Crater Cassini

Crater Cassini 

  Day eight of a lunation is a favorite time to witness interesting light and shadow
play along the terminator from north to south. Crater Cassini is a very eye
catching crater and with a diameter of nearly 60km it is an attractive target for
telescopes of all sizes. At more than 3.5 billion years of age, Cassini is an old
battered nearly circular crater on the eastern edge of Mare Imbrium. The lava
basin around the crater appears mostly smooth and relatively dark. The ejecta
blanket immediately around this crater has an odd almost melted appearance. The
crater is shallow and the floor appears to be higher in elevation than the
surrounding mare; although this may be illusionary. Two large craters are visible
on Cassini’s floor. Crater A is the largest at 15 km.and the smaller B is about 9
km in diameter. Beyond the crater I sketched craters F, M and W all about 7 km in
size.
  Between Crater A on the floor of Cassini and the nearest inner wall is a series of
rilles and hills that resemble fish bones. At other times I have seen a nice dome
to the lower left (northeast) of Cassini but with the crater too far from the
sunrise terminator I could not pick it out.
  
  Sketching:
  For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’
  pastel pencils and a  blending stump.
  Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
  Date: 3-27-2007 12:15-1:20 UT
  Temperature: 20° C ( 69° F)
  Partly cloudy, calm
  Seeing:  Antoniadi  III
  Colongitude 8.5 °
  Lunation 8 days
  Illumination 63.5 %
  
  Frank McCabe

Three near the seashore

Archimedes et al 

Archimedes et. al.

Finally, I was blessed with a clear sky. It has been 26 days since the beginning of the year and this is my fourth clear or mostly clear night. With the moon well into lunation 1040, it was bright and high in the sky at nightfall. After observing the lunar surface for about forty-five minutes, I selected a favorite region in eastern Mare Imbrium for sketching.

As an eighth grader with a new 4.25 inch f/10 Newtonian telescope, Archimedes was the first crater I remember identifying with this scope. I selected my 10 inch f/ 5.7 Dobsonian and 6mm eyepiece to make my sketch of this region. In the sketch below the three craters in counterclockwise direction from smallest to largest are: Autolycus, Aristillus and Archimedes. About half way between Autolycus and Archimedes is the impact site of the first spacecraft to reach the moon September 14, 1959. It was Luna 2 and after crossing through the Van Allen belt it detected and confirmed the solar ions known as the solar wind particles just prior to its lunar rendezvous.

The two smaller craters are from the Copernican period and the larger crater Archimedes is an ancient crater that dates back beyond 3 billion years ago. The terraced walls of Archimedes stand 2000 meters above the flat lava flooded floor of this crater. I was unable to detect at this observation any of the craterlets on the floor. This crater is 85 km. across. Autolycus is less than half the diameter of Archimedes has a higher rim (3000 meters) and an irregular floor. Aristillus which is intermediate in size (56 km diameter) has the tallest rim at 3500 meters and 3 mountains on its floor up to 900 meters tall.

For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’
pastel pencils and a soft piece of leather for  blending. Image was slightly darkened using Imageenhance software.
Date 1-27-2007 1:10-2:40 UT
Temperature: 3.8° C (39° F)
Windy with strong gusting
Seeing average Antoniadi: III
Colongitude: 10.5 °
Lunation: 7.9 days
Illumination: 62.3 %

Frank McCabe

Lights Out for Eratosthenes

Eratosthenes

   At the southern end of the lunar Apennines on the border between the Bay of
Billows (mostly in darkness) and Sea of Rains lies 60 km. crater Eratosthenes. I
was off and on observing over most of the night. By morning twilight when the moon
was high in the east, Eratosthenes crater was experiencing sunset. The deep, dark
caldera-like aperture was undergoing sunset at the beginning of my sketch. This
3.2 billion year old land mark crater is the defining feature of the Eratosthenes
time period. While sketching I could clearly see much of the ejecta pitting of
Copernicus and its ray material which crossed the region 2 billion years after
Eratosthenes formed. I did not include much of the Copernicus crater impact
features because they are in my opinion more suitable for high resolution
photography or direct visual examination at high power. In this sketch I tried to
briefly capture the overall eyepiece view.
  
  
  Sketching:
  For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’
  pastel pencils and a blending stump. Contrast was slightly increased after scanning.
  Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
  Date: 7-8-2007, 9:15-10:30 UT
  Temperature: 22° C (73° F)
  Clear to partly cloudy, light winds
  Seeing:  Antoniadi II
  Colongitude 190.2 °
  Lunation 23.25 days
  Illumination 42.2 %
  
  Frank McCabe

On the shores of a Stormy Ocean

Hevelius and neighbors 

Hevelius & neighbours

Sketched on the 29th May 2007 from my home observatory using a Antares 105mm F15
Achromatic refractor. Working at 163x through a Denk binoviewer.

Sketch made on a black spiral bound Daler-Rowney 6″x6″ sketch pad using a
combination of Conte sticks, watercolour and pastel pencils. Image scanned in
Greyscale but unprocessed.
  
Dale Holt

The Ever Popular Rupes Recta

Rupes Recta

In the morning hours before sun-up the early waning crescent moon was superimposed
on the firmament just west of the Pleiades. I was somewhat transfixed by this
scene but I was set up to sketch “straight wall” on the floor of the lunar Sea of
Clouds. From the eastern edge of Mare Nubium you can see the Triplet craters
Thebit (57 km), A and L. Next moving westward is the Imbrian escarpment Rupes
Recta , not a true wall in the usual sense but on one side standing more than 300
meters high at some  points and 114 km in length. The scarp face would be visible
from crater Birt (17 km) to the west, the youngest of the larger craters sketched
here. Touching the rim of Birt to the east is Birt A.  Continuing westward we see
Rima Birt a 51 km rille from the Imbriam epoch. At the end of the rille to the
south, is tiny 3 km crater Birt F seen in this sketch. Finally sitting on a
wrinkle in the floor of the mare is crater Nicollet (15 km) a Eratosthenian epoch
impact scar.
  
  
  Sketching:
  For this sketch I used: white copy paper, graphite pencil and pen and ink 
  Contrast adjusted with Imageenhance software
  Telesccope: 18 inch f/ 5 Dobsonian working at 222X (9mm ocular)
  Date: 8-16-2006 9:30-10:35 UT
  Temperature: 17°C ( 62°F)
  Clear, calm
  Seeing:  Antoniadi  III
  Colongitude 178 °
  Lunation 22.3 days
  Illumination 45.9%
  
  Frank McCabe

Cup of nectar

Bohnenberger 

Crater Bohnenberger in Eastern Mare Nectaris
  
From my location, this evening presented the best observing conditions since June
of last year. As the sun set in the west-northwest the crescent moon was riding
about 55° above the horizon, so I spent about hour looking for potential targets
to sketch. Crater Taruntius presented an interesting sketching target with its
central peak and unusual wall but I wanted to sketch closer to the terminator. I
finally settled on crater Bohnenberger just west of the Lunar Pyrenees Mountains
that define the eastern edge of the Sea of Nectar.

Bohnenberger is an old Pre-Imbrium crater 33 km diameter. Bohnenberger has a pair
of broad central peaks, a break in its northern wall and a crater on its western
floor. Crater Bohnenberger A about the same size (30 km) with a bright, shallow,
flat floor can be seen to the south with 12 km crater G between them. Some 100 km
to the west of Bohnenberger A, crater Rosse could be seen among the lunar ridges
in the Sea of Nectar. The high walls of Rosse were brightly lit against the dark
frozen lava of the mare. The dark shallow crater about the same size as Rosse at
the bottom of the sketch is crater Gaudibert H. Within the region of the sketch a
great deal more could be seen but was beyond my ability to record in a reasonable
time as the shadows and light continued to change.
  
  Sketching:
  For this sketch I used: black Strathmore 400 Artagain paper 9”x12”, white and
  black Conte’ pastel pencils and a blending stump.
  Before submitting I changed slightly the contrast using Imageenhance software
  Telesccope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
  Date: 4-22-2007 1:35-2:40 UT
  Temperature: 20° C (69° F)
  Clear, calm
  Seeing:  Antoniadi  I-II
  Colongitude 325.7 °
  Lunation 4.5 days
  Illumination 27.5 %
  
  Frank McCabe

Heavy light

Heavy light 

Cardanus, Krafft, Eddington,Seleucus,Briggs, Briggs B, W Oceanus Procellarum
South Telescope build by Grubb Dublin 1868

Fl ? 18Ft 10.7inches/Objective 11.75 inches

Eyepiece? Objective by Cauchoix 1829
Dunsink Observatory Dublin
53° 22′ 60N  6° 19′ 60W
April 30th 2007
20:50UT – 21:57UT
Lunation 13.43 days
Illumination 98%
Seeing 1-2
T poor/hazy
300gm Daler Paper/Daler Soft Pastels/Conte Crayons/ Quilling
needle/Blending stick

   

I was fourteen years when old I first looked through the South Telescope in Dunsink Observatory. I had pestered my dad to bring me out there, a bit of a long drive in those days, before motorways.

Jupiter was on view that evening, it was crystal clear.  The planet must have been quite high as I could look through the Grubb standing up.

I had my own little Tasco scope on a plastic tripod at the time not much to see in it, but the moon always got a look. Ever since I wanted to revisit that moment and look once again through the eyepiece of this well constructed classic telescope. Over the years I paid several visits to the observatory public nights, but always cloud or rain or both.

I got an idea in my head a few months ago, I asked for time to sketch something through the eyepiece this request yielded a positive answer, but it took time to set up.

April 30th 2007 I got a phone call from, let’s say my host in Dunsink “would you like to try tonight”? I was out the door and on the M50 with my gear in less then 10 minutes, an hour’s drive to the Observatory.

I was greeted warmly and the dome was opened, the scope set up, the steps in place.

My position for the next hour and ten minutes was probably the most uncomfortable sketching position in which I had ever worked. I was neither seated or standing, no tracking, and a big telescope to move.

 The Grubb was so well balanced, easy to use, a joy to hold, and a privilege to use.

 Left alone for the most part I quickly got into my zoned in or zoned out

 (depends on your point view) sketching mode.

The eyepiece was low powered generating most likely 125X, used for public viewing, other eyepieces maybe available if I get to repeat this astronomical adventure.

Apart from the difficult sketching position, I felt so at home in Dunsink Observatory, it felt so moreish. Up and down moving the steps, to follow the Moon as she charged along heading for her bed. My concentration waned after an hour, more work to do than in my garden. I was stiff the next morning but I was high as a kite, I got to do something with this instrument made so carefully many years ago in Dublin. A full circle moment in my life, moments that seem to happen with more frequency these days.

In brief periods, when the image was still I could see much more detail and fine tones of grey than in my Dob. Eddington gave me great shapes and that ridge was so so slender, only 2% of the Moon was in darkness and even a little of that was seeping through the blackness into the day.

I admire Arthur Stanley Eddington for his communication prowess during his life.

A poem he wrote came to mind on the way home,

Oh leave the Wise our measures to collate
One thing at least is certain, light has weight
One thing is certain and the rest debate
Light rays, when near the Sun, do not go straight. “ A.S.Eddington

Apart from this poem being about gravitational lensing, the phrase “light has weight” sticks out to me as an artist. Drawing in the sunlit wall on the western side of Eddington, 138km or so of sunlit weight, which was up till that lunation invisible, non existing until our sun made it so.

On the edge of a fertile sea

Langrenus and the Sea of Fertility 

Langrenus at the Edge of the Sea of Fertility

With the Harvest moon just past and the shadow of the setting sun approaching the eastern shore of the Sea of Fertility, crater Langrenus stands out in all its glory. Langrenus is an Eratosthenian Period crater, between one and three billion years old. This crater is about 133 km. in diameter with a rim 2.6 km. above the bright, mostly flat floor. Mountain peaks near the center stand 1 km. high. Rays from the crater can be seen projecting in a westward direction across the Sea of Fertility. Much older (four billion plus years) and slightly larger than Langrenus to the south along the terminator is the crater basin Vendelinus. The walls of this crater were dealt crushing blows delivered by the impacts that created craters Lohse, Lame  and Holden which are drawn clockwise from north to south. Many additional smaller crater impacts on Vendelinus attest to the age of this old battered basin.

More than 400 km. to the northwest, grazing angle impaction created the craters Messier and Messier A. These craters exhibit a long pair of rays extending westward across the remainder of the mare. Note the perpendicular (north-south) rays centered on Messier. Laboratory experiments have demonstrated this pattern of so called “butterfly rays” can be duplicated with shallow angle high speed impacts.

Frank McCabe

Sketching:
For this sketch I used: white copy paper 6”x 8”, and a 2HB graphite pencil
at the eyepiece with the addition of marker ink to darken shadows indoors.

Telesccope: 10 inch f/ 5.7 Dobsonian and 9mm eyepiece
Date: 10-9-2006 5:00-5:45 UT
Temperature: 10°C (50°F)
Clear
Seeing:  Pickering 5
Co longitude: 114 °
Sunset longitude: 66.1° E.
Lunation:  16.8 days
Illumination:  94%

Lunar luminaries

2006 07 07

Lansberg/Gamma and Delta

“Wednesday night (Thursday for UT), was a practice session for imaging with my
Rebel.  I finally bought a t-ring adaptor during a star party a few weeks ago and
had some fun playing with the new toy. The guys in the DSLR forum are giving me some
great pointers.  Feels very strange entering that realm, but I have a feeling it
will compliment the sketching well for my observations.  Plus gives me yet another
way to enjoy this hobby to the fullest!

It was then time to put the camera away and dig out my sketch kit.  Paul, being the
thoughtful husband that he is, bought Tom L’s binoviewers for me last month.  Tom,
if you’re reading this, I absolutely LOVE them!  Wow!  Thank you both so much!!!
I’ve been having a lot of fun with black Strathmore paper and Conte’ crayons for my
solar work, so with Rich in mind, I got up the nerve to try my first lunar sketch
with this media. Lansberg and the surrounding craters were my main targets that
night.  I explored the terminator, tried to count craterlets in Plato, and admired
Copernicus (and was tempted to try it again, as the last time I tried to sketch that
beauty, my sketch was cut short and it was never completed).

Lansberg is from the Imbrian period and is about 41km.  The central mountains stuck
out like two eyeballs in a dark room and I was pleased to see some terracing.  All
the little craterlets around Lansberg belong to it with Kunowsky D being the
exception to the NW.  Reinhold is trying to slip into the scene to the NE, but got
its toe stuck in the door.  Montes Riphaeus was very dramatic, or at least compared
to the rest of the scene in that area.

Lansberg

After a great day today, which included solar observing (boy, that sun feels
great!), I set up with the binoviewers again tonight.  Although seeing was poor, I
went ahead and bumped up magnification with 8mm TV Plossls (love that EP so much, I
had to get another one!).  It was good enough to support the level of detail needed
to observe domes.  Had I wanted to jump into a few complex craters, I believe a 20mm
would have been best.  So, domes it was and why not a pair?  Mons Gruithuisen Delta
and Gamma were flagging me down and I just could not resist. 

Gruithuisen Domes Delta and Gamma

They are also from the Imbrian period and close to 20km each.  Looking at VMA, Delta
is classified as a mountain and Gamma is a dome.  Rukl calls both of them a domelike
mountain massif.  Hmmm, let’s see what Chuck Woods has to say about them.  Aha!  He
calls them domes, most likely formed of silicic volcanic rocks.  For more reading on
this, see The Modern Moon, page 37.  I would love to be one of the geologists that
Chuck suggests may someday bang on the domes with their rock hammers to see what
they are made of.
It was a bit disappointing that I didn’t see the summit crater on Gamma, but there
was an obvious darkened area on the western top portion of it.  I loved buzzing
around in the all the little dips and valleys to the north of it, though.  The
little raised line between Gamma and Gruithuisen K looked like a pea pod. Isn’t the
lava covered floor beautiful in that region?”
Sketches done with black Strathmore Artagain paper and white Conte’ crayons

Erika Rix

Zanesville, Ohio