It’s been around two weeks of constant clouds here in the UK, so it’s been really difficult to get out into the back garden. However, the cloud cleared the other night for a couple of hours!
Since my last imaging session I’ve fine tuned my mount again. Completely removing the declination motor block gave me access to the worm-gear adjustment, allowing me to remove that last little bit of backlash. It did take a few tries to get it perfect so the gears wouldn’t bind, making a horrible sound in the process. It gave me a mini heart attack each time, and I had to quickly scramble to hit the stop button in EQMOD! Learn from your mistakes…
With everything eventually re-built on the mount, and the entire rig set up in my new place at the bottom of the ramp, I had to first re-calibrate PHD2 guiding before I could start imaging. This was an easy enough task to do, as I had finally managed to get Stellarium working with ‘Telescope Control’. Quickly allowing the scope to slew to 30º Altitude on the southern meridian – best place to calibrate, as this is where the stars seemingly move the quickest. Unfortunately, after a good hour fettling with the gears during the day, it only made a small reduction in backlash; I think I’ll just have to live with it for now.
Now to decide on a target. For this session, it was relatively easy to choose. At the time that I started to set up, Cassiopeia was directly overhead. This meant I could track it westward for quite a while from where the telescope is located. Using Stellarium again, I decided on an object that is well known in that region, and one that I have wanted to image for a while. NGC 281 – The Pac-Man Nebula!
With everything entered and located within N.I.N.A., the evening started off relatively calmly, with a few clouds quickly passing through. However as the evening progressed, the wind quickly picked up. Even though my rear garden is fully enclosed on all sides, it still caught the telescope like a wind sail. I didn’t realise how much of an effect this would have on each exposure.
Once again, I was taking my now-seemingly standard five minute exposure time. Out of the 20 exposures that I did manage to capture, I was only able to stack 12 of them. Nearly half of all my exposures had massive star streaks where the wind had unfortunately rocked the telescope. To make matters worse, just after a meridian flip around 10:30PM, blanket cloud cover rolled in from the west, bring an end to my imaging run.
I ended the session by taking dark frames. I didn’t get chance to take any bias frames before the rain started, so at a push, I used my bias frames from my previous image of the Cocoon Nebula. Not ideal I know, but it did work. With only 60-minutes of usable data, I really did not expect to get anything that was anywhere near useable.
How wrong I was…
The image above shows what a one of my single 300-second exposure looked like. As you can see, for a single image, it shows a decent amount of data with lovely star colour ranging from deep oranges to cool blues. I really do love the Hutech IDAS NGS1 for this!
I initially loaded all my exposures into Deep Sky Stacker, and registered them. I then used the scoring system to determine how many exposures can be stacked in the final image – as mentioned previously, only 12 were of any use.
Within Deep Sky Stacker, I always have a go at stretching the final exported image, just to get an idea of what is possible within Photoshop. I was honestly shocked to see what could be bought out! I quickly imported it into photoshop and went through my now-instinctively editing routine. I did have to crop out quite a bit of the final image as stacking artefacts caused faded lines in certain sections. However because I use 2x drizzle within Deep Sky Stacker, I have enough resolution to crop a good portion of the image away and still have a final image resolution 18MP.
For only 1-hour of exposure though, I am delighted with the final outcome! It does make me wonder though, what could be accomplished with a dedicated astrophotography camera like the Altair Astro 269C? A future purchase I think!
Since then, the clouds have been none stop in the evenings, and haven’t been able to get outside at all! Hopefully by the time I can get back outside, Orion will have started to rise earlier and I can finally image it from my back garden! I REALLY want to image this region of the night sky, as objects like the Orion Nebula and the Horsehead and the Flame Nebulas are some some of the targets that got me excited when I first started!
I’ll have to wait and see. Till then, clear skies!