Category: Pastels

Gassendi Crater

Gassendi Crater
Gassendi Crater
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2012 06 01, 0238 UT – 0446 UT Gassendi
PCW Memorial Observatory, Texas, Erika Rix
www.pcwobservatory.com

Celestron Omni XLT 102mm, 24-8mm Baader Planetarium Mark III Hyperion, 2x Barlow, 250x
Temp 71° F, 60% humidity, S: Antoniadi II, T: 5/6
Eyepiece sketch black Strathmore Artagain paper, Conte crayon and pastel pencil, charcoal pencil
Phase: 45.8 deg, Lunation: 11.21 d, Illumination: 84.8%
Lib. Lat: +05:08, Lib. Long: -04:13
Az: +209:11, Alt: 41:03

Located on the northern border of Mare Humorum, crater Gassendi is an impact crater formed during the Nectarian period (-3.92 to 3.85 billion years ago) that later was modified after volcanic activity, becoming a fractured-floor crater. Gassendi is believed to have been filled with lava from the inside, raising its floor, creating stress fractures in the process. This would explain it being considered a walled plain with a shallow depth of 2.8 km. The central peaks (~1200 m high) remain and several rilles (called Rimae Gassendi) were formed on the lava-filled floor during the Imbrian geological period -3.85 to –3.2 billion years ago.

Crater Gassendi A was formed during the Copernician period (–1.1 billion years ago to the present day) and overlaps Gassendi’s northern rim. The pairing of Gassendi and Gassendi A resembles a diamond ring and makes a very striking feature to observe 3 days after first quarter or two days after last quarter of lunation. My observation was nearly three days after first quarter.

Gassendi’s southern rim was swallowed by the lava of Mare Humorum leaving only a thin crest line to support its circular shape. Dorsa ran from the southern rim to Gassendi O (11 km wide). The sharp ridge that defines the border of Mare Humorum to the SW of Gassendi adds to the crater’s unmistakable identification.

At the beginning of my session, Spica and Saturn lined up to align with the Moon. Spica was 2.08 degrees north of the Moon and Saturn was 6.9 degrees north of the Moon. Extending further north, Arcturus was nearly in line as well at 31.8 degrees north of the Moon

Craters Mercator, Campanus and Ramsden at Sunrise

Craters Mercator, Campanus and Ramsden
Craters Mercator, Campanus and Ramsden
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After another canceled public telescope viewing Friday evening due to thick clouds and light snow, I was pleased to see a nice Saturday filled with sunshine followed by a clear night.

With no particular sketching targets in mind, I scanned the terminator for interesting sketching targets and stopped when I could see sunrise at Ramsden (26 km.) along with all those crisscrossing rimae (rilles).

Northeastward away from Ramsden and across Palus Epidemiarum, I also added two additional ancient craters Mercator (49 km.) and Campanus (49 km.).

This break in our poor Chicagoland spring weather was long overdue.

Sketching:

For this sketch I used: 400 series black Strathmore Artagain paper 9″x 9″, white and black Conte’

pastel pencils , and Conte’crayons, a blending stump, plastic eraser.

Telescope: 10 inch f/5.7 Dobsonian with 6mm (241x)

Date: 4-21-2013 01:00 – 02:45 UT

Temperature: 7.2°C (45°F)

Weather: clear, calm

Seeing: good Antoniadi II-III

Co longitude: 35.4°

Lunation: 10.6 days

Illumination: 74.1%

Frank McCabe

Theophilus and Cyrillus

Theophilus and Cyrillus
Theophilus and Cyrillus

As the evening progressed the sky became mostly clear with some ground fog adding to the light scatter and the inevitable falling temperatures of an early spring night. Nevertheless, it was good enough for some observing and sketching. Crater Theophilus (100km.) was more than 450 kilometers from the terminator but remained an attractive target in the eyepiece as the Moon cleared a nearby building in my southeast.

Theophilus is a complex Erastothenian era crater at just over 1.3 billion years in age with large central peaks of deep crustal material that formed on the rebound from the initial impact. The appearance looks fresh when compared to its much older Nectarian period neighbor Cyrillus (100 km.). It was evident while observing this pair that Cyrillus was showered with ejecta from Theophilus and prior millennia of countless strikes by incoming rocks from space. The central peaks of Cyrillus are smaller, more muted and worn down. 300 kilometers to the west of Theophilus the Apollo 16 astronauts Charles Duke and John Young collected 96 kilograms of rocks over 3 days back in 1972 which included some ejecta from the Theophilus formation.

Remote sensors on the orbital spacecraft Chandrayaan-1 detected Iron rich Magnesium –Aluminum oxides on the central peaks of Theophilus adding to the knowledge of the composition to the deep lunar crust as indicated by a publication last spring.

Two other craters included in the sketch are Mädler (29 km.) also of Erastothenian age and Ibn-Rushd (34 km.) an ancient one at more than 3.2 billion years.

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper 8″ x 10″, white and black Conte’ pastel pencils, a blending stump, white Pearl eraser. Contrast was slightly increased after scanning.

Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X

Date: 3-30-2013; 04:30-05:35 UT

Temperature: 2° C (36° F)

Some thin clouds, calm

Seeing: Antoniadi IV poor

Colongitude 128.9 °

Lunation 18.4 days

Illumination 90.1 %

Frank McCabe

H-Alpha Sun – April 1, 2013

H-Alpha Sun - April 1, 2013
H-Alpha Sun – April 1, 2013

Working with different gray pastel pencils works fine on the Moon. I tried the same technique on the Sun and was quite happy with the result. Hope you like it too.

Clear skies

Jef De Wit

Object: Sun

Location: Hove, Belgium (51°09’ N 4°28’ E)

Date and time: 1 April 2013, around 9.30 UT

Equipment: Lunt LS35T

Eyepiece: 13mm Nagler T6 (31x)

Medium: white, gray and black pastel pencils on black paper, scanned, colored with Paint Shop Pro, text added with Paint

Lunar Volcanism

Pyroclastic deposits in Alphonsus
Pyroclastic deposits in Alphonsus

Hi all,

I’ve been itching to have a go again at Alphonsus for some time. Along with its two buddies, Arzachel (to left) and Ptolemaeus (at right), this trio are a time line of Lunar history.

Ptolemaeus is the oldest. The crater floor is totally flooded, even the central peak is covered. It was fromed when the Moon was still very hot and lava readily flowed with a large impact.

Arzachel is the youngest. The crater floor is intact with no flooding, the crater walls are terraced with land slides both inside and outside of the crater.

Alphonsus sits bewteen the two in age. The crater floor is only partially flooded with the central peak still visible. The Moon has cooled since Ptolemaeus and lava flow has slowed. BUT, volcanic activity was still occuring after the flooding process had stopped. This is seen from the pyroclastic deposits that sit within Alphonsus. Four deposits lie within this crater and are marked in the labelled pic, and are seen as the darker shaded areas that are easy to see through the eyepiece.

Quite remarkable to consider that from here on Earth we can see the effects of ancient volcanism on a body that isn’t Earth.

Another treasure of the night was the Celestron Ultima LX 8mm eyepiece I used. These eyepiece are much underrated, but are surprisingly good. The 8mm in particular is easy to use for extended viewing. It made the 2.5 hours much more bearable, and my eyes were not as fatigued as they have been after with other sketches that have taken less time to do. It’s one of my favourite eyepieces.

Object: Pyroclastic deposits in Alphonsus
Scope: C8, 8″ SCT
Gear: 8mm Celestron Ultima LX, 250X
Location: Sydney, Australia
Date: 19th March 2013
Media: Soft Pastel, charcoal and white ink on A4 size black paper
Duration: approx 2.5 hrs

Pyroclastic deposits in Alphonsus - Labeled
Pyroclastic deposits in Alphonsus – Labeled

Comet PanSTARRS and the 1 Day Old Moon

C/2011 L4 (PanSTARRS) and Crescent Moon
C/2011 L4 (PanSTARRS) and Crescent Moon

On the evening of March 12, 2013, I was treated to a pleasant view of the 1.26 day old Moon (1.8% illuminated) and comet C/2011 L4 Pan-STARRS from 07:00pm to 07:20pm local time Mesa, Arizona. I had an excellent view of the clear western sky and I could see the comet naked eye about 6.5 diameters to the south of the Moon.

To assist in making the rough graphite sketch I used a 5x 50mm finder scope removed from an Orion telescope. After returning home from Arizona to Illinois I made a color drawing from field notes and the graphite sketch. I was planning on a color sketch but the number of colors need and blending seemed too much for the 30 minutes to comet set.

Sketching:

Graphite pencils: 6B, 4B and 2B also black and white pastel pencils on white sketching paper.

Color drawing was made with black and white charcoal pencils and an assortment of color pencils on medium blue paper.

Frank McCabe

Hipparchus, Albategnius and environs

Hipparchus, Albategnius and environs
Hipparchus, Albategnius and environs

Object Name: Moon landscape
Object Type Lunar Craters
Location Montreal, Canada
Date November 2, 2011
Media Pastel, black paper.

Here is a sketch I made on the 2nd of November between 21 :00 and 21:45 (local time in Montreal). Overlapping the terminator line, craters Hipparchus and Albategnius put on a nice show that evening. The high contrast of the landscape was propitious for a pastel sketch at the telescope. As the sun rose on the higher mountains and crater’s edge, the interplay between light and darkness slowly unveiled new features on the moon surface. I captured an incomplete “X” at the upper right.

The sketch was scanned and the legend was added with Photoshop. The sketch however has not been “retouched”. I present it as it was at the end of the session.

Jean Barbeau