M56 with C8, 9x100s, Calibration, Stack and Process

M56 is a globular cluster of magnitude 8.3 in the constellation of Lyra.  It's about 33,000 light years distant.  This is compared a magnitude of 5.9 for M13, that I have imaged a few times before, hence the greater difficulty in getting quality data. I had to reprocess multiple times as the flat frames didn't get rid of the dust donuts on the optics. They are still visible, which means my optics must be filthy.  This was probably all picked up during my excursion to Worcestershire a couple of weeks ago. I'm still not very happy with the result, but there was more mist in the air than was visible when capturing, and this drastically reduced the number of images available to stack.  This image is composed of 9 x 100 seconds exposures.  Out of a total of 37 subs, having only 9 barely usable ones is a bit disappointing - there were also many that were out of focus at the edges.  This is partly due to the big drop in temperature during the data capture (although I did auto-focus with FocusMax beforehand), and compounded by the fact the telescope needs collimating. I cropped and stretched the data in MaximDL, and then adjusted levels, curves, saturation, Gaussian blurred, and despeckled in Photoshop.

Normal Guiding Service Resumed

A little less drift, but again, seeing conditions not ideal, so I am just happy to be imaging M13 again...

I've just noticed PHD was set to not guide on declination, so recalibrating with it set to north.

After getting enough data on M13, although it's late, M57 (the Rin Nebula in Lyra) came up into view, above the dirty grey zone of the horizon.  This is one of the joys of imaging where an image seemingly so bland as a grey smudge, will turn into a beautiful nebula once enough data is captured.  Yes, the grey smudge in the middle is what I am so excited about...

When I zoom in, this is what the camera is capturing, a planetary nebula 2,300 years from earth:

Once the image is processed, although it won't be nearly as good as the colour image below (from Stellarium), it's one of the personal rewards of astrophotography.

Below is one 120 second image converted to colour.  No other processing...

I wish I had more time to get more data, but as is often the case, M57 will have to wait for another day until I and my equipment can do it justice.

Apart from the odd blip, as below, (probably caused by "stiction" (static friction in the gears) - the CG-5 mount is reknowned for it), guiding has been good tonight, just a pity I have to close up shop...  The clouds are due to descend for a few days however, so at least I have plenty of data to process.

Typical Night Imaging

As many people publish finished (calibrated, stacked and processed) images, I thought it would be more educational to show a screenshot of what I see when actually imaging (this is what I would like to have seen before I got into this time-consuming hobby).  This is the part of astronomy that I enjoy the most, except perhaps that eureka moment when processing a series of images and teasing out the detail of an image that seemed invisible, but there have been very few of those so far...

PHD Guiding (above) and MaximDL Image Capture

The 2 monitors above show the guiding software (PHD) tracking a star while the imaging software below (MaximDL) controls the camera.  The image in the bottom left is a raw CCD image of a 50 second exposure of M13 (The Great Cluster in Hercules), a globular cluster in the constellation of, you've guessed it, Hercules.

It's actually pretty pointless doing this imaging, as the "seeing" (the quality of the atmosphere) is so appalling that the resultant stacked image will be blurry and without definition or colour, but as I have just reattached my mount to the pier, I am checking to see how well it tracks or guides.  As you can see from the red line on the graph the telescope is drifting away from the target.  This tells me my polar alignment is not very good, but probably adequate for such short exposures, especially when I'm going to delete all of the images.

I was going to image M101 tonight, but this happened:

Satellite Track Ruins Image

No, not the satellite track across the image.  Look closer, follow the arrow before the satellite track, and the bright spot is the core of M101, a spiral galaxy (that is usually readily visible after a 120 second exposure, which is what this is):

Closer look shows M101 hidden behind mist, cloud and poor seeing

It's barely visible, which tells me the "seeing" is rubbish.  It's hazy, misty, and the pollution (dust and particulates rather than light pollution) reduces the amount of light getting to the telescope from the object.  So it's simply not worth trying to image anything faint.  Hence I turned to M13 (which happens a lot).  The other globular clusters, which I have become all too familiar with, are M3, M5,  M92.... see for yourself - this is how I find them (there are many, many, more than this, and Charles Messier only catalogued the most visible ones):

Globular Clusters on Chart

Here is a zoomed raw image of M13 hot off the CCD chip (or rather cold off the CCD chip, as it's presently running at -20 degrees celsius):

Close up of (cloud covered) raw image of M13

Not too good? A few moments later, this:

Same close up, but less cloud

Same exposure, only about 5 minutes later.  Maybe the clouds are passing... This is more like what I would expect - much better definition of individual stars near the core of the cluster.

In case you're wondering about my guiding graph, yes, the drift continues:

Red line (declination axis) continues to drift

However, the clouds have improved, and definition in the images is improving...  So out comes the adjustable spanner, half a turn on the declination axis to flatten the red line.... and:

Whoops, wrong way (graph goes down even steeper (far right of red line)):

User error - excessive use of spanner in wrong direction...

To cut a long story short (and one which will be told in future) I messed up my guiding big time, just by turning that bolt half a turn.  Another 20 minutes later, the graph looks like like this:

What you guiding graph should not look like

By which time it is time the clouds have returned. I eat, do a few chores, get ready to pack up, and loh, there is a gap in the clouds. I try to guide again, but it's so late, the telescope has slewed over the meridian... Time to call it a night.