May 2021 the Lunar Observer by the Numbers

Home , Archytas (crater), Babbage (crater), Blancanus (crater), Blanchinus (crater), Boscovich (crater), Cassegrain (crater)

A Publication of the Lunar Section of ALPO Edited by David Teske: [email protected] 2162 Enon Road, Louisville, Mississippi, USA Back issues: http://www.alpo-astronomy.org/

Online readers, May 2021 click on images In This Issue for hyperlinks

Observations Received 2 By the Numbers 4 Stöfler and Maurolycus Region, H. Eskildsen 5 North-ish, R. Hill 6 Medii to Delaunay and a Concentric Crater, H. Eskildsen 7 The Greatest Crater? R. Hill 8 The Glorious Rupes Cauchy, A. Anunziato 9 The Western Chain on the Eastern Moon, H. Eskildsen 10 A Scarp by any Other Name, R. Hill 11 Mädlers Bright Streak, Ray or Elevation? A. Anunziato 12 Caucasus to Mare Vaporum, Close-Up Images of Aristillus, Autolycus and Putredinis Domes, H. Eskildsen 15 Images of Crater Schickard, J. D. Sabia 17 Another Trio, R. Hill 18 Mare Vaporum to Sinus Medii and Associated Domes, H. Eskildsen 19 Focus-On: The Lunar 100 Features 61-70, J. Hubbell 21 Lunar 61-70, A. Anunziato 24 Mösting A, R. H. Hays, Jr. 26 Hortensius and Domes, R. H. Hays, Jr. 53 Mare Humboldtianum, the Other Multi-Ring Lunar Basin, D. Teske 75 Recent Lunar Topographic Studies 81 Lunar Geologic Change Detection Program, T. Cook 100 ALPO 2021 Conference News 108 Lunar Calendar May 2021 110 An Invitation to Join ALPO 110 Submission Through the ALPO Image Achieve 111 When Submitting Observations to the ALPO Lunar Section 112 Call For Observations Focus-On 112 Focus-On Announcement 113 Key to Images in this Issue 114

The May issue of The Lunar Observer features a number of interesting articles by Howard Eskildsen, Rob- ert H. Hays, Jr., Rik Hill, Alberto Anunziato, John D. Sabia and David Teske. Jerry Hubbell and Alberto Anunziato tackle the Lunar 100 numbers 61-70 with a number of great images, drawings, paints and articles. Observers from 10 countries contributed to this issue of The Lunar Observer! Tony Cook keeps us abreast on Lunar Geologic Change, as always with interesting reports.

Take a look at just what is in one lunar image. Howard Eskildsen finds a “new” concentric crater (page 7). Who knows what you will find! Clear and steady skies.

The Lunar Observer/May 2021/ 1

Lunar Topographic Studies Coordinator – David Teske - [email protected] Assistant Coordinator– Alberto Anunziato [email protected] Assistant Coordinator – William Dembowski - [email protected] Assistant Coordinator – Jerry Hubbell – [email protected] Assistant Coordinator-Wayne Bailey– [email protected] Website: http://www.alpo-astronomy.org/

Observations Received

Name Location and Organization Image/Article Alberto Anunziato Paraná, Argentina Article and drawing The Glorious Rupes Cauchy, Mädler’s Bright Streak: Ray or Elevation, Lunar 61- 70, drawings of Rümker, Sergio Babino Montevideo, Uruguay, SAO- Image of Mädler, Descartes, Hor- LIADA tensius Domes, Copernicus and Mare Humboldtianum. Juan Manuel Biagi Oro Verde, Argentina, SLA Images of Mons Rümker, Francisco Alsina Cardinalli Oro Verde, Argentina, SLA Images of Mädler (2), Mösting A (2), Boscovich (2), Julius Caesar (2), The- ophilus, Flamsteed P, Copernicus (3) and Mare Humboldtianum. Jairo Chavez Popayán, Colombia, SLA Image of Descartes, Flamsteed P, Leonardo Alberto Colombo Molinari, Argentina Images of the waxing gibbous Moon (2). Michel Deconinck Siguret lake - French Alps - Pastels of Rümker, Flamsteed and France Mare Humboldtianum. Walter Ricardo Elias AEA, Oro Verde, Argentina Image of Aristarchus (3), Lichtenberg, Mare Humboldtianum, Plato, Riccioli, Copernicus (2), Janssen, Messier and Proclus. Howard Eskildsen Ocala, Florida, USA Articles and images Caucasus to Mare Vaporum: Close Up Images of Aristil- lus, Autolycus and Putredinis Domes, Stöfler and Maurolycus and Region, Mare Vaporum to Sinus Medii and Some Associated Domes, Medii to Delaunay and a Concentric Crater and The Western Chain on an Eastern Moon Desiré Godoy Oro Verde, Argentina SLA Images of Mösting A (3), Julius Cae- sar, Hadley Rille, Victoria Gomez AEA, Oro Verde, Argentina Image of Mare Humboldtianum. Facundo Gramer AEA, Oro Verde, Argentina Image of Gassendi. Marina Grandolio Oro Verde, Argentina Image of Aristarchus, Atlas and Ty- cho. Many thanks for all these observations, images, and drawings.

The Lunar Observer/May 2021/ 2

LunarObservations Topographic Received Studies

Coordinator – David Teske - [email protected]

Assistant Coordinator– Alberto Anunziato [email protected] Assistant CoordinatorMany thanks – William for all Dembowskithese observations, - dembowski@zone images, and drawings.-vx.com Assistant Coordinator – Jerry Hubbell – [email protected] Assistant Coordinator-Wayne Bailey– wayne.bailey@alpo -astronomy.org Website: http://www.alpo-astronomy.org/

Name Location and Organization Image/Article Marcelo Mojica Gundlach Cochabamba, Bolivia, SLA Images of Mösting A, Julius Caesar, Copernicus (3) Robert H. Hays, Jr. Worth, Illinois, USA Articles and drawings Mösting A and Hortensius Domes. Guy Heinen Linger, Luxembourg Images of Hortensius Domess. Rik Hill Loudon Observatory, Tucson, Arizona, Article and image The Greatest Crater?, A Scarp USA by Any Other Name, North-ish, Another Trio, images of Copernicus (8), Hortensius domes, Kepler, Apollo 15 landing site(2), Hadley Rille (2), Mare Humboldtianum, Endymion, Ariadaeus (2), Hyginus, Triesnecker (2), Mare Vaporum (2), Reinhold to Parry, Apollo 14 base (2), Fra Mauro, Eratosthenes, Copernicus to Eratosthe- nes, Stadius, Alphonsus, Rümker (4), Apollo 16 site (4) and Flamsteed. Felix León Santo Domingo, República Dominicana Images of Gassendi, Schickard, Schiller, Waxing Gibbous Moon, Vieta, Reiner Gamma, Aristar- chus, Eddington, Crüger, Bailly, Mons Rümker, Descartes, Copernicus, Daniel Marcus Plainfield, Vermont, USA Paintings of Schiaparelli and

Jesús Piñeiro San Antonio de los Altos, Venezuela, Image of Copernicus SLA Pedro Romano San Juan, Argentina Images of Archimedes and Plato.

John D. Sabia Keystone College Thomas G Cupillari Images and article Images of the Crater Schick- Observatory, Fleetville, Pennsylvania, ard USA Camilo Satler Oro Verde, Argentina, SLA Image of Descartes,

Leandro Sid AEA, Oro Verde, Argentina Images of Waxing Gibbous Moon and Eratosthe- nes. David Teske Louisville, Mississippi, USA Article and images Mare Humboldtianum, the Other Multi-Ring Lunar Basin, image of Theoph- ilus and Mösting A. Román García Verdier Paraná, Argentina, SLA Images of Mösting A, Fabio Verza SNdR, UAI, Milan, Italy Images of Bailly, Moretus, Plato, Messier, Montes Alpes, Schickard, Tycho, Mare Hum- boldtianum, Cleomedes, Petavius Ignacio Villarraza San Nicolás de los Arroyos, Argentina, Image of Mare Humboldtianum. SLA

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May 2021 The Lunar Observer By the Numbers

This month there were 146 observations by 28 contributors in 10 countries.

Obbservers and Observations by Country May 2021 60 50 40 30 20 10 0

bservers Observations

The Lunar Observer/May 2021/ 4

Stöfler and Maurolycus and Region Howard Eskildsen

Battered craters Stöfler (left) and Maurolycus (right) appear to have battled for continued existence just above the center of this image. Stöfler nearly destroyed two craters on its SW margin and cast its ejecta into Fernelius to the north. Later, it was partly filled, possibly by fluidized ejecta from distant, basin-forming impacts, and its central peak is no longer visible. A rugged ridge angles across its eastern interior, perhaps remnants of a subsequent crater that that was in turn destroyed by Faraday, which centers on what had once been the SE rim of Stöfler. Two younger, small craters pocked its rim on the SW and NW margins, and help Stöfler stand out from the tortured background. Under some illuminations this crater grouping reminds me of a ladybug with Faraday as the head and Stöfler the body.

Maurolycus lies to the right of Stöfler and has its own state of degradation. It does appear to be less battered than its companion, still has a visible central peak complex, and only about half of its floor appears partially filled. Its emplace- ment nearly obliterated an older crater whose remnants are visible on the lower left margin of Maurolycus. Remnants of another earlier crater lie outside its upper left rim. On its lower right, Barocius appears to be of similar age, and it is difficult to tell which formed first.

Below Stöfler, the trio of Licetus, Cuvier, and Heraclitus form what I think of as the "Rat Fink" formation (with apologies to Ed "Big Daddy" Roth) for its resemblance to a long-snouted rat with two large, round ears. Heraclitus, with its strange central ridge, forms the snout and terminates with the younger Heraclitus D as its nose. At the op- posite end of the tortured Heraclitus, Licetus and Cuvier form the round ears of "Rat Fink."

To the lower right of this trio, many more craters appear imbedded in a seemingly powdery terrain that appears about to spill over the craters' rims. This is the region of the Mutus-Vlacq basin; a hidden basin that was filled by craters and ejecta. Vlacq is visible at the lower right corner of the image. Since this basin is so old and hidden, it was relatively recently discovered through its mass concentration as detected by the tan- dem GRAIL orbiters. (Gravity Recovery and Interior Laboratory)

Maurolycus-Stöfler, Howard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:45 UT, colongitude 4.5o. Celestron 9.25 inch Schmidt- Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6.

The Lunar Observer/May 2021/ 5

North-ish Rik Hill

The libration favored the south pole of the Moon this night but the landscape (selenoscape?) to the north was remarkable with broad tracts of mare material and many large flat floored craters. The pole here is over the limb and out of site but we have Aristoteles (90 km) in the lower right corner to the shadow filled Anaxago- ras (31 km) in the upper left. Just to the right of Anaxagoras is a much larger crater, Goldschmidt (124 km) with long shadows from the jagged peaks on the east side of the floor. Further to the east (right) is another large crater Barrow, always worth watching the shadow play on its floor as the Sun is rising. North of Bar- row is the large cloverleaf shaped plain formed from the confluence of at least four craters called Meton and to the left of it is the very foreshortened crater Scoresby (58 km) which is about as far north as we can go here.

Due south of Goldschmidt is a crater coming out of shadow. Epigenes (56 km) and to its right is the mon- ster of this image, the very square W. Bond. It’s listed as 163 km in diameter but I can’t imagine how they got a “diameter” on this one! On the south side of W. Bond is the crater Timaeus (34 km). South and east (right) is the smaller Archytas (32 km) and further is Protagoras (22 km). These last three are all on the northern shore of Mare Frigoris.

Just to the right of the center of the image is the nicely formed C. Mayer (39 km). About one third of the distance from this towards Aristoteles is the crater Sheepshanks (26 km). Going north from Aristoteles, we come to the small crater Democritus (41 km). Left from Democritus is another large crater, Arnold (99 km) taking us full circle through this image. There are many more named features here but this outline should help you navigate around.

Barrow to Meton, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 21 April 2021 01:43 UT, colongitude 17.2o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132 M camera. Seeing 8/10.

The Lunar Observer/May 2021/ 6

Medii to Delaunay and a Concentric Crater Howard Eskildsen

This image follows the region near the terminator from Sinus Medii to craters La Caille and Delaunay. Hip- parchus lies southeast of Sinus Medii and has a debris-filled floor burying its central peak. Horrocks on its NE floor impacted after the fill occurred and is younger than Imbrium since it was not scarred by the Imbri- um impact. A small rille can just be seen crossing diagonally across the central floor of Hipparchus.

Just above the center of the image, craters Ptolemaeus and Albategnius form a notable pair. Ptolemaeus, closest to the terminator, has a fresh crater on its NE floor, Ammonius, and just north of this small crater, appears a softened depression consistent with a partially filled crater. Several more similar features are visible on the floor of Ptolemaeus and these have been informally labeled "saucers," Look closely at Albate- gnius; a few more, less prominent saucers can be seen in the central crater area.

Now look just south of the rim of Al- bategnius where a small dark partial arc partly outlines an unnamed crater (see arrow) between Parrot D and Parrot R. Review of the LROC QuickMap shows that this is a concentric crater, which is a rare feature in the lunar highlands. I was not aware of this before, and wonder how many more undiscovered (at least to me) concentric craters are hiding in plain sight.

South of Ptolemaeus, craters Alphon- sus an Arzachel lie partly shadowed with their central peaks basking in the rays of the rising Sun. To the lower right of Arzachel, a cloven crater, De- launay, resembles the hoof print of a cow (perhaps the one that didn't make it over the Moon). La Caille and Blanchinus angle away from the SW rim of Delaunay, towards the bottom of the image.

Sinus Medii to Delaunay, Howard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:40 UT, colongitude 4.5o. Celestron 9.25 inch Schmidt-Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6.

The Lunar Observer/May 2021/ 7

The Greatest Crater? Rik Hill

One of the greatest craters on the Moon, depending on your definition I suppose, is the iconic Clavius (231 km) seen just left of center here. It has a beautiful arc of secondary craters of decreasing diameters on its floor, from right to left starting with Rutherford (56 km) on the southern wall going to Clavius D (28 km), C (21 km), N (13 km), and lastly J (12 km). The crater on the north wall of Clavius is Porter (54 km). You can just make out a couple craterlets on the floor. These are about 2 km in diameter, the limit for this image. On the nights of best seeing, at perigee, this system can make out craters down to 1 km.

The crater filled with shadow south of Clavius is Blancanus (109 km) and farther down near the bottom of this image is the beautifully formed Moretus with a sharp central peak and nicely terraced walls. North of Clavius is the largely ruined crater Maginus (168 km). Take a look in the upper right corner of the image. Ever see a crater like that? It’s Heraclitus (50 x 60 km) with the crater Heraclitus D (52 km). The former is the merge of several craters creating that elongated central peak. It’s very identifiable when you pass over it. Below it is a similar sized crater with a small central peak, Lilius (63 km) and a little farther on is the slightly larger Zach (73 km). Notice how the southern wall of Zach has slumped onto the floor. These land- marks can lead you to a lot of enjoyable exploration of this region when the light is right!

Clavius to Moretus, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 23 March 2021 01:52 UT, colongitude 15.1o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132 M camera. Seeing 9/10.

The Lunar Observer/May 2021/ 8

The Glorious Rupes Cauchy Alberto Anunziato

Rupes Cauchy's descriptions have always been enthusiastic, but I had never identified it before while observing near the terminator. Until one night I saw it. It is really very beautiful, the sketch that I present doesn’t do it justice. In front of the eyepiece, I remembered the adjective Charles Wood used in "The Mod- ern Moon": "a glorious one." We see the segment that runs from Cauchy C (4 km diameter) to the west to Cauchy F (4 km diameter) to the east. The south wall is the one that casts most prominent shadow with the sun illuminating from the east. To the north we have Cauchy (12 km diameter). A series of dorsa emerge from the south wall, they seem low in height.

Rupes Cauchy, Alberto Anunziato, Paraná, Argentina, 18 January 2021 00:00-00:15 UT. Meade EX 105 mm Mak- sutov-Cassegrain telescope, 154 x.

The Lunar Observer/May 2021/ 9

The Western Chain on the Eastern Moon Howard Eskildsen

Four large craters are seen in this image standing in the setting sun. Langrenus, Vendelinus, Petavius, and Furnerius lie along the eastern margin of the Moon per Apollo age conventions. Prior to Apollo, this was considered the western side of the moon and the four craters had an unofficial designation, the "Western Chain." Their alignment suggested a linear crack in the crust of the Moon through which volcanic activities created the craters. However, since the Apollo days that has all been turned around.

For one thing the craters show vastly different degrees of degradation, hence ages. Youthful Langrenus, near the top of the image, appears fresh with terraced walls, scattered secondary craters and hints of rays, even at this illumination. It has a fresh central peak complex, the tips of which are illuminated and cast shadows on the eastern rim of the crater. Old Vendelinus, on the other hand is severely degraded by later impacts, and fill from unknown events have buried its central peak.

Petavius still retains many of its original features but had a significant impact on its western rim that produced the 58 km crater Wrottesley. Also, it has signs of floor uplift as seen in the rille radiating from its central peaks to the lower left rim. Additionally, a dome is present on the lower right crater floor adjacent to the shadow on the southern interior, showing that the crater has been modified over the eons.

Finally, on the lower left image, Furnerius has severe degradation of its walls and interior with several craters splashed about its bounds. Its floor is also filled with ejecta and possibly some basalt as well.

So instead of "proof" of a volcanic origin of craters, the "Western Chain" shows a comparative geology of impact crater aging on the eastern side of the Moon.

Langrenus to Furnerius, “Western Chain”, How- ard Eskildsen, Ocala, Florida, USA. 29 April 2021 07:27 UT, colongitude 117.5o. Celestron 9.25 inch Schmidt-Cassegrain telescope, Skyris 236 M camera. Seeing 6/10, transparency 3/6. Two image composite.

The Lunar Observer/May 2021/ 10

A Scarp by Any Other Name... Rik Hill

Beset by clouds and winds for weeks now, I’ve gone back to the superb night, 30 March 2021 (UT) when I found Rupes Altai, or the Altai Scarp as us old-timers once knew it, near the terminator showing off many wonderful treats that lie south of Theophilus. First is the anchor of the rupes at the bottom of the image just right of center, Piccolomini (90 km) with its spectacular stepped or terraced inner walls. To the left of Pic- colomini is the smaller Rothman (43 km) with the heart-shaped Rothman B just below it. Farther on is Lin- denau (54 km). The scarp or rupes itself runs from Piccolomini north for some 495 km terminating west or left of the crater Catharina (104 km) at the top of the image, and is 1 km high for much of its length. Below Catharina is the flat-floored crater Polybius (43 km) and west of it are two merged craters Polybius C and F (20 km and 21 km respectively). Notice the straight shared wall between them.

Another dominant feature in this crowded image is the “U” shaped Fracastorius (128 km) east (right) of Catharina on the southern shore of Mare Nectaris. With this lighting you can see the skinny rille on its floor. The rille is only 1-1.5 km across! Between Fracastorius and Catharina is a small copy of Fracastori- us, Beaumont (54 km) peppered with 1-3 km secondary craterlets from the great Theophilus impact event to the north.

There is so much going on west of the scarp that it is impossible to detail it here, but you can enjoy it and get out your atlas or go to the LROC QuickMap and explore away!

Rupes Altai, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 20 March 2021 01:01 UT, colongitude 346.8o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132 M camera. Seeing 9/10.

The Lunar Observer/May 2021/ 11

Mädler's Bright Streak: Ray or Elevation? Alberto Anunziato

Looking for images to report to this month's Focus-On Section (Lunar 61-70), I found this old image of The- ophilus covered in shadows. Theophilus is one of the most attractive craters on the Moon and it dulls the features that are around it, that is why this image attracted me: it occupies the central place but we only see its western edge illuminated by the rising sun, two bright points that correspond to two of the central peaks and the eastern ejection mantle. Much smaller (28 km in diameter) is the crater on the right, Mädler, from which we perceive its bright rims, the west wall being brighter, which appears to be higher and casts a prominent shadow. In “The Moon and How to Observe It” (page 216) Peter Grego refers to Mädler as “an elongated crater whose rim is intruded upon by a prominent 30-km-long ridge to the north, has a bright, single ray that stretches for 130 km eastwards across northern Mare Nectaris, covering the southern floors of two ghost craters, an unnamed one (54 km) and Daguerre (46 km), both of whose southern rims have been completely submerged”. Image 1 clearly shows the ridge that ends at the northern edge.

Image 1, Mädler, Francisco Alsina Cardinalli, Oro Verde, Argentina. 15 January 2016 00:10 UT. 10 inch Meade LX200 Schmidt-Cassegrain telescope, Canon EOS Digital Rebel XS camera.

The Lunar Observer/May 2021/ 12

And you can also see that bright line that begins on the eastern rim and crosses the two barely visible submerged craters, which was most likely the reason we took this image five years ago. This "bright, single ray" seems to be an exception to the main characteristic of bright rays: they shine in frontal sunlight and are invisible in oblique light. In image 2 we see it sharp very close to the terminator, a year after the first observation, with reverse illumination (setting sun) I made a primitive sketch of Mädler (which appeared in the December 2017 issue of "The Lunar Observer" with the title of “The Long Shadows of Mädler”) fascinated by the shadow of the eastern wall. Revisiting that drawing, I see that what appears to be the bright ray also appears, which I have taken at the time of observation as a raised area, although Mädler is even closer to the terminator (colongitude 146.8°). With frontal sunlight (98 % illumination), we see that the streak in question is the edge of a bright triangular area that occupies a large part of Mädler itself and goes beyond (Image 3, 78.6° colongitude).

Image 2, Mädler, Alberto Anunziato, Paraná, Argentina, 16 April 2016 04:40-05:15 UT. Meade EX 105 mm Maksutov-Cassegrain telescope, 154 x. Seeing 7/10.

To further complicate things, with a full Moon we see dark areas that could be shadows of a small elevation (Image 4, detail of Image 3). Could the brightness be due to a small elevation? This would explain the brightness with oblique light near the terminator. For greater difficulty Thomas G. Elger, in "The Moon" (1895 edition), does not define it as a bright ray but as "what appears to be under a higher sun a bright elbow-shaped marking, in connection with which I have often suspected a delicate cleft" (page 136). Oblique illumination would favor the observation of a small elevation, which can be suspected in image 3 (Full Moon) but not in images 1 and 2. A real mystery that deserves further observations, specifically looking for a small elevation running towards Daguerre from the east. The terrain is extremely rugged, it is part of the materials ejected by the Theophilus impact, as can be seen in Image 5 (with illumination similar to that of image 2, longitude 145.6°), although in this image there does not seem to be any an elevation that can explain the bright streak, which looks very faint.

The Lunar Observer/May 2021/ 13

Image 3, Mädler, Francisco Alsina Car- dinalli, Oro Verde, Argentina, SLA. 16 June 2016 03:23 UT. 10 inch Meade LX200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 807 nm filter, QHY5-ll camera.

Image 4, Mädler, Francisco Alsina Car- dinalli, Oro Verde, Argentina, SLA. 16 June 2016 03:23 UT. 10 inch Meade LX200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 807 nm filter, QHY5-ll camera. (Close-up of figure 3)

Mädler, Sergio Babino, Montevideo, Uruguay, SAO- LIADA. 14 March 2020 04:49 UT. 203 mm catadrioptic telescope, zwo asi174 mm camera.

The Lunar Observer/May 2021/ 14

Caucasus to Mare Vaporum Close up Images Aristillus, Autolycus, and Putredinis Domes Howard Eskildsen

Montes Caucasus course downward from the upper right of this image and arc towards Montes Apenninus, which dominate the central image. The two ranges are separated by the Straits of Fresnel, also known as The Great Pass. The crater Cassini is visible near the upper central image margin. Below it, the rims of Aristillus and Autolycus outline their shaded interiors. Broad low domes are visible to the right of each crater, one near the southern end of Montes Caucasus and the other about a crater diameter to the right of Autolycus.

Palus Putredinis extends from half- visible Archimedes to the northwestern margin of Apenninus, and a dome is visible on its eastern margin. Rima Hadley winds in and out of the shadow near the central image with Hadley C crater just emerging from the darkness. Crater Co- non lies almost dead center in the image, on the rubbly Apenninus downslope.

Mare Vaporum dominates the lower image and the rill and collapse pits of Rima Hyginus angle to the lower right margin of the image. Mare Serenitatis the upper right margin of the image and the dimin- utive Linné is visible surrounded by its ejecta halo.

Montes Caucasus to Mare Vaporum, How- ard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:43 UT, colongitude 4.5o. Celestron 9.25 inch Schmidt-Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6.

The Lunar Observer/May 2021/ 15

Montes Caucasus to Mare Vaporum, Howard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:43 UT, colongitude 4.5o. Celestron 9.25 inch Schmidt-Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6. Be- low, domes are noted with white lines.

The Lunar Observer/May 2021/ 16

Images of Crater Schickard John D. Sabia

On the evening of April 21, 2021 EDT from 9:00 to 10:00 pm. I observed the progress of a light ray develop in the interior of the crater Schickard.

The view in the 9.5-inch (24.13 cm) f/15 Alvan Clark refractor was very calm in the 21 mm Plössl eyepiece view. First views showed a hazy elongated rectangular grey patch within the crater away from the northern wall.

Within 20 minutes the patch was a well illuminated rectangular patch of the crater floor. A small bright spot near the northern part of the rectangle was casting a thin shadow down the center of the rectangle, half way to the other end of the illuminated floor.

In between public observing at Keystone College Thomas G Cupillari Observatory, I was able to mount my camera onto the telescope for a series images at prime focus of the telescope. The first set of photos were taken at 1/250 ISO 1600 of the hazy rectangular patch within the dark crater floor. A while later the camera was once again (Canon T5 camera) on the telescope to image the well illuminated rectangular section of the floor and other illuminated areas at 1/50 ISO 200. The two sets of images were stacked using Registax.

Schickard, John D. Sabia, Key- stone College Thomas G Cupil- lari Observatory, Fleetville, Pennsylvania, USA. 24 April 2021 01:18 UT. 9.5 inch f/15 Alvan Clark refractor telescope, Canon T5 camera, 1/250 second exposure, ISO 1600.

Schickard, John D. Sabia, Keystone Col- lege Thomas G Cupillari Observatory, Fleetville, Pennsylvania, USA. 24 April 2021 01:55 UT. 9.5 inch f/15 Alvan Clark refractor telescope, Canon T5 camera, 1/50 second exposure, ISO 200.

The Lunar Observer/May 2021/ 17

Another Trio Rik Hill

I enjoy triplets of craters like Ptolemaeus, Alphonsus, Arzachel and here the gathering of Archimedes (85 km), Aristillus (56 km) to the upper right with the nice radial ejecta splash pattern and then below it the smallest member of the trio, Autolycus (41 km). The Soviet Luna 2 spacecraft impacted the Moon about one-third the way from Autolycus to Archimedes releasing two sphere shaped markers just before impact. Archimedes was once a crater similar to Copernicus with central peak(s) and all, until the Imbrium impact event when the crater was flooding from Imbrium lavas oozing up through cracks in the crater floor. This all happened from 3.2-3.8 billion years ago (b.y.a.) called the Upper Imbrium period. The other two craters were formed much more recently in the Copernican period in the last billion years, as their fresh look might indicate (and the preservation of ejecta around Aristillus). The little sea to the right of Archimedes is Palus Putredinis that contains a nice dome pointed out by the arrow. A little further to the right, you’ll see a little “o” that marks the Apollo 15 base at “Hadley Rille” now known as Rima Hadley.

The mountains above Archimedes are the Montes Spitzbergen and they just sparkle in the early lunar morn- ing light. In the upper right corner of the image can be seen some of the Montes Caucasus and in the lower right are the northern peaks of the Montes Apenninus. The northernmost point is Promontorium Fresnel with the Rimae Fresnel to the left of that. Below P. Fresnel is the small crater Santos-Dumont (9 km) and the large mountain below that is Mons Hadley rising 4.8 km above the Apollo 15 site.

Archimedes, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 21 April 2021 01:58 UT, colongitude 17.2o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132 M camera. Seeing 8/10.

The Lunar Observer/May 2021/ 18

Mare Vaporum to Sinus Medii and Some Associated Domes Howard Eskildsen

Several domes are visible on the cropped image, including Manilius 1 and Manilius 2 domes, as indicated on the labeled image. Hyginus 1 dome is just visible to the lower right of center, and Yangel 1 can be seen on the upper margin of Mare Vaporum. Another elevation rise that appears dome-like on the LROC QuickMap is marked with the question mark. A dark halo crater is noted just to the left of Manilius

In the full image, Mare Vaporum dominates the upper central region with Manilius to its right. Rima Hygi- nus angles away from Vaporum's lower margin and contains various collapse pits including the named crater Hyginus. The rille's western end splits and the upper branch intersects with the western branch of Rima Ari- adaeus.

West Hyginus, the irregular rim of Ukert lies among rounded mountains that were heavily scoured by the Im- brium impact. I wonder about the origin of those mountains. Near the center of the image, Triesnecker lies next to its namesake rilles which extend northward nearly to Mare Vaporum. The rilles also extend southward along the eastern margin of Sinus Medii just below the image center. One branch of the Rimae Tri- esnecker appears to end at the rugged terrain just north of the ruined crater Rhaeticus. Another unnamed rille, about 70 km long, appears to arise near the western margin of Rhaeticus and terminates just north of Hippar- chus.

Mare Vaporum to Sinus Medii, Howard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:41 UT, colongitude 4.5o. Celes- tron 9.25 inch Schmidt-Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6.

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Rima Oppolzer originates on the southern floor of Oppolzer, crosses the northernmost floor of Réamur and angles slightly upward across the southern margin of Mare Vaporum in the direction of Rhaeticus. Another rille, Rima Réamur originates outside the eastern rim of its namesake crater and angles about 45 km to the northwest margin of Hipparchus. Finally, multiple scars cross the extreme lower right image, remnants of the Imbrium impact eons ago.

Mare Vaporum to Sinus Medii, How- ard Eskildsen, Ocala, Florida, USA. 20 April 2021 00:41 UT, colongitude 4.5o. Celestron 9.25 inch Schmidt- Cassegrain telescope, Skyris 236 M camera. Seeing 7/10, transparency 4/6.

The Lunar Observer/May 2021/ 20

Focus On: The Lunar 100 Features 61 through 70

Jerry Hubbell Assistant Coordinator, Lunar Topographical Studies

This is the seventh article of ten in a series on Chuck Wood’s Lunar 100 list. Chuck Wood, the founder of the Lunar Photo of the Day (LPOD) (Ref.), first discussed this list of lunar features in a Sky & Telescope article published in 2004, and later published on the Sky & Telescope website (Ref.). This series will run from May 2020 until January 2022. I may insert a few other topics in between this series so the end date for this series may extend out to the end of 2022. Chuck wanted this list of lunar features (L1 to L100) to be like the well-known list of Messier objects that would give lunar observers a way to progress in their study of the moon and become life-long observers. The list contains all the diverse features of the Moon including Mare, Craters, Rilles, Mountains, and Volcanic Domes. The list starts out with the naked eye view of the full disk of the Moon and progresses through more difficult features.

This series of Focus On articles is meant to be the basis for a lunar visual observing program but is not lim- ited to that. It can be the basis for starting your own image-based study of the Moon, which will enable you to use the Lunar Terminator Visualization Tool (LTVT) (Ref.), a sophisticated software program used to do topographical measurements of the lunar surface. These articles will introduce and show each of the Lunar 100 features as observed and submitted by our members through drawings, images, and narrative descriptions. Although you can use your naked eye and binoculars to start observing objects L1 – L20, observing objects L21 – L80 will require the use of a 3-inch (76-mm) telescope. Features at the end of the list (L81 – L100) will require a 6 to 8-inch (152 to 203-mm) telescope. Many of the features are best observed at different phases of the Moon.

One of the best ways to help you learn the features of the Moon is through sketching the lunar surface. Dur- ing this series of articles, we will highlight drawings of many of the Lunar 100 features. Springer Books publishes an excellent book, released in 2012, called Sketching the Moon (Handy, et al.) (Ref.). There are other resources on the Internet to help you get started observing and sketching the Moon including the ALPO’s excellent Handbook of the ALPO Training Program (Ref.)

In this article we continue with features 61 through 70 on Chuck’s list. This article highlights the excellent drawings of each of these features submitted by Michel Deconinck from Provence, France and paintings from Daniel Marcus of Plainfield, Vermont, USA. Here is a list of features 61 – 70:

L Feature Significance Rükl 61 Mösting A Simple crater close to the center of the lunar near side 43 62 Rümker Large volcanic dome 8 63 Imbrium sculpture Basin ejecta near and overlying Boscovich and Julius Caesar 34 64 Descartes Apollo 16 landing site; putative region of highland volcanism 45 65 Hortensius Domes Dome field north of Hortensius 30 66 Hadley Rille Lava channel near Apollo 15 landing site 22 67 Fra Mauro Formation Apollo 14 landing site on Imbrium ejecta 42 68 Flamsteed P Proposed young volcanic crater and Surveyor 1 landing site 40 69 Copernicus secondary cra- Rays and craterlets near Pytheas 20 ters 70 Humboldtianum basin Multi-ring impact basin 7

The Lunar Observer/May 2021/ 21

This month we had a great response to our request for images and drawings for the seventh set of 10 features of the Lunar 100 (L61 – L70). I am grateful for all the submissions we received. Most of the images came from Alberto Anunziato’s groups, SAO-SLA, and LIADA. Early on he prefaced the images he sent on be- half of his group this way:

“LUNAR 100 PROGRAM Sociedad Astronómica Octante-Sociedad Lunar Argentina

When we found out that the next objectives of the Focus On Section would be the features listed in the Charles Wood's famous Lunar 100, the members from Sociedad Lunar Argenti- na (SLA) and Sociedad Astronómica Octante (SAO) of the República Oriental del Uruguay, we considered interesting to join the initiative of "The Lunar Observer" (TLO) and therefore we launched our Lunar 100 Program, under the auspices of the Lunar Section of the Liga Iberoamericana de Astronomía (LIADA). The objective is twofold. We will report the images submitted to the program to "The Lunar Observer". And we will also publish them in all the media of SLA, SAO and LIADA. We think it is a great opportunity to stimulate amateur lunar observation and if the call is successful, we can dream of some final joint publication.”

We look forward to future drawings and images submitted by ALPO, SLA, SAO, LIADA members and others from across the world. Please share with us any images you have in your image catalog; we hope to see everyone participate in these Focus On articles.

– Jerry Hubbell

COMPUTER PROGRAMS

Virtual Moon Atlas https://sourceforge.net/projects/virtualmoon/

Lunar Terminator Visualization Tool (LTVT) http://www.alpoastronomy.org/lunarupload/LTVT/ ltvt_20180429-HTML.zip

REFERENCES

Chuck Wood, The Lunar 100 (November 2012), Sky & Telescope Magazine (website), https:// skyandtelescope.org/observing/celestial-objects-to-watch/the-lunar-100/ (retrieved April 26, 2020)

Handy R., Kelleghan D., McCague Th., Rix E., Russell S., Sketching the Moon, 2012 Springer Books, https://www.springer.com/us/book/9781461409403 (retrieved April 26, 2020)

Association of Lunar and Planetary Observers, Handbook of the ALPO Training Program, http:// www.cometman.net/alpo/ (retrieved April 26, 2020)

Chuck Wood, Lunar Photo Of the Day (LPOD), https://www2.lpod.org/wiki/LPOD:About (retrieved April 26, 2020)

Lunar Reconnaissance Office ACT-REACT Quick Map, http://target.lroc.asu.edu/q3/ (retrieved October 31, 2017)

The Lunar Observer/May 2021/ 22

Patrick Chevalley, Christian Legrand, Virtual Moon Atlas, http://ap-i.net/avl/en/start (retrieved June 30, 2018)

International Astronomical Union Gazetteer of Planetary Nomenclature, Crater Tycho, https://planetarynames.wr.usgs.gov/Feature/6163 (retrieved March 1, 2020)

Wikipedia, The Lunar 100 , https://en.wikipedia.org/wiki/Lunar_100 (retrieved April 26, 2020)

Aeronautical Chart Information Center (ACIC), United States Air Force, LAC Series Chart Reference, host- ed by the Lunar and Planetary Institute, https://www.lpi.usra.edu/resources/mapcatalog/LAC/ lac_reference.pdf (retrieved September 1, 2019)

Lunar and Planetary Institute, Digital Lunar Orbiter Photographic Atlas of the Moon, http:// www.lpi.usra.edu/resources/lunar_orbiter/ (retrieved September 1, 2017).

ADDITIONAL READING

Bussey, Ben & Paul Spudis. 2004. The Clementine Atlas of the Moon. Cambridge University Press, New York.

Byrne, Charles. 2005. Lunar Orbiter Photographic Atlas of the Near Side of the Moon. Springer-Verlag, London.

Chong, S.M., Albert C.H. Lim, & P.S. Ang. 2002. Photographic Atlas of the Moon. Cambridge University Press, New York.

Chu, Alan, Wolfgang Paech, Mario Wigand & Storm Dunlop. 2012. The Cambridge Photographic Moon Atlas. Cambridge University Press, New York.

Cocks, E.E. & J.C. Cocks. 1995. Who’s Who on the Moon: A biographical Dictionary of Lunar Nomencla- ture. Tudor Publishers, Greensboro

Gillis, Jeffrey J. ed. 2004. Digital Lunar Orbiter Photographic Atlas of the Moon. Lunar & Planetary Insti- tute, Houston. Contribution #1205 (DVD). (http://www.lpi.usra.edu/resources/lunar_orbiter/).

Grego, Peter. 2005. The Moon and How to Observe It. Springer-Verlag, London.

IAU/USGS/NASA. Gazetteer of Planetary Nomenclature. (http://planetarynames.wr.usgs.gov/Page/MOON/ target).

North, Gerald. 2000. Observing the Moon, Cambridge University Press, Cambridge.

Rukl, Antonin. 2004. Atlas of the Moon, revised updated edition, ed. Gary Seronik, Sky Publishing Corp., Cambridge.

Schultz, Peter. 1972. Moon Morphology. University of Texas Press, Austin. The-Moon Wiki. http://the- moon.wikispaces.com/Introduction

Wlasuk, Peter. 2000. Observing the Moon. Springer-Verlag, London.

Wood, Charles. 2003. The Moon: A Personal View. Sky Publishing Corp. Cambridge.

Wood, Charles & Maurice Collins. 2012. 21st Century Atlas of the Moon. Lunar Publishing, UIAI Inc., Wheeling.

The Lunar Observer/May 2021/ 23

Lunar 61-70 Alberto Anunziato We reached number 70 on the Lunar 100 list, which implies that for 14 months lunar observers from around the world have coordinated their efforts to find images that portray each of the included lunar features. It has been an enriching experience to search the folders of our computers for images of the most difficult features or to prepare the observation so that the illumination is adequate and to capture that elusive feature that we had never observed (and that the clouds sometimes cancel). Features become increasingly difficult to find, and from number 80 their observation requires larger telescopes or more exceptional illumination conditions. Let's hope we get at least one observation for every Lunar 100 moon feature. But whether we get it or not, we think it has been a great experience for all of us who participated.

We present a brief introduction to each lunar feature, from Lunar 61 to 70, extracted from the book by Charles Wood, also author of the Lunar 100 list, “A Modern Moon. A Personal View,” the 2003 Sky Pub- lishing Corporation edition. The book is prior to the list, so we can infer that the importance that the author gives to each feature included in the list is illustrative of the reason why he included it.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Lunar 61 Mösting A: Simple crater close to center of lunar near side We promised a brief intro from "The Modern Moon," but we failed to find Lunar 61, about which there is no reference in the book. Mösting A is a simple 13 km diameter Copernican crater that does not display special characteristics, surely Wood included it like challenge of visual observation, to find the center of the Moon. Looking for it in images with the help of a map is much easier, although it is always overshadowed by Ptolemaeus, Alphonsus, Arzachel and Alpetragius

Mösting A, Desiré Godoy, Oro Verde, Argentina, SLA. 10 December 2016 01:59 UT. Meade LX200 10 inch Schmidt -Cassegrain telescope, 742 nm filter.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Mösting A Robert H. Hays, Jr.

I observed this crater and vicinity on the evening of May 23/24, 2018. This area is near the center of the visible side close to Sinus Medii. Mösting A is a crisp round crater with a bright interior. The small pit just east of Mösting A is Flammarion D, and Flammarion B is the similar crater to its south. Several nearby mounds are part of the broken ring of grayish Flammarion. There is a great variety of elevations in this area which I have tried to draw as well as possible. A large low mound in its north side is just west of Mösting A, and a similar mound is to its northwest. A large triangular hill with dark shadowing is southwest of Mösting A. This hill is surrounded by smaller peaks with mostly lighter shadowing except for one to its west. Another peak with dark shadowing is the roundish one well north of Mösting A. A large, roughly Y- shaped complex is farther to the west. The southeast end is a narrow, broken ridge. The southwest arm is a strip of dark shadow generally widening to the south. This arm did not show a sunlit side. The area south of the Y junction is gray and smooth except for two tiny peaks. North of the Y junction is a low mound with some interior shadowing. Mösting B is the larger of a close pair of craters to the west; its smaller neighbor is Mösting BA. All of the intact craters in this drawing are crisp and round. An elongated hill with fairly dark shadowing is between the B-BA pair and the north end of the Y complex. Several small low peaks are also in this area.

Mösting A, Robert H. Hays, Jr. Worth, Illinois, USA. 24 May 2018 02:45-03:45 UT. 15 cm reflector, 170 x. Seeing 8/10, transparency 5/6.

This originally appeared in the December 2018 The Lunar Observer.

The Lunar Observer/May 2021/ 26

Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Mösting A, De- siré Godoy, Oro Verde, Argentina, SLA. 28 August 2020 23:41 UT. 200 mm refractor telescope, 742 nm filter, QHY5-ll camera.

Mösting A, Francis- co Alsina Cardinalli, Oro Verde, Argenti- na, SLA. 09 Decem- ber 2016 04:04 UT. 10 inch Meade LX200 Schmidt- Cassegrain telescope, 742 nm filter.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Mösting A, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 25 February 2018 00:48 UT. 200 mm refractor telescope, QHY5-ll camera.

Mösting A, David Teske, Louisville, Mississippi, USA. 21 April 2021 02:20 UT, colongitude 15.3o, ZWO ASI120mm/s camera, 500 frames, seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Mösting A, Desiré Godoy, Oro Verde, Argentina, SLA. 08 November 2019 01:04 UT. 200 mm Newtoni- an reflector telescope, 742 nm filter, QHY5-Lll M camera.

Mösting A, Román García Verdier, Paraná, Argenti- na, SLA. 26 September 2020 23:59 UT. 180 mm Newtonian reflector telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 61 Mösting A

Thebit to Oppolzer, Richard Hill, Loudon Ob- servatory, Tucson, Arizona, USA. 13 September 2008 06:24 UT. Celestron 14 Schmidt- Cassegrain telescope, 2 x barlow, UV/IR blocking filter, SPC900NC camera. Seeing 5/10.

Mösting A, Marcelo Mojica Gundlach, Cochabamba, Bolivia, SLA. 14 May 2019 04:43 UT. 150 mm refractor telescope, zwo asi120 camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 62 Rümker Lunar 62 Mons Rümker: Large volcanic dome

Mons Rümker is a fascinating lunar feature, not only because it is the most “terrestrial” volcano on the Moon, but because its location so close to limb makes it a very elusive and difficult to observe wonder. On page 165 of "The Modern Moon" we read:

“The so-called Rümker Hills are the smallest and northernmost of three volcanic complexes (…) The most noticeably feature of Rümker is a diamond-shaped depression on its eastern flank. Besides being lower, this area is smoother. The relatively high-Sun Lunar Orbiter images don’t emphasize this aspect, and isn’t men- tioned in any of the scientific literature I’ve read. The depression mislead early selenographers into mistak- ing Rümker for an old battered crater, but to a geologist a depression on the flank of an obvious volcanic mound immediately suggests a caldera or volcanic collapse crater. If it is a caldera (and there really is no other evidence to support this speculation), it would be one of the largest on the Moon”.

Mons Rümker, Daniel Marcus, Plainfield, Vermont, USA. The painting of this 25-day moon image is based on drawings made at an 8” Meade LX90, Schmidt-Cassegrain telescope, mostly at 154x. Acrylic on paper, 8” x 10 1/2. Dan- iel adds “Situated in Sinus Roris, Rumker is an oval plateau about 73 km in diameter. It’s covered with small domes and secondary craters in an area that was flooded with mare basalt. Off to the west is visible the crater Harding and off on the horizon the jumble of rough country along the western limb. It’s a fascinating area of the moon, well worth study.”

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Recent Topographic Studies Focus-On: The Lunar 100: Number 62 Rümker

Rümker, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 07 May 2009 04:18 UT. Celestron 14 Schmidt-Cassegrain telescope, 2 x barlow, f/22, UV/IR blocking filter, DMK21AU04 camera. Seeing 7/10.

Mons Rümker, Juan Manuel Biagi, Oro Verde, Argentina, SLA. 21 September 2014 05:59 UT. Meade LX200 10 inch Schmidt-Cassegrain telescope, Canon EOS 400 Rebel.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 62 Rümker

Mons Rümker, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 25 March 2013 02:05 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 656.3 nm filter, DMK21AU04 camera. Seeing 7/10.

Mons Rümker Felix León, Santo Domingo, República Dominicana. 27 March 2021 00:15 UT. 5 inch Maksutov- Cassegrain telescope, DMK21618AU camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 62 Rümker

Mons Rümker, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 04 May 2012 05:32 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, Wratten 23 filter, DMK21AU04 camera. Seeing 7/10.

Mons Rümker, Alberto Anunziato, Para- ná, Argentina, 20 September 2020 04:40- 05:15 UT. Meade EX 105 mm Maksutov -Cassegrain telescope, 154 x. Seeing 7/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 62 Rümker

Mons Rümker to Gruithuisen Domes, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 25 February 2021 05:31 UT, colongitude 69.1o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132M camera. Seeing 8/10.

Rümker, Michel Deconinck, Aquarellia mobile observatory - Siguret lake - French Alps - France. 24 February 2021 05:00 UT. 102mm x 1000 mm refractor telescope, 12 mm eyepiece, 83 x.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Lunar 63 Imbrium Sculpture: Basin ejecta near & overlying Boscovich and Julius Caesar

The identification of Mare Imbrium as the largest impact basin on the near side of the Moon, and also the most recent, was a result of pioneering works such as those of G. Gilbert and R. Baldwin, which only in the 1960s it became a certainty. The 63rd place on the list was reserved by Wood for the marks of destruction caused by the mega-impact of Mare Imbrium (page 58):

“The movement of material from Imbrium must have included a near-surface flow of debris-some preexist- ing craters like Julius Caesar and Boscovich were so heavily pelted that the sides of their rims radial to the center of Imbrium were eroded almost completely flat. (…) until Lunar Orbiter photography demonstrated that the similarly battered terrain around the Orientale basin was due to massive scouring and deposition of ejecta. Once again, without spacecraft images we would never have correctly understood the Moon”.

Rima Ariadaeus, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 01 July 2017 02:43 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 656.3 nm filter, Skyris 445 M camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Mare Vaporum and Sinus Medii, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 09 April 2014 02:21 UT. TEC 8 inch f/20 Maksutov -Cassegrain telescope, 656.3 nm filter, SKYRIS 445M camera. Seeing 7/10.

Boscovich, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 21 August 2016 04:21 UT. Meade LX200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 742 IR-pass filter, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Mare Vaporum and Sinus Medii, Richard Hill, Loudon Observatory, Tuc- son, Arizona, USA. 08 April 2014 02:11 UT. TEC 8 inch f/20 Maksutov -Cassegrain telescope, 656.3 nm filter. Seeing 8/10.

Julius Caesar, Marcelo Mojica Gundlach, Cocha- bamba, Bolivia, SLA. 30 April 2020 23:24 UT. 150 mm Skywatcher Mak- sutov-Cassegrain telescope, zwo asi178 B/N camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Julius Caesar, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 01 July 2017 23:26 UT. 200 mm refractor telescope, QHY5-ll camera.

Triesnecker to Ariadaeus, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 24 May 2007 04:12 UT. Celestron 14 Schmidt- Cassegrain telescope, 1.6 x barlow, UV/IR blocking filter, SPC900NC camera. Seeing 7/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Julius Caesar, Francisco Alsi- na Cardinalli, Oro Verde, Argentina, SLA. 01 July 2017 23:37 UT. 200 mm refractor telescope, QHY5-ll camera.

Triesnecker, Richard Hill, Loudon Observa- tory, Tucson, Ari- zona, USA. 20 February 2013 01:38 UT. TEC 8 inch f/20 Mak- sutov-Cassegrain telescope, 656.3 nm filter, DMK21AU04 camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Hyginus to Sabine and Ritter, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 20 June 2010 02:33 UT. Celestron 14 inch Schmidt-Cassegrain telescope, 2 x barlow, f/22, 656.3 nm filter, DMK21AU04 camera. Seeing 8/10.

Julius Caesar, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 01 July 2017 23:34 UT. 200 mm refractor telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 63 Imbrium Sculpture

Rima Ariadaeus, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 28 April 2012 02:33 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, Wratten 23 filter, DMK21AU04 camera. Seeing 7/10.

Julius Caesar, Desiré Godoy, Oro Verde, Argentina, SLA. 16 October 2018 01:07 UT. 200 mm refractor telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Lunar 64 Descartes: Apollo 16 landing site; putative region of highland volcanism

Three of the sites included in numbers 61-70 correspond to landing sites of the Apollo missions. Lunar 64 corresponds to the Descartes region (page 115):

“the Descartes site was exciting because it was in the unsampled lunar highlands and apparently included two different types of two non-mare volcanic materials… Subsequent examination of the 95 kilograms of Apollo 16 samples confirmed the astronauts impressions-nearly all the rocks rocks proved to be impact breccias and impact melts. The entire reason for going to Descartes was based on incorrect interpreta- tions!”

Theophilus, David Teske, Louisville, Mississippi, USA. 07 September 2020 08:18 UT, colongitude 146.3o. 4-inch f/15 refractor telescope, zwo ASI120mm/s camera, 500 frames, Firecapture, Registax, Photoshop. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Apollo 16 Site, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 09 July 2019 02:37 UT, colongitude 351.3o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 445M camera. Seeing 8/10.

Theophilus, Fran- cisco Alsina Car- dinalli, Oro Verde, Argentina, SLA. 01 July 2017 23:20 UT. 200 mm refractor telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Apollo 16 Sire, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 20 May 2010 02:33 UT. Celestron 14 inch Schmidt-Cassegrain telescope, 2 x barlow, f/22, 656.3 nm filter, DMK21AU04 camera. Seeing 8/10.

Descartes, Felix León, Santo Domingo, República Dominicana. 27 March 2021 00:00 UT. 5 inch Maksutov- Cassegrain telescope, DMK21618AU camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Apollo 16 Site, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 03 October 2015 09:17 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 656.3 nm filter, Skyris 445M camera. Seeing 8/10.

Descartes, Jairo Chavez, Popayán, Colombia, SLA . 10 June 2019 01:18 UT. 10 inch Truss-tube Dobsonian reflector telescope, Sony DSC-WX 50 camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Apollo 16 Site, Richard Hill, Loudon Observa- tory, Tucson, Arizona, USA. 12 July 2016 02:50 UT. TEC 8 inch f/20 Maksutov- Cassegrain telescope, 665 nm filter, Skyris 445M camera. Seeing 9/10.

Descartes, Camilo Satler, Oro Verde, Argentina, SLA. 22 April 2018 00:34 UT. Celestron 11 inch Schmidt-Cassegrain telescope, Samsung Galaxy J7 cell phone camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 64 Descartes

Descartes, Sergio Babino, Montevideo, Uruguay, SAO-LIADA. 29 February 2020 22:46 UT. 203 mm catadrioptic telescope, zwo asi174 mm camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 65 Hortensius Domes

Lunar 65 Hortensius Domes: Dome field north of Hortensius

On page 61 Wood refers to Lunar 65 as "domeland." Domes are very important at Lunar 100. L65 is the fifth dome zone to appear on the list. It is a progression according to the difficulty of the observation: L32 Arago Alpha and Beta, L42 Marius Hills, L49 Gruithuisen Delta and Gamma, L60 Kies Pi and L 65 (page 61):

“The area south and west of Copernicus is characterized by clustered and isolated hills, surrounded by relatively thin mare lava flows. Presumably the hills are tops of continuous ejecta from the Imbrium basin that have been buried by later lavas (…) The easiest domes to find are a cluster of six just north of the 15-km- wide crater Hortensius located west-southwest of Copernicus. Each dome measures about 6 to 8 km wide and a few hundred meters high, and thus has very gentle slopes. Five of the six Hortensius domes have tiny summit pits, which are a real test to a telescope’s optical quality and the atmospheric seeing conditions. They are difficult features for 6-to 10-inch instruments, even on a very steady night”.

Hortensius Domes, Guy Heinen, Linger, Luxembourg. 22 April 2021 20:38 UT. Takahashi Mewlon CRS250 Dall- Kirkham telescope, IR pass filter, Skyris 236 camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 65 Hortensius Domes

Hortensius Domes, Richard Hill, Loudon Observato- ry, Tucson, Arizona, USA. 10 May 2016 01:23 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 656.3 nm filter, Skyris 445 M camera. Seeing 7/10.

Milichius-M1 to M24-Hortensius-1-2-3-4-5-6, Guy Heinen, Linger, Luxembourg. 22 April 2021 20:38 UT. Takahashi Mewlon CRS250 Dall-Kirkham telescope, IR pass filter, Skyris 236 camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 65 Hortensius Domes

Copernicus, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 17 May 2016 02:27 UT. Questar 3.5 inch Maksutov-Cassegrain telescope, 1.7 x barlow, 656.3 nm filter, Skyris 445 M camera. Seeing 7/10.

Hortensius Domes, Sergio Ba- bino, Montevideo, Uruguay, SAO-LIADA. 26 February 2018 00:01 UT. 203 mm catadrioptic telescope, zwo asi174 mm camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 65 Hortensius Domes

Kepler Sunrise, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 26 March 2010 04:08 UT. Celestron 14 inch Schmidt-Cassegrain telescope, 2 x barlow, f/22, UV/IR blocking filter, DMK21AU04 camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 65 Hortensius Domes

Hortensius and Domes Robert H. Hays, Jr.

I drew this area on the evening of May 7/8, 2006 before the Moon hid ZC1643 and 80 Leonis. Hortensius is a modest, ordinary crater west of Copernicus. It showed considerable external shadow at this time. The presence of several domes north of Hortensius make this area interesting. The feature closest north of Hor- tensius is the dome Hortensius omega, according to the Lunar Quadrant map. The larger of the pair nearest to Hortensius omega is probably Hortensius tau, and Hortensius sigma would be the smaller dome east of Hortensius tau. Hortensius phi is likely the large dome northeast of tau and sigma. Hortensius phi appears to have a smaller dome attached to its west side. All of these domes are at least approximately round with only modest shading on their shadowed sides, but omega’s shading appears slightly darker than the others. Hortensius gamma is farther to the northeast, but this is not a dome. Hortensius gamma is a double peak with black shadow. The sizable pit toward the southeast is Hortensius C. North of C is a small group of peaks with a tiny craterlet mixed in. A shadowless bright spot is between this group and Hortensius. A faint ray extends eastward from Hortensius, passing just north of C. Near Hortensius and toward the west are some linear shadows which are either wrinkles or low ridges.

Hortensius and Domes, Robert H. Hays, Jr. Worth, Illinois, USA. 08 May 2006 02:00-02:30 UT. 15 cm reflector, 170 x. Seeing 7-8/10, transparency 6/6.

This originally appeared in the November 2006 The Lunar Observer.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 66 Hadley Rille

Lunar 66 Hadley Rille: Lava channel near Apollo 15 landing site

Without a doubt, the landing site of the Apollo 15 mission was the most sublime lunar landscape visited by humans: spectacular mountains and a deep, scenic canyon. On page 32 we read:

“Another discovery consistent with previous Earth-based observations was that Hadley Rille was not carved by running water but is a typical (albeit huge) lava channel like those found in Hawaii (…) The rille is only a little more than 1 km wide, but it can be made out in a 5-inch telescope in the patch of mare just in front of the Apennines. The actual landing site is at the northern end of the rille where it turns away from the mountain”.

Hadley Rille, Desiré Godoy, Oro Verde, Argentina, SLA. 10 September 2016 22:56 UT. Celestron 11 inch Edge HD Schmidt-Cassegrain telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 66 Hadley Rille

Apollo 15, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 24 May 2018 01:52 UT, colongitude 19.6o. TEC 8 inch f/20 Maksutov- Cassegrain telescope, 610 nm filter, Skyris 445 M camera. Seeing 8/10.

Hadley Rille, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 22 May 2010 01:42 UT. Celestron 14 inch Schmidt-Cassegrain telescope, 2 x barlow, f/22, UV/IR blocking filter, DMK21AU04 camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 66 Hadley Rille

Apollo 15 Site, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 29 May 2012 02:42 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, W23 blocking filter, DMK21AU04 camera. Seeing 7-8/10.

Hadley Rille, Richard Hill, Loudon Observatory, Tuc- son, Arizona, USA. 14 April 2019 02:46 UT, colongitude 21.1o. TEC 8 inch f/20 Maksutov- Cassegrain telescope, 610 nm filter, Skyris 445 M camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 67 Fra Mauro Formation

Lunar 67 Fra Mauro Training: Apollo 14 landing site on Imbrium ejecta

Related to Lunar 63 and the Mare Imbrium mega-impact basin, Lunar 67 draws attention to the selection of a lunar landing site to collect samples that could solve the riddle of its formation (page 149):

“South of Copernicus and west of Ptolemaeus lies a complex of old and battered craters that are often passed over but are of fundamental importance to understanding the Moon’s history (…) it was the main ejecta from the excavation of the Imbrium basin. The goal of Apollo 14 was to sample Fra Mauro to see if it really was ejecta and, if so, to determine the age of the Imbrium impact by dating shocked and melted debris. On January 31, 1971, the lunar module Antares brought the Apollo 14 astronauts down on the Fra Mauro Formation just 40 km north of the crater of the same name. The rocks they brought back were, exactly as predicted, breccias presumably excavated by the Imbrium impact (…) Lunar geologist argue whether most of the brecciation in the Apollo 14 rocks is from the initial Imbrium impact of it occurred largely as the result of the secondary cratering at Fra Mauro (…) The truth is probably a combination of the two ideas”.

Reinhold to Parry, plus Apollo 12 and 14, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 24 April 2018 02:55 UT, colongitude 26.3o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 445 M camera. Seeing 8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 67 Fra Mauro Formation

Apollo 14 Base, Richard Hill, Loudon Observatory, Tucson, Ari- zona, USA. 09 May 2014 03:59 UT. TEC 8 inch f/20 Maksutov- Cassegrain telescope, 656.3 nm filter, Skyris 445 M camera. Seeing 8/10.

Fra Mauro, Marcelo Mojica Gundlach, Cochabamba, Bolivia, SLA. 01 May 2020 23:58 UT. 150 mm Skywatcher Maksutov-Cassegrain telescope. ZWO ASI178 B/W camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 67 Fra Mauro Formation

Fra Mauro-Apollo 14, Richard Hill, Loudon Observatory, Tuc- son, Arizona, USA. 14 April 2019 02:25 UT, colongitude 21.1o. TEC 8 inch f/20 Mak- sutov-Cassegrain telescope, 610 nm filter, Skyris 445 M camera. Seeing 8/10.

Fra Mauro, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 28 April 2015 01:20 UT. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 656.3 nm filter, Skyris 445 M camera. Seeing 9/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 68 Flamsteed P

Lunar 68 Flamsteed P: Proposed young volcanic crater & Surveyor 1 landing site

Flamsteed P is a beautiful formation of what look like circular hills, but it is actually the contour of an an- cient crater submerged in basaltic lava. The northeastern edge of Lunar 68 is a historic site: there it landed, and is still, the Surveyor 1 ship. Here's how Wood refers to this site (page 172):

“Oceanus Procellarum is characterized mainly by the arcuate remnants of older craters that have been partially buried by lavas. Examples include the Flamsteed P ring, Letronne, and Wichmann R. The most likely explanation for the occurrence of so many flooded in the south may be that the south is covered by a thin veneer of lavas, whereas mare lavas in the north completely bury older craters”.

Flamsteed, Richard Hill, Loudon Observatory, Tucson, Arizona, USA. 24 April 2021 05:32 UT, colongitude 55.8o. TEC 8 inch f/20 Maksutov-Cassegrain telescope, 610 nm filter, Skyris 132 M camera. Seeing 7-8/10.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 68 Flamsteed P

Flamsteed, Michel Deconinck, Aquarellia mobile observatory - Siguret lake - French Alps - France. 24 February 2021 17:45 UT. 102mm x 1000 mm refractor telescope, 12 mm eyepiece, 83 x.

Flamsteed P, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 30 April 2016 08:57 UT. Meade LX200 Schmidt- Cassegrain telescope, QHY5-ll camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 68 Flamsteed P

Flamsteed P, Jairo Chavez, Popayán, Colombia, SLA . 18 January 2019 03:10 UT. 10 inch Truss-tube Dobsonian reflector telescope, Sony DSC-WX 50 camera.

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Recent Topographic Studies Focus-On: The Lunar 100: Number 69 Copernicus Secondary Craters Lunar 69 Copernicus Secondary Craters: Rays and craterlets near Pytheas

Wood's choice to select the most representative field of secondary impacts was clearly wise, as always: the secondary craters of Copernicus show an impressive series of scars from the monstrous and recent impact that formed the crater that gives its name to the most recent geological era of our natural satellite (page 50):

“Under very low lighting angles, these herringbone patterns can just be glimpsed, especially along the secondary chain that lies between Eratosthenes and the Eastern end of the Carpathian Mountains, northwest of Copernicus. Given the impressive number of secondary pits around Copernicus, it is surprising that only around 2 percent of the volume of lunar rocks that were excavated to form the main crater main made sec- ondaries. The remaining material was either pulverized into pieces to produce secondary craters or was ejected at speeds great enough to escape the Moon’s gravitational hold. Almost certainly some of Coperni- cus’s ejecta rained down on the Earth a billion or so years ago.”

Copernicus, Marcelo Mojica Gundlach, Cochabamba, Bolivia, SLA. 01 May 2020 22:58 UT. 150 mm Skywatcher Maksutov-Cassegrain telescope. ZWO ASI 178 B/W camera.

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