1.628583333;-57.23666667; Eri; Achernar;0.45
2.065;42.32972222; And; Almaak;2.1
2.119555556;23.4625; Ari; Hamal;2
2.322416667;-2.9775; Cet; Mira;6.47
2.530194444;89.26416667; Umi; Polaris;2
2.971027778;-40.30472222; Eri; Acamar;2.88
3.038;4.089722222; Cet; Menkar;2.54
3.136138889;40.95555556; Per; Algol;2.09
3.405388889;49.86111111; Per; Mirphak;3.82
3.791416667;24.105; Tau; Alcyone;2.85
4.598666667;16.50916667; Tau; Aldebaran;0.87
5.242305556;-8.201666667; Ori; Rigel;0.18
5.278166667;45.99805556; Aur; Capella;0.08
5.418861111;6.349722222; Ori; Bellatrix;1.64
5.438194444;28.6075; Tau; Alnath;1.74
5.47075;-20.75944444; Lep; Nihal;2.81
5.533444444;-0.299166667; Ori; Mintaka;2.25
5.5455;-17.82222222; Lep; Arneb;22.58
5.603555556;-1.201944444; Ori; Alnilam;1.69
5.679305556;-1.942777778; Ori; Alnitak;1.74
5.795944444;-9.669722222; Ori; Saiph;2.06
5.919527778;7.406944444; Ori; Betelgeuse;0.45
6.378333333;-17.95583333; Cmi; Mirzam;1.98
6.399194444;-52.69583333; Car; Canopus;-0.62
6.628527778;16.39916667; Gem; Alhena;1.93
6.752472222;-16.71611111; CMa; Sirius;-1.44
6.977083333;-28.97222222; Cma; Adara Adhara;1.5
7.139861111;-26.39333333; Cma; Wezen;1.83
7.401583333;-29.30305556; Cma; Aludra;2.45
7.576666667;31.88861111; Gem; Castor;1.58
7.655027778;5.225; CMi; Procyon;0.4
7.75525;28.02611111; Gem; Pollux;1.15
9.459777778;-8.658611111; Hya; Alphard;1.99
10.13952778;11.96722222; Leo; Regulus;1.36
10.33286111;19.84166667; Leo; Algieba;2
11.03069444;56.3825; Uma; Merak;2.34
11.06213889;61.75083333; Uma; Dubhe;1.81
11.23513889;20.52361111; Leo; Zosma;2.56
11.81766667;14.57194444; Leo; Denebola;2.14
11.89716667;53.69472222; Uma; Phad;2.41
12.25711111;57.0325; Uma; Megrez;3.32
12.44330556;-63.09916667; Cru; Acrux;0.77
12.90047222;55.95972222; Uma; Alioth;1.76
12.93380556;38.31833333; CVn; Cor Caroli;2.89
13.03627778;10.95916667; Vir; Vindemiatrix;2.85
13.39875;54.92527778; Uma; Mizar;2.23
13.41988889;-11.16138889; Vir; Spica;0.98
13.42041667;54.98805556; Uma; Alcor;3.99
13.79233333;49.31333333; Uma; Alkaid;1.85
14.06372222;-60.37305556; Cen; Hadar;0.61
14.07313889;64.37583333; Dra; Thuban;3.67
14.11138889;-36.37; Cen; Menkent;2.06
14.26102778;19.1825; Boo; Arcturus;-0.05
14.65997222;-60.83527778; Cen; AlphaCentauri RigilKentaurus;-0.01
14.74977778;27.07416667; Boo; Izar;2.35
14.84508333;74.15555556; Umi; Kocab;2.06
15.57813889;26.71472222; CrB; Alphekka Alphecca;-0.01
15.73780556;6.425555556; Ser; Unukalhai;2.63
16.00555556;-22.62166667; Sco; Dschubba;2.29
16.49011111;-26.43194444; Sco; Antares;2.04
17.17297222;-15.72472222; Oph; Sabik;2.43
17.24413889;14.39027778; Her; Rasalgethi;2.78
17.56013889;-37.10388889; Sco; Shaula;2.82
17.58225;12.56; Oph; Rasalhague;2.08
17.94344444;51.48888889; Dra; Eltanin;2.24
18.40286111;-34.38472222; Sag; Kaus Australis;1.79
18.61563889;38.78361111; Lyr; Vega;0.03
18.92108333;-26.29666667; Sag; Nunki;2.04
19.51202778;27.95972222; Cyg; Albireo;3.05
19.771;10.61333333; Aql; Tarazed;2.72
19.84638889;8.868333333; Aql; Altair;3
19.92188889;6.406666667; Aql; Alshain;0.76
20.69052778;45.28027778; Cyg; Deneb Alpha Cygni;1.25
20.77019444;33.97027778; Cyg; Gienah;2.58
21.30966667;62.58555556; Cep; Alderamin;2.45
21.73644444;9.875; Peg; Enif;2.38
22.09638889;-0.319722222; Aqr; Sadalmelik;2.95
22.13722222;-46.96111111; Gru; Alnair;1.73
22.96086111;-29.62222222; PsA; Fomalhaut;1.17
23.06291667;28.08277778; Peg; Scheat;2.44
23.07936111;15.20527778; Peg; Markab;2.49

[Imd]

I'm sorry I don't know the answer to your question but I think this idea I really interesting. I don't suppose you add to the thread a link for Chris's YouTube video?

Could you not replace the lst file for another which contains just the alignment stars you want to use for that particular night so that the skewing is more predictable and you get the triangle of stars you want or am I missing something?

[SniffTheGlove]

Link link to the EQTour vids is http://www.youtube.com/user/chrisshillito/search?query=eqtour

EQTour allows you to select the magnitude of stars to work with so you could select Mag 2 and get quite a few stars or select Mag 0 or even Mag -1 to get just the prominent bright stars. You can also set the horizon and EQMod/EQTour will only select the stars that are above your selected horizon.

It is possible to edit the list down to a small quantity of stars manually but then you would need a list for that will be promient for the month/time you do the alignment which will require additional work. Much easier to allow EQMod select from the list.

The more stars aligned the better the precision in EQMod when working out the 3 point alignment. The vids explain all this.

I just want to shorten the alignment process into the most efficient time as like last night as I had finished alignment the clouds rolled in ......bah

[chrisshillito]

Link link to the EQTour vids is http://www.youtube.c...ch?query=eqtour

EQTour allows you to select the magnitude of stars to work with so you could select Mag 2 and get quite a few stars or select Mag 0 or even Mag -1 to get just the prominent bright stars. You can also set the horizon and EQMod/EQTour will only select the stars that are above your selected horizon.

It is possible to edit the list down to a small quantity of stars manually but then you would need a list for that will be promient for the month/time you do the alignment which will require additional work. Much easier to allow EQMod select from the list.

The more stars aligned the better the precision in EQMod when working out the 3 point alignment. The vids explain all this.

I just want to shorten the alignment process into the most efficient time as like last night as I had finished alignment the clouds rolled in ......bah

You are of course free to change the lst files and sort in any order you like - some of them have dupiclates sorted by RA others are ordered by constellation (I think - its been a long time!).The current Alignment Stars list was contributed to the project as an attempt to reproduce the synscan set . Please note it was never the intention for folks to use every star in the list as an alignment point. When choosing alignment stars what you ideally want is a set that vary significantly in RA and DEC and that cover all four quadrants of the sky - the more mount movement you get the better - it is the errors in movement we're trying to model.

Personally I find a planetarium far better for alignment as you can see where the stars actually are and choose those that best give a decent coverage in all four quadrants (if I'm going or an all sky model I ususally do 12 stars forming a large triangle in each quadrant) - the alignment points editor display is also quite handy to check the point distribution. If you're aligning every night at around the same time then you will probably you can get away with using the alignment starsover a period of a few weeks - in which case a tour of those stars might speed up setup.

Chris.

Chris.

[SniffTheGlove]

Thanks Chris. When at my pier I am not near my PC so the point of doing the Alignment Tour and putting the slew command on the gamepad was to stop me running into the house to choose a star (slew) then running outside to the pier the us the game pad to fine align and sync then go back in the house to move to the next star. I have a spinal problem and using the TOUR means it is so much easier.

I just would like to know if the alignment list is sorted in RA/Dec is better than Dec/RA or even the standard constellation order the come as.

IE I believe RA/Dec is the better way for me (at least) and the the RA axis will just move slightly why the DEC axis will rotate arround to align then move the RA.

If noone knows I can just try both ways when we have a clear night and see which is quickest but clear nights are hard to come by.

[SniffTheGlove]

Did a quick test this morning and doing the alignment tour in RA order was much much faster, so that is how I will do it from now on.

[chrisshillito]

Just keep in mind that the whole purpose of alignment is to measure the mounts pointing accuracy and to build a model that can be extrapolated to cover the area of sky you intend to observe in. To do that you generally need alignment points that provide large swings in both RA and DEC. In my view it would be a mistake if your were to use say the first 6 points in a tour ordered by RA as that isn't going to exercise the RA axis fully so your model isn't likely to compensate effectively in RA either.

If your intention is to use alignment to provide an "all sky" model then as a minimum I would recomend choosing stars from the tour list that form two triangles, one each side of the meridian. Choosing stars on the basis of 'saving time' is unlikely to result in an optimal alignment model. Perhaps the best approach therefore to use your planetarium, EQTOUR and the EQMOD simulator to identify the best candidates for alignment stars and build your own tour file of those points. You can then have EQTOUR connect to the mount itself and execute the tour via the gamepad.

Chris.

[SniffTheGlove]

Just keep in mind that the whole purpose of alignment is to measure the mounts pointing accuracy and to build a model that can be extrapolated to cover the area of sky you intend to observe in. To do that you generally need alignment points that provide large swings in both RA and DEC. In my view it would be a mistake if your were to use say the first 6 points in a tour ordered by RA as that isn't going to exercise the RA axis fully so your model isn't likely to compensate effectively in RA either.

I see what you are saying Chris. I suggested and went with RA order of the alignment star list as the current alignment list is stored in Constellation Order and sorting into a more time saving way would be better and quicker.

For example I have just done a daylight test using the alignment lst file in 3 different sorted orders.. Setting my horizon and a magnitude of 2 and brighter I got 25 stars showen in the EQTour window, that is the same 25 stars presented in each sorted file. Here are the times to build an alignment map in EQMod. I just loaded the tour and slewed. As soon as the slew was complete I synced and slewed to the next target. This si just a time test so there was no fine alignment slewing, just slew, slew complete, sync then slew to next target.

Constellation Order: Time to complete 19 minutes

Dec Order: Time to complete 21 minutes

RA Order: Time to complete 8 minutes

So regardless of how the alignment lst file is sorted I always get the same amount of stars.

Are you saying that by being systematic and using the lst in either RA order or even maybe Dec order will not produce a suitable alignment map in these axis and that the standard constellation order is better?

To me I am thinking that as long as the alignment map is made up of xx points, does it matter in the order you created the alignment map as all 3 alignment maps looked the same to me.

[chrisshillito]

What I'm saying is it really doesn't matter how you sort the points - what matters is that the points you use are reasonably evenly distributed across the area of sky you wish to go to. The tour list just gives you a selection of bright, well known stars to use. The list wasn't designed with the intention that folks would align on every single star but rather that they would select from that list those stars that meet their individual needs. Some folks are only interested in aligning around their target for the night, others don't have a definite plan and want to tour around the sky, some folks align every night, others are observatory based and will use the same alignment model for weeks/months. So different horses for different courses.

As I see it your particular requirements are:

all sky coverage,

an alignment list you can just step sequentially through using the gamepad,

The quickest possible execution time

8 minutes for 25 alignments is pretty good going! But, just in case > mag2 stars aren't that distributed, you might consider editing/copying the original tour so produce a new one that has just one star per constellation (preferably in the centre of it) and that has a good variation of RA and DEC values. This should give you a well distributed point set which you can then sort by RA and have EQTOUR further filter by azimuth (all the alignment stars should be bright so no need to filter any out by mag).

Chris

[Daddystu]

Thanks Chris. When at my pier I am not near my PC so the point of doing the Alignment Tour and putting the slew command on the gamepad was to stop me running into the house to choose a star (slew) then running outside to the pier the us the game pad to fine align and sync then go back in the house to move to the next star. I have a spinal problem and using the TOUR means it is so much easier.

I just would like to know if the alignment list is sorted in RA/Dec is better than Dec/RA or even the standard constellation order the come as.

IE I believe RA/Dec is the better way for me (at least) and the the RA axis will just move slightly why the DEC axis will rotate arround to align then move the RA.

If noone knows I can just try both ways when we have a clear night and see which is quickest but clear nights are hard to come by.

I've just built a new pier and I too was concerned about polar alignment (alt/az adjustment) as the laptop is in the shed 3m away. However, I found a nice little remote desktop app for my Symbian phone. My plan is to set up crosshair view in APT or sharpcap then centre alignment stars using alignmaster+mobile phone. It should be invaluable in winter.