Sunday, 16 November 2014

What targets to observe? How I plan....

Good evening!
Winter has most certainly arrived in Ross Vegas, and the cold dark nights have imposed themselves upon us for what I hope will be an excellent winter of observing.  The darker evenings give us working mortals more chance to set up a scope for a session, and still get to bed as a reasonable time on a school night.  Providing the weather plays ball of course!
Recently, I’ve been speaking to several people in reference to observing sessions, and how I decide what to observe in a session.  Of course, there are a vast amount of targets available to go after.  Some of them are arranged in catalogues, such as the famous Messier catalogue, and then there are the planetary targets in our solar system and the various moons associated with them.  All these things provide a vast list of things to go at.
In this blog entry, I will attempt to describe how I plan my observing sessions and how I have found to get the best out of them.  I don’t think that there is a definitive right or wrong way to go about this and in my short time as an amateur observer and stargazer, I’m always on the lookout for help and advice from other members of the astronomy community who have a lifetime more experience than me.  So, let’s begin.
Observing sessions for me usually last in the 2 to 3 hour range, longer on weekends.  As well as time and visibility, I also find that the temperature and dew can restrict the time I spend at the eyepiece.  Without the various dew shields and straps that can be bought for telescopes, after a while, dew and frost will ultimately win and often dictates the end of the session.  So, it’s important to be prepared.
My preparation for a session usually starts on the days leading up to the time when I go out. 
The first consideration I make is the time of year.  As any budding enthusiast will tell you, the time of year will determine what is available in the night sky to be observed due to the seasonal skies around us.  Any good star atlas, or chart will be able to tell you what is visible at different times of the night for any period of the year.  I also refer to forums such as Stargazers Lounge, magazines such as Astronomy Now, and The Sky At Night and TV programmes to find out about any unusual or rare objects that can be observed.  A recent example of such an object was C2/2014 E2 Jacques.  Usually, the rare objects will take some sort of precedence on the plan. 
The next consideration I make, or rather, the next decision I make, tends to be to choose a specific area of the sky to work with for the evening. Usually, I will chose a specific constellation or two, or depending on the moon phase, plan a lunar observing session.  I have to bear in mind where my observing is going to be completed from.  For instance, if I go back yard observing, then there are several impediments to my view of the night sky such as buildings.  If I am to observe from somewhere else, I will usually have an idea of the views to horizons and take these into consideration.
Now is the time to reach for a more detailed star atlas, or programme such as Stellarium.  It’s time to do a bit of research.  Like most people, when you have used a specific telescope for any amount of time, you get to know its limiting factors, especially its limiting magnitude in given conditions.  I refer to an atlas and pick out objects that I think that I will be able to view with my scope.  This can mean a bit of time online too, in order to get the correct magnitudes.  Time can be quite precious, so I don’t really want to be stuck trying to find an object with a magnitude so dim that it is beyond the capability of my scope and eyepieces.  When lunar observing, knowing what parts of the lunar surface are going to be visible is important, as well as the times for moonrise and moonset.
Usually, I’ll note down around 6 to 8 targets of varying magnitude to give me a good spread of targets to look for.  I will also try to familiarise myself with their respective locations amongst the constellations to make navigating to them an easier task.
I find that by keeping a potential target list at this sort of length for an evening’s observing is ample to get on with.  When I first started, I used to find myself rushing around the sky trying to seek out as many targets as I possibly could.  They are exciting times indeed, but I have since slowed my observing pace down a little.  I now spend much more time on an individual target and allow myself the opportunity to explore it fully, to tease out as much detail as possible using a selection of eyepieces.  If my research before the session suggests that a target is better viewed with a specific filter, then I will make sure I take the time to use that filter if I have it and compare the images I see.
I have learned that it isn’t important to achieve everything on the intended list for the night.  If I only end up seeing 1, 2 or 3 targets on the list for that session, then so be it.  There will always be another time to go back and tick them off again at a later date.
I like to record what I see and when.  Indeed, a large part of this blog is given over to my observational records.  I also have a field notebook which comes outside with me, and is with me when I plan what to see.  It’s also got plenty of scribbles and notes on anything astronomy related that I might one day want to refer back to.  And finally, I also have a book solely for observations.  As much as I use and embrace IT, computers and the internet, there is no guarantee that all my observing records are always going to be available to me online for the rest of my days.
And finally, another lesson that I’ve learnt is that you soon get some favourite targets that you find yourself drawn to time and again.  Typically, things like M31, the Andromeda Galaxy, the Double Cluster in Perseus and M57, the Ring Nebula in Lyra.  Not to mention the giant planets Saturn and Jupiter.  I’m drawn to these for a reason, whatever that might be.  It’s important for whatever that reason might be, that I spend time re-visiting them.  As they are favourites, they tend to be easy to locate the 4th, 8th 10th or whatever time, and it’s always a nice way to end a session by re-visiting one, or some of these targets. 
So, in brief then, my top tips for planning an observing session:
1.       Research what’s available for the time of year.
2.       Research any special or rare targets observable at the time.
3.       Consider the observing site you intend to use and account for any viewing restrictions in place.
4.       Focus on one or two constellations, a lunar, or a planetary session.
5.       List between 6 and 8 achievable targets in your chosen area.
6.       Take your time on each target and experiment with all available options to get the best views.
7.       Don’t rush to tick off all the targets in a single session.  If you miss some out, they will usually be around next time.
8.       Revisit at least one favourite from previous sessions.
9.       Note the observations and record.
10.   If there targets remaining on the list at the end of the session, use them on the next target list.

Thanks for ready,
Clear skies,

MMM

No comments:

Post a Comment