The Libration Zones

The first two pictures below are both mosaics of two or three separate frames.  The pictures are rather flat because the phase of the Moon (days 21.8 and 22.9) meant that the Sun was overhead on this part of the Moon and so there were few shadows.  This is always a problem imaging the limb areas, either the Sun is high in the lunar sky or it is behind the camera, either way there are few shadows to bring out the detail.  In particular the outer ring of mountains, the Cordillera, really do not show at all.  They are steeper on the western side (the inside of the ring) and in the first picture below the Sun was about 13° west of north as seen from that part of the Moon (latitude 80° west).  In the second picture, taken a day later, the Sun had only moved to about 25° from north so little more detail was showing.  The third picture below was taken 2 days later when the Sun had sunk to 40° above the lunar horizon.  I only managed the one frame; on day 25.2 of the lunar cycle, the Moon was only 32° higher in my sky than the Sun, so a fainter Moon was in a brighter sky making imaging even more difficult.  (I should have got up earlier!)  Many craters have become more visible, but the Cordillera Mountains are still not clearly visible.

I have departed from my usual practice of using the formal names on my mouseovers and the common names in my notes for the Rook Mountains.  Montes Rook includes both the inner rings of the basin and are distinguished as the Inner Rook and Outer Rook mountains.  Lacus Veris is a long slender strip of mare lava falling between the two rings on their eastern side.  Similarly, Lacus Autumni falls between the outer Rook Mountains and the Cordillera Mountains.

Move your mouse over the picture to see the names of the various features.

	This is the same picture as shown at the top of the page but orientated more conventionally.  It is a mosaic of four images taken on 26th June 2008 when the Moon was 21.8 days old. The libration was -7° 16' in longitude, -3° 48' in latitude, almost ideal for showing Mare Orientale.  The mountains that form three rings around the basin are not clearly seen except for the Inner Rook Mountains on the far side of the basin which are on the limb.  If you click on the image you will be taken to a page showing a picture taken two days earlier, in the mouseover of which I have tried to indicate where these three rings actually are. The scale markers are approximately 100 Km north and west and apply at Lacus Autumni.  Both vary across the image.  The north-south scale does not change much and the direction can be taken as parallel to the limb.  The east-west direction stays much the same but the scale alters dramatically depending on the distance from the limb.  I have also shown the position of the lunar equator. Date and Time: 26 June 2008 04:39 to 04:50 UT Lunar Phase: 273.5° Colongitude: 183.5° Libration: Latitude -3° 48', Longitude -7° 16' Camera: Atik 1-HS Telescope: LX200 at prime focus Capture: K3CCDTools. Low gamma, 1/250", 16% gain, ~600 frames Processing: Registax. Histogram as necessary*, wavelets 1 = 10, 2 = 5 *See comment below the picture below
	This picture was taken the following morning when the Moon was 22.9 days old.  The libration was -6° 40' in longitude, -4° 53' in latitude, which is a little less favourable for Orientale than the previous morning.  It is a mosaic of three images taken using my ETX125.  This has a shorter focal length than my LX200 so that the scale of the picture is smaller. I was particularly pleased with how well the Sirsalis Rille shows up in this picture (several little arrows in the mouseover).  This rille is 310 Km long by about 3 Km wide and starts at Sirsalis K and winds south between Sirsalis F and J, clips Cruger C, passes through de Vico A before curling round to disappear into the ejecta of Byrgius A.  Byrgius A itself is an interesting crater.  It is small, at 11 Km in diameter, but it is the centre of a bright ray system, which can be seen in these pictures.  Its age does not seem to be known, but it is evidently young, probably less than 1,000 million years old. I've provided two sets of scale markers which approximately 100 Km north and west.  The left set applies at Lacus Autumni, and the right set applies at Sirsalis. Date and Time: 27th June 2008 05:45 to 05:57 UT Lunar Phase: 260.8° Colongitude: 195.7° Libration: Latitude -4° 53', Longitude -6° 40' Camera: Atik 1-HS Telescope: ETX125 at prime focus Capture: K3CCDTools. Low gamma, 1/100", 15% gain, ~700 frames Processing: Registax. Histogram as necessary*, wavelets 1 = 10, 2 = 5 *See comment below the image.

I have modified the way I post-process my images in Registax.  After stacking, I now stretch the histogram to the maximum extent of the data within the image first and apply the wavelets afterwards.  I think this produces better pictures than my old way of doing the wavelets first.  In the case of histograms, each frame is stretched to fill the same range of intensities, so that when I combine them in iMerge I do not need to use the autobrighten feature which, I find, tends to produce ever darkening (or brightening) images as one stitches up a mosaic of the complete Moon.

A new picture of Mare Orientale taken on Day 21.4 at much the same phase and libration as for the images above.  It was taken in infra-red light and I used the ×2 teleadaptor lens on my LX200 telescope. The picture is a 2-frame mosaic. I have rotated this picture 90° clockwise from the original.  North may be taken as parallel to the limb and doesn't change much in a small area. For example a line through Darwin C and Rocca A is about 8½° east of due north.  West is roughly at right-angles to the limb.  I show no scale markers.  There is too little detail for me to determine scale at all accurately and, in any case, it changes quite dramatically across the picture. Date and Time: 9th October 2020 05:27 UT Lunar Phase: 279.4° Colongitude: 177.6° Libration: Latitude -1° 13', Longitude -6° 59' Camera: DMK 21AF04 Telescope: LX200 with ×2 teleadaptor lens Capture: ICCapture. 1/218", gain 1023, 1780 frames Processing: Registax6. 38 alignment points, 400 frames stacked per point. Gaussian wavelets Scheme 10, gamma 0.7

The image above was taken four days after the previous one (on Lunar Day 25.5), so that now the light is coming towards the camera.  The libration is slightly less favourable but the far side of the Inner Rook mountains is still visible on the limb.  But the Cordillera mountains are still not clear in the image.  On the mouseover I have indicated where the three rings intersect the limb and the Cordilleras run roughly through Schaler and Eischstardt, and Lacus Autumni is inside the ring.  Similarly Lacus Veris is inside the Outer Rook mountains.  Click on the image to see the full-sized picture and a discussion of the features of the Orientale basin and the problems of photographing it.
The picture is a mosaic of four pictures merged in iMerge.
Date and Time: 13th October 2020 06:00 UT
Lunar Phase: 229.8°
Colongitude: 126.6°
Libration: Latitude -5° 42', Longitude -5° 51'
Camera: DMK 21AF04
Telescope: LX200 with ×2 teleadaptor lens and IR-pass filter
Capture: ICCapture. 1/367", gain 1023, 1800 frames
Processing: Registax6. 35-40 alignment points, 400 frames stacked per point. Wavelets 1-2=10.       Focus Magic 4.

The image above was taken on Day 24.4 when the libration was very good for this part of the Moon.  It was taken at 05:04 UT in conditions on Earth about as bad as they could be.  I could only manage a single 2-minute capture before the Moon disappeared behind ever-increasing cloud.  Indeed the poor conditions can be seen from the ridiculously long exposure time I had to use.  It is largely thanks to John Leach of the Mexborough & Swinton Astronomical Society and his skills in post-processing that I have a presentable image.
Date and Time: 31st October 2021 05:04 UT
Lunar Phase: 242.3°
Colongitude: 215.1°
Libration: Latitude -6° 20', Longitude -6° 47'
Camera: DMK 21AF04
Telescope: ETX125 with IR-pass filter
Capture: ICCapture. 1/23", gain 1023, 1876 frames
Processing: Registax5, 891 frames stacked, wavelets 1-2=10
            John Leach, DeNoise, Sharpen AI, and Photoshop to increase the resolution to 150 and various other subtle adjustments that have made a huge improvement to my original image.
            Finally a pass through Focus Magic, with a radius of 2, sharpened the image just a little.

In this image of the Orientale Basin, I have managed to render the foreground details much bettre than before.  In particular, at the bottom of the picture, I have captured part of the Sirsalis Rille which was described by Chuck Wood in his LPOD of 20 January 2012 repeated on 2nd December 2021.  Since there is much to talk about in this image I have made it a link to another page where I show a larger version with a mouseover.
The image is a mosaic of three frames, taken on Day 23.9.
Date and Time: 29th November 2021 06:41-56 UT
Lunar Phase: 248.9°
Colongitude: 208.7°
Libration: Latitude -5° 29', Longitude -7° 11'
Camera: DMK 21AF04
Telescope: LX200-10 with IR-pass filter
Capture: ICCapture. 1/500", 1/367", 1/183", gain 1023, ~3380 frames each
Processing: Registax5, ~3000 frames stacked with drizzling, wavelets 1-2=10
            Mosaic assembled in iMerge and passed through Focus Magic 4 pixels.

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