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.
27 March 2007
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.
25 March 2007
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!
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
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.
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.
18 March 2007
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.
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.
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.
10 March 2007
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.
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.09 March 2007
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.
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.
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.
07 March 2007
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.
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.
04 March 2007
Lunar Eclipse
Date: 4 March 2007 U.T.
Time: 1:03 - 1:26 U.T.
Telescope: 102mm SCT
Magnification: 34x
Seeing: Bad
NELM: Bright Twilight
Temperature: +37 F (+ 3 C)
The rising Moon was spotted in the trees at 1:03 U.T. -- just nine minutes before the end of the umbral phase of the eclipse. The Earth's shadow along the Moon's eastern limb was obvious in the telescope as well as to the unaided eye.
The seeing was very unsteady. Rapidly moving undulations were in constant motion along the limb as well as over the face of the Moon.
Colors: The Moon was a golden, yellow-orange color outside the umbra. No colors other than shades of gray were noticed near and within the umbra.
Observational Highlights: As occasionally happens in this hobby, I started out with the objective of observing one thing (the final phase of an eclipse) and ended up with a bit more. Due to atmospheric refraction the rising Moon appeared noticeably 'squished'. It appeared shorter along its vertical axis than along its horizontal axis. But of greater interest were the colors (due to atmospheric refraction) hugging the lunar limb. From top to bottom along the lunar limb the colors were: blue, green, yellow, orange, and red. As the Moon rose higher in the sky these colors became less noticeable.
The Penumbra and Clouds: An attempt was made to observe how long the Earth's penumbra could be positively distinguished on the Moon after the umbral phase of the eclipse had ended. Unfortunately, at 1:25:30 U.T. a thin cloud began covering the Moon. Up until that point in time it was possible to distinguish (with telescope as well as with the unaided eye) the effect of the penumbra of the Earth's shadow on the Moon. It seemed ill-advised to continue the observation with the complicating effect of clouds.
Time: 1:03 - 1:26 U.T.
Telescope: 102mm SCT
Magnification: 34x
Seeing: Bad
NELM: Bright Twilight
Temperature: +37 F (+ 3 C)
The rising Moon was spotted in the trees at 1:03 U.T. -- just nine minutes before the end of the umbral phase of the eclipse. The Earth's shadow along the Moon's eastern limb was obvious in the telescope as well as to the unaided eye.
The seeing was very unsteady. Rapidly moving undulations were in constant motion along the limb as well as over the face of the Moon.
Colors: The Moon was a golden, yellow-orange color outside the umbra. No colors other than shades of gray were noticed near and within the umbra.
Observational Highlights: As occasionally happens in this hobby, I started out with the objective of observing one thing (the final phase of an eclipse) and ended up with a bit more. Due to atmospheric refraction the rising Moon appeared noticeably 'squished'. It appeared shorter along its vertical axis than along its horizontal axis. But of greater interest were the colors (due to atmospheric refraction) hugging the lunar limb. From top to bottom along the lunar limb the colors were: blue, green, yellow, orange, and red. As the Moon rose higher in the sky these colors became less noticeable.
The Penumbra and Clouds: An attempt was made to observe how long the Earth's penumbra could be positively distinguished on the Moon after the umbral phase of the eclipse had ended. Unfortunately, at 1:25:30 U.T. a thin cloud began covering the Moon. Up until that point in time it was possible to distinguish (with telescope as well as with the unaided eye) the effect of the penumbra of the Earth's shadow on the Moon. It seemed ill-advised to continue the observation with the complicating effect of clouds.
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