Sunday, 19 April 2015

Observing Report - The SBT shows off it's capabilities.

Good day to you!
I start off by planning a bit of trial for this update.  For a while, I've been trying to think of a way to allow people to see something resembling the views I have through the eyepiece.  We have all seen the images produced by the Hubble space telescope, and by amateurs who dedicate their time and savings into very expensive equipment to bring awesome views.  In reality though, these images are nothing like what we see through the eyepiece.  So, how do I try to convey what I see, without exaggeration.  I have seen many excellent sketches that people have made of their observations.  These sketches have given the best representation that I have so far come across.  One problem though, I'm not really blessed with artistic talents.  So, I have decided to turn to that well known amateur astronomy tool, Stellarium. Stellarium has a feature called 'Ocular View' that you can set the parameters of your scope and eyepieces in, allowing the program to give you a representative field of view.  I have decided to use this feature to give an idea of how big these features are through the scope, although what I can't always replicate is their brightness.  So, the report.
The weather has been settled for the last 5 days or so, with pleasant Spring sunshine on most days.  The ongoing battle of lighter evenings, resulting in later nights conflicting with 6 am wake up calls for dog walks mean that at the moment, opportunities for observing have to be carefully selected.  The day and night of 18th April had an excellent forecast.  Barely a cloud crossed the sky all day, but the breeze was very evident.  I set up the SBT out the back garden just after the sun set.  The astronomy forecast was looking good with wind slightly decreasing through the night.  Whereas the wind can prove to be a nuisance with seeing conditions sometimes, it does keep the dew away from the optics and Telrad.
First task when I went outside was to line up the Telrad which I did on Jupiter.  However, I noticed some very strange 'smearing' in the bright image.  A collimation check with the laser collimater showed that the secondary was way out of line.  Thankfully, one of the original upgrades I did on the scope was to fit thumbscrews to the secondary to make collimation much easier.  Less than 2 minutes later, I was all aligned, up and running and ready for a great nights observing.
The constellation of Leo had already risen high enough in the sky for me to see it in its entirety.  Leo is awash with plenty of targets for a 12 inch dobsonian scope.  The constellation can be seen below, complete with Stellarium artwork to help bring out the shape of the constellation.

Constellation of Leo - Stellarium
There are two well known collections of galaxy target to look at in Leo.  Both of them can be found across the belly and hind of the lion.  My first objects to look at were the Leo Triplet of M65, M66 and NGC 3628.  Using Stellariums ocular view feature, I can show how the triplet is set out in the eyepiece.  The galaxies appeared much dimmer through the eyepiece of the telescope, but the moonless night and very good seeing conditions meant that they were easily picked out again the darker background of the night sly.

Leo Triplet in ocular view - Stellarium

The Leo triplet were one of the first collections of galaxies I looked at through the SBT, and at over magnitude 9 shows what the SBT is capable of.  It gives an excellent benchmark.  The other well know collection of targets in Leo that were next on my list were part of the Leo group of galaxies, M95, M96, M105 and NGC 3384.  These are two spiral galaxies and two elliptical galaxies.  The 4 targets were a little too big to fit in a single field of view using the 32mm Panaview eyepiece. I made a brief sketch in my notebook which showed M95 as I looked at the collection was just above and left of the field of view as I looked through the eyepiece.  At first, I didn't really know for sure what target was what, especially taking into account the strange things two mirrors and a bunch of lenses in the eyepiece does by flipping the image back and forth.  However, from the sketch in the notebook, and using Stellarium, I was able to confirm the targets after the session.

The Leo Group of galaxies - Stellarium
Up until that point, that part of the session had been spent re-visiting targets that I had seen before.  With nothing planned for Sunday, and good clear weather forecast all night, I new that I could take my time.  This proved to be a good thing given the amount of light pollution caused by the neighbors insecurity light in his back garden.  I knew that it would be a test of will and patience,  From my semi-reclined position, slumped in my camping chair next to the scope, I decided that I plenty of both.  During that time, I noticed the constellation of Virgo had also climbed above the roof tops and was now easily view-able.  I set about looking through my Telrad charts and star atlas to look for more targets.  The first new target for the night was M100.  It's a spiral galaxy in the constellation of Coma Berenices just above Leo and Virgo.  Though slightly less well known than the other constellations to many,  it is the home to another vast array of targets, many of which are beyond the limit of even the SBT!  Taken from my notes from the evening...

"Feint but with defined almost perfect round core in center".

M100 in ocular view - Stellarium

In the view above, the spiral galaxy is very bright.  In reality, it was much dimmer in the eyepiece, but the core was easily picked out against the smudge of the rest of the structure.
M99 is another spiral galaxy in the same constellation.  It's is of higher magnitude than nearby M100 meaning that it appears dimmer through the eyepiece.  Again, back to the notes from the evening...

"Slightly dimmer than M100.  Appears smaller too.  Possibly see structure @25 mm but hard to say for sure."

For this target, I changed the to the 25 mm BST eyepiece.  I expected to lose some of the brightness of the structure, but I couldn't really detect any loss in quality of the image.  It is a target that I would like to return to in the future and spend more time observing at different magnifications.

M99 in ocular view - Stellarium

Now, onto the highlight of the observing night for me.  My notebook gives a little description of what it was like.  But, there was so much more going on in the eyepiece.  I had switched back to the 2 inch Panaview eyepiece ready to start observing around Virgo.

"Virgo - wow!  Counted 9 other galaxies + possibly more!  Just amazing.  Problem with big dob here - too much to see."

The three constellations of Leo, Virgo and Coma Berenices hide vast riches of galaxies and other targets.   A positive treasure trove of targets for galaxy hunters with big light bucket gathering dobsonians.  So, here's the list of targets I think I observed.  It's very hard to be absolutely sure at my skill level, without the help of computer or Go To abilities to positively confirm the targets, but I've done the best I can..
M88, M86, M84, M87, M89, M90, M59, M58, M60 and M91.  They can be seen scattered around the image below, each circled in red and labelled.

Virgo Realm of Galaxies - Stellarium
This is certainly an area of the sky that I will be revisiting at the earliest opportunity.  Also, hopefully, skies will be clear at astrocamp and I shall spend a good chunk of time observing around these constellations from there too.  It really is tricky to convey how crammed this area of the sky is with targets, many of which are observable using the SBT, but a majority of which are beyond the ability of even the SBT I think.
Leaving that plethora of targets, I decided to try to hone in on single targets again.  So, I started to track down M49, another elliptical galaxy in Virgo.

"To cap off an awesome part of the session!  Very nice elliptical galaxy.  Slightly brighter than the others in the Virgo cluster than I have seen tonight."

M49 ocular view - Stellarium

Though in the same constellation as the others, as you can see in the ocular view above, the galaxy is a little more detached from many of the other targets.  Nevertheless, it's still about 56 million light years away.
One of the features to keep an eye out for this month is the path of Jupiter passing close by to my next target, M44, or, The Beehive Cluster.  It is a target I have visited through the scope many times before, mostly with the SBT's little brother, the 150p.  It is a vast open cluster with very bright stars.  Conditions were very good, dark and clear, enough so that I could just make out the cluster naked eye.  It was sure to be an awesome site through the 2 inch EP and the SBT.

"M44 - Beehive Cluster.  First time @32mm.  V-bright and rich cluster.  Poss naked eye tonight..."

The ocular view below is quite realistic in this case.  The brightness is quite well adjusted within the computer program.

M44 The Beehive Cluster ocular view - Stellarium
Leaving M44 behind, I tracked down another cluster.  This time the globular cluster of M53.  It's much more condensed that M44, but is still very bright and pretty.  I decided to stay with the 32 mm EP, but I think with the 18 mm BST I should be able to resolve many more individual stars next time I come across the target.

M53 in ocular view - Stellarium
The cold was starting to penetrate through the layers.  I had dressed more for a summers evening observing session than a spring session.  The night time temperatures reminded me that we have barely said goodbye to winter.  I was having such a good session that I didn't want to stop, but I was starting to get a bit cold.  It's not often I get the chance to have a fully free session with no considerations for the next day.  A couple more targets to finish off and that would be me done for the night.
M65 is known as The Black Eye galaxy and take it's name from a very distinctive small black area of dust and gas close to the brighter core of the spiral galaxy.  This is sometimes said to be visible in smaller amateur scopes.  I'd like to think that I could make out the black eye, but with my own tired eyes, it was hard to confirm.  It's a cracking little target though!

M64 The Black Eye galaxy in ocular view - Stellarium
The final target of the session proved to be a bit of mystery until this morning.  Whilst having a final 'look and nudge' with the SBT in Coma Berenices. I came across a very thin and really pretty target.  It was surely another elliptical galaxy, but I didn't know what one.  That area of the sky only has limited stars of naked eye visibility, so I struggled with the Telrad to identify what it was I had seen.  It was all the more tricky when I take into consideration how many potential observable targets there are in that section of the sky.  I ended up resorting to drawing what I saw in the field of view on the eyepiece.  I was using the 2 inch panaview 32 mm, so I decided to draw around the eyepiece cap which then give me the template to draw in what I was seeing.  I estimated the target to be above magnitude 9 which i was able to do by comparing what I been looking at throughout the session.  I sketched in the main target and relative size.  Next, I added the stars that I was able to pick out with ease and put them in their relative positions.  I hoped that this would be enough for me to use Stellarium and its ocular feature to pick out the features I had recorded in the sketch.
This morning, I fired up Stellarium and started to browse around the constellation of Coma Berenices.  I new that it was reasonably significant due to its magnitude and size, so it ought to be listed and perhaps photographed too.  After a while, I found what I was looking for, but as it turned out, there is no picture in my version of Stellarium of the target.  What I had stumbled across is designated NGC 4565 and C38 - The Needle Galaxy.  It's a sideways on spiral galaxy which appears very long and thin.  A bit more time looking for images on line confirmed what I had sketched whilst at the EP.
With fingers beginning to go numb, and the task of having to transport the SBT back out to the garage, it was time to close the session.  It's been the best session for quite a while.  For once, free time, weather and opportunity have all come together in my favour.  A marathon of a session deserves a marathon write up.  I hope that the pictures taken from Stellarium have given people at least a small understanding of what it can be like to view through the eyepiece.
Until next time!  Thanks for reading.

1 comment:

  1. Sounds like a long session Tony. You've got more stamina than me! Next time I'm out with the JLT I will try to spot some of the galaxies that you found. - Jim