Impact on Jupiter!

Date: 21 July 2009
Time: 8:52 - 9:02 U.T.
Telescope: 13cm refractor
Magnification: 218x
Seeing: Fair
NELM: 6.5
Temperature: +46 F (+8 C)

The above sketch is mirror-reversed due to the use of a star diagonal. North is up. Preceeding is to the left. The dark spot to the lower left (southwest) is a new impact scar on Jupiter. The small, dark, impact scar was spotted as soon as I looked into the eyepiece and focused the telescope at 218x.

Anthony Wesley, an amateur astronomer in Australia, was the first person to discover this impact scar on the 19th of July. Thanks to the Internet, I heard about the dark spot shortly thereafter.

Considerable fine detail was visible within the two major belts, but I would have had to up the magnification a bit (and taken more time) in order to sketch it. Meanwhile, Jupiter's rapid rotation would have taken the impact scar closer to the planet's preceeding limb and shortly thereafter onto the far side of the planet.

Sunspots: 9 July 2009

Today's sunspot observation was made with the help of Buttercup, a 60mm achromat refractor. The above photo of Buttercup was taken shortly after I had completed today's sunspot sketch. The short cardboard tube visible on the front of the telescope is a home-made solar filter utilizing safe, Baader Solar Filter material. Permanent eye damage or blindness is likely to occur if proper safety procedures are not followed when observing the sun. The telescope's finder has black covers over both ends as a further safety measure.

Today's sketch, shown above, has north up and preceeding to the left. The image is mirror-reversed due to the use of a star diagonal. A magnification of 70x was utilized. The sketch shows just a small region within the telescope's field of view.

When sunspots are observed near the limb of the sun one should always look for faculae -- areas that appear brighter than the background solar surface. Faculae were noticed and sketched today, but those regions do not show up well in the scanned image.

July 7th Sunspot Group

The above sketch shows the sunspot group observed from 15:54 until 16:04 U.T. on 7 July 2009. A 60mm f/11 achromat refractor (Buttercup) was used at 70x for the observation and sketch. Use of a star diagonal resulted in a mirror-reversed view. North is up and preceeding is to the left. It's good to finally see some sunspot activity on our nearest star!

Moon Occults Venus

The above sketch shows Venus and Earth's moon after sunrise, but just before the moon passed in front of Earth's sister planet on Earthday morning. The sketch is a fairly close approximation of the view through 20x80 binoculars. East is toward the lower left. North is toward the upper left.

Later in the day I showed students our moon, Venus, and the sun using Buttercup (a 60mm refractor) at 28x. Some of the students managed to see the moon and Venus in the daytime with their unaided eyes! By this point in time Venus was a fair distance west of the moon.

Buttercup views Saturn: 16 March 2009

Saturn and Titan were sketched last night while observing with Buttercup, a 60mm refractor. The planet was tiny at 28x and still rather small at 70x -- the magnification used for the above observation. North is approximately up. Preceding (west) is to the left. A subtle, slightly darker band was just visible (or suspected) north of and running parallel to the ring plane. The point of light to the left of Saturn is Saturn's largest moon, Titan.

Sun & Venus 15-16 March 2009 U.T.

The above sketch shows Venus at 0:55 16 March 2009 U.T. as it appeared in "Buttercup", a 60mm refractor, at 70x. The observation was made around sunset under fair seeing conditions through thin clouds. The planet's apparent diameter was quite large. Even at 28x the planet seemed large! North is up. Preceding (west) is to the left. Though a complete disk appears in the sketch, only the bright, thin crescent was visible.

The sun appears in the above sketch with clouds sihlouetted against the bright solar disk. The observation was made through thin clouds at 28x with a full-aperture, objective solar filter at 23:10 on 15 March 2009 U.T. The densest clouds were even visible against the background sky. Unfortunately they don't show up in the scanned image of the sketch. No sunspots were noticed. Limb darkening and clouds were all that was noticed on (or in front of ) the sun's disk. The solar filter was home-made using Baader Solar Filter material. Never look at the sun without proper eye protection!

"Buttercup"

Shown above is the same old, banged-up 60mm refractor that appeared earlier in this blog. The telescope has been improved here and there. After adding some weight inside the rear of the OTA the scope balances better in its fork. The altitude trunnions have been attached more solidly than before. The tube assemblies have been painted yellow with black trim. The wood tripod legs have had their dark paint removed and replaced with a somewhat lighter stain and varnish.

In the tradition of my other telescopes, this one also has acquired a name. Today marks the birth and first-light of "Buttercup".

Venus was Buttercup's first target. Shown above is the rough, at-the-telescope sketch of Venus made at 1:00 on 04 March 2009 U.T. at 70x. Unfortunately the sky had clouded over by the time I went back outside in the hope of observing the moon.

Comet Lulin (C/2007 N1) 22 Feb. 2009

The above sketch shows the full-field view I had of Comet Lulin last night with 25x100 binoculars. Comet Lulin was easily visible to my unaided eyes from my dark-sky (Naked Eye Limiting Magnitude 6.5), rural location. North is up and east is to the left in the sketch. The field of view is approximately 2.3 degrees. From a dark sky any pair of binoculars will provide a pleasant view of Comet Lulin.

I've been observing this comet for a while now, but this is obviously my first blog entry on our latest celestial visitor. There's just so much to do these days . . .

Measuring the Sky

Above is a sketch showing approximately what's seen when one looks through a Celestron Micro Guide eyepiece. The linear scale has a real length of 6 millimeters. Adjacent scale divisions are 1/10 of a millimeter apart. I'll be using the Micro Guide eyepiece to make a variety of measurements while using Excalibur - my 13cm refractor.

The separation distance between scale divisions will of course vary depending upon the magnification that the eyepiece provides with a given telescope. My measurements indicate that the divisions are about 24.80 seconds of arc apart when the eyepiece is used with Excalibur without a barlow. With my three barlows the divisions become 11.06, 10.36, and 7.84 arc-seconds apart.

The linear scale will be used to measure linear distances such as the separation of double stars. The outermost circular scales will be used to measure position angles.

I was stricken be a sore throat on the 5th of October. Some congestion and an occassional cough remains. Hopefully it's not progressed to bronchitus or pneumonia. Currently I'm not sure if this situation is getting better or worse, but at the moment I'm feeling healthier than I was earlier. I might be feeling up to at least a brief observing session tonight. I stepped outside this morning in time to catch sight of Saturn in the east-southeast with the unaided eye.

Lunar Limb - Daylight Observation

Date: 24 August 2008

Time: 17:18 - 17:33 U.T.

Telescope: 80mm f/5 achromat

Magnification: 70x

Filter: Polarizing

Seeing: Fair - Good

NELM: Daylight

Temperature: +85F (+29C)

Wind: Calm

Transparency: Very Good (cloud-free sky


The above sketch shows two lunar mountains that were silhouetted against the darker sky background. North is up. Lunar East (preceding) is to the left in this mirror-reversed view. The sketched region is at 90 degrees west longitude and approximately 12 or 14 degrees south latitude. The moon was a fat, waning crescent at the time of the observation.

Not shown in the sketch is Lacus Aestatis which was seen as a dark patch to the left of the lower mountain peak beyond the sketched region. A very rough, larger scale sketch was made to facilitate finding this region on a lunar map. That sketch showed Lacus Aestatis, Cruger, Grimaldi, and Riccioli all as dark patches.

The sun was still spotless today. I used the 80mm refractor at 24x. A glass, white-light solar filter covered the front of the telescope. The filter gave the sun a soft, golden, peachy color. There was something aesthetically pleasing about observing a spotless sun through a telescope with one's own eyes.

Comet C/2007 W1 (Boattini)

Date: 13 July 2008 U.T.
Time: 9:40 - 9:50 U.T.
Telescope: 13cm refractor
Magnification: 66x
NELM: dark twilight, growing brighter
Temperature: +41 F (+6 C)

The above sketch shows an approximately 0.54 degree wide portion of the telescopic field centered on Comet Boattini. North is up. West is to the left in this mirror-reversed view.

Comet Boattini is currently visible with binoculars in the early morning sky, low in the east, prior to the onset of bright twilight. The time of this observation in local time was 3:40am - 3:50am. Earlier the comet would be seen in a darker sky, but it would also have been closer to (or even below) the horizon. Later, morning twilight would have had a more drastic, negative effect on the comet's visibility. This comet will be climbing higher in the morning sky with each passing day, but moonlight will soon add a negative element to this comet's visibility.

Comet Boattini is heading out away from the sun now, so it can be expected to grow smaller and fainter in the upcoming weeks. Currently the comet appears like a round 'fuzzball' with an outer boundary the blends into the background sky. The comet is brighter closer to its center. I noticed no tail and no central condensation (or pseudonucleus). This comet was not visible to my unaided eyes - at least not under the twilight sky in which this observation was made.

This comet looks like a typical, relatively bright, telescopic comet. That is, it's easily visible with a telescope or even binoculars; but it has no (visible) tail and presents nothing out of the ordinary to see - at least not at this time.

Comet 17P/Holmes (12 Dec. 2007 UT)

Date: 12 December 2007

Time: 2:05 U.T.

Instrumentation: 20x80 Binoculars

Seeing: Good

NELM: 6.5 or better

Temperature: +21 F (-6 C)

The above sketch shows the full, three degree field of the 20x80 binoculars. North is up. West is to the right. Not all of the field stars that were seen were recorded in the sketch.

Comet Holmes is now clearly larger in apparent size than a full moon. (The apparent diameter of a full moon is about 0.5 degrees, or one-sixth of the binocular field.) As I was observing this comet I was reminded of the general appearance of a fossilized trilobite.

Comet Holmes remains easily visible to the unaided eye. It appeared to be clearly brighter than the nearby Perseus Double Star Cluster.

Comet 17P/Holmes (03 Nov. 2007 UT)

Date: 03 November 2007
Time: 2:18 - 2:40 UT
Instrument: 25x100 Binoculars
Mount: Altaz/Tripod
Seeing: Good
Transparency: Good
NELM: 6.5 or better
Temperature: +27 F (-3 C)


Shown above is the full 2.33 degree field of view of the large, 25x100 binoculars with Comet Holmes near the center. West is up, and north is to the left. The sun is toward the north-northeast. Many of the fainter stars that were visible were not included in the sketch.

The comet's inner coma was sharpest and brightest on its sun-facing side. The outer coma was noticeably more diffuse, fainter, and less sharply defined than it has appeared previously.

The brighter portions of the comet (within the inner coma) were a subtle greenish-blue color. The color was initially noted with the 25x100 binoculars, but was even more apparent with de-focused 8x42 binoculars.

This comet has pretty much maintained its brightness over the past several nights. It remains easily visible to the unaided eye as a moderately bright 'fuzzy star'.

When scanning the sky with 8x42 binoculars in the general vicinity of the comet this evening I spotted the diffuse glow of the nearby open star cluster NGC 1528.

This observation was made in the evening, local time. The comet was also briefly observed and sketched on the previous morning using 20x80 binoculars.

Comet 17P/Holmes (30 Oct. 2007 UT)

Date: 30 October 2007
Time: 2:45 UT
Instrument: 20x80 Binoculars
NELM: 6.2
Transparency: smoky sky


The above sketch gives some idea of the appearance of Comet 17P/Holmes with 20x80 binoculars under a darker (moonless) sky. The comet's outer coma, which was not seen previously under bright moonlight is now easily visible. North is approximately to the upper left; and west is approximately to the upper right in this erect-image view. The binoculars were used hand-held. A wall provided an anchor to steady the view.

A subtle 'rift' was visible along the northeastern edge of the comet's bright inner coma. The southwestern extremity of the outer coma appeared to be a bit darker and more diffuse than elsewhere. The presence of the comet's bright pseudo-nucleus was hinted at as a brighter spot near the center of this fascinating comet. For reference purposes, the sun is to the northeast (to the left at a slight downward angle from the comet).

At the time of the observation the orange (from a smoke filled sky) moon was just rising. Comet Holmes is bright and distinctly non-stellar (though still rather small) to the unaided-eye. The comet's coma has been steadily growing larger since the outburst that occurred about one week ago. One of many sources of information and images on this comet can be found at http://www.spaceweather.com/

Comet 17P/Holmes (28 Oct. 2007 UT)

Date: 28 October 2007
Time: 2:08 - 2:17 UT
Telescope: 130mm Refractor
Magnification: 111x
Seeing: Good
NELM: 5.0 (Bright Moon)
Temperature: +39 F (+4 C)

The above sketch shows Comet 17P/Holmes. South is up, and west is to the right in this mirror-reversed view. The bright, stellar pseudo-nucleus was easily visible on this night using the 5.1 inch refractor. As in previous sketches, some bright cometary material is visible on the southwest side (the side opposite the Sun) of the pseudo-nucleus. Also noted was a brighter ring near the outer edge of the comet's outer coma. This ring appeared
to be somewhat less bright to the southwest, perhaps due to the sunlight having to pass through the rest of the comet's coma in order to provide illumination.

No color was noticed at 111x; but at significantly lower magnifications the comet appeared to have a subtle, yellowish tint. The view is aesthetically more pleasing at lower magnifications; but higher magnifications (such as 111x) make it easier to see some of the details.

Comet Holmes remains very bright in the night sky and is visible to the unaided eye as a slightly fuzzy star. Even the slightest optical aid (such as a small pair of binoculars) is sufficient to reveal the non-stellar nature of this interesting comet.

Comet 17P/Holmes

Below are some recent sketches of Comet 17P/Holmes with brief notes below each. Notes are brief due to limited time. This blog has just been "cleared" so that I can once again make postings and I need to leave for my day-job in a few minutes . . .

Above is a sketch made from 1:58 until 2:10 UT on 26 October 2007. A 102mm SCT was used at 80x for this observation. North is up and west is to the left in this mirror-reversed view.

Note the tiny star-like pseudo-nucleus in the center of the larger glow and the broad, fan-shaped region south of center.

Above is a close-up of the visual appearance of the comet as seen with tripod-mounted 25x100 binoculars from 1:30 until 1:52 U.T. on 25 October 2007. North is up and west is to the right in this view.

Above is the full-field view of the comet on 25 October (1:30 until 1:52 U.T.) as seen with the 25x100 binoculars. The apparent size of the comet has been enlarged a little to better show the comet and its brightness relative to the stars in the field. Also shown is the observing form I now use for many of my sketches.

Jupiter 11 Sept. 2007 U.T.

Date: 11 September 2007 U.T.

Time: 1:35 - 1:47 U.T.

Telescope: 13cm refractor

Magnification: 138x

Seeing: Very Poor - Fair

NELM: Twilight

Temperature: +68 F (+20 C)

Shown above is my rough, at-the-telescope sketch of Jupiter. North is up. Preceding is to the right. As part of an experiment a 1.25 inch, 90-degree, erect-image diagonal was used. Also in use was a new filter wheel; but no filters were used during the making of the above sketch. The filter wheel was loaded with various filters for deepsky use; but the planned observing session was cut short due to clouds and high humidity.

Jupiter's North Equatorial Belt was the darkest feature on the planet. It had a subtle, somewhat rusty color. The other belts on the planet appeared to be blue-gray in color. The following limb of the planet was somewhat darker than the preceding limb due to the sun angle (a phase effect).

At times the seeing was very bad, leaving nothing more than the NEB visible on the planet. At other times the seeing was fair, approaching good. The seeing was both, worse at times and better at times than it was for my previous Jupiter observation; but for the most part it was better.

Jupiter & Lambda Ophiuchi

Date: 03 September 2007 U.T.
Time: 2:03 - 2:15 U.T. (Jupiter)
Telescope: 130mm refractor
Magnification: 138x (Jupiter)
Filter: Moon-SkyGlow (Jupiter)
Seeing: Poor to Fair
NELM: Twilight (Jupiter)
Temperature: +83 F (+28 C) (Jupiter)

The above rough (at the telescope) sketch of Jupiter has North up and Preceding to the left.

Due to poor seeing conditions small-scale, moving "ripples" were constantly visible around the limb of the planet. The "star" to the upper right of the planet is Io, one of Jupiter's moons. A little later in the evening Io was seen in transit across the planet's disk. The following limb of the planet was slightly darker than the preceding limb due to the sun angle (a slight phase effect). At times more detail was visible; but under the circumstances (poor seeing and a relatively quick observation and sketch) some of the details shown may not be particularly accurate.

The planet's North Equatorial Belt (the darkest belt on the planet) appeared brownish-red in color. Other features had colors that were too subtle to differentiate from shades of gray.



After completing the Jupiter observation I observed and sketched Lamda Ophiuchi A&B, a close double star. The above sketch (greatly enlarged from the telescopic view) shows this double with North up and West to the left. A #82A Light Blue filter sharpened the view a bit under the relatively poor seeing conditions. The "A" star appeared to have a yellow or yellow-orange color while the "B" component appeared bluish. A narrow gap was visible between the two stars during intervals of somewhat improved seeing conditions. A weak, broken, diffraction ring was also visible at times around the two stars. A magnification of 218x was used for this observation.

Venus - 13 July 2007

Date: 13 July 2007 U.T.

Time: 2:50 U.T.

Telescope: 80mm f/5 achromat

Magnification: 85x

Filter: #56 Light-Green

Seeing: Fair

NELM: Bright Twilight

Temperature: +80 F (+27 C)

The above (mirror-reversed) sketch has North up and Preceding to the left. It shows the basic appearance of Venus as seen in a small telescope.

As the planet's phase changes from full to quarter (half) to crescent to new the planet's disk appears larger and larger. When Venus's phase is near full the planet is on the far side of the Sun. When the planet is a crescent it's on the near side of the Sun. These changes have a dramatic effect on the apparent size of the planet as seen in a telescope.

Currently Venus is moving closer to Earth as it orbits the Sun. As a result it's appearing increasingly larger as seen in a telescope and its phase is becoming a thinner crescent.

Venus is currently visible in the evening sky in the west immediately following sunset. It's by far the brightest object in that area of sky and readily visible to the unaided eye.

Comet LINEAR - 12 July 2007

Date: 12 July 2007 U.T.

Time: 6:32 U.T.

Telescope: 30cm Newtonian

Magnification: 90x

Seeing: Fair

NELM: 6.5

Temperature: +58 F (+14 C)

After the previous night's look at C/2006VZ13 LINEAR with binoculars I decided to have a go at it with a telescope.

In the above sketch South is up and West is to the left. I experimented with magnifications from 60x to 120x before settling on 90x as my preferred magnification for this comet. I worked on the sketch for 20 minutes while observing the comet; but the comet's position was "frozen" (in relation to the stars) at 6:32 U.T.

For those unfamiliar with comets, the stars in the vicinity of the comet in the above sketch are different from those seen on the previous night's sketch. This is because comets are solar system objects that are moving in orbits around our central star (the Sun). They appear to slowly move against the background stars. It can take seconds, minutes, or hours before one notices the motion - depending on the comet, its distance from the Earth and Sun, and the solar system geometry of the line of sight.

This particular comet looks pretty much like a "generic" telescopic comet. There's no easily visible tail. The comet simply looks like a circular, fuzzy, disk of light with a brighter central region. This is what most telescopic (and binocular) comets look like.