SAPA - a Synscan Alignment Planning Aid

[Zermelo]

I created the attached spreadsheet for my own purposes, but then I thought it might be of some use to others.

So, I had to give it a name (easy enough), to tidy it up (not so easy), and to document it (the longest part – it seems to be a trueism that it’s much quicker to do something than it is to explain how and why you did it).

 

What is it for?  From the attached User Guide:

- to assist the observer in selecting effective stars for the Synscan alignment of Sky‑watcher telescopes, in advance of an observing session

- to support the collation of a history of the alignment details used for each observing session, and a record of the pointing and tracking performance of the mount for those sessions.

 

What does it do?

Basically, you tell it where you’ll be observing from, and when. It will analyse all the stars that Synscan uses and rank each combination, using the guidelines in the Synscan user manual, but with more control.

You can tinker with the configuration of the alignment rules, and weight them differently. You can ignore specific stars. You can create your own map of local obstructions, and it will ignore any stars that will be obstructed when you align. You can compile a list of alignment stars for different times in the evening. You can copy all the details into a log, along with your rating of how your scope/mount performed.

You pick the stars from the output that suit you, and choose them at alignment time from the app or handset.

 

Some Notes and Caveats

If all you want to do is use it in it’s simplest form, you don’t need to read much. The User Guide has a very short “quick start” section.

If you want to play with the settings, read the rest of the User Guide. If you want to understand how it’s working, have a look at the Design Notes document.

The tool works for Alt-az alignments using two stars (incl. “brightest star”, “North level”), because that’s what I use.

The spreadsheet was created with Excel 2016, but I have also tried it successfully on Office 365.

It includes VBA code, so it’s saved as an .xlsm. That means you will need to enable the content when you open it, and possibly copy it to a trusted location first, depending on how your Excel security is set up.

I’m not too bad with Excel, but this was my first time coding in VBA.

It’s my first foray into positional astronomy, so it has been a steep learning curve. I’m sure that there are people out there who will be able to put me straight on a few things.

I’ve been using it for a while now, but I’ve also been making changes as I went. I gave it all another test before posting it, but I don’t (yet) have anything like a proper test suite to run through. So of course, any feedback on bugs/ suggestions for changes will be very welcome.

 

Spreadsheet:

*** UPDATED 05/04/2023 ***

SAPA 1_2.xlsm

 

User Guide:

*** UPDATED 05/04/2023 ***

SAPA User Guide 1_1.docx

 

 

Design Notes:

*** UPDATED 05/04/2023 ***

 

SAPA Design Notes 1_1.docx

 

Edited April 5, 2023 by Zermelo
Updated V1.1

[Zermelo]

Suggestions for Changes

(1) Parameters sheet: default the Date and Time cells to the current values, which can be retained or overtyped by the user. If the user changes these and saves the spreadsheet then of course the formulae will be gone, though a macro could probably be created to repopulate them each time it is opened.

>>> included (modified) in v1.2

(2) Print sheet: define a print area that excludes the print buttons (which force the printing of a second sheet)

>>> included in v1.2

 

Edited April 5, 2023 by Zermelo

[PeterC65]

Wow! And I thought I was a whiz with Excel!!

This looks like a really handy tool as I often struggle, particularly with the second alignment star, when the SynScan offers me a bunch of options most of which I've never heard of ... because I use GOTO and so don't know the sky!

I'm working my way through the tool and have fallen at an early stage. I've persuaded Excel to trust the document and enable macros, filled in the basic location data, but when I click Determine Alignment Candidates on the Output sheet it can't find the macro. Looking at the list of macros, it is indeed missing, so I've assigned the button to the AutoSession macro instead. Is that correct? It seems to be working.

 

[Zermelo]

Thanks for looking Peter

 

19 minutes ago, PeterC65 said:

when I click Determine Alignment Candidates on the Output sheet it can't find the macro. Looking at the list of macros, it is indeed missing, so I've assigned the button to the AutoSession macro instead. Is that correct? It seems to be working

Now that is odd.

The macro behind that button should be called DisplayCandidates.  The AutoSession macro basically strings a number of those together, so you can sort of emulate it by running AutoSession with one iteration. But they're different.

Now, when I select (in base Excel now) "View", "Macros" I see the following:

but if I choose any of the macros and click "Edit", then in the edit dialogue I see the missing macro in the list:

and I can then select and display it (and of course, run it).

I'm mistified, but I'll have a think.

 

[PeterC65]

I'm working this through and got to the same point. I can't see the DisplayCandidates macro in the list of macros to assign to a button, but the macro is there when I open the macro editor.

 

[PeterC65]

The issue seems to be that macros with calling parameters are not listed in the assignable to a button list. If I comment out the calling parameter then the macro is listed.

 

[Zermelo]

 

11 minutes ago, PeterC65 said:

The issue seems to be that macros with calling parameters are not listed in the assignable to a button list. If I comment out the calling parameter then the macro is listed.

Odder still.

Now, in my spreadsheet, the button is assigned currently, but if I unassign it and try to re-assign it, it's not in the list!

Must be some kind of scope/permissions thing. BUT you can just type in the name yourself.

However, as it happens, the parameter for DisplayCandidates is optional, and by good fortune I wrote the code to check it "the other way", i.e. the IF statements look for "auto" from the internal call from AutoSession.

So, if you edit the button and set the macro to 'SAPA 1_0.xlsm'!DisplayCandidates

without a parameter, it works as it should.

I'll replace the copy I posted.

Thanks.

 

 

Edited January 18, 2023 by Zermelo

[Zermelo]

Updated to 1.1 in original post.

That didn't last long!

[PeterC65]

I've managed to fix my version as you suggested above. I'll keep playing with it.

 

Edited January 18, 2023 by PeterC65

[PeterC65]

I'll comment as I go if that's OK ...

I've just set the location horizon filter as my field of view is very limited to the North and West. This was easy to do and seems to work. A very nice feature.

While checking some of the suggested alignment stars I noticed that they are not all named as per Stellarium, so I was having trouble finding some of them. I've had this issue before when creating a Stellarium Observing List of the alignment stars (which has turned out to be not that useful). Alnath is called Elnath or Al Nath in Stellarium for example. Phad is called Phecda for example. There are only a few of these and I've changed them in the Alignment Star Database sheet which seems to work.

Just a suggestion, in the Parameters sheet, have the Date cell set to =TODAY() by default and the Time cell set to =NOW(). Then you have the current time and date but can over-write them if you want a date / time in the future.

I'll stop now for tonight but this spreadsheet is looking very handy. I can see myself using it to determine suitable alignment stars before starting a session rather than letting the hand controller suggest a second star that I can't find without coming inside and looking it up on Stellarium!

 

[Zermelo]

3 hours ago, PeterC65 said:

While checking some of the suggested alignment stars I noticed that they are not all named as per Stellarium, so I was having trouble finding some of them.

Yes, section 7 of the Design Notes explains the derivation of the catalogue. There are indeed several stars in Synscan that don't use the standard IAU names (which presumably are what Stellarium uses). I chose to change the names in SAPA to be exactly what Synscan uses, because otherwise someone doing an alignment would find that the star they were expecting from SAPA's output isn't listed by the app or handset.

Of course, that means that those names won't match what you see in your planetarium software when you're planning, but at least when you're inside you have a bit more time to look them up. In the spreadsheet catalogue sheet, I have included Bayer or Flamsteed designations for every entry, so that can be used to cross-reference the mis-named stars. I also copied into the "Catalogue refs" column any other information that I found in the source catalogue, such as synonyms.

 

3 hours ago, PeterC65 said:

Just a suggestion, in the Parameters sheet, have the Date cell set to =TODAY() by default and the Time cell set to =NOW(). Then you have the current time and date but can over-write them if you want a date / time in the future.

I can see the advantage of that. I reserved the first comment slot above, one reason was to collate suggestions.

 

3 hours ago, PeterC65 said:

I'll stop now for tonight but this spreadsheet is looking very handy.

Thanks, I'll be very interested in how you get on.

 

[PeterC65]

11 hours ago, Zermelo said:

Yes, section 7 of the Design Notes explains the derivation of the catalogue. There are indeed several stars in Synscan that don't use the standard IAU names (which presumably are what Stellarium uses). I chose to change the names in SAPA to be exactly what Synscan uses, because otherwise someone doing an alignment would find that the star they were expecting from SAPA's output isn't listed by the app or handset.

That's a good point. I've reverted to your original list and just added the names used by Stellarium in brackets after the primary name.

[PeterC65]

I used the spreadsheet in anger for the first time tonight. Right before the session I used it to compute the best alignment stars (using =TODAY() and =NOW()) then looked up the most sensible pair of stars on Stellarium (there were only two pairs on offer and one pair was more obviously in the direction I was planning to observe). It really helped knowing where the second alignment star was located and I will use this spreadsheet every time form now on. Thanks very much for putting it together and sharing it.

 

[PeterC65]

I have a Stellarium Observing List of all of the SynScan alignment stars which I've had to update recently after upgrading to Stellarium v1.2. In doing so I've used the same list used in @Zermelo SAPA tool. I've also noticed that the JSON file that stores the Observing List can be hand edited to make the star names the things that get highlighted. This is exactly what you need when trying to work out where those alignment stars listed by the handset might be located.

Here is the JSON file.

Stellarium Observing List - SynScan Alignment Stars.json

Just download it, in Stellarium, create a new observing list, import this file, save and close.

 

[Zermelo]

UTC functionality:  just a note to say that, since the change to BST, I've noticed that the local<>UTC conversion is wrong!

I have fixed it, and will post an updated version imminently, but for now if you keep the UTC offset for your location as zero, and enter alignment times in UTC, it will continue to work. The possibility of a clear evening may take precedence over my updating the documentation.

 

[Zermelo]

I’ve updated the spreadsheet (v1.2) to deal with UTC offsets correctly.
Apologies, I’ve no idea how I didn’t spot that. The system tester has been taken out the back and shot.

I took the opportunity to include a button to set the alignment date and time to the current values with one click, and defined a print area on the Print sheet to exclude the buttons.

Slightly amended versions of the User Guide (1.1) and Design Notes (1.1) are also included.

[PeterC65]

Just looking at v1.2, it's showing the same values for Time (local) and Time (UTC) on the Parameters tab. Is that correct?

 

[Zermelo]

It should reflect whatever you have set as the UTC offset in column P, for your selected location.

For UK in BST, that should be +01:00, but I chose to save all the values as 00.00 as I didn't want to have it reflect the time of year that I posted it.

[PeterC65]

OK. I was thinking that it might be automatic!

 

[Zermelo]

18 minutes ago, PeterC65 said:

OK. I was thinking that it might be automatic!

 

At one point, I did think about trying to use the latitude and longitude in the table to map each location onto a scheme of country timezones, supplement it with a database of local daylight saving regimes, and so calculate the UTC offsets.

I thought about it for all of three seconds.