July 2020 in This Issue Online Readers, ALPO Conference November 6-7, 2020 2 Lunar Calendar July 2020 3 Click on Images an Invitation to Join ALPO 3 for Hyperlinks

Home , Albategnius (crater), Anaximenes (crater), Antoniadi (lunar crater), Arzachel (crater), Autolycus (crater), Blanchinus (crater)

A publication of the Lunar Section of ALPO Edited by David Teske: [email protected] 2162 Enon Road, Louisville, Mississippi, USA Recent back issues: http://moon.scopesandscapes.com/tlo_back.html July 2020 In This Issue Online readers, ALPO Conference November 6-7, 2020 2 Lunar Calendar July 2020 3 click on images An Invitation to Join ALPO 3 for hyperlinks. Observations Received 4 By the Numbers 7 Submission Through the ALPO Image Achieve 4 When Submitting Observations to the ALPO Lunar Section 9 Call For Observations Focus-On 9 Focus-On Announcement 10 2020 ALPO The Walter H. Haas Observer’s Award 11 Sirsalis T, R. Hays, Jr. 12 Long Crack, R. Hill 13 Musings on Theophilus, H. Eskildsen 14 Almost Full, R. Hill 16 Northern Moon, H. Eskildsen 17 Northwest Moon and Horrebow, H. Eskildsen 18 A Bit of Thebit, R. Hill 19 Euclides D in the Landscape of the Mare Cognitum (and Two Kipukas?), A. Anunziato 20 On the South Shore, R. Hill 22 Focus On: The Lunar 100, Features 11-20, J. Hubbell 23 Recent Topographic Studies 43 Lunar Geologic Change Detection Program T. Cook 120 Key to Images in this Issue 134

These are the modern Golden Days of lunar studies in a way, with so many new resources available to lunar observers. Recently, we have mentioned Robert Garfinkle’s opus Luna Cognita and the new lunar map by the USGS. This month brings us the updated, 7th edition of the Virtual Moon Atlas. These are all wonderful resources for your lunar studies.

This month, The Lunar Observer features Jerry Hubbell’s Focus On article, Lunar 100, Features 11-20. This has proven to be an incredibly popular series! My new page By the Numbers (page 7) tells of 34 observers submitting 215 lunar observations for this issue. Many of those images grace these pages, and all are in the ALPO Lunar Image Gallery. Also be sure to check out page 10, the 2020 ALPO Walter H. Haas Observer’s Award. All this, plus articles by Alberto Anunziato, Rik Hill, Howard Eskildsen and Tony Cook. Enjoy and be safe.

The Lunar Observer/July 2020/ 1

ALPO Conference November 6-7, 2020

Interested parties are hereby invited to submit papers and research posters on the astronomy-related topics of their choice for presentation at the next ALPO conference to be held jointly with the Georgia Regional As- tronomers Meeting (GRAM) when that group meets on November 6 and 7, 2020.

This will be the second time the ALPO has participated with the GRA group, the first time being the autumn of 2017.

Like last time, the was made after an online discussion and vote by the ALPO board of directors.

This year's conference will be at North Georgia College in Dalton, Georgia, approximately a one-and-a-half- hour drive north of downtown Atlanta. The ALPO portion of the conference will commence with the ALPO board meeting on Friday, November 6, to be followed by an informal gathering that evening with a lecture, social gathering with snacks and observing at the school’s on-campus observatory.

All papers will be presented the following day, Saturday, November 7, between 9 a.m. and 5 p.m.

Also as we did in 2017, there will be an ALPO dinner on Saturday evening where the Walter Haas Observ- ing Award and the Peggy Haas Service Award will be presented.

We have been allotted up to at least four (4) time slots for ALPO papers of no more than 15 minutes in length; the preferred method is 12 minutes for the paper presentation plus 3 minutes for follow-up questions. The preferred format is Microsoft PowerPoint.

We have also been invited to participate with wall-mounted research posters which are also commonly done at academic and professional conferences everywhere.

Participants are encouraged to submit research papers, presentations, and experience reports concerning var- ious aspects of Earth-based observational astronomy. Suggested topics for papers and presentations include the following: • New or ongoing observing programs and studies, specifically, how those programs were designed, im- plemented and continue to function. • Results of personal or group studies of solar system or extra-solar system bodies. • New or ongoing activities involving astronomical instrumentation, construction or improvement. Challenges faced by Earth-based observers such as changing interest levels, deteriorating observing condi- tions brought about by possible global warming, etc. A hard-copy version of your paper should be made available for future web site publication.

More details about paper presentations and to whom they should be sent will be published in the Summer issue of the ALPO Journal for release in early June.

The Lunar Observer/July 2020/ 2

Lunar Calendar July 2020

Date Time UT Event July 2020 5 Moon greatest southern declination -24.1o 5 0444 Full Moon 5 2200 Jupiter 1.9o north of Moon 6 0900 Saturn 2o north of the Moon 6 East limb most exposed +5.0o 11 North limb most exposed +6.8o 11 2000 Mars 2.0o north of the Moon 12 1900 Moon at apogee 404,199 km 12 2329 Last Quarter Moon 17 0700 Venus 3o south of the Moon 19 West limb most exposed -5.4o 19 Moon greatest northern declination +23.9o 20 1733 New Moon Lunation 1207 25 South limb most exposed -6.7o 25 0500 Moon at perigee 368,361 km 27 1232 First Quarter Moon

The Lunar Observer welcomes all lunar related images, drawings, articles, reviews of equipment and reviews of books. You do not have to be a member of ALPO to submit material, though membership is highly encouraged. Please see below for membership and near the end of The Lunar Observer for submission guidelines.

Comments and suggestions? Please send to David Teske, contact information page 1. Need a hard copy, please contact David Teske.

AN INVITATION TO JOIN THE A.L.P.O.

The Lunar Observer is a publication of the Association of Lunar and Planetary Observers that is available for access and participation by non- members free of charge, but there is more to the A.L.P.O. than a monthly lunar newsletter. If you are a nonmember you are invited to join our organization for its many other advantages. We have sections devoted to the observation of all types of bodies found in our solar system. Section coordinators collect and study members’ observations, correspond with observers, encourage beginners, and contribute reports to our Jour- nal at appropriate intervals. Our quarterly journal, The Journal of the Association of Lunar and Planetary Observers-The Strolling Astronomer, contains the results of the many observing programs which we sponsor including the drawings and images produced by indi- vidual amateurs. Additional information about the A.L.P.O. and its Journal is on-line at: http://www.alpo-astronomy.org. I invite you to spend a few minutes browsing the Section Pages to learn more about the fine work being done by your fellow amateur astronomers. To learn more about membership in the A.L.P.O. go to: http://www.alpoastronomy.org/main/member.html which now also provides links so that you can enroll and pay your membership dues online.

The Lunar Observer/July 2020/ 3

Lunar Topographic Studies

Acting Coordinator – David Teske - [email protected]

Assistant Coordinator – William Dembowski - [email protected]

Assistant Coordinator – Jerry Hubbell – [email protected] Assistant Coordinator-Wayne Bailey– [email protected] Website: http://moon.scopesandscapes.com/

Observations Received

Name Location and Organization Article/image Aylen Borgatello Alaniz AEA - Oro Verde, Entre Rios, Ar- Image of Messier (2), Proclus and gentina Plato. Jay Albert Lake Worth, Florida, USA Images of Aristarchus, Gassendi (2), Sinus Iridum and drawing of Posido- nius. Alberto Anunziato Paraná, Argentina, SLA Article and drawing Euclides D in the Landscape of Mare Cognitum (and Two Kipukas?), images of Peta- vius (2), Aristarchus (2), Gassendi (3), Sinus Iridum (2) and Vallis Alpes Jorge. Arranz Lunar Group of the Madrid Astro- Drawing of Gassendi. nomical Association (AAM), Ma- drid, Spain Sergio Babino Montevideo, Uruguay Image of Tycho, Proclus, Gassendi, Vallis Schröteri (3), Mare Serenita- tis (2), Vallis Alpes and Posidonius. Francisco Alsina Cardinalli Oro Verde, Argentina, SLA Images of Aristarchus (7), Proclus (6), Gassendi, Sinus Iridum, Rupes Recta (3), Vallis Schröteri (4), Mare Serenitatis (4), Vallis Alpes and Po- sidonius (2). Jairo Chavez Popayán, Colombia, SLA Image of Gassendi, Sinus Iridum, Vallis Schröteri and Mare Serenitatis Abel David Emiliano Gonzalez Cian AEA - Oro Verde, Entre Rios, Ar- Image of Aristarchus, Mare Crisium, gentina Langrenus and Petavius. Leonardo Alberto Colombo Córdoba, Argentina Image of the waxing gibbous Moon. Michel Deconinck Aquarellia Observatory, south France Sketches and pastels of Aristarchus, Proclus, Gassendi, Sinus Iridum, Straight Wall, Petavius, Schröter’s Valley, Dark Edges of Mare Sereni- tatis, Alpine Valley and Posidonius. Walter Ricardo Elias AEA - Oro Verde, Entre Rios, Ar- Image of Mons Piton (2), Aristar- gentina chus, Deslandres and Plato. Desiré Godoy Oro Verde, Argentina, SLA Image of Aristarchus, Proclus and Gassendi. Many thanks for all these observations, images, and drawings.

The Lunar Observer/July 2020/ 4

Name Location and Organization Article/image Eskildsen, Howard Ocala, Florida, USA Article and image Musing on The- ophilus, Northern Moon, Northwest Moon and Horrebow, image of Mons Rumker, Marius, Lichtenberg, Gri- maldi and Sirsalis. Fernando Gimenez Montevideo, Uruguay Image of Tycho. Fernando Gomez Montevideo, Uruguay,SAO Image of Sinus Iridum. Martín Queirolo Gomez Montevideo, Uruguay, SAO Image of Proclus, Sinus Iridum (2) and Mare Serenitatis (2) and Rupes Recta Marcelo Mojica Gundlach Cochabamba, Bolivia, SLA Image of Gassendi, Sinus Iridum, Mare Serenitatis and Vallis Alpes (3). Robert H. Hays, Jr. Worth, Illinois, USA Drawing and article Sirsalis T. Rik Hill Tucson, Arizona, USA Image and article Almost Full, Long Crack, On the South Shore and A Bit of Thebit. Jerry Hubbell Wilderness, Virginia, USA Article Focus-On Lunar 11-20 Carlos Lobato San José de Carrasco, Uruguay, SAO Drawing of Gassendi. Ángel Manuel López Lunar Group of the Astronomical Image of Mare Serenitatis. Association from Madrid, Spain Frank Melillo Holtsville, New York, USA Image of Lunar X Luigi Morrone SNdR Luna UAI, Agerola, Italy Image of Rima Ariadaeus, Lade, Endymion, Atlas and Hercules, Aris- toteles and Eudoxus, Theophilus and Cyrillus, Vallis Alpes, Rima Hygi- nus, Purbach, Mons Hadley, Meton, Maurolycus, Cassini and Albate- gnius. Rafael Lara Muñoz Guatemala, Guatemala, SLA Images of Earthshine, Mare Serenita- tis, Montes Apenninus, Copernicus and Aristarchus. Cyntia Olivera Santiago del Estero, Argentina, SLA Image of Sinus Iridum. Raúl Roberto Podestá Formosa, Argentina, SLA Image of Rupes Recta. Re, Gabriel AEA - Oro Verde, Entre Rios, Ar- Image of Aristarchus (2), Gassendi gentina and Mare Frigoris. Sid, Leandro AEA - Oro Verde, Entre Rios, Ar- Image of Bullialdus (2), Copernicus, gentina Darney, Waxing Gibbous Moon, Plato, Tycho, Aristarchus, Cassini and Proclus. Fernando Surà San Nicolás de los Arroyos, Argenti- Image of Proclus. na, SLA-LIADA Michael Sweetman Tucson, Arizona, USA. Sky Crest Image of Mare Crisium and Anaxag- Observatory oras.

Many thanks for all these observations, images, and drawings.

The Lunar Observer/July 2020/ 5

Observations Received

Name Location and Organization Article/image Steve Thornton Images of the Straight Wall and Ptol- emaeus. Fabio Verza UAI Italy Moon Section SNdR Luna Image of Sinus Iridum (3), Full UAI - Italy Moon, Janssen, Theophilus (3), At- las, Piccolomini (2), Archimedes, Longomontanus, Clavius, Montes Apenninus (2), Last Quarter Moon, Mare Imbrium, Ptolemaeus, Coper- nicus, Clavius, Anaximenes, Archi- medes, Montes Recta, Plato, Pur- bach, Pythagoras, Rupes Recta (2), Bullialdus, Pitatus Montes Carpatus, Waxing Crescent Moon (2), Grove, Mare Crisium, Mare Serenitatis, Burg, Janssen, Mare Fecunditatis, Mare Nectaris(2), Mare Tranquillita- tis, Posidonius, Pitiscus, Endymion, Aristoteles, Calippus, Boussingault, Julius Caesar, Manilius, Maurolycus, Meton, Playfair and Vallis Alpes. Dennis Wilde Transit Dreams Observatory, Cam- Image of Proclus. pobello, South Carolina, USA

Many thanks for all these observations, images, and drawings.

The Lunar Observer/July 2020/ 6

July 2020 The Lunar Observer By the Numbers

This month there were 215 observation by 34 observers from 10 countries.

The Lunar Observer/July 2020/ 7

SUBMISSION THROUGH THE ALPO IMAGE ARCHIVE ALPO’s archives go back many years and preserve the many observations and reports made by amateur astronomers. ALPO’s galleries allow you to see on-line the thumbnail images of the submitted pictures/observations, as well as full size versions. It now is as simple as sending an email to include your images in the archives. Simply attach the image to an email addressed to [email protected] (lunar images). It is helpful if the filenames follow the naming convention : FEATURE-NAME_YYYY-MM-DD-HHMM.ext YYYY {0..9} Year MM {0..9} Month DD {0..9} Day HH {0..9} Hour (UT) MM {0..9} Minute (UT) .ext (file type extension) (NO spaces or special characters other than “_” or “-”. Spaces within a feature name should be replaced by “-”.) As an example the following file name would be a valid filename: Sinus-Iridum_2018-04-25-0916.jpg (Feature Sinus Iridum, Year 2018, Month April, Day 25, UT Time 09 hr16 min) Additional information requested for lunar images (next page) should, if possible, be included on the image. Alternatively, include the information in the submittal e-mail, and/or in the file name (in which case, the coordinator will superimpose it on the image before archiving). As always, additional commentary is always welcome and should be included in the submittal email, or attached as a separate file. If the filename does not conform to the standard, the staff member who uploads the image into the data base will make the changes prior to uploading the image(s). However, use of the recommended format, reduces the effort to post the images significantly. Observers who submit digital versions of drawings should scan their images at a resolution of 72 dpi and save the file as a 8 1/2'“x 11” or A4 sized picture. Finally a word to the type and size of the submitted images. It is recommended that the image type of the file submitted be jpg. Other file types (such as png, bmp or tif) may be submitted, but may be converted to jpg at the discretion of the coordinator. Use the minimum file size that retains image detail (use jpg quality settings. Most single frame images are adequately represented at 200-300 kB). How- ever, images intended for photometric analysis should be submitted as tif or bmp files to avoid lossy compression. Images may still be submitted directly to the coordinators (as described on the next page). However, since all images submitted through the on-line gallery will be automatically forwarded to the coordinators, it has the advantage of not changing if coordinators change.

The Lunar Observer/July 2020/ 8

When submitting observations to the A.L.P.O. Lunar Section In addition to information specifically related to the observing program being addressed, the following data should be included:

Name and location of observer Name of feature Date and time (UT) of observation (use month name or specify mm-dd-yyyy-hhmm or yyyy-mm-dd-hhmm) Filter (if used) Size and type of telescope used Magnification (for sketches) Medium employed (for photos and electronic images) Orientation of image: (North/South - East/West) Seeing: 0 to 10 (0-Worst 10-Best) Transparency: 1 to 6

Resolution appropriate to the image detail is preferred-it is not necessary to reduce the size of images. Additional commentary accompanying images is always welcome. Items in bold are re- quired. Submissions lacking this basic information will be discarded.

Digitally submitted images should be sent to: David Teske – [email protected] Jerry Hubbell –[email protected] Wayne Bailey—[email protected]

Hard copy submissions should be mailed to David Teske at the address on page one.

CALL FOR OBSERVATIONS: FOCUS ON: Lunar 100 Focus on is a bi-monthly series of articles, which includes observations received for a specific feature or class of features. The subject for the July 2020 edition will be the Lunar 100 numbers 11- 20. Observations at all phases and of all kinds (electronic or film based images, drawings, etc.) are welcomed and invited. Keep in mind that observations do not have to be recent ones, so search your files and/or add these features to your observing list and send your favorites to (both): Jerry Hubbell –[email protected] David Teske – [email protected]

Deadline for inclusion in the Lunar 100 numbers 11-20 article is June. 20, 2020

FUTURE FOCUS ON ARTICLES: In order to provide more lead time for contributors the following future targets have been selected: The next series of three will concentrate on subjects of the Selected Areas Program.

Subject TLO Issue Deadline Lunar 100 (numbers 21-30) September 2020 August 20, 2020 Lunar 100 (numbers 31-40) November 2020 October 20, 2020

The Lunar Observer/July 2020/ 9

Focus-On Announcement

We are pleased to announce the future Focus-On topics. These will be based on the Lunar 100 by Charles Wood. Every other month starting in May 2020 , the Focus-On articles will explore ten of the Lunar 100 targets. Targets 21-30 will be featured in the September 2020 The Lunar Observer. Submissions of articles, drawings, images, etc. due by August 20, 2020 to David Teske and Jerry Hubbell.

L Feature Name Significance Rükl Chart 21 Fracastorius Crater with subsided and fractured floor 58 22 Aristarchus Plateau Uplifted region with pyroclastics 18 23 Pico Isolated Imbrium basin-ring fragment 11 24 Hyginus Rille Rille containing rimless collapse pits 34 25 Messier and Messier A Oblique ricochet-impact pair 48

26 Mare Frigoris Arcuate mare of uncertain origin 2-6

27 Archimedes Large crater lacking central peak 12, 22

28 Hipparchus First drawing of a single crater 44, 45 29 Ariadaeus Rille Long, linear graben 34 30 Schiller Possible oblique impact 71

Explore the Lunar 100 on the link below: https://www.skyandtelescope.com/observing/celestial-objects-to-watch/the-lunar-100/

The Lunar 100: Features 1-10 May 2020 Issue – Due April 20, 2020 The Lunar 100: Features 11-20 July 2020 Issue – Due June 20, 2020 The Lunar 100: Features 21-30 September 2020 Issue – Due August 20, 2020 The Lunar 100: Features 31-40 November 2020 Issue – Due October 20, 2020 The Lunar 100: Features 41-50 January 2021 Issue – Due December 20, 2020 The Lunar 100: Features 51-60 March 2021 Issue – Due February 20, 2021 The Lunar 100: Features 61-70 May 2021 Issue – Due April 20, 2021 The Lunar 100: Features 71-80 July 2021 Issue – Due June 20, 2021 The Lunar 100: Features 81-90 September 2021 Issue – Due August 20, 2021 The Lunar 100: Features 91-100 November 2021 Issue – Due October 20, 2021 Jerry Hubbell –[email protected] David Teske – [email protected]

The Lunar Observer/July 2020/ 10

Howard-

As the Chairman of the 2020 ALPO The Walter H. Haas Observer’s Award, it is my extreme pleasure to let you know that you have been selected to be the recipient of the 2020 The Walter H. Haas Observer’s Award.

The Walter H. Haas Observer’s Award is bestowed annually (generally when the ALPO meets in the summer), to an amateur astronomer for excellence in observational Solar System astronomy. This award is named after our founder and original executive director and was established in 1985. The selection of this award is conducted by a committee convened by its committee chairman, Timothy Robertson. The composi- tion of the committee changes from year to year so that the responsibility of selection is shared by a wider group of members in the ALPO that are well qualified, while allowing others that vote one year, to be considered for the award in another year, when not serving on the committee.

This award is given for excellence in Solar System observational amateur astronomy. Work done as part of the observer’s job must be regarded as professional work and is not considered as an amateur effort for this award. However, a professional astronomer can be recognized for work done when he or she was an amateur.

The Award itself consists of an engraved plaque. The awardee also receives a two-year complimentary membership in the ALPO.

This year the ALPO conference is at the University of North Georgia in Dahlonega, Georgia, where this No- vember's ALPO meeting is scheduled to be held in conjunction with the Georgia Regional Astronomers Meeting on November 6 and 7. However, with the current situation, discussions are in place on canceling or changing the dates of the event.

Congratulations of being selected as the 2020 ALPO The Walter H. Haas Observer’s Award winner.

Tim Robertson

Howard,

Congratulations on your being awarded the 2020 ALPO Walter H. Haas Observer’s award! You are very well deserving of this honor. The Lunar Observer is frequently graced with images and articles provided by you. These are always enlightening to our readers. In addition to the work with The Lunar Observer, you are a frequent contributor to the Lunar Domes Gallery with high resolution images on said domes. Along with these lunar contributions, you frequently supply the ALPO Solar Program with daily images of the Sun in white light, hydrogen alpha and calcium wavelengths. These all take much time and work to produce.

Thank you and congratulations for your award!

David Teske

The Lunar Observer/July 2020/ 11

Sirsalis T Robert H. Hays, Jr.

Sirsalis T, Robert H. Hays, Jr. Worth, Illinois, USA. 07 March 2020 0242-0326; 0344-0356 UT. 15 cm reflector, 170 x. Seeing 8-9/10, transparency 6/6.

I observed this crater and vicinity on the evening of March 6/7, 2020. This area is in far southwest Oceanus Procellarum. Sirsalis T is a half-crater at the southern end of a wide ridge. It is open to the southwest. This configuration resembles the end of a wrench. A detached peak is off the west end of Sirsalis T, and another peak is south of its center. Three short ridges are south of its east end. A tiny pit and a small peak are just east of the center-ridge junction, and a short ridge is to their north. A long, broken ridge is northwest of Sirsalis T. The north end of the ridge is quite substantial with interior shadowing and with small peaks nearby. There is a low half-crater well north of Sirsalis T. This crater is open to the north, nearly the opposite of Sirsalis T. Its west rim is wider but shorter than the narrow east rim. The wide, curved ridge farther to the west is Sirsalis epsilon. This is part of the broken ring Sirsalis E. Two peaks and a wrinkle ridge are to its north.

The Lunar Observer/July 2020/ 12

Long Crack Rik Hill

The Moon is almost full and it seems like there is little to see. But on the southwest terminator is a grouping of craters that lead us to one of the longest cracks on the Moon. Near the top of the image are two overlap- ping craters. The one on the top is Sirsalis (43 km). You will notice a rima running north-south just to the right of it. This is, appropriately enough, Rimae Sirsalis, one main rima with several smaller, shorter, thin- ner ones on the side. The main Rima is 309 km long, its southern end in shadow here and the northern end of the top of this image. Just to the right of the nameplate on this image is the faintest traces of the upper edge of a crater wall. This is the crater Crüger (48 km) with the satellite crater Crüger A (27 km), the sharp crater next to the rima. Further on the same direction is a shallow flat-bottomed crater, Fontana (32 km). In the lower corner of this image is the half-illuminated crater De Vico (20 km). Lastly, is the odd dark feature on the far eastern (right) edge of this image below the black overlap insert. This is Zupus, listed as 49 km diameter but it was hardly circular. It appears to be a small piece of the Oceanus Procellarum material to the north. In fact, it is the flooded remains of an ancient crater whose eastern wall rises 1.3 km above the surrounding interior. I’s sure this range would be an impressive sight at sunset from the flooded floor!

Sirsalis, Richard Hill, Tucson, Arizona, USA, Loudon Observatory. 04 June 2020 0550 UT, colongitude 66.7o. Dynamax 6 telescope plus 2x barlow, 850 nm filter, Skyris 132M camera. Seeing 8/10.

The Lunar Observer/July 2020/ 13

Musings on Theophilus Howard Eskildsen

Theophilus dominates this image with its sharp crater rim, multiple terraces, complex central peak and pools of impact melt indicated on Figure 1 with an “I.” The area with the “?” label is also likely impact melt as well, probably first from Theophilus and later covered over by ejecta or melt from Mӓdler which lies to the lower right of the “?” label. While the cause for confusion is not readily visible in Figure 1, Figure 2 shows a close-up view from the LROC QuickMap and reveals the reason for question of origin.

Note the density of the small craters on the impact melt in the interior of Theophilus on Figure 2. Compared to the impact melt outside its north rim the crater density appears about the same, but on the area of the “?”, craterlets are nearly absent and are more like the crater density in Mӓdler. Also, the LROC image shows this area to have a darker albedo than the other melt areas. Assuming this area contains impact melt from The- ophilus, it should have the same craterlet density as the melt on the interior of the crater and similar albedo, so something must have covered any melt from Theophilus. I suspect that impact melt, fluidized ejecta, or probably both, from Mӓdler covered over of the older deposit and changed the albedo and crater count.

The pools of impact melt outside Theophilus are located to the north and east of the crater, and the rim elevation is lower on those sides as well. LROC QuickMap measurements north-south and west-east paths through the central peak area show a western rim elevation of 900 meters above mean lunar radius (MLR), while the eastern rim is 890 meters below MLR, a difference of 1790 meters over a measured distance of 103 km. Similarly, the southern rim is 63 meters above MLR while the north rim is 520 meters below MLR, or 583 meters higher than the southern rim over a measured distance of 97m. I wonder if this contributed to the location of melt pools on that side or if they are simply a result of asymmetrical ejection of the melted material.

Using the LROC QuickMap measurements, the average of the two diameters is 100 km, the depth 4640 meters with a depth/diameter ratio of 0.046. The highest central peak measured 2780 meters above the lowest part of the crater floor. This compares to diameter of 98.59 km, depth of 4100 meters, with central peak height of 1810 as listed in Luna Cognita, page 11-26, by Robert Garfinkle. These differences are not surpris- ing since the crater is not exactly round and measurement techniques of the crater depths and central peak heights is challenging due to the uneven elevation of the crater floor, even with LROC data. Also, the rim of Theophilus is not even in elevation. The southwest rim that overlaps Cyrillus has collapsed and is nearly 800 meters lower than the western rim of the crater, so the two measurements done probably overestimate the mean rim elevation and therefore the depth of the crater.

It also raises another question, should the rim elevation be estimated using all parts of the rim, including areas where slumping occurred, or should only the original intact rim be used to measure mean rim height and be used to calculate crater depths?

Online readers, click on images for hyperlinks.

The Lunar Observer/July 2020/ 14

Figure 1, Theophilus, Howard Eskildsen, Ocala, Florida, USA. 10 June 2020 0949 UT, colongitude 142.0 degrees. Celestron 9.25 inch Schmidt- Cassegrain telescope, f/10, fl 2395 mm, Celestron Skyris 236M camera. Seeing 6/10, transparency 4/6.

Figure 2, The- ophilus, Image from LROC Quickmap

The Lunar Observer/July 2020/ 15

Almost Full Rik Hill

About a day before Full Moon you can see this amazing landscape in the center of the terminator. The large dark crater just left of center is Grimaldi (228 km), one of the stepping stones to Mare Orientale when the libration is right. There’s a cluster of craters east (right) of Grimaldi. The easternmost one is Dam- oiseau (37 km). South of this is a well-defined crater near the bottom of the image, Sirsalis (43 km). In the lower right corner is the dark crater Billy (48 km), distinctive for its dark floor, darker than the surrounding Oceanus Procellarum making it stick out visu- ally.

Grimaldi, Richard Hill, Tucson, Arizona, USA, Loudon Observatory. 06 May 2020 0548 UT, colongitude 70.0o. Dynamax 6 telescope plus barlow, 665 nm filter, Skyris 445M camera. Seeing 8/10.

Above Grimaldi is another large crater Hevelius (109 km) with the small crater Lohrmann (32 km) just below. Above Hevelius is a deeper crater, Cavalerius (60 km). Notice the apparent gash between Hevelius and Grimaldi. There is a shallow valley here, seen on the LROC Quick Map, and a couple of small craters add to the effect, but it looks more dramatic than the true topography at this lighting. On both sides of Lohrmann, note the unnamed system of rimae. I’s quite surprised they are not named. Another curious gash is below to the right of Grimaldi. It appears to pass through two craters but in fact is a linear alignment of around 10 eroded craters. Then south of Grimaldi are more rimae. These are named Rimae Grimaldi. They lead into a flat area further to the south that is Rocca W (102 km). As big as Hevelius but, alas, only a satellite crater to Rocca. This is definitely a region worthy of careful examina- tion… just when you thought the Moon was almost full and there was nothing left to see!

The Lunar Observer/July 2020/ 16

Northern Moon Howard Eskildsen

This image shows favorable libration of the northern Moon. Just west of the terminator, a distinctive group of craters form what I think of as steppingstones to the north pole. Scoresby is easy to spot above Meton at any libration, Challis and Main overlap just above Scoresby, and beyond them Byrd lies indented by the crater Gioja. In the darkness north of Byrd lies Peary and the north pole rests on its upper rim somewhere in the darkness to the left of the center of Byrd.

A seldom-seen crater, Hermite peers from the top of the image and behind it is another surprise crater that will be revealed in the next image I send.

North Pole Region, Howard Eskildsen, Ocala, Florida, USA. 10 June 2020 0941 UT, colongitude 142.0 degrees. Celestron 9.25 inch Schmidt-Cassegrain telescope, f/10, fl 2395 mm, Celestron Skyris 236M camera. Seeing 6/10, transparency 4/6.

Online readers, click on images for hyperlinks.

The Lunar Observer/July 2020/ 17

Northwest Moon and Horrebow Howard Eskildsen

This image also shows the northwestern Moon including Sinus Roris and beyond, with selected craters la- beled. One of the strangest craters is Horrebow. An obvious slump of the rim occurred on the southwest part of the crater, but a strange ridge appears to the northeast where it overlaps with Horrebow A. It almost appears as if part of the lower rim of Horrebow A persisted in the face of the Horrebow impact, or perhaps part of Horrebow's NE rim slumped into Horrebow A. Maybe there is another explanation, but I find this to be another intriguing part of the Moon.

Northwest Moon, Howard Eskildsen, Ocala, Florida, USA. 12 June 2020 0950 UT, colongitude 166.4 degrees. Celestron 9.25 inch Schmidt-Cassegrain telescope, f/10, fl 2395 mm, Celestron Skyris 236M camera. Seeing 7/10, transparency 3/6.

The Lunar Observer/July 2020/ 18

A Bit of Thebit Rik Hill

Here we have a wonderful area on the Moon that bears a lot of study. Our crater that lends its name to this image, Thebit (60 km) is in the center with Thebit A (20 km) breaching its upper left (northwest) wall. Above this crater and a little to the right (east) is the wonderfully terraced crater Arzachel (100 km) with nice rimae on its floor. A little to the northwest of this is the unusual crater Alpetragius (41 km) with a broad round central peak. It has been appropriately likened to an egg in a basket. Due west of Thebit you’ll see a dark slash. This is the 114 km long Rupes Recta or the “Straight Wall”. It is not terribly straight and given a little more resolution than we have here you would see that. The wall looks like an abrupt cliff but actually is fairly sloped but as we see it here it is only about 1-1.5 km wide. Consider what this is from your home. Most people can easily see a kilometer in some direction unless they live in a forest. West of this is the relatively young crater Birt (17 km). A small rima extends to the northwest from the north wall of this crater. This is Rima Birt and it too is only about a kilometer wide!

Below Thebit is a large shallow crater, Purbach (121 km) with a very unusual central peak, probably the remnants of a previous crater wall. To the east is a flat floored crater, la Caille (70 km) and south of it is Blanchinus (also 70 km). Purbach lays on top of an even older crater to the south, Regiomontanus (129 km) with a central peak that has a more-or-less central crater. (No, it is not a volcano.) Lastly, we have that very circular crater with thin terraced walls in the lower right corner of the image. This is Werner (71 km) with a fresh crater and white ejecta blanket on the north inner slope. We know its fresh (relatively) because it is lighter colored. Its composed of the same material as the rest of the crater but when it’s crushed and pulver- ized it takes on a higher albedo, or reflectivity and thus look white.

Thebit, Richard Hill, Tucson, Ari- zona, USA, Loudon Observa- tory. 03 April 2020 0211 UT, colongitude 28.8o. Dynamax 6 telescope plus 1.5 x barlow, 610 nm filter, Skyris 132M camera. Seeing 8/10.

The Lunar Observer/July 2020/ 19

Euclides D in the Landscape of the Mare Cognitum (and Two Kipukas?) Alberto Anunziato

The intricate landscape of the Mare Cognitum is fascinating as the terminator passes through it, and oblique sunlight illuminates an expressionist setting in which the resolution of small telescopes like mine is substan- tially improved. The always remembered Peter Grego says in “The Moon and How to Observe It” (page 173): “Mare Cognitum is a dark lava plain, somewhat oval in shape, measuring 330 km from Montes Riphaeus in the northwest to its southeastern shoreline near Guericke. Mare Cognitum, the “Known Sea”, takes its name from the fact that the probe, Ranger 7, secured the first detailed close-up photographs of the Moon's surface prior to its (intended) crash-landing on the sea in July 1964”. In the sketch we can see the small Euclid D (5 kilometers in diameter) casting a long shadow to the northwest, with its bright outline, although brighter in the east than in the west. We have to imagine that the Riphaeus Mountains are located exactly to the west of the image, shining beautifully in the terminator (beautiful vision of impossible execu- tion). A dorsum extends from west to east, interrupted by Euclid D. We can venture that it is the least elevated, since it is perceived only by the brightness of its elevated areas. Another shorter one extends in the same direction further north, casting partly shadow, so it would be higher than the previous one (and brighter). A third extends from north to south and is clearly the highest: brighter, with a blacker shadow and more distin- guishable shapes, at its northern end the light and shadow glimpses a crater. South of Euclid D there is an imprecise bright spot and further to the south a second one, smaller but casting a small shadow. The first one seemed to correspond to a brighter ground coloration, but the second one looks like a dome, as I can see a dome with my 105mm telescope. The search in the charts was unsuccessful. In Grego's quoted book we read that “Near its western shoreline can be found a teardrop-shaped dome 20 km long. Unique among lunar domes, it is composed of brighter material than the surrounding mare, and it can be seen under a high illumi- nation. A group of hills to its west also have a high albedo. It is possible that the dome and the nearby hills are the remnants of a submerged crater, the dome representing the crater’s central uplift”. Clearly it is not the dome quoted by Grego, which would be much larger. In "Lunar Domes. Properties and Formation Pro- cesses” (Raffaello Lena et al.), a formation is mentioned in Mare Cognitum (page 54), a kipuka “surface parts surrounded by the flooding mare lavas. Kipukas usually consist of a different material than the surrounding mare, such that a spectral contrast would have to be observed. A typical example of a lunar kipuka is the formation Darney Chi located in western Mare Cognitum, an elevated section of Highland terrain em- bayed by mare lava”. But Darney Crater is much further south. Perhaps it is one of the hills to which Grego refers "A group of hills to its west also have a high albedo". And these hills could be two 6-kilometer kipukas west of Darney Chi, according to "Lunar kipukasas evidence for an Extended Tectonic and Volcanic History of the Maria" (D.J. Nichols et. Al.). After reading the sources quoted, I was left with a bit of remorse for not having pointed out more precisely, while observing, these two oddities in that strange landscape, full of wonders, which is Mare Cognitum.

The Lunar Observer/July 2020/ 20

Euclides D, Alberto Anunziato, Paraná, Argentina. 31 May 2020 2220-2245 UT. 105 mm Maksutov-Cassegrain telescope (Meade EX 105), 154 x.

The Lunar Observer/July 2020/ 21

On the South Shore Rik Hill

The whole rim of Mare Nectaris is populated with wonderful features. Here we have the south side of the big scarp Rupes Altai below and left of center stretching from the beautiful crater Piccolomini (90 km) at the bottom going all the way up past Catarina (104 km) some 495 km. You can just barely see another pressure ridge, concentric to Mare Nectaris, running from Catharina down south of the large “U” shaped crater above center, Fracastorius (128 km). Unfortunately, the nice east-west rima that bisects this crater is just beyond the resolution of this image. But there are many secondary craters on its floor and a splattering of them in the upper left covering Beaumont (54 km), a little brother to Fracastorius. These secondaries are likely ejecta from the Theophilus impact to the north which must have been a fantastic sight!

Fracastorius, Richard Hill, Tucson, Arizona, USA, Loudon Observatory. 28 May 2020 0211 UT, colongitude 339.8o. Dynamax 6 telescope plus 2x barlow, 850 nm filter, Skyris 132M camera. Seeing 8/10.

The Lunar Observer/July 2020/ 22

Focus On: The Lunar 100 Features 11 through 20

Jerry Hubbell Assistant Coordinator, Lunar Topographical Studies

This is the second 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 descrip- tions. 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 11 through 20 on Chuck’s list. This article highlights the excellent drawings of each of these features submitted by Michel Deconinck from Provence, France. Here is a list of features 11 – 20:

Designation Feature Name Description/Significance L11 Aristarchus Very Bright Crater with Dark Bands on its Walls L12 Proclus Oblique-Impact Rays L13 Gassendi Floor Fractured Crater L14 Sinus Iridum Very Large Crater with Missing Rim L15 Rupes Recta AKA “Straight Wall” - Best Example of a Lunar Fault L16 Petavius Crater with a Domed and Fractured Floor L17 Schröter's Valley Giant Sinuous Rille L18 Mare Serenitatis Distinct Mare Areas with Different Compositions L19 Alpine Valley Lunar Graben L20 Posidonius Floor Fractured Crater

The Lunar Observer/July 2020/ 23

The Lunar 100: Feature 11 and 17—Aristarchus and Schröter's Valley

Figure 1. Aristarchus & Schröter's Valley Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 09 June 2014, 2100 UT, Colongitude 53.8°, Bresser refractor 102/1000, 10mm Delos eyepiece, Magnification 100x, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Up, East/Right. Online readers, click on images for hyperlinks.

The Lunar Observer/July 2020/ 24

The Lunar 100: Feature 11 and 17—Aristarchus and Schröter's Valley

Figure 2. Ar- istarchus & Schröter's Valley, Alberto Anunziato (Paraná, Argentina, SLA), 19 June 2016 0215 UT, Colongitude 77.9°, 250 mm. Schmidt-Cassegrain (Meade LX 200), QHY5-II Camera, North/Left, East/Up.

The Lunar Observer/July 2020/ 25

The Lunar 100: Feature 12 Proclus

Figure 3. Proclus Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 04 May 2014, 2100 UT, Co- longitude 334.1°, Bresser refractor 102/1000, 26mm Bresser eyepiece, 10mm Delos eyepiece, Magnification 38x, 100x, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Down, East/Right.

The Lunar Observer/July 2020/ 26

The Lunar 100: Feature 12 Proclus

Figure 4. Proclus, Sergio Babino, Montevideo, Uruguay, SAO, 29 April 2020, 2244 UT, Colongitude 356.2°, 8-inch (200 mm) Schmidt-Cassegrain, Camera ZWO174mm. North/Up, East/Right.

The Lunar Observer/July 2020/ 27

The Lunar 100: Feature 13 Gassendi

Figure 5. Gassendi Sketch (rotated 180°), Jorge Arranz, Lunar Group of the Madrid Astronomical Association (AAM), Madrid, Spain, 07 March 2009, 2227 UT, Dobsonian 250mm f/5, 15 mm eyepiece, 282x magnification, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. Colongitude 47.4°, North/Up, East/ Right.

The Lunar Observer/July 2020/ 28

The Lunar 100: Feature 13 Gassendi

Figure 6. Gassendi, Jerry Hubbell, Lake of the Woods Observatory (I24) Locust Grove, Virginia, USA, 04 February 2012 0058 UT, Colongitude 48.2°, Meade 10-inch LX5 Schmidt-Cassegrain, DMK21AU04AS camera. Seeing 6/10, Transparency 5/6. North/Up, East/Right.

The Lunar Observer/July 2020/ 29

The Lunar 100: Feature 14 Sinus Iridum

Figure 7. Sinus Iridum Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 05 June 2017, 1930 UT, Colongitude 45.3°, Bresser refractor152mm/1200mm, 10mm Delos eyepiece, Magnification 120x, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Up, East/Left

The Lunar Observer/July 2020/ 30

The Lunar 100: Feature 14 Sinus Iridum

Figure 8. Sinus Iridum, Jay Albert, Lake Worth, Florida, USA, 05 October 2019 at 0103 UT. Colongitude 345.3°, 200 mm f/10 Celestron 8” NexStar Evolution SCT, 7mm Orthoscopic eyepiece projection, iPhone 6s Camera, Seeing 5/10, Transparency 3/6 North/Up, East/Left.

The Lunar Observer/July 2020/ 31

The Lunar 100: Feature 15 Straight Wall

Figure 9. Rupes Recta “Straight Wall” Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 07 May 2014 2140 UT, Colongitude 10.8°, Bresser refractor 102/1000, 26mm Bresser eyepiece, 10mm Delos eyepiece, Mag- nification 38x, 100x, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Up, East/Left.

The Lunar Observer/July 2020/ 32

The Lunar 100: Feature 15 Straight Wall

Figure 10. Rupes Recta “Straight Wall”, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 20 December 2015 0031 UT, Colongitude 19.6°. 250 mm Meade LX200 SCT, Canon EOS Digital Rebel XS camera, North/Up, East/Right.

The Lunar Observer/July 2020/ 33

The Lunar 100: Feature 16 Petavius

Figure 11. Petavius, Alberto Anunziato, Oro Verde, Argentina, SLA, 04 March 2018 at 0748 UT. Colongitude 114.6°, 280 mm f/10 Celestron CPC 1100 SCT, Canon EOS Digital Rebel XS, Seeing 6/10, North/Up, East/Right.

The Lunar Observer/July 2020/ 34

The Lunar 100: Feature 18 Mare Serenitatis

Figure 12. Mare Serenitatis Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 05 April 2018, 2000 UT, Colongitude 150.1°, Mewlon CRS (Dall Kirkham) 250mm f10 Ethos 13mm eyepiece 192x magnification, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Up, East/Right.

The Lunar Observer/July 2020/ 35

The Lunar 100: Feature 18 Mare Serenitatis

Figure 13. Mare Serenitatis, Marcelo Mojica Gundlach, Cochabamba, Bolivia, SLA, 30 April 2020, 2324 UT, Colon- gitude 8.8°, 6-inch Maksutov FL=1800mm SkyWatcher, ZWO ASI178. Seeing 7/10, Transparency 5/6, North/Up, East/Right.

The Lunar Observer/July 2020/ 36

The Lunar 100: Feature 19 Alpine Valley

Figure 14. Alpine Valley Sketch, Michel Deconinck, Artignosc-sur-Verdon, Provence, France, 03 May 2020, 2115 UT, Colongitude 44.3°, Mewlon CRS (Dall Kirkham) 250mm f15 Ethos 13mm eyepiece 288x magnification, pastels Conté grey, black and white + blending stump on Canson paper 240gr black. North/Left, East/Up.

The Lunar Observer/July 2020/ 37

The Lunar 100: Feature 19 Alpine Valley

Figure 15. Alpine Valley, Marcelo Mojica Gundlach, Cochabamba, Bolivia, SLA, 05 January 2020, 2254 UT, Colon- gitude 36.2°, 6-inch Maksutov SkyWatcher FL=1800 mm, ZWO ASI178. Seeing 5/10, Transparency 5/6, North/Up, East/Right.

The Lunar Observer/July 2020/ 38

The Lunar 100: Feature 20 Posidonius

Figure 16. Alpine Valley, Jay Albert, Lake Worth, Florida, USA, 20 May 2011, 0615 UT, Colongitude 120.8°, 11- inch Celestron SCT, 311x magnification. Seeing 5/10, Transparency 4/6, Northeast/Up, Northwest/Right.

The Lunar Observer/July 2020/ 39

The Lunar 100: Feature 20 Posidonius

Figure 17. Posidonius, Sergio Babino, Montevideo, Uruguay, SAO, 14 March 2020, 0458 UT, Colongitude 145.3°, 203 mm SCT, ZWO 174mm camera, North/Up, East/Right. Once again, we had a very large response to our request for images and drawings for the second set of 10 features of the Lunar 100 (L11 – L20). As in the last article, we again had images taken with cellphone cam- eras. I am grateful for all the submissions. We had a total of 87 images and drawings submitted from over 20 astronomers. Most of the images came from Alberto Anunziato’s groups, SAO-SLA, and LIADA. Previ- ously he prefaced the images he sent on behalf of his group this way:

The Lunar Observer/July 2020/ 40

“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. 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)

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)

The Lunar Observer/July 2020/ 41

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/July 2020/ 42

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus Plateau, Jay Albert, Lake Worth, Florida, USA. 05 May 2020 0223 UT. Celes- tron NexStar Evolution 8 inch Schmidt- Cassegrain telescope, iPhone 6s, Photoshop El- ements. Seeing 6/10, transparency 3/6.

Online readers, click on images for hyperlinks.

Aristarchus, Michel Deconinck, southern France. 21 May 2013 2015 UT. Bresser 102mm/1000mm refractor telescope, 100 x with Delos 10mm eyepiece.

The Lunar Observer/July 2020/ 43

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Francisco Alsina Cardinalli ,Oro Verde, Argentina, SLA. 17 February 2019 0441 UT. 200 mm refractor telescope, 742 nm filter, QHY5-II camera.

The Lunar Observer/July 2020/ 44

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Francisco Alsina Cardinalli ,Oro Verde, Argenti- na, SLA. 19 April 2019 0209 UT. 105 mm Meade ETX Mak- sutov-Cassegrain telescope, QHY5-II camera.

Aristarchus, Desiré Godoy, Oro Verde, Argentina, SLA. 21 August 2016 0337 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, QHY5-II camera.

The Lunar Observer/July 2020/ 45

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Francisco Alsina Cardinalli ,Oro Verde, Argenti- na, SLA. 20 December 2015 0045 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Canon EOS Digital Rebel XS camera.

Aristarchus, Francisco Alsina Cardinalli ,Oro Verde, Argentina, SLA. 21 April 2016 2209 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Canon EOS Digital Rebel XS camera.

The Lunar Observer/July 2020/ 46

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Alberto Anunziato, Paraná, Argen- tina, SLA . 19 April 2019 0645 UT. 105 mm Meade ETX Maksutov-Cassegrain telescope, QHY5-II camera.

Aristarchus, Rafael Lara Muñoz, Guatema- la, Guatemala, SLA. 17 May 2020 0535. 114 mm reflector telescope, Samsung Note 9 cell phone camera.

The Lunar Observer/July 2020/ 47

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Walter Ricardo Elias, AEA - Oro Verde, Entre Rios, Argentina. 03 June 2020 0225 UT. Meade LX200 10 inch Schmidt-Cassegrain telescope, ZWO ASI 120 mm/s camera.

Aristarchus, Leandro Sid, AEA - Oro Verde, Entre Rios, Argentina. 03 June 2020 0026 UT. Meade StarNavigator NG 90 mm fl 1250 mm Maksutov- Cassegrain telescope, Samsung J7 Prime camera.

The Lunar Observer/July 2020/ 48

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 11, Aristarchus

Aristarchus, Gabriel Re, AEA - Oro Verde, Entre Rios, Argentina. 02 June 2020 2212 UT. Meade LX200 10 inch Schmidt- Cassegrain telescope, ZWO ASI 120 mm/s camera.

Below, Aristarchus, Abel David Emiliano Gonzalez Cian, AEA - Oro Verde, Entre Rios, Argentina. 03 June 2020 0109 UT. 10 inch Meade Light Bridge reflector telescope, Nikon 3100 camera.

The Lunar Observer/July 2020/ 49

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Proclus, Dennis Wilde, Transit Dreams Observa- tory, Campobello, South Carolina, USA. 27 April 2020 2359 UT. 250 mm Schmidt- Cassegrain telescope, Canon 60 da camera, 100 frames, BYEOS, Registax, Pho- toshop Seeing 7/10, top of image is 20 east of North.

Proclus, Francisco Alsina Cardinalli ,Oro Verde, Argenti- na, SLA. 14 May 2016 0216 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 742 IR-pass filter, QHY5-II camera.

The Lunar Observer/July 2020/ 50

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Mare Crisium, Michael Sweetman, Sky Crest Obser- vatory, Tucson, Arizona, USA. 07 June 2020 1043 UT. 8 inch f/12 Guan Sheng Classical Cassegrain telescope, Skyris132M camera, Orion red filter. East up North left. Seeing-3-4/10, Transparency- 3/6. Two panel mosaic.

Proclus, Martín Queirolo Gomez, Montevideo, Uru- guay, SAO. 28 De- cember 2015 1937 UT. 114 mm Newto- nian reflector telescope, Nikon D5100 camera.

The Lunar Observer/July 2020/ 51

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12,Proclus

Proclus, Francisco Alsina Cardinal- li ,Oro Verde, Argentina, SLA. 09 December 2016 0400 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 742 IR-pass filter, QHY5-II camera.

Proclus, Francisco Alsina Cardinalli ,Oro Verde, Argentina, SLA. 11 December 2016 0433 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Astronomik ProPlanet 742 IR-pass filter, QHY5-II camera.

The Lunar Observer/July 2020/ 52

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Proclus, Francisco Alsi- na Cardinalli ,Oro Verde, Argentina, SLA. 20 Au- gust 2018 2343 UT. 200 mm refractor telescope, QHY5-II camera.

Proclus, Fernando Surà, San Nicolás de los Ar- royos, Argentina, SLA- LIADA . 09 May 2020 2220 UT. 127 mm. Mak- sutov-Cassegrain telescope, filter, Neximage 5 camera.

The Lunar Observer/July 2020/ 53

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Proclus, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 11 Sep- tember 2018 0101 UT. 279 mm Celestron 11 Edge HD Schmidt- Cassegrain telescope, QHY5-II camera.

Proclus, Desiré Godoy, Oro Verde, Argentina, SLA. 08 November 2019 0126 UT. 200 mm Newtonian reflector telescope, QHY5-II camera.

The Lunar Observer/July 2020/ 54

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Proclus and Mare Crisium, Fabio Verza, Milan, Italy. 26 June 2020 2011 UT. Celestron 4 inch Maksutov-Cassegrain telescope, Astronomik IR filter, ZWO ASI 290 MM camera.

Proclus, Leandro Sid, AEA - Oro Verde, Entre Rios, Argentina. 27 June 2020 2219 UT. Meade StarNavigator NG 90 mm fl 1250 mm Maksutov-Cassegrain telescope, Samsung J7 Prime camera.

The Lunar Observer/July 2020/ 55

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 12, Proclus

Mare Crisium and Proclus, Abel David Emiliano Gonzalez Cian, AEA - Oro Verde, Entre Rios, Argentina. 08 June 2020 0306 UT. 10 inch Meade Light Bridge reflector telescope, Nikon 3100 camera.

Proclus, Aylen Borgatello Alaniz, AEA - Oro Verde, Entre Rios, Argentina. 27 June 2020 2121 UT. Meade LX200 10 inch Schmidt-Cassegrain telescope, ZWO ASI 120 mm/s camera.

The Lunar Observer/July 2020/ 56

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Jay Albert, Lake Worth, Florida, USA. 04 April 2020 0156 UT. Celestron NexStar Evolution 8 inch Schmidt-Cassegrain telescope, iPhone 6s, Pho- toshop Elements. Seeing 6/10, transparency 2/6.

Gassendi, Michel Deconinck, southern France. 02 May 2012 1820 UT. Bresser 102mm/1000mm refractor telescope, 100 x with Delos 10mm eyepiece.

The Lunar Observer/July 2020/ 57

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Francisco Alsina Cardinalli, Oro Verde, Argentina, SLA. 20 January 2016 2145 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, Canon Eos Digital Rebel XS camera.

Gassendi, Gabriel Re, AEA - Oro Verde, Entre Rios, Argentina. 02 June 2020 2238 UT. Meade LX200 10 inch Schmidt- Cassegrain telescope, ZWO ASI 120 mm/s camera.

The Lunar Observer/July 2020/ 58

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Alberto Anunziato, Oro Verde, Argentina, SLA. 30 April 2016 0906 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, QHY5-II camera.

Gassendi, Desiré Godoy, Oro Verde, Argentina, SLA. 14 August 2016 0353 UT. 130 mm. Newtonian reflector (Celestron Astromaster 130). .

The Lunar Observer/July 2020/ 59

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Alberto Anunziato, Oro Verde, Argentina, SLA. 30 April 2016 0902 UT. 250 mm Meade LX 200 Schmidt-Cassegrain telescope, QHY5- II camera.

Gassendi, Jairo Chavez, Popayán, Colombia, SLA. 10 Oc- tober 2019 0129 UT. 10 inch truss Dobsonian telescope, Sony DSC-WX 50 camera.

Online readers, click on images for hyperlinks.

The Lunar Observer/July 2020/ 60

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Sergio Babino, Montevideo, Uruguay. 08 March 2020 0134 UT. 203 mm Schmidt-Cassegrain telescope, ZWO ASI 174 mm camera.

Gassendi, Carlos Lobato, San José de Carrasco, Uru- guay, SAO. 04 April 2020 2230 to2233 UT. 130 mm Newtonian reflector telescope, 257 x.

The Lunar Observer/July 2020/ 61

Recent Topographic Studies Additional Focus-On Images of Lunar Feature 13, Gassendi

Gassendi, Alberto Anunziato, Oro Verde, Argentina, SLA. 11 December 2016 0155 UT. 250 mm Meade LX 200 Schmidt- Cassegrain telescope, Astronomik ProPlanet 742 IR- pass QHY5-II camera.

Gassendi, Marcelo Mo- jica Gundlach, Cochabamba, Bolivia, SLA . 04 May 2020 0330 UT. 150 mm fl 1800 mm Skywatch- er Maksutov- Cassegrain telescope, ZWO ASI 178 b/w camera.

The Lunar Observer/July 2020/ 62