I took the opportunity to do some further imaging of the Moon and Jupiter during a clear evening on the 17th March – as is common, the moon was high, and the transparency wasn’t great for any narrowband work, and as such it gave me an opportunity to work more on some high resolution work.
The seeing wasn’t great, and I took a different approach to imaging this time by using subframes on the ASI 120MM to get a high frame rate and allow large numbers of frames to be captured (thus increasing the chance of capturing good frames).
Images as below are of Clavius, Tycho, Rupes Recta (the Straight Wall) and Rima Birt, and Vallis Alpes (Alpine Valley) with the central rille (just!).
Planetary work is not really my strongest skill in astrophotography, but with Jupiter near it’s highest in this and the past few years, it is well placed for photography from the UK.
Additionally, this is one of the first chances I have had to get images with the large 14″ reflector using my ZWO ASI-120MM. I chose to use the Astronomik 742nm Near-IR filter to try to improve the results: on both occasions it has resulted in much better resolution than with unfiltered white light. In addition I used a Meade Series 4000 2x Barlow lens. With regard to conditions, I think I’m a little limited by my observing location where I have to observe over the top of our row of houses – the thermal currents (including from boilers, open fires, etc) are likely to do little to help the seeing here..!
First image is from the 17th March during Callisto’s shadow transit (taken at 23:08UT) – Callisto itself is also visible at about 7 o’clock (and clearly resolved into a disc – at 1.5″ the seeing was clearly not so bad..!).
Second image was taken on 22nd March 2016 – the results weren’t quite as sharp as those from the 17th. Unsure if this is a focus/collimation issue, or if the seeing just wasn’t as good. The processing is a little heavier to try and bring out the cloud contrast where possible too. Collimation of an f4.5 scope is fairly critical, and any slight shift can reduce image quality quickly. Equally, at f9, focusing is tricky with a fairly dim extended object – this is something I need to work on in the future – a Bahtinov mask is on the list of makes for when I have successfully rebuilt this scope.
All images were 2 min videos, recorded using FireCapture, processed in AutoStakkert, Registax 6 and Photoshop CS4.
A very quick post of the conjunction tonight between the Moon and Jupiter. I find these types of conjunction notoriously hard to photo, especially close to full moon. This is mostly due to the wide field required and the difference in brightnesses between the two objects.
I’ve tweaked the curves a little within Photoshop to allow both objects to be displayed without blitzing out the lunar details – but the eye is much better at coping with these scenarios with its non-linear response and massive dynamic range!
The wider field of the Nikon lens for these photos shows just how good telescope optics are as well compared to “standard” DSLR lenses – there is a fair bit of blue fringing around the moon’s eastern limb, which isn’t particularly obvious in photos through the Takahashi FC60 or the William Optics FLT110.
RA (centre): 05h 35m 10.9s
Dec (centre): -05° 28′ 54.4″
(Results from nova.astrometry.net)
On February 10th, I managed to get some first data on a project in imaging the Orion Nebula with the FLT110/ST2000-XM combo. I had a fair bit of equipment issues here before starting – I have changed scope and was trying a newer PC. I had issues in getting the computer to connect to the ASCOM focuser and so resorted to an old laptop, thus wasting time.
I also had some guiding issues with PEC on – I think this is related to balance (the mount should have been more weighted towards the east) – and not to mention the object skirting the trees resulting in some spurious guiding results and the loss of 6 frames…
Finally (!), it became apparent when doing the flats that there was frosting on the chip – I’m not sure if this was the case before (though it doesn’t show), but this did mean I needed to run the flats at 2C, rather than -20C like the lights.
Even so, results are encouraging – this is the result of 27 x 3min with an Astrodon 6nm filter – this is one of the older narrowband range filters – running at -20C at f7. This needs much more data, as well as luminosity and colour channels to allow me to merge it into an L/Ha-Ha/R,G,B image – the fainter regions are fairly noisy, which is not helped by short exposure, and the introduction of noise from the warmer flats, and dark frames for the flats.
Processing objects like the Orion nebula is always a little tricky, and I’ve tried to tame the vast dynamic range here by using luminosity masks in Photoshop (with four differently processed versions of the same image) to preserve the detail within the Trapezium, while also allowing me to bring out outer detail. If I can get a good enough night to get more data, I should be able to further blend in more data for the outside regions (possibly by using longer subs). The RGB combine should be interesting, and might need a bit of pushing of the H-Alpha data as it does get a bit diluted in the process.
We’ve had some poor weather this winter so far for astronomy, but we’ve had some clearer nights in the last week, but with the moon at a fairly full phase. So I’ve been working with the 14″ SPX350 in honing my high resolution lunar work a bit.
I had two fairly average sessions working with the ZWO camera in unfiltered mode, but suffered a lot from poor seeing (potentially due to thermals from houses I image over) especially with stacks coming out with “ghost craters”. However, for this run of images, I used an Astronomik ProPlanet 742 filter I have just purchased (this is a near IR filter passing wavelengths longer than 742nm).
This has given a very good set of results – with three images surpassing the resolution I’d previously been able to get – and working at a focal length around 3200mm too by using a Meade series 4000 barlow lens in front of the camera and filter (giving a resolution of about 0.24″/pixel). Previously, I’ve only got good results at prime focus. From a first time using it, it certainly appears that this filter does help with larger apertures where seeing is not perfect. Images, while not totally unaffected by seeing, seemed a lot more stable in terms of high speed jitter or double vision on craters.
Images were taken around 98% illumination so all the images are from areas around the eastern limb of the moon – with limited targets available and with cloud rapidly rolling in, the session was somewhat curtailed!
Grimaldi, Hevelius, Cavalerius:
Phocylides, Nasmyth, Wargentin and Schickard: