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Captured 11th April 2025, around 22:00. This is a 97% waxing moon at an elevation of 24°. Captured whilst waiting for astro dark to arrive.


Equipment: Vixen 81s refractor, Atik 314L+ CCD camera, ZWO EFW filter wheel, Telescop RGB filters.
Software: SharpCap 4.1, Autostakkert!3, Registax, WinJupos, GIMP.
Capture: Focusing was carried out on Regulus using a Bahtinov Mask. The focus was tested on all 3 filters and it was noted that no adjustment was required. At each filter change, exposure adjusted so histogram just over 50% saturation.
Data: R, G, B filters 30 frames each. Exposures 2.5 - 3.5ms, MONO16, 0.5fps.
Processing: AS!3 stack best 75% of each filter. Mild sharpening with Registax 6. WinJupos for RGB combine. GIMP for saturation & contrast.


A single R frame in FITS Liberator:
A worthwhile 3 minutes of capture, with the ray systems of Copernicus and Tycho clearly visible. The full moon is not an easy target.

Dave

That's great Dave. High quality in a short take and a great picture not that far from totality.

On thing that I found interesting compared to my own 'work' (funny word that - that astronomers use --I think Patrick Moore started it -- a more honest word would perhaps be 'play' ) was just how high quality the average frame was there --averaging above 75% according to Autostakkert. Is this something that you often see or that was peculiar to this occasion? In the few lunar images that I have done the average quality is much lower --a few spikes up above 75% -- and so I limited the selection down to just the top 25% or less.

I was wondering to what extent do you think that getting exceptional lunar images comes down to selecting windows of really good seeing? So that success might best come from taking a lot of 1 min ser files on a single night and throwing most away?

Tim

Thanks Tim, trying to preserve detail on a >90% moon does take some practice.

I was surprised by the Autostakkert Quality Graph being mostly above 75%. If I look back through my older posts then typically I take the best 25% that are above the 50% quality line. I don't know the reason for this. Capturing in FITS rather than SER is one difference, note that the Max ADU in FITS Liberator is 46,000 which means the 3ms captures did not saturate the sensor. Also there is the camera pixel size. The Atik has 6.45µm pixels. However I have also had good results with a QHY5LII-M (3.75µm), Skyris 618M (5.6µm) and Altair 183M (2.4µm) - for these 3 cameras, drizzle 1.5 in Autostakkert seems to give a better image. On Astrobin, the camera of choice (if you want IOTD or Top Pick) seems to be the ZWO 174MM (5.86µm) coupled with a C14/C11 scope. Some more data capture and investigation required.

Seeing is a lottery. I have captured 20,000 frame SER files to get 10% above the 50% Quality line - that must have been a turbulent atmosphere. Filters do help - Red with lower elevation and the IR685 pass filter for high elevation or when still light. The most stable atmosphere I have found to be in the early morning before sunrise. Some of my best lunar images have been just before twilight with the IR685. Some IR685 evaluation notes from the Baader website:

https://www.baader-planetarium.com/en/d ... -paech.pdf

https://www.baader-planetarium.com/en/d ... -paech.pdf

I have been experimenting with processing the RGB data using only PixInsight. I have managed to produce this:



I am now working on where the colour went. PixInsight processing was as follows:

Stacking - use FFTRegistration to stack the R, G, B data sets. The same file must be used as the reference file (I just used the first red).


Colour combination of the R, G and B stacks using ChannelCombination. The image shows the R, G, B readout values.

Sharpening using MultiscaleLinearTransform, note how small the values are.


Before carrying out CurvesTransformation for stretching/saturation I applied a mask generated by RangeMask to protect the brighter areas.


IntegerResample and Rotation were used to finish off. This was the final result. I have some work to do here but it is early days yet.


I have found a well planned lunar session (using Virtual Moon Atlas) can generate 50Gb of data in a 1 hour session.

Dave

Dave. Thanks so much for that very useful response and taking the trouble to supply the Baader references which I read with interest.

So seeing is quite variable and critical - under perfect conditions the C14 in Namibia was separating features on the moon close to only 400m separation apparently -- but 'normally' and anyway in daylight where twilight can afford best seeing (I hadn't even considered that) it is usually better to sacrifice a bit of 'theoretical best possible resolution and use the 680nm IR pass filter -- I could see the improvement in contrast in the sample pictures. Another bit of useful learning was from the picture of Copernicus -- I didn't like my own image of it that much because of the overexposed crater sides and hadn't thought about the possibility of fixing it through increasing the overall dynamic range by using a different exposure for just that part of the image.

Also interesting to see what you have been doing in PixInsight. I didn't know that the FFT registration script existed - so I will probably have a play with that too (after using PIPP to convert .ser files into .fit files).

On cameras --it is interesting to see that 'real' lunar imagers seem to go with mono. But I find the idea of an OSC attractive - at least in theory -- i.e when possible to get enough good frames fast enough -- then winjupos would not be necessary for alignment and you get a 'mineral' moon immediately from just the one data set?

I was interested though what you did with winjupos ..anyway this looked interesting on Cloudy nights.. https://www.cloudynights.com/topic/6944 ... nce-frame/

Tim

Thanks for the CloudyNights link - a heavy read but very interesting.

I saw the reference to the Copernicus crater in the Baader article - HDR for a crater. I have always had trouble with Copernicus and will be trying this technique next time around.

Undoubtedly, an OSC camera does make acquiring a mineral moon a lot easier - I managed that with a ZWO ASI 120MC see viewtopic.php?t=5421 post #10.

The image above was just an inspired capture whilst waiting for astro dark with a setup geared for M101.

The start of May will be good for lunar imaging with an elevation >60°.
See https://www.timeanddate.com/moon/uk/man ... &year=2025 but you need to change Manchester to your location for accurate data.

I use Virtual Moon Atlas https://www.ap-i.net/avl/en/download for planning lunar imaging sessions. The Date/Time can be set on the Ephemeris tab to visualise the moon at the planned time of imaging.



Dave