Observing for a long time

astroAJ · #1 30-12-2007, 06:17 PM

Hi every one

Its so amazing to hear how people on IIS can observe objects for such a long time. When I observer objects I look at them for 7 mins but some people can observe objects for more then 15mins. What do you look at when observing an objects and how can you observe an object for such a long time?

thanks

iceman (Mike) · #2 31-12-2007, 08:52 AM

I guess people would look with different eyepieces, to see what it looks like at different magnifications and different fields of view.

I'm generally not a very patient person and spend no more than 1 minute on an object

CoombellKid · #3 31-12-2007, 09:26 AM

Just my opinion, but for me I think for your eyes you have object adaptation
just like dark adaptation. The longer you spend with an object the more you
see. Put together with fluctuations in seeing conditions during the observation.
A good thing to do to improve what you see is try to sketch the object, even
spend time over several nights where conditions will vary from night to night.

regards,CS

ngcles · #4 31-12-2007, 03:15 PM

Hi Astro AJ,

I think it will depend quite a bit on what you are observing and what the conditions are like.

One example is Mars at the moment. At best it is less than 30 degrees above the N horizon and the seeing will never be consistently good there -- indeed it will be rarely good let alone very good or excellent.

On an average night's seeing there will only be maybe 5 or so seconds out of 10 minutes when the seeing will settle to the point where most of the available detail will be apparent to the eye. If you are not at the eyepiece when that happens you miss out. In this situation it would be common for me to spend 20-odd minutes on Mars out of which perhaps 30-odd seconds will be truly worthwhile and your task in those 30 seconds will be to see and record in the brain-box or on paper as a sketch, as much as possible.

As for deep-sky observing, the seeing does play a role but not a big one -- transparency is more important and it does not vary from minute to minute so the view per-se won't change. But your eyes will. Move away from the scope and look at a map (even with a dim red light) or a lap-top or what-not and you loose _a degree_ of dark adaptation. Time spent at the eyepiece looking at a dark field will bring it back in. Also a lot of deep sky objects, particularly very faint galaxies or PNe are only one or so percent brighter than the native sky background. It will take time to notice them if they are really faint -- even if you do know precisely where to look. Time staring through the eyepiece does that.

My general routine (for what it is worth) if I am going through a list of galaxies or PNe, is that I will look at my paper list and find the catalogue number of the next object to look at. Then go to the laptop (with a _heavily reddened_ screen) and look it up on megastar and see the field and then superimpose a real-sky (DSS) image so I know what to look for and the star patterns. Go to the scope, dial it in on the Argo Navis and hit the slew button. Slew finished I look in the eyepiece and confirm (using star-patterns etc) I'm at the right location from the DSS/Megastar. All this takes maybe 90 secs to 2 mins.

Then I spend a _minimum_ of 3-5 minutes looking -- just looking and trying to see as much as possible. There might be three or four galaxies in the field -- hunt them! While this is going on my dark adaptation from looking at the screen is coming back to maximum.

After this time I whip out the Dictaphone and speak some notes on the galaxies in the field. What size are they? What PA? Distances from each other? Superimposed stars? Internal structure? Nucleus? Etc etc. This takes about another 3-5 minutes. Then move on to the next thing on the list.

Assuming there are no changes in eyepiece or identification/finding probs, an observation of a field takes about 8-10 minutes. The field might contain one object, or maybe 5. In this way I usually manage to get through about 15 objects per hour.

My observing is not always this "structured" though. I take little breaks, enjoy the naked-eye view of the sky etc. There are of course many, many occasions when I don't bother with a list and just look at favourites. But, I still spend a minimum 3 minutes each.

Longer at they eyepiece? Yep, you see more!

Best,

Les D
Contributing Editor
Australian Sky & Telescope

astroAJ · #5 31-12-2007, 06:09 PM

Thanks everyone for your advice.
It’s going to help me a lot at the EP.

astroAJ

Rodstar (Rod) · #6 31-12-2007, 07:17 PM

Just to add to Les' comments, in the three years that I have been observing with a telescope, I have learnt to see far more in any object that I did when I first started out. That is, observing is a skill, and it requires a certain degree of practice and determination to improve.

Some objects have such complexity about them that if you are truly looking, you will learn something new every time you look at them. The Tarantula Nebula is one which I am spending a lot of time observing at the moment, because there is just SO much to see.

Other objects are extremely faint. As Les has said, there will often be only brief moments when you can actually see any significant detail, particular during times when the seeing is varying a lot. An example from my current observing predelictions is NGC 1365, the "Zorro Galaxy" as I call it. Under suburban skies in my 20 inch scope, the central bar is prominent with a cursory glance, but the spiral arms are not at all obvious. They take patience and careful examination to see. In poor seeing it can take 4 or 5 minutes before I have become confident of their exact location and form in terms of the overall field of view.

Many seasoned observers testify to the fact that they build up a mental library of what they have observed over the years. Each time they observe, they will bring to the subject a certain amount of memory from previous sessions, and in some way this helps them to see more at the present time, than another observer who has had less time looking at the same object in the past. It is something like an elite batsman in cricket who can anticipate and better see a cricket ball coming out of the hand of the bowler than an average player.

The message is keep looking, keep looking, keep looking. There is so much more to see than a cursory glance at an object will ever suggest.

ngcles · #7 31-12-2007, 08:02 PM

Hi Astro AJ, Rod & All,

Amen and amen to everything Rod wrote above. Experienced observers see more not because their eyesight is better, but because their perceptions of what to look for are well tuned and they are more patient. Observing is a skill and there is only one way to get more experience -- practise, practise, practise!

Best to all for the New Year.

Looking forward to getting some photons over the next night or so.

Les D
Contributing Editor
AS&T

astroron (Ron) · #8 31-12-2007, 11:37 PM

I may not have as good as eyesight as other observers who come to Cambroon observing nights,but because I have been observing deepsky objects for a long time I have trained my eyes to see faint fuzzies that other observers cannot see or have great difficulty observing.
As Rod and Les has said the more you look the more you train your eyes to see.
Happy New Year Ron

jjjnettie (Jeanette) · #9 01-01-2008, 01:29 AM

When I observe an object, I'll look at it through different eyepieces from widefield to as high a magnification as practical, maybe see what a colour filter or O111 filter will do to the view, I'll try to extract more detail by using averted vision or even tapping the side of the ep gently to get a bit of vibration going which can bring out more detail sort of.