CCD imaging activity as it happens
After some disappointing weather over the last 12 months, I've taken my first proper deep sky image again in 2016. NGC 281, The Pac-Man Nebula is a nice easy target in Cassiopeia. This latest image is simply 2.5 hours of hydrogen alpha data, no darks, flats or bias frames. Naturally the image will be reprocessed when these calibration frames are available. I also want to add another evening's worth of data when the weather allows it.
NGC 281 will be my project focus over the nest few sessions. Firstly I will create a HaRGB image, then shoot O-III and S-II data to create a Hubble Palette image. The narrowband data will need to be several hours per filter to achieve a good image. I will be aiming for at least 5-6 hours per channel.
I am now using PHD2 autoguiding software with its added features. In order to improve guiding performance I have started using the polar align assistant which allows even greater polar alignment accuracy than the Takahashi EM-200 polar alignment scope does. Given the declination backlash which unfortunately plagues the EM-200, a very accurate polar alignment will reduce much of the declination drift and any necessary corrections. Guiding performance was very good last night despite the wind. Polar alignment was accurate and declination guiding corrections kept to a minimum. Sub-pixel guiding was still achieved with round stars in each of the subframes.
Well I finally managed a Hubble Palette image of NGC 7380 after gathering 4.25 hours of S-II data over a couple of evenings. This one took a lot of processing but I found the chapter on narrowband imaging in 'Lessons from the Masters' very useful. One of the main challenges was getting the colour balance right-the H-a data can really swamp the image. The addition of the super-luminance layer also really helped to preserve some fine detail.
De-saturation helped get rid of the strong magenta in the star colours.
On with the next target.....
Well the nights have started to draw in a bit now which means that the new imaging season can start. I've decided to continue with Hubble Palette narrowband imaging this year so look forward to getting some decent images!
My latest image is a bicolour (Ha:sG:OIII) process of NGC 7380-The Wizard Nebula, a large nebula in Cepheus. Total exposure time - 3.5 hours hydrogen alpha (from 2011) and 4 hour of oxygen-III. Although the skies have been clear, the seeing hasn't been great and individual 15 minute O-III subframes have shown little nebulosity. Despite this I hope I've managed to come up with a decent image. The next plan will be to add some S-II data to develop a Hubble Palette image
Well the shorter nights have made deep sky imaging pretty much impossible when you have to be up early in the morning! I have however just uploaded a shot of the Leo Triplet from some data captured back in February. Since I last had a go at this object I have discovered how to process the data without burning out the galaxy cores. This meant that the detail in the galaxy arms has been preserved. Obviously some RGB data would be nice but that will have to wait.
Currently the cameras are off the scopes and I have spent a few evenings observing the planets Saturn and Mars. I'd forgotten just how sharp my Takahashi FS-102 was on planets. Saturn looked stunning in particular.
Looking forward to the nights drawing in a bit so I can get some imaging done at reasonable hours! Still deciding on a target but I'm keen to try some more tricolour narrowband imaging in the next few months
It has certainly been a better week this week for astronomy, although the Moon has been quite high in the sky for astroimaging. Nevertheless I managed an image of a beautiful spiral galaxy in Ursa Major. Galaxy season is now here, so I have decided to try LRGB imaging again as the evenings aren't dark enough at this time of year for the hours of exposure demanded by narrowband imaging. I've selected a number of galaxy groupings and star clusters to target over the next couple of months.
This week I also had to replace the desiccant within my CCD camera. I had started to notice a patch of condensation appearing on the images-a sign that the desiccant needed replacing. This is relatively straightforward although it does involve dismantling the camera and opening the CCD chamber itself. It was also a good opportunity to give the filters a clean in readiness for the galaxy imaging.
On the visual astronomy front, I have spent a couple of enjoyable sessions viewing Jupiter with the 8'' Newtonian. At high power, some detail is visible within the cloud bands. Earlier this week there was a shadow transit of Io which was great to see, as was the emergence of the moon itself from in front of the planetary disk. Last weekend I spent a couple of hours tracking down some galaxies in Leo and Ursa Major. The EQ-5 setting circles aren't bad and do seem to work! The Leo Triplet was nice to see, although quite washed out in the moonlight. This will certainly be one of my next targets. I did try it a couple of years ago, but was not happy with the result. Now being more familiar with the CCD and image processing I look forward to giving it another go.