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 Holmes (10 Dec. 2007)

Date: 10 December 2007 U.T.
Time: 2:40 U.T.
Instrumentation: Unaided Eye, 8x42 & 20x80 Binoculars
Seeing: Good
NELM: 6.5
Temperature: +15 F (-9 C)

Comet Holmes continues to be easily visible to the unaided eye -- at least from a dark sky. To the unaided eye the comet looks like a round, nebulous patch of light that's somewhat comparable to a full moon in angular size.

With 20x80 binoculars the comet had the appearance of a huge, oval (somewhat egg-shaped) patch of light occupying roughly one quarter of the binocular's three-degree field of view. The comet's sunward side was somewhat better defined than its fuzzier, anti-sunward side. Gone is the distinction between an inner and outer coma. The previously visible outer coma has probably enlarged and faded too much for my eyes to notice. No tail was noticed.

Within the comet's coma was a distinctly brighter bar of light. The bar was brightest and widest on its sunward end. Several stars were visible through the comet's coma. The comet's pseudo-nucleus was not visible. Comet Holmes now has the appearance of a giant, celestial Easter egg.

The view with 8x42 binoculars was essentially a smaller version of the 20x80 binocular view. At this point in time binoculars probably provide better views of this comet than most telescopes can provide.

I've made a few other observations of Comet Holmes between this blog entry and my previous blog entry; but other interests, activities, and necessities have taken precedence over blogging. Such is life . . .

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 (27 Oct. 2007 U.T.)

At 2:06 U.T. on 27 October to the unaided-eye Comet Holmes looked like an ever so slightly bloated, pale yellow-orange star. It was definitely brighter than Delta Persei and seemed to be slightly brighter than Gamma Persei.

At 2:22 U.T. with 8x42 binoculars the comet appeared to have a slight yellow-orange color. It appeared as a small bright spot surrounded closely by a somewhat less bright coma. The bright spot appeared off-centered even at the low, 8x magnification.

At 2:31 U.T. with hand-held 20x80 binoculars (an outside wall was used to steady the view) Comet Holmes was very beautiful indeed! An off-centered (south of center) pale yellow-green bright spot was visible within a larger, less bright yellow-blue-green coma. The outermost edge of the coma seemed to have a slightly reddish tint. The comet looked very much like a planetary nebula.

From 3:08 until 3:26 U.T. I observed and sketched the comet with a 102mm SCT at 80x. The comet appeared to be a bit "fuzzier" (less sharply defined) than it was on 26 October. The central pseudo-nucleus was at the limit of visibility. Most of the time it was invisible; but from time to time it could be seen with certainty. The larger bright spot appeared shifted southwestward of the center of the coma. The outer 'edge' of the bright spot as well as the outer edge of the coma appeared fuzzier and less distinct than they appeared on 26 October. Only shades of gray were noted in this telescopic view. The comet has been steadily increasing in size ever since its sudden, unexpected brightness outburst.

The temperature at the beginning of this session was +32 degrees F. At the end it was +30 degrees F. My NELM (Naked-Eye Limiting Magnitude) was 4.9 on this (nearly full) moonlit night.

Comet 17P/Holmes was significantly fainter than Pluto a few nights ago -- too faint to be seen visually with most amateur telescopes. Then it brightened tremendously, becoming nearly one million times brighter, bright enough to be easily visible to the unaided-eye even in the presence of a full moon!

I've seen many comets; but Comet Holmes is the only one I've seen that has looked so much like a planetary nebula and so little like a comet. The current apparition of Comet Holmes will surely find its place in the astronomical history books!

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.

Comet C/2006 VZ13 (LINEAR) & Aurora

Date: 11 July 2007 U.T.
Time: 5:50 U.T.
Instrument: 20x80 Binoculars
Seeing: Steady (for binoculars)
NELM: 6.5
Temperature: +55 F (+13 C)


The above sketch shows the basic appearance of Comet C/2006 VZ13 LINEAR as seen with hand-held 20x80 binoculars. Only a few of the many visible field stars appear in this sketch. South is up. West is to the left. The comet is the large, round, nebulous object with a brighter middle. The galaxy, NGC 6015 was visible in the 20x80 binoculars as a much smaller and fainter nebulous object to the west of the comet. The comet was easily visible with 8x42 binoculars as well as with the 20x80s.

The comet was in the constellation Draco. Its rough location at the time of this observation was RA 15hr 57min, Dec. +62 degrees 28min. I estimated the comet's coma to be about 0.2 degrees in diameter. The comet is currently well placed in the evening sky for observers at mid-northern latitudes.

An aurora was visible a few degrees above my northern horizon. The aurora was somewhat brighter (with a small amount of structure visible) around 5:20 U.T. than it was at the time of the comet observation (5:50 U.T.). The aurora never extended very much above my northern horizon and seemed to have little or no effect on the limiting magnitude higher in the sky.

Venus & Saturn - Together

Date: 2 July 2007 U.T.
Time: 2:40 - 3:40 U.T.
Telescope: 80mm f/5 (ST-80) refractor
Magnifications: 22x, 24x, 39x, 54x
Seeing: Fair
Transparency: Good
NELM: Bright Twilight
Temperature: +77 F (+25 C)

Venus and Saturn shared the same low to medium powered telescopic field this evening. Venus was a brilliant, white crescent while Saturn appeared roughly half as large and much fainter. At all of the listed magnifications it was possible to observe both planets simultaneously in the same field of view.

Venus was visible to the unaided eye prior to sunset; but Saturn proved difficult in the telescope until after the sun had set. Later, in a darker sky both planets became easily visible to the unaided eye in the western, evening sky.

A sketch was made of the relative sizes and orientations of the two planets, but in order to show both together, as they appeared in the telescope it would be necessary to render the planets as very tiny objects.

The small, portable telescope was set up on my north porch for this evening's observation.

Venus - 19 June 2007

Date: 19 June 2007 U.T.
Time: 22:40 - 22:50 U.T.
Telescope: 102mm SCT
Magnification: 72x
Seeing: Poor - Fair
Transparency: Partly Cloudy (thin clouds)
NELM: Daytime observation
Temperature: +86 F (+30 C)

The above is my rough, at-the-telescope sketch. North is up. Preceding is toward the left. Disk details are questionable under the seeing conditions; but the south cusp was suspected to be somewhat brighter than the north. The limb was brighter than the terminator. The planet appeared white against the blue daytime sky.

I went outside around 4:00 pm local time, looked up, saw the Moon, looked a few degrees west of the Moon and spotted Venus with the unaided eye. Afterwards I set up the telescope and made the above observation.

Observational Slow-Down:
Lately a combination of factors have slowed down the frequency of my astronomical observations. Among those factors is increased activity in my other (long neglected) hobby - chess. If my renewed interest in chess continues long enough I may start an additional blog devoted to that interest.

Sunspot - 03 June 2007

Date: 03 June 2007 U.T.
Time: 16:53 - 17:22 U.T.
Telescope: 102mm SCT
Magnifications: 40x, 90x
Filter: Baader, white light
Seeing: Fair
Transparency: Scattered Clouds

The above sketch shows the sunspot group (Sunspot 960) that has recently rotated to the earth-facing side of the Sun. Preceding is up and south is to the left in this mirror-reversed view. At times during this session clouds blocked the Sun from view.

For most of the observation the telescope was used at 90x. Later 40x was used for the faculae portion of the sketch.

After completing this observation the view was shared with a guest.

Sharing the View

Date: 3 June 2007 U.T.
Time: 3:00 - 5:00 U.T.
Telescope: 13cm refractor
Magnifications: 35x, 90x, 170x, 240x
Filters: #56 and #58 Green (for Venus only)
Seeing: Good
Transparency: Bright and darkening twilight

After many cloudy or otherwise missed nights everything fell into place for a good evening. The telescope was set up on on an equatorial mount with an electric RA drive. The motorized tracking simplified sharing the view with two guests.

Venus was our first target, and for a long while our only target. The seeing was very steady with the refractor -- one of the benefits to using a relatively small telescope. The planet's sharply defined quarter (or 'half-moon') phase was easily visible to everyone present.

The green filters helped cut down the brightness of the brilliant, white planet to a more tolerable level. We took turns studying the planet at 90x. Through the use of questions and answers, it looked like the guests may have been able to perceive some of the subtle markings in the Venusian atmosphere.

Eventually the sky darkened enough for the younger guest to spot Saturn in the twilight sky. We shared views at 35x and gradually worked our way up to 240x. Titan was immediately noticed near the ringed planet. After the sky had darkened a bit more we saw three more of Saturn's moons. The two moons between Titan and the planet, one above the other, were later identified as Tethys (to the north) and Rhea (south of Tethys). Just off the north-following limb of the planet was Dione.

At the higher magnifications the ring was visible in front of the planet. The guests also noticed Saturn's South Equatorial Belt (SEB). Cassini's Division presented a challenge for the guests, but they eventually succeeded in seeing this division between Saturn's A and B rings -- at least on one side of the ring system. The shadow of the planet on the ring system proved to be a bit more of a challenge for the guests.

After Saturn we took a look at the globular cluster, M13 in Hercules. Next was the Ring Nebula (M57) in Lyra. The final object was Albireo (Beta Cygni) -- one of the northern hemisphere's "showpiece" double stars.

Twilight had still not quite ended by the sessions end. Nevertheless, part of the summer Milky Way was seen. We also saw at least one meteor, an airplane and at least one satellite.

Sunspot - 18 May 2007

Date: 18 May 2007 U.T.
Time: 17:04 - 17:29 U.T.
Telescope: 102mm SCT
Magnification: 90x
Filter: Baader, White-Light
Seeing: Fair
Transparency: Clear with Haze
Temperature: +80 F (+27 C)

The above sketch shows the general appearance of sunspot #956 -- looking somewhat like a smiling, cartoon alien. North is up and preceding is to the left in this mirror-reversed view.

The thin haze in my sky is most likely from a distant forest or grassland fire. It's been enough to discourage me from attempting deep-sky observing on the past couple of nights.

Thoughts on Observing Venus

Despite my involvement in amateur astronomy since the late 1960's, I still consider myself a beginning, visual observer. There is much that I still do not know; and I'm continually learning more. Take Venus for instance:

Back in the late 60's I made observations of Venus using an inexpensive, 60 to 65mm refractor. My observations showed the changing phases of the planet. I was able to see how the apparent size of the planet varied as Venus travelled around the Sun. The planet appeared noticeably smaller when near full, on the far side of the Sun than it did when near new, on the near side of the Sun. Venus was a brilliant, white, featureless planet - excepting only its changing apparent size and phase.

Only rarely since those early observations have I re-visited Venus. I had rarely, if ever, heard other amateurs mention observations of albedo variations on Venus. There seemed little point in observing a planet on which one cannot see surface nor atmospheric features.

This year my attitude toward Venus has changed. The change had its origins in a thread pertaining to the visual observation of Venus in the Usenet group: sci.astro.amateur. Apparently, some people could see a sharply defined (yet, pretty much featureless) planet when they observed Venus through their telescopes, while others could see little more than a bright, boiling blob of ever-changing color.

In the saa discussion, mention was made of the visibility of subtle, atmospheric details that some have claimed to see. So, I decided to start observing the planet on a more or less regular basis with my current arsenal of telescopes and filters - to see what I could see . . .

After experimenting with filters, I found that a green filter (with or without a Moon-SkyGlow filter) seemed to work best on Venus for my eyes. As a result, most of my subsequent Venus work has involved the use of a green filter.

I soon found myself "suspecting" subtle detail in the Venusian clouds; but it took a while before I felt confident enough to attempt sketches of those details. Within this blog I often prefaced references to Venusian details with the qualifier: "suspected". This was because I was not fully convinced that the subtle details that I saw were truly details within the Venusian clouds. When observing near one's limits, other factors can enter the equation. The human eye, for instance, is a far from perfect optical instrument.

As I made more observations, I became more convinced that I was seeing actual albedo variations on Venus. Nevertheless, due to their subtle nature and the less than perfect seeing conditions it has remained difficult to record those variations with a high degree of confidence and/or accuracy.

I take my own Venus observations with a grain of salt. The main reason for this self-scepticism has to do with the subtleness of the suspected details. Observing detail on Venus is not like looking out a window and seeing a tree. It's more like looking out a window on a very foggy morning and "suspecting" a tree. In the case of Venus, atmospheric turbulence (in Earth's atmosphere) causes subtle planetary detail to be visible sometimes and invisible at other times - during the same observing session. It's necessary to patiently study the planet in the eyepiece, waiting for the detail to show itself. It's very much like catching intermittent glimpses of a tree as the fog thickens and thins.

Atmospheric turbulence was noticeably less problematic during my last Venus observation. The subtle Venusian details could be seen more consistently than ever before. Furthermore, I was using my largest telescope (and a green filter). Also, Venus was nearer to Earth and thus appeared larger than it had for my earlier observations. For that observation, I can remove the qualifier; "suspected". Detail was very definitely being seen, and that detail originated within the Venusian atmosphere.

So what about the boiling, colorful blob that some see when they look at Venus?

When conducting a test, the only time I could see color around Venus when using my Newtonian (a telescope type that does not suffer from chromatic aberration) without filters was either when I viewed the planet using an eyepiece that was poorly corrected for chromatic aberration, or when I waited for Venus to settle lower in my sky -- allowing Earth's atmosphere to bend the different colors by noticeably different amounts.

Of course, the "boiling" aspect that some have mentioned is due entirely to thermal effects in the line of sight between the observer's eye and the planet. More specifically, these thermal effects exist either in the air above the telescope, in the air inside the telescope, or both.

Some telescopes are less susceptible to internal thermal effects than others. Some observers exercise more care in avoiding telescope thermal effects than others. Some observing sites are better than others. Certain times of the year may be better than other times for a given location. Venus is not equally high in the sky near local sunset for observers observing from different latitudes. The list goes on . . .

I'm fully convinced that Venus can be an interesting and rewarding planet to observe for those willing to devote the necessary time and effort.

I.S.P. Disappointment & sci.astro.amateur

Almost one week ago the newsgroup feed from my Internet Service Provider ceased. It took a few phone calls and a few days to learn what little I now know about the situation.

I've participated for several years, under one identity or another, on the unmoderated Internet Usenet group: sci.astro.amateur. My presence in sci.astro.amateur pre-dates the origin of my website. As a matter of fact, it was discussions on saa that led me to create the website.

Initial contact with my ISP indicated that they were unaware of what a newsgroup was and unaware that they had been providing the feed.

After the passage of several days I was informed that my ISP had been under the impression that they had dropped newsgroups last October! When asked if they were going to turn back on the newsgroup feed, their response was; "No."

Unfortunately, options are very limited in my rural area when it comes to ISPs. It's possible to access Usenet in other ways; but so far I've not found an alternative that I'm entirely comfortable with. So, at least for the time being, I can read postings to saa; but I'm unable to make responses.

Sunspot - 07 May 2007

Date: 07 May 2007 U.T.

Time: 16:54 - 17:14 U.T.

Telescope: 102mm SCT

Magnification: 90x

Filter: Baader White-Light

Seeing: Fair

Transparency: Clear

Temperature: +63 F (+17 C)

The above sketch shows the same the sunspot that I've been following for the past several days. North is up; and preceding is to the left in this mirror-reversed view. This sunspot will soon be transferred to the far side of the Sun via the Sun's relatively slow rate of rotation.

Sunspot - 02 May 2007

Date: 02 May 2007 U.T.

Time: 16:40 - 17:00 U.T.

Telescope: 102mm SCT

Magnifications: 70x and 90x

Filter: Baader, Objective Solar Filter

Seeing: Fair

Transparency: Thin Clouds

Temperature: +76 F (+24 C)

The above sketch shows the same sunspot as the previous three sunspot sketches. North is up; and preceding is to the left in this mirror-reversed view.

The thin clouds were too thin to be noticed through the telescope as silhouetted forms against the bright sun.

Venus (01 May 2007)

Date: 01 May 2007 U.T.
Time: 1:46 - 1:56 U.T.
Telescope: 102mm SCT
Magnification: 150x
Filter: #56 Green
Seeing: Fair to Good
NELM: Sunset - Bright Twilight
Temperature: +68 F (+20 C)

The above sketch shows the general appearance of Venus on this date. North is up; and preceding is to the left in this mirror-reversed view. The region in the neighborhood of the north cusp seemed to be a little brighter than the rest of the planet.

The subtleties of light and shade on Venus are roughly comparable to what one would see when examining a small section of an egg shell. When observing Venus it's not easy to tell exactly where the borders lie between regions of different shadings. Nevertheless, with experience it is possible to detect subtle variations within the Venusian atmosphere.

One of the joys of amateur astronomy is the acquisition of observing skills. Arguably, one might say that much, or even most of what an experienced observer sees when studying an object would go completely unnoticed by a beginner or by a much less experienced observer. If there were few challenges involved in this hobby I would have dropped out long ago.

After completing my sketch I tried using a violet filter. Under bright twilight with the 102mm telescope at 150x the violet filter was found to be too dense. Next I tried a variable polarizing filter. Unfortunately the seeing conditions deteriorated fairly rapidly, forcing an end to such experimentation.

Sunspot - 01 May 2007

Date: 01 May 2007 U.T.

Time: 16:25 - 16:40 U.T.

Telescope: 102mm SCT

Magnifications: 70x and 90x

Filter: Baader, Objective Solar Filter

Seeing: Fair

Transparency: Clear

Temperature: +67 F (+19 C)

The above sketch shows the same sunspot that was observed on the previous two sessions. North is up; and preceding is to the left on the mirror-reversed image. A mild wind was effectively blocked by the walls of the "Colosseum".

Sunspot - 29 April 2007

Date: 29 April 2007 U.T.
Time: 15:50 - 16:20 U.T.
Telescope: 102mm SCT
Magnification: 90x
Filter: Baader Solar Filter (Objective)
Seeing: Fair
Transparency: Thin (Cirrus) Clouds
Temperature: +71 F (+22 C)

The above sketch shows the same sunspot that was observed two days earlier. North is up. Preceding is to the left (mirror reversed image).

A comparison of the this sketch with the previous sketch will give an idea of how quickly the appearance of a sunspot can change. Even during the thirty minute's it took to make this observation minor changes could be noticed.

Sunspot - 27 April 2007

Date: 27 April 2007 U.T.
Time: 18:56 - 19:12 U.T.
Telescope: 102mm SCT
Magnification: 90x
Filter: Full Aperture, Baader, White-Light Solar Filter
Seeing: Fair
Transparency: Mostly Clear with Scattered Clouds
Temperature: +67 F (+19 C)


The above sketch shows the sunspot that was near the Sun's following limb on this date. The view is mirror-reversed. North is up. Preceding is to the left.

A mild wind was blowing during this observation; but the curved wall of the "Colosseum" blocked most of it. Clouds briefly blocked the Sun a couple of times during the observation.

Venus & Saturn with ST-80

Date: 25 April 2007 U.T.

Time: 2:31 - 4:42 U.T.

Telescope: 80mm f/5 refractor

Magnification: 105x

Filters: #58 Green, #12 Yellow

Seeing: Good

NELM: Bright Twilight (later 5.3)

Temperature: +45F (+7 C)

Above is Venus as seen with the small refractor from 2:31 until 2:36 U.T. North is up. Preceding is to the left. A 90 degree, mirror diagonal was used, resulting in a mirror-reversed image. A #58 Green filter was also used for this observation.

The planet's phase was slightly gibbous, almost quarter. The sunlit limb of the planet (to the left) appeared to be a little brighter than the rest of the planet. Two darker regions were suspected as shown in the above sketch.

Above is Saturn with Titan to the upper right. This observation was made from 4:22 until 4:42 U.T. As with Venus, north is up; and preceding is to the left. A #12 Yellow filter was used for this observation. (The Venus and Saturn sketches are not to the same scale!)

Visible features include the C-ring where it crosses in front of the planet, the shadow of the planet on the ring system, the Cassini Division (appearing as ill-defined, somewhat darker arcs near the outer edges of the ring system), and the South Equatorial Belt (the subtle, dark 'band' running parallel to the planet's equator (and ring system) in the planet's southern hemisphere.

After observing Saturn I took a look at Earth's Moon, which was near Saturn in the sky. A tremendous amount of detail was visible at 105x. Some of the lunar mountains were casting long, pointed shadows. I was tempted to sketch the crater Cassini; but instead decided to end the session early.

Two Galaxies and a Planet

Date: 17 April 2007 U.T.
Time: 1:50 - 5:50 U.T. (with breaks)
Telescope: 30cm Newtonian
Magnifications: 150x (Venus)
160x (M81)
250x (M82)
Filters: Moon-SkyGlow & #58 Green (Venus)
None (Galaxies)
Seeing: Fair to Poor
NELM: Bright Twilight (Venus)
6.5 (Galaxies)
Temperature: +43 F (+6 C)

Venus was observed and sketched near sunset. The planet's gibbous (approaching quarter) phase was obvious. Subtle markings were difficult to pin down due to relatively poor seeing conditions. Nevertheless, I was able to complete a rough sketch.

M81, a bright, spiral galaxy in Ursa Major was observed and sketched at 160x. This galaxy had a small, bright, central region surrounded by a fainter, oval glow. Upon closer inspection one of the galaxy's spiral arms became evident on the north following side of the galaxy's nucleus. Other arms were suspected as glimpses were caught of darker regions within the faint glow of M81's outer regions.

M82 is a bright, irregular galaxy near M81 in Ursa Major. A few brighter and darker regions were seen without much difficulty in this interesting, cigar-shaped galaxy.

Green Venus & More

Date: 14 April 2007 U.T.
Time: 1:50 - 2:06 U.T.
Telescope: 30cm Newtonian
Magnification: 150x
Filters: Moon-SkyGlow & #58 Green (simultaneously)
Seeing: Fair to Poor
NELM: Bright Twilight
Temperature: +45 F (+7 C)


The above sketch gives a better idea of how Venus looks when using a Green filter (with or without an MSG filter). In the sketch, South is up and Preceding is to the left. Seeing conditions were a little worse than they have been for most of my earlier observations of this planet. The cause might be related to warmer daytime temperatures. Seeing conditions seemed to have improved later in the night when I targeted other objects.

Using words, the south polar region of the planet seemed to have a bit more white than elsewhere on the planet. A large dusky region was suspected in the mid-southern latitudes. A smaller dusky region was suspected in the mid-northern latitudes. The limb region away from the terminator appeared somewhat brighter than the rest of the planet.

The highlight of this night's observing were my later, deep-sky observations. Seeing conditions improved, and transparency proved to be very good some time after the Venus observation. Careful observations and sketches were made of NGC 3242 (The Ghost of Jupiter) at 250x and NGC 4565 (The Needle Galaxy) at 120x. Both objects were nicely shown by the 30cm Newtonian.

By the time I had completed the above observations (6:07 U.T.) with a break between each, I had grown rather fatigued. At one point I had decided to attempt to stay awake until Jupiter reached my south meridian; but fatigue ended up the winner of that battle and I eventually called it a night.

A Brief Binocular Session

Date: 13 April 2007 U.T.
Time: 4:00 - 4:30 U.T.
Binoculars: 20x80 (hand-held)
Seeing: Good
NELM: 6.4 (or better)
Temperature: +29 F (-2 C)

Three relatively bright non-Messier objects were targeted this evening. The first was NGC 2403. This galaxy was very easy to see with the large binoculars. It looked like a small, distinct patch of nebulosity and was more readily visible than many of the Messier galaxies.

Next was NGC 3242 "The Ghost of Jupiter". This object is a small, but very bright planetary nebula. Through the binoculars it resembled a slightly bloated, slightly fuzzy star. The detailed charts in the Uranometria Atlas allowed for easy identification via the surrounding star field.

Last on my list was NGC 4565 "The Needle Galaxy". This well-known, edge-on, spiral galaxy was visible in the binoculars as a small, faint, elongated glow with a somewhat brighter middle.

For whatever reason, I found myself looking in the vicinity of M81 with the unaided eye. I noted the nearby star pattern as plotted on atlas charts. All of the nearby stars plotted in the Cambridge Star Atlas (2nd edition) were visible to the unaided eye. In particular, I noted 24 Ursae Majoris and the unlabeled star between 24 and M81. At times I suspected a tiny, faint glow at the exact spot where M81 was supposed to be.

I'm not positive that I saw M81 with the unaided eye on this evening; but I'll try to remember to look for this relatively bright galaxy from time to time (with the unaided eye) when conditions are favorable.

M 104 (The Sombrero Galaxy)

Date: 8 April 2007 U.T.
Time: 5:17 - 5:40 U.T.
Telescope: 30cm Newtonian
Magnifications: 250x and 120x
Seeing: Fair to Poor
NELM: 6.5
Temperature: +22 F (-6 C)

The Sombrero Galaxy is a beautiful object! It consists of a small, bright, central core surrounded by an elongated (east-west), fainter glow. The glow is widest in the central region, growing progressively narrower further out. Just south of the core a narrow, dark, dust-lane was visible running the length of the galaxy. The galaxy's glow to the south of the dust lane was considerably fainter than the glow to the north. The galaxy appeared to be slightly brighter along its western extension than along its eastern extension.

The overall shape of M 104 was similar to that of two saucers with their rims in contact with one another -- viewed edge-on.

A magnification of 250x was used for most of the observation and sketching. Later I dropped the magnification down to 120x. It may have been possible to see the faint, outermost glow of the galaxy a little better at the lower magnification; but details showed up better at the higher magnification.

Venus (08 April 2007)

Date: 8 April 2007 U.T.
Time: 1:55 - 2:10 U.T.
Telescope: 30cm Newtonian
Magnification: 150x
Filters: Moon-SkyGlow and #58 Green (simultaneously)
Seeing: Fair
NELM: Bright Twilight
Temperature: +29 F (-2 C)

The gibbous disk of Venus was sharply defined. Suspected, subtle darkenings on the planet's disk were sketched. The planet appeared to have a bright, featureless, narrow rim around (just inside) its limb everywhere excepting the planet's terminator. The largest suspected dusky marking was in the planet's southern hemisphere. A possibly connected, smaller, dusky feature was suspected in the planet's north-preceding quadrant. Two subtle, dark 'notches' were suspected along the planet's terminator. One was near the center of the terminator. The other (slightly larger) notch was a bit more to the north.

It's difficult to be certain of suspected features in the Venusian clouds. The planet appears to be almost without visible markings. The suspected markings mentioned above may or may not be actual features in the Venusian atmosphere.

My typical procedure (and the one followed on this evening) is to set up the telescope prior to sunset after the wall of my open-air observatory is casting a high enough shadow to place the telescope's lower section (containing the large, primary mirror) in shade. Sunlight shining on that section of the telescope might prolong cool-down of the mirror. (The telescope has a built in cooling fan; but I've never felt a need to use it.) The observation of Venus began shortly after sunset, after the telescope had been outside for over an hour.

Venus (27 March 2007)

Date: 27 March 2007 U.T.
Time: 1:30 - 1:50 U.T.
Telescope: 80mm refractor
Magnifications: 20x, 40x, 67x
Filters: None, #56
Seeing: Fair
NELM: Bright Twilight
Temperature: +53 F (+12 C)

Tonight's observation was made using a relatively simple, 80mm, f/5 achromatic refractor. Such telescopes are occasionally used by individuals just starting out in amateur astronomy. More experienced amateurs sometimes use such instruments as quick-look, grab-and-go telescopes or even as finders for larger telescopes.

I chose this particular telescope this evening for the following reasons: Predictions called for bad seeing, wind, and increasing clouds. I wanted to see what Venus looked like through a small and relatively low quality telescope on a relatively poor night.

At 20x Venus looked like a tiny blob of bright light surrounded by a substantial, mostly purple glow. Yellow-green light was occasionally also seen around the planet. These colors were due primarily to the telescope's achromatic objective lens. Such objectives fail to bring all colors to the same focus; but often, particularly when looking at much less brilliant objects, this defect can go unnoticed. At 20x the planet's disk could not be made out with any degree of certainty.

At 40x the planet's disk was clearly visible. It was difficult, but possible to discern the planet's gibbous phase. False color surrounded the planet just as it did at 20x. The planet's normally white disk appeared somewhat yellowish due to the 80mm achromat's chromatic aberration.

At 67x the planet's disk was clearly visible; and its gibbous phase was clearly discernable. The wind was strong enough to shake the telescope a little; but it wasn't strong enough to compromise the observation. The false color extended outward from the planet in all directions a distance of at least three planetary diameters. The disk of the planet was only mildly discolored (like it was at 40x).

At 67x with a #56 Light Green filter the planet looked much better. Green was the only color visible with the filter. For all practical purposes the filter effectively eliminated the achromat's false color. The purple glow around the planet was gone and replaced by a much weaker greenish glow. The seeing conditions caused the planet to jiggle a little as if it were made of jello; but the jiggling was quite mild. The planet's gibbous phase was well defined and obvious.

Moon - Unaided-Eye

Date: 27 March 2007 U.T.

Time: 1:15 U.T.

Instrument: Unaided-Eye

Temperature: +55 F (+13 C)

As the above sketch shows, a telescope is not always necessary in order to make observations of other worlds. North is up and lunar east is to the right in the sketch.

Predictions called for bad seeing, wind, and increasing clouds; but meanwhile the sky was mostly clear so I decided to skip out on setting up a large telescope and instead make a quick, unaided-eye observation of the Moon. After all, it's often said that one can see more on the Moon with the unaided-eye than one can see on Mars with the aid of a telescope.

Saturn's Moons (25 March 2007)

Date: 25 March 2007 U.T
Time: 6:45 U.T.
Telescope: 30cm Newtonian
Magnification: 300x
Seeing: Poor to Bad
NELM: 5.7 (Moonlight)
Temperature: +40 F (+4 C)

I had hoped for (and was expecting) better seeing conditions. Under the circumstances, 3oox was way too much magnification; but I kept looking and hoping for conditions to improve (Clear Sky Clock had predicted improved seeing). In the end, I had to skip the planned Saturn observation and instead record nothing more than Saturn's brightest moons.

In the above sketch a more or less 'generic' Saturn is shown looking much sharper than it actually looked during this session. South is up. Preceding is to the left.

The brightest moon, to the lower left of the planet is Titan. Titan was discovered on this very date in 1655 by Christian Huygens. Proceding clockwise from Titan, the other Saturnian moons are: Tethys, Dione, Iapetus, and Rhea.

After I posted the above sketch I noticed that some of the moons didn't show up as well as I had hoped. Iapetus should be the faintest moon. It's located to the right of Saturn about one ring system span from the rightmost tip of Saturn's ring system. Rhea is about midway between Iapetus and the ball of the planet, but shifted a small distance downward. Rhea appeared to be second in brightness after Titan; but doesn't show up that way in the above sketch.

Tethys and Dione, both to the left of the planet should appear approximately equally bright (but don't appear so in the sketch) -- just slightly fainter than Rhea.

I had tried something a bit different in the creation of the above sketch; but the final result didn't turn out as well as I had hoped. I'll know better next time!

Maskelyne (lunar crater)

Date: 25 March 2007 U.T.

Time: 3:19 - 4:05 U.T.

Telescope: 30cm Newtonian

Magnification: 145x

Filter: Moon-SkyGlow

Seeing: Fair to Poor

NELM: 5.6

The above sketch shows Maskelyne, an oddly-shaped, 24km wide crater in the south-central portion of the Moon's Sea of Tranquility.

This is my first lunar observation with the MSG filter. The filter appeared to remove the yellow color from the Moon, creating more of a black and white landscape; but I didn't notice any improvement in visible detail.

Venus (25 March 2007)

Date: 25 March 2007 U.T.
Time: 1:30 - 2:30 U.T.
Telescope: 30cm Newtonian
Magnifications: 60x, 200x, 250x, 395x
Filters: none, #47, #38A, #58, MSG
Seeing: Fair (most of the time)
NELM: Bright, then darker Twilight

The phase of the planet had changed by a small, but very noticeable amount since my last observation. The planet is slowly growing in apparent size. Its phase is gradually changing from a fat gibbous toward quarter. Much of the following experimentation with magnifications and filters was inspired by recent discussion on the newsgroup; sci.astro.amateur.

The above sketch shows the general appearance of the planet as observed on this evening. South is up. Preceding is toward the left.

A page full of notes was taken as I experimented with magnifications and filters. I started with a magnification of 60x without the use of any filters. The planet's phase was immediately evident. The disk was well defined. The planet appeared white, devoid of any false color.

Next up was a huge jump to 395x. Atmospheric turbulence became significantly more noticeable. The planet's phase remained easily visible. Some false color ranging from rust orange to blue to gray was introduced by the eyepiece optics in the sky immediately adjacent to the planet's limb. The planet itself remained essentially color-free.

I tried 250x next. The small amount of false color around the planet varied with eye placement. It was evident that this eyepiece had better color correction than the previously used eyepiece.

The ideal magnification for the telescope, object, and sky conditions seemed to be 200x. Once again, the small amount of false color in the sky immediately adjacent to the planet's limb varied with eye placement. The planet itself remained white with no false color. Up until this point in time no filters were used.

For most of the remaining of the session I maintained a magnification of 200x. A #47 Violet filter was tried. The image became steadier. The filter introduced a weak, violet, reflected image that overlapped the image of the planet when the planet was far from the center of the eyepiece's field of view. Otherwise that reflection was not seen.

I prefered the brighter image offered by a #38A Blue filter over the denser violet filter; but the seeing seemed to be a little better with the violet filter. I next combined the Moon-SkyGlow (MSG) filter with the blue filter. A very subtle improvement in the view of the planet was suspected over the blue filter alone.

The blue filter was replaced with a #58 Green filter. Some subtle albedo markings on the planet were suspected. The planet's terminator appeared to darken relative to the rest of the planet.

I removed the MSG filter. With the #58 Green filter alone the subtle detail seemed a little more difficult to detect. It would appear that the combination of the MSG and #58 Green filters may work best for my eyes, Venus, and the 30cm Newtonian.

The MSG filter was tried without any other filters. It imparted a very weak, purple (but almost white) color to the planet. The color was easier to notice with the planet placed out of focus.

By now Venus had dropped lower in my sky -- lower than I've previously observed the planet this year; but I remained curious about all the false color that other's have mentioned when observing this brilliant planet. I lowered the magnification to 60x to brighten the planet in the darkening sky in an attempt to exaggerate any false color. Venus now had a blue glow above its disk and a red glow below. Perhaps the planet had dropped low enough in my sky for Earth's atmosphere to refract the different colors differently enough to notice. Nevertheless, it remained very easy to see the planet's disk and phase despite the planet's much smaller apparent size and much greater apparent brilliance.

My attention was now drawn to the diffraction spikes created by the telescope's spider. In the darker sky it was possible to see that the spikes consisted of a rainbow pattern of color. At increasing distances from the planet, the color in the spikes changed from yellow to orange to red to blue and green. The pattern repeated further from the planet as the light in the diffraction spikes grew weaker. The planet itself remained free from such 'false' color.

Saturn (18 March 2007)

Date: 18 March 2007 U.T.
Time: 3:15 - 3:42 U.T.
Telescope: 13cm refractor (full aperture & stopped down to 30mm)
Magnifications: 66x, 80x, 138x, 218x
Filters: Moon-SkyGlow and unfiltered
Seeing: Good
NELM: 6.5
Temperature: +45 F (+7 C)

This session started with a test. Several years ago I made a series of Saturn sketches using the same telescope stopped down to effective apertures of 10mm, 20mm, 30mm . . . 100mm, 110mm, 120mm. At that time I noted that the presence of Cassini's Division could be detected as a subtle shading near the outermost edges of Saturn's ring system with a 30mm aperture.

Some have doubted that observation, so this evening I attempted to duplicate it. I placed a mask with a 30mm circular opening in front of the telescope. Saturn was then studied at 66x and 80x without the use of any filters. Even though the ring system was opened less now than it was several years ago, I was still able to detect (though not as easily as before) the shading near the outer edges of the rings caused by the presence of Cassini's Division. Furthermore, with the 30mm aperture the ring was visible as a darker line where it passed in front of the planet. It was also possible to discern which part of the ring system Saturn's globe was casting its shadow on.

Saturn at full aperture: The 30mm mask was removed and the planet was studied primarily at 218x. I found that I preferred the view without the Moon-SkyGlow filter, so the MSG filter was removed for most of the session.

Five suspected Saturnian moons were sketched, but later it was discovered that one of the suspects was a star. Titan, Dione, Tethys, and Rhea were all positively identified. Tethys was very close to the south-following limb of the planet. Of these four moons, Titan was the only one noted with the 30mm aperture.

Overall, Saturn looked very much as it did when I observed and sketched it several nights ago using a 30cm Newtonian. The larger telescope resolved the Cassini Division better, particularly near the limb of the planet. Saturn's narrow Equatorial Belt, just south of the ring system in front of the planet was more difficult to see with the 13cm refractor. Saturn's South Equatorial Belt was suspected to be double in the Newtonian; but it appeared single in the refractor. (A blue filter was used with the Newtonian observation.)

One probable error in the earlier Saturn sketch involved a dark line adjacent to the north edge of the ring system in front of the planet. That dark line should probably have been the outermost edge of the A-ring itself. Such was the general appearance this evening with the 13cm refractor.

Venus (18 March 2007)

Date: 18 March 2007 U.T.
Time: 1:17 - 2:00 U.T.
Telescope: 13cm refractor
Magnification: 218x
Seeing: from Fair to Poor to Bad
NELM: bright twilight
Filters: Moon-SkyGlow, #47, #80A, #23A, #21, #58, #56, #11, #15

This observation began shortly after sunset using only the Moon-SkyGlow filter under Poor seeing conditions. The planet's gibbous phase and slightly shaded terminator were easy to discern. For the remainder of the observations the MSG filter was used in addition to the various colored filters.

At 1:25 I tried a #47 Violet filter, but found the resulting image to be too dark.

At 1:30 a #80A Blue filter was used. The seeing improved to Fair. The limb of the planet (away from the terminator) seemed to be brighter than the rest of the planet. The planet's disk and phase were fairly sharply defined. Hints of subtle shadings were suspected on the planet's disk.

At 1:37 a #23A Red filter was used. The visible details were similar to those seen with the #80A filter.

At 1:39 a #21 Orange filter was used. The planetary limb remained bright. Disk detail became less distinct.

At 1:42 a #58 Green filter was used. At this point in time the subtle, disk details became more distinct than with any of the previous filters. The subtle shadings were sketched.

At 1:46 a #56 Green filter was used. Seeing became suddenly worse, ranging from Poor to Bad.

At 1:50 a #11 Yellow-Green filter was used. Seeing remained Poor to Bad. Nevertheless, the terminator shading was suspected to be enhanced. The disk details may have also been enhanced; but the Poor to Bad seeing made it difficult to be certain.

1:53 a #15 Yellow filter was used. The seeing turned Bad.

1:55 the #58 Green filter was tried again. The seeing appeared to improve. Another sketch was made of suspected disk details. This time a small bright patch was suspected along the north-preceding limb. The other disk details were in good agreement with the earlier (1:42 U.T.) sketch.

Conclusions: The #58 Green filter seemed to bring out the most detail. It's unknown if the addition of the Moon-SkyGlow filter helped or not when used with the various color filters. The 2-inch MSG filter was screwed into the 2-inch star diagonal while the various 1.25-inch color filters were, one at a time, screwed into the eyepiece. It's unknown if any of the filters were responsible for improved or worsened apparent seeing conditions.

The so called subtle disk details may or may not have been actual albedo variations in the atmosphere of Venus. It's easy for the eye to be tricked into seeing such things. Further observations will be necessary in order to draw any meaningful conclusions.

20x80 Binoculars - M51 etc.

Date: 10 March 2007 U.T.
Time: 6:30 - 7:50 U.T.
Binoculars: 20x80
Seeing: Good
NELM: 6.5 (mostly)
Temperature: +28 F (-2 C)



The above sketch shows the general appearance of M51, also known as the Whirlpool Galaxy as seen with 20x80 binoculars. The smaller fuzzy spot just above (north of) M51 is NGC 5195.

At sunset my sky remained cloudy. When the sky finally cleared I decided to continue my hunt for Messier objects using the large binoculars. In Messier number order I observed the following objects: M3, M5, M13, M40, M44, M51, M53, M63, M67, M68, M81, M82, M83, M92, M94, M97, M101, M104, M106, M108, and M109. Over the past few months I've observed all of the Messier objects using 20x80 binoculars.

The month of March is sometimes referred to as the Messier month. From some locations it's possible in March to observe all the Messier objects in a single, moonless night. Such an all night session is known as a Messier marathon.

I prefer to spread the observations out over a few months. In this manner I can observe the objects when they're higher in my sky and easier to see. Besides, it can be quite difficult catching some of the objects in March from my latitude. Nevertheless, if opportunity knocks I might be tempted to attempt a Messier marathon.

M83 proved to be the most elusive object. I looked for it at irregular intervals for the last 35 minutes of the observing session. A long, thin cloud hung out over this galaxy for much of the night. Finally, as the Moon was rising I managed to see M83. The galaxy was just a little brighter than the background sky at that time. It's even possible that I was observing M83 through a thin cloud layer.

20x80 Binocular Session

Date: 9 March 2007 U.T.
Time: 5:37 - 6:45 U.T.
Binoculars: 20x80 (hand held)
Seeing: Good
NELM: 6.0 - 6.5
Temperature: +28 F (-2 C)

High Humidity and Clouds: A small amount of rain fell during the day prior to this session. The floor of my open-air observatory remained damp. Clouds didn't dissipate until sometime after sunset. Due to these conditions I decided to not set up a telescope. By the time of the observation a fairly thick layer of frost had formed on the porch, etc.

At the start of the binocular session my sky was clear in the west. The rest of the sky seemed to be covered with very thin clouds. Later, conditions improved enough to allow me to see most of the objects that I wanted to observe.

M41 is an open star cluster in Canis Major. Someone had recently mentioned on the newsgroup, sci.astro.amateur that they were disappointed in the appearance of this cluster in their 130mm telescope. I made a response as to some possible reasons, and mentioned that M41 was visible to the unaided eye under a sufficiently dark sky. So, with a clear sky, I decided to pay a visit to M41.

Sure enough, the cluster was a relatively easy object to detect with the unaided eye. Through the binoculars M41 was resolved into numerous individual stars. I found the view to be 'rather nice' despite the cluster's low altitude in my southwestern sky.

Galaxies in Leo, Virgo and Coma Berenices: Next on my agenda were the Messier galaxies in the Virgo region. The above sketch has north up and west to the right. It shows the general appearance of M65 (the galaxy to the right of center), M66 (the galaxy to the left of center), and NGC 3620 (the fainter galaxy north of the other two). Galaxies tend to look like faint,fuzzy stains against the background sky when observed with 20x80 binoculars.

In addition to the three objects mentioned above, I observed the following galaxies: M58, M59, M60, M64, M84, M85, M86, M87, M88, M89, M90, M91, M95, M96, M98, M99, M100, and M105.

Near the end of the session the Moon rose. The high humidity scattered the moonlight, making the sky much brighter than it would have otherwise been.

M 78

Date: 07 March 2007 U.T.
Time: 2:34 - 2:54 U.T.
Telescope: 30cm Newtonian
Magnification: 90x
Seeing: Good
NELM: 6.5
Temperature: +43 F (+6 C)

M78 is a bright patch of nebulosity in Orion. Two bright stars and one fainter star were seen within the nebulosity. A fourth star was briefly suspected, but not recorded. The northwestern edge of the nebula was brightest and best defined. The rest of the nebula fanned out south-southeastward like a short, but very wide cometary tail.

Nearby, just northwest of M78 was a fainter, elongated patch of nebulosity, NGC 2067. Oddly enough, I noticed a dark lane between the two nebulous patches before I realized that there had to be a second patch of nebulosity to complete the appearance of a dark lane. This nebula came as a surprise to me. If I had seen it before I had forgotten about it.

A third patch of nebulosity, NGC 2071 was easily seen surrounding a bright star in the same field of view north-northeast of M78.

After looking up M78 in various books and atlases I noted a fourth patch of nebulosity, NGC 2064 southwest of M78. I failed to notice this patch at the telescope; but now that I know it's there I can look for it next time.

Venus (07 March 2007)

Date: 07 March 2007 U.T.
Time: 1:28 - 1:42 U.T.
Telescope: 30cm Newtonian
Magnification: 200x
Filters: #80A (Blue), Moon&SkyGlow (Multiband)
Seeing: Poor to Fair
NELM: Twilight
Temperature: +46 F (+8 C)




The above sketch shows the basic appearance of Venus on this evening. South is up. Preceding is to the left. The 'X' shaped pattern was caused by 'spider diffraction.' The telescope's diagonal mirror is supported in the center of the tube by four, thin vanes (the spider). Usually spider diffraction isn't noticed; but on bright objects such as Venus enough light is transferred to the diffraction pattern for the eye to notice.

The fat, gibbous phase of the planet was the only obvious feature seen. During the first half of the observation a #80A filter was used. During the second half of the observation a Moon-SkyGlow filter was used along with the #80A filter. The #80A filter transmits 30% of the incident light. The Moon-SkyGlow filter transmits significantly more light and works like an RGB-Intensifier.

The filters gave the planet a weak, bluish tint. The diffraction spikes had a silver-gray color. The background sky was grayish. A break (gap) in the diffraction spikes was apparent approximately 5 or 6 planetary diameters from the planet.

Part of the west wall of my open-air observatory was lowered earlier in the day in order to allow the telescope to 'see' lower in my western sky. In an earlier attempt to observe Venus with the 30cm telescope the wall had gotten in the way.