Where's the moon?

[jacko61]

I had a bit of a breakthrough moment last night when I finally got platesolving working under APT.  Slewed to various objects in Stellarium then platesolved them pretty quickly in APT - wonder why it's taken me so long to get round to it!  

Anyway, after 90 minutes of adding data to my M81 folder I thought I'd have another play with the GOTO's in stellarium and practice the platesolves. After a handful, Goto's were very nearly landing right on the spot BUT around 1:30am I thought I'd take a look at the moon. Pointed to it in Stellarium, clicked current object then slew and watched as the mount failed to point within 5 degrees of the moon.  It ended up pointing much further west and lower in the sky.  Odd.  A subsequent click on Capella brought that star right into the centre of the frame. Targetting the moon once again brought the scope pointing further west - looked like exactly the same spot as before.

My coordinates in Stellarium match those in EQMOD and the time is picked up from my laptop.

Anyone else see this sort of behaviour using stellarium?   

Graeme

[Carbon Brush]

It sounds like a date issue. Maybe the year?
If stars are 'near enough but not quite' then date is within a day, or a different year.
Though a day error is more like a 15deg error in moon position.

Watching with interest.

[jacko61]

Not sure how it could be a date or time thing. they are both picked up from the laptop.  The slews I was platesolving have all been very close to start with. targetting the moon was several degrees away.  Very odd. Maybe stellarium itself was wrong 😮 

Graeme.  

edit. What surprised me was the fact that subsequent slews right across the sky were all very accurate - capella, M90, M3 etc but slewing back to the moon again was off by the same amount. 

Edited February 11, 2022 by jacko61

[The Lazy Astronomer]

Well this is quite the opposite to normal - easy to find DSOs but difficult to find the moon! 😁

Surely if the coordinates of the mount matched Stellarium, then it must be Stellarium that's wrong about the moon's position. Were there any stars near the moon that you could use to verify if Stellarium had the moon in the right place?

[Carbon Brush]

I'm not saying where the date is wrong. Just looking at symptoms.

When you get different 'boxes' and software involved there is the potential for error.

Plenty of us have got confused about DST, UTC, BST, GMT, etc. when setting mounts and computers.
Then of course March 3rd and October 10th are easily mixed due to some mounts etc. using the date format that only the US seem to use. 
Though neither of the above would give the problem described by the OP. I mention them only to illustrate potential for error.
Back in the days of DOS computers, I remember some newer files being over written because one package numbered months 0-11, and another 1-12!

The stars are near enough and moon is well off target being west and lower.
Was the moon error 5deg, or was this a guess? If >5deg (nearer 15deg) and west and lower, does the mount/computer think it is yesterday?

Adding planetary errors might help narrow it down between the day and year off theories.
A day difference being a small planetary move, but a year puts them in completely different places.

I would be really really surprised if it is a basic error in a popular star chart programme. It would have been noticed by others.

[The Lazy Astronomer]

58 minutes ago, Carbon Brush said:

I would be really really surprised if it is a basic error in a popular star chart programme. It would have been noticed by others.

Oh yeah, I didn't word it very well - I didn't mean an actual error in Stellarium, l was concurring that it must be something in the settings that's caused Stellarium to think the moon is somewhere where it isn't, and at the same time seeing if the OP could verify this by judging the moon's position relative to nearby stars in the program, and real life. 

[Louis D]

1 hour ago, Carbon Brush said:

Then of course March 3rd and October 10th are easily mixed due to some mounts etc. using the date format that only the US seem to use. 

Off topic, but why didn't you phrase it as 3rd of March and 10th of October to be consistent, or were you just baiting us Americans?  Until computers became ubiquitous, American wrote the date (on checks and such) as Mar 3, YYYY or Oct 10, YYYY.  Thus, there was no confusion in the pre-computer days because no one substituted the numeric equivalent for the month.  Americans only reverse the spoken month and day for a very few holidays like the 4th of July and Cinco de Mayo.

Logically, for computers to properly sort dates, the only order I use on file names is YYYYMMDD.  Otherwise, using left to right sorting with DDMMYYYY as in Europe, all dates sort first, then months, then years.  That is not a particularly useful way to sort hand dated documents.

[jacko61]

I've cleared all the SYNC points in EQMOD. Hopefully we'll get a clear night again soon so I can do so more sluething.

Graeme

[jacko61]

oh - icing on the cake...  All my Bodes subs from last night have dark spots in the stars so DSS won't stack them. I must have had mirror flop between focusing on Polaris (with a bhatinov) and slewing to M81

Graeme

[michael8554]

The moon and planets have very dynamic orbits that many mounts don't have the data to accurately position.

Unlike the stars and DSO's that are essentially fixed.

Luckily the moon is big and bright enough that you don't need an accurate GoTo.

Michael

[Carbon Brush]

19 minutes ago, Louis D said:

Off topic, but why didn't you phrase it as 3rd of March and 10th of October to be consistent, or were you just baiting us Americans? 

No not all. I was thinking of the way dates have been entered in a lot of mounts as numbers only, before they had good enough hardware to keep RTC on board and decent displays.
The only assistance available being reading the manual - in the dark😁

When dealing with anyone worldwide, I avoid 'number only' dates in written messages to avoid confusion. Sticking with the month as a word, albeit sometimes abbreviated.
Worldwide, whether presented as 3rd March 2022 or March 3rd 2022 doesn't cause offence and is well understood.
It also allows 21st March 22 to be recognised and not confused with 21 March 22 or 22 March 21.

By comparison a USA based carrier, UPS, who ship worldwide, seem to think that number only dates in USA format, and a time stamp in a USA time zone are useful and readily understood worldwide🤣
Here is an extract from shipping progress on a Janaury (or will that be November?) shipment.
Last Updated: 02/11/2022 10:15 A.M. EST

Yes time and date formats can be confusing.

David.

[ollypenrice]

Have you seen the film, The Dish?  It's an entertaining film and highly relevant to this conversation...

👹lly

 

[Shimrod]

21 hours ago, Carbon Brush said:

Plenty of us have got confused about DST, UTC, BST, GMT, etc. when setting mounts and computers.
Then of course March 3rd and October 10th are easily mixed due to some mounts etc. using the date format that only the US seem to use. 

I am assuming those dates should really be 10th March and 3rd October, because in the two dates quoted it doesn't matter whether month and day are transposed....

 

[Carbon Brush]

40 minutes ago, Shimrod said:

I am assuming those dates should really be 10th March and 3rd October

Well spotted! Yes thanks. That is what happens when typing in a hurry. Thats my excuse anyway😁

As to why it took 21 hours and multiple readers and new posts to get picked up.........🤔

[Marvin Jenkins]

Alt Az mount and all is forgiven. The moon doesn’t need a computer to find it. In fact I find it is in the way of DSO stuff a lot of the time😂

[Scooot]

On 11/02/2022 at 18:28, ollypenrice said:

Have you seen the film, The Dish?  It's an entertaining film and highly relevant to this conversation...

👹lly

 

That’s a coincidence reading this. I have the DVD and watched it again with my brother yesterday evening who hadn’t seen it.