Tŷ Du Observatory

Happy New Year

A new year and a new start for me. I’ve bought a QHY-5 guide camera and some scope rings to have a go at autoguiding. I had several viewing sessions towards the end of last year, but haven’t updated the site as most of the images are duplicates of those I’ve taken before. Now that I can improve my images I will consider rebuilding this site to make it easier for me to update.

I’m looking forward to being able to start imaging fainter objects and also to tease more detail out of those I have imaged in the past now that I can do longer exposures.

Initial tests look promising but I’ve had to overcome a number of issues, such as the guide software crashing every 5 minutes and the weather not cooperating! Last night was my first chance to get everything working but it didn’t clear until after 10pm so I didn’t get to bed until after 3am but I did leave the scope tracking so as not to miss this rare opportunity to image with a clear sky.

Here are a couple of images from last night:

The Horsehead Nebula in Orion	M1 – The Crab Nebula	NGC457 – The Owl Cluster
NGC891 – Edge on Galaxy	NGC2403 2×5 minutes	NGC2403 6×1 minute
NGC2841 – 100×2 minutes

Guided using Guidemaster 2 (beta) 70mm refracter and QHY-5 guide camera. Guide signals from camera to mount, not ASCOM.

Images with 254mm Skywatcher relector on EQ6 Pro Mount with Atik 16ic mono camera.

NGC457 the Owl Cluster was one of the first objects I imaged, so I thought it fitting that I was able to include this amongst my first autoguided images.

Sunday was clear but I knew I’d be up at 6:30am for work so thought it best not to image into the early hours. Instead I completed converting my PC to Linux and set about looking for image processing tools. Hmmm, I’ve been spoiled with the options available to me under Windows and now I’m struggling to find anything that will stack multiple FITS. I can do post processing using the GIMP but without a stacking option (and histogram stretch options) I found I had to revert back to K3CCDTools under Windows. I ran Windows in a VMWare session though

Monday was clear but by the time I get home from Karate it’s too late to set up and I don’t have the energy anyway

So here we are on Tuesday, a clear sky, the nights drawing in and I have everything set up by 7:30pm. I decided to pick out some old friends towards the North, which turned out to give me an insight into the issues I have with mount movement. Focusing my attention on object close to the meridian I was able to increase exposures to 60 seconds in some cases. I had to discard a large number of frames, but those that were usable had much better dynamic range than the 10, 20 and 30 second shots I’d been taking recently.

NGC4605 – Galaxy	M27 – The Dumbbell Nebula	NGC6503 – Galaxy
NGC6946 – Galaxy	NGC5907 – The Splinter Galaxy

I returned to NGC6946 to see if there was any trace of SuperNova SN2008S. I had taken images in January and February around the time this SuperNova was discovered and wanted to see if anything remains. I’ll have to create one of those blink images to show where it is, not tonight though.

Another clear night, even though I can barely keep my eyes open I know these opportunities don’t come around too often so I’d be a fool not to get the scope out again.

I’m still disappointed with the results, the short frame times result in images that lack any depth and need to be stretched to the point that they become black and white
as opposed to shades of grey. But I know this is going to take some time to master so I can be critical as it pushes me to do better next time.

M2 – Globular Cluster	M27 – The Dumbbell Nebula	M81 – Bode’s Galaxy
M92 – Globular Cluster	M102 – Galaxy	M109 – Galaxy

Another clear night, and it looks like there’ll be a few more over the weekend.

I spent some time playing with PemPro and PERecorder to see if I could make a PEC curve for the mount. It looks like each worm cycle has a different profile so I’m not sure how much help it would be. After spending several hours using the webcam to record PE I decided enough was enough and moved on to imaging with the Atik 16ic.

I didn’t get much, it was already late so really it was just a test of the PEC experiment.

M15 – Globular Cluster

M27 – The Dumbbell Nebula

M57 – The Ring Nebula

Even after applying PEC I was still unable to manage more than about 30 seconds per frame.

I wasn’t expecting a gap in the clouds but I made the most of the opportunity when it came. I only wish I’d been able to stay awake longer to take advantage of this rare occurrence.

As I noticed the clouds breaking up I decided to do some mount tuning before starting an imaging session. I’ve had a couple of attempts since the last post, but haven’t been happy with the amount of movement in the images.

I started by realigning my polar scope. I did this during daylight by sighting on my neighbours weather vane and rotating the mount to make sure the cross hairs stay centered. Some adjustment was required but it only took a few minutes to rectify the issue.

Next I found I could detect movement in the mount head by rocking it with my hand. I made some adjustments to the hex bolts and was able to remove all movement, but knew this could have an affect on the gear mesh so my next step was to power it up and slew the scope around. Sure enough the mesh was too tight and I had to make some minor adjustments to make sure the gears moved without jamming and there was no movement when I rocked the mount head.

What else could be affecting my imaging? Well I’ve always been a little concerned about the third weight I use to balance the scope. I described in an earlier post how I picked up a 5KG weight-lifting weight from a local supermarket to help balance the scope and sandwiched this between the 2 weights that came with the mount. The central hole in the weight is too big for the shaft but until now I hadn’t taken any notice of this. To remedy this issue I took a roll of masking tape and wound it around the shaft until the weight fitted snuggly over – problem solved.

So now I only had to wait for darkness to see if I’d made things worse or better.

Turning on “Messier labels” in Starry night showed me a number of the southern M’s were within reach being higher in the sky during the summer months. Some of these I’ve never imaged before so I set about what turned into a miny Messier marathon. Initially I was limited to 10 second images as the sky was not yet fully dark and longer exposures where not possible. I started with the lowest M I could get at given the obstacles that hinder my South and South West view. So the session went something like M28,M22, M8, M21, M23, M9, M18, M17 and M16.

M8 was disappointing, I found I was still getting movement in the images so longer exposures were not possible. For this reason I skipped M20 the Triffid stayed mostly with Clusters.

I finished the evening by looking at PemPro and PERecorder to see if I could create a PEC curve to help with the mount movement, but time ran out and at 1:20am I called it a day. Next time I get a clear night I’ll start recording PE earlier to make sure I have enough time to do this properly. What I did find was it looks like the mount has +20 to -20 Arcsecond movement which seems to be about normal for an EQ6. I think need at least half this for decent images.

So here are the new images, I’ll have to remember to update the Messier Catalogue on the images page.

M9 – Globular Cluster	M16 – The Eagle Nebula	M17 – The Swan Nebula
M18 – The Black Swan	M21 – Open Cluster	M22 – Saggittarius Cluster
M23 – Open Cluster	M28 – Globular Cluster