Comparing list of observable objects with skycharts

Posted January 12th, 2010 by lucyberthoud

Hi guys,
Another (probably daft) question: why are some objects on the skycharts but not on the spreadsheet list of observable objects. Eg: for Jan 19th I am looking at chart for 2007/1/21 12:00 and I can see M67, M36, M108, NGC 2264 etc on the chart but not on the list of observable objects. Which one is likely to be correct?
Any advice gratefully received.
Thanks,
Lucy

Submitted by lucyberthoud on 2 February 2010 - 11:26am.

Thanks Sarah, so, if I understand you right: there are objects on the Starry Night skycharts that will not be on the lists as they are too big for the telescope to see?
That makes sense if I have got that right. But why are there objects on the lists which the telescope will not go to eg: M1 or M50? Are they too small? Or maybe I just got the visibility a bit wrong and they were out of the FoV?
Any ideas?
Thanks so much for your help.
Lucy

Submitted by sroberts on 8 February 2010 - 10:33am.

Hi Lucy,

Yes you're right - there are objects on the skycharts which aren't on the lists as they're too big to see, and as we compiled the lists ourselves by hand to only include suitable objects for the FTs, they won't include ones that are too large for the FOV.

The lists won't contain any objects which the telescope won't point to either - M1 and M50 are definitely observable and suitable for the telescopes, so I'm not sure why you couldn't view them - which session (time and date) did you try looking at them, and how did you input them in the telescope control (with the Search/Browse mode or entering their RA/Dec?). If you let me know how you tried to observe them I'll have a look to see what happened!

Thanks,

Sarah

Submitted by lucyberthoud on 10 February 2010 - 8:58am.

Hi Sarah,
Thanks for your reply. Our session was at 1300 UTC on 19 Jan 2010. I always use the search/browse mode, should I be using RA/Dec? I noticed there weren't any pics of them in the archive either, but maybe that doesn't mean anything...
With thanks,
Lucy

Submitted by sroberts on 10 February 2010 - 2:33pm.

Hi Lucy,

I've just checked and the 2 objects (M1 and M50) which you tried searching for, for some reason don't have their Messier names in
the telescopes database at the moment, so a search for them with the names M1 and M50 wouldn't find them (even though they are actually in the database, just under different names - e.g. M1 is in there under 'Crab nebula').

We're really sorry about this, and we are now working on making sure that all the Messier objects are in the database, with ALL their correct names!

I would always recommend using the Search/Browse function, and in the next day or so, the database will be updated to include the Messier names, so you shouldn't have this problem again!

Sarah

Submitted by sroberts on 13 January 2010 - 12:48pm.

Hi Lucy,

Not a daft question at all! The sky charts were generated using Starry Night, and as such, they have lots more objects labelled on them than are on the chart as you can't specify what size objects to put on there. The lists aren't a comprehensive list of what's visible at that time - they only contain objects which would fit into the field of view of the telescope, and aren't too big for it. On the charts themselves, objects which may be too big to fit into the telescope's field of view may be labelled on there, but that's mainly because there's no easy way in Starry Night to only highlight the smaller objects, and also because it then gives students (and teachers!) the chance to do a bit of background research into their list of possible objects and they can check the suitability themselves.

Hope that clears thing up!

Sarah