Date: 13 January 2008
Time: 3:05: 3:25 U.T.
Binoculars: 8x42 & 20x80
Telescope: 80mm f/5 Achromat
NELM: 6.0 to 6.5
Comet Holmes was visible to the unaided eye, but it was significantly better with the binoculars. A crescent moon was above the horizon to the southwest, but appeared to have little if any adverse effect on the evening's viewing. Clouds were approaching from the west.
Mars looked like a tiny, yellow-orange disk in the ST-80 at 105x without filters. Markings on the planet were difficult to see with the small telescope, but they became easier when the planet's brightness was reduced and contrast was increased via the use of a #23A Light Red filter. The #23A filter transformed the color of the planet to a orange-red. Normally I wouldn't consider using such a small telescope on Mars, but I was curious concerning what could be seen with minimal optical aid. Without any filters, the ST-80 is likely to disappoint just about anyone when viewing Mars. With filters, a fair amount of patience, a bit of observer experience (and a good solid mount!) it's possible to conduct some regular study of Mars when the planet is near opposition, but I would strongly suggest that any interested observer use a larger, higher quality telescope.
Surface markings were ill-defined and difficult to pinpoint in location due to the telescope's small aperture, the relatively low (for Mars) magnification, the less than perfect (achromatic) optics, and the somewhat uncooperative, home-made mount (One of these days I should add a friction adjustment to the mount's altitude axis).
After Mars I lowered the magnification to 22x using a wide-angle eyepiece. I took quick looks at the Great Orion Nebula, the Andromeda Galaxy (and its two nearby satellite galaxies), M33, and Comet Holmes. The ST-80 and its home-made, alt-az mount seem to perform at their best when used for such low magnification purposes. All of these objects were very pleasing in the small, short telescope. Comet Holmes looked like a fairly bright, diffuse (amorphous) cloud occupying approximately one-third of the 3.34 degree field of view.
In the course of the evening's short session I never felt any need to uncap the telescope's finder. It was easy enough to point the telescope at Mars, etc. with the 22x eyepiece in place prior to switching to higher power.
I brought the telescope and mount inside, leaving the tripod out in case I decided to try out a 102mm (4-inch) SCT on Mars. Later, when I went back outside, I discovered a cloud covered sky and frost on the tripod. It was clearly time to bring the tripod inside and wait for another clear night.
13 January 2008
02 January 2008
Two Bright Comets
Date: 2 January 2008
Time: 4:30 - 4:50 U.T.
Instrumentation: Binoculars and Unaided Eye
NELM: 6.5 or better
Temperature: +3 F (-16 C)
Comet 17P/Holmes remains an easily visible naked-eye comet. I was able to immediately spot and recognize this comet with the unaided eye upon stepping outside. The view was improved with 8x42 binoculars, and improved even more with 20x80 binoculars. Comet Holmes has increased in size and become a bit more diffused in appearance since my last blog entry.
Comet 8P/Tuttle was initially spotted near the Aires - Pisces border with the 8x42 binoculars. It was better seen (as a circular haze with a brighter center) with the 20x80 binoculars. At times I suspected Comet Tuttle as being visible to the unaided eye, but I was never 100% convinced.
These observations were made from my south porch after a period of indoor dark adaptation. The floor of the Colosseum (my open-air observatory) has been coated with a layer of ice for the past couple of weeks. Thus it would be ill advised to set up a telescope at that location.
Future Plans: At present I'm inclined to make fewer blog entrees and post even fewer sketches in 2008; but one never knows for certain what the future may hold.
Time: 4:30 - 4:50 U.T.
Instrumentation: Binoculars and Unaided Eye
NELM: 6.5 or better
Temperature: +3 F (-16 C)
Comet 17P/Holmes remains an easily visible naked-eye comet. I was able to immediately spot and recognize this comet with the unaided eye upon stepping outside. The view was improved with 8x42 binoculars, and improved even more with 20x80 binoculars. Comet Holmes has increased in size and become a bit more diffused in appearance since my last blog entry.
Comet 8P/Tuttle was initially spotted near the Aires - Pisces border with the 8x42 binoculars. It was better seen (as a circular haze with a brighter center) with the 20x80 binoculars. At times I suspected Comet Tuttle as being visible to the unaided eye, but I was never 100% convinced.
These observations were made from my south porch after a period of indoor dark adaptation. The floor of the Colosseum (my open-air observatory) has been coated with a layer of ice for the past couple of weeks. Thus it would be ill advised to set up a telescope at that location.
Future Plans: At present I'm inclined to make fewer blog entrees and post even fewer sketches in 2008; but one never knows for certain what the future may hold.
12 December 2007
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.
10 December 2007
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 . . .
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 . . .
03 November 2007
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.
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.
30 October 2007
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/
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/
28 October 2007
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 appearedto 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.
27 October 2007
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!
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!
26 October 2007
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.
11 September 2007
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.
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