Sunday, 16 August 2015

Sometimes, you’ve just got to do it.

This weekend has been the start of a 5 day break of work for me.  So, with bits and bobs planned, I’ve had the luxury of not really needing to be up and about at any particular time.  Except that is for the Great British Beer Festival in London Olympia.  But that’s another story.  Coming back from London on the train, I had a quick look at the weather forecast, and it showed the potential for some scope action overnight.  Slightly jaded, and somewhat tired from the trip to GBBF and a day at the Science Museum, it was going to be touch and go if I could stay awake long enough.  Coffee was the answer!
Skies were clearer earlier that forecast, so I set the SBT up around 9.30 ish, checked the collimation and had a quick scan about.  It was still too light to start any sort of observing, so I left the kit out and returned inside, but by 10pm I was back outside and ready to go.  First of all, a quick trip around some targets that I have seen before.  Doing this, I find it gives me an indication of how good the conditions are for observing.  I’m able to compare familiar targets to how they appeared on previous occasions.  Conditions were good, though not excellent to start. There was still a high thin layer of cloud just taking the edge of things, but as the evening progressed and the temperature dropped, conditions improved.
The first targets for the evening were the Ring Nebula, the Dumbbell Nebula and the open cluster M52.  When observing the Dumbbell Nebula, I thought it was a good opportunity to try out one of my filters.  I haven’t used any of my filters with the SBT so thought, again while on a familiar target, that I could try it out.  Without the aid of a filter, I felt the best view was given by my 25mm eyepiece.  The nebula was distinct, with the rough circular appearance characteristic of it.  However, no sign of the shape which gives it its name that it is often present in photographs.  I chose the OIII filter and attached it to the same 25mm eyepiece.  The difference was certainly notable.  Though in practice, any filter reduces the amount of light entering the eyepiece, different filters will block light of different wavelength.  So, the overall effect of this particular filter on this target was that the background sky was darkened significantly, without having the same dimming effect on the rest of the nebula.  With the filter in place, I was able to see the start of the more traditional shape, now that the nebulosity was sticking out better against a darker background.  This was just the start of my play with filters for the evening. 
In my last post, I referred to the list of the Messier catalogue object which I made in my notebook that I have left to observe.  I again referred back to this list for my next two targets.  The first of these targets, and the first new tick for the evening was M94, a spiral galaxy in Canes Venatici.  Whether it was the seeing conditions still hadn’t settled down, or this object is genuinely tricky to see I don’t know, but I found the target easy to locate, but hard to define.  It’s magnitude of 9 is well within the capability of the SBT, but I found it hard to not any structure on it at all.  I observed the galaxy at 32mm and 25 mm and could make out the bright core with ease, but little else.
Undeterred, I moved on to the second new target, M106.  This is also a spiral galaxy in the same constellation as M94.  Again, this was tricky to locate, showing its bright core with ease.  However, it didn’t appear as bright as M94, but oddly, M106 did seem to show slightly more stretched structure.  To try and get as much light from these objects into the eyepiece as possible, I only observed at 32mm.
During my last session, I was really pleased with my first observations with the Veil Nebula, but noted that I could only see the Eastern Veil.  Tonight though was to be significantly different.  In an ever darkening sky, I brought the SBT around to the constellation of Cygnus, and the location of the nebulae that make up the Cygnus Loop.  I easily located the star 52 Cygni again, which I did observe previously, but reported that I failed to make out any nebulosity.  However, this time, I thought I could make out a slight colour variant stretching through the star and out each side.    NGC 6960 goes by a number of names and designations.  Notably, the Bridal Veil Nebula, Caldwell 34, the Western Veil Nebula, and the Witches Broom Nebula.  It was time to break out the filters again.  I did a direct comparison at 25mm with firstly, the OIII filter.  I then switched to the UHC (Ultra High Contrast) filter.  Out of the 2 filters, this time, I think the UHC filter performed the better.  These are the notes I made in my book from the night.

                “Fantastic nebula.  Filters do an amazing job, but UHC better out of the 2 I think.  Wide and well defined, narrowing to star 52 Cygni, then wonderfully thin and extended.”

The nebular, with the aid of the filters, stepped out of the darkness brilliantly.  Both filters in their own ways brought the grey wispy nebulosity into sharp definition from the darkened background of the rest of the night sky.
I felt I was on a bit of a role, and decided to look out some other objects not on the Messier catalogue, but that I had heard of previously.  So, next, I chose to look for NGC 4490, the Cocoon galaxy.  I seemed to take a long time to try to locate the galaxy, though looking seemingly in the right place.  According to the charts and my Telrad rings, I could locate Cor Caroli, following it along until I come to the galaxy.  I found the galaxy though quite dim, but couldn’t for sure say that this was correct.  The star atlas say that I should also see NGC 4485, a magnitude 12.5 galaxy in the same vicinity.  I think I could make something out the prime target, but more of the appearance of a lightly smudged star.  The two galaxies apparently look like there are interacting in some way.  However, because of the low elevation of the target in the sky, I expect that conditions were hampering the quality of the observation.  Nevertheless, I had seen enough to convince myself that I was looking at the correct galaxy, especially when re-referencing back to my Telard chart and sky atlas.
Time was now pressing on, the bells in Ross had rung for midnight some time ago.  The temperature had dropped significantly, and there was a heavy dew on the lawn.  I’m pleased to say that this didn’t seem to effect the performance of the telescope through the evening, but did give an indication of how much moisture there was in the atmosphere.
I decided to call it an evening around 1am and retire to bed.  Though I hadn’t observed lots of targets, the ones I did were important.  Put together with the experience of using the filters with the SBT for the first time, I feel I now have a bit more idea of the circumstances I can use them.  All in all, an excellent night with some good quality observations.

Cheers!

No comments:

Post a Comment