Astro-Blog

This version of my amateur astronomy weblog is now using WordPress to manage the content. The older version, which was a static html page, is left as an archive.

November 30, 2007

Venus in the daytime

Filed under: Naked eye observing, Observing — nick @ 10:05 pm

30 November 2007: Early morning naked-eye observations

Around 6:30 am I was outside to let the dog out. The sky was still dark, and it was crisp and clear. I looked around and saw the moon (about half-full), Mars, Saturn, and Venus (shining like a bright jewel in the eastern sky) strung out in a line, demarcating the plane of ecliptic. Orion was also astride the sky in the southwest with another dog or two nearby to keep him company, and to the north the great bear was upside-down.

Around 8:00, after the kids were off to school, I took my dog for a walk before going to work. It was bright and clear, so I decided to see if I could do a naked-eye sighting of Venus after sunrise. I had spotted Venus in the daytime a couple of times in the past, but only with a visual cue such as nearby moon to help out. I scanned the sky in the area I thought Venus should be. I had an early success! A point of light flitted into view for a brief few seconds before I lost sight of it.

Maddeningly, I then spent a few minutes trying to repeat the observation. Fortunately my dog was very patient because she found some kind interesting smell to keep her occupied. It can be very frustrating experience attempting to find a rather small point of light at infinite focus without nearby visual cues to help. Other thing interfered as well; I became acutely aware at the number of floaters and other junk that had accumulated within my eye over the last 47 years. Also, I began to experience the blue field entoptic phenomenon. This is when you can actually see the movement of blood within the capillaries of your retina; it appears as tiny points of light that follow defined tracks within your field of view.

Well, fascinating as this was from a physiological point of view, it was no help at all in finding Venus. At last, however, I caught site of the elusive planet and held it in my gaze for about half a minute. I checked the time on my cell phone: it was 8:14 am (EST), fully half hour after the local time of sunrise, according to the paper. This was the deepest into daytime that I had seen Venus with my naked eye, and also the only time observing it in the daytime without a visual guide such as the moon nearby or the with aid of binoculars to use as a finder.

Comet Holmes

Filed under: Comet Holmes, Observing — nick @ 3:51 am

28 November 2007: Comet Holmes, Mars

Over the last few weeks either circumstances or weather conspired to keep me from tracking Holmes, but tonight I had a chance and the sky was clear with only a few high clouds scattered about. Around 7:30 I scanned the area around Perseus with my binoculars. The comet was no longer visible to the naked eye (at least not around here) and even with binoculars it was hard to find—it had grown much larger but also much dimmer than it was before. It appeared as a large (greater than a full moon’s-width) but dim, gray, fuzzy smudge just to the east of Mirfak.

With the comet  as dim as it was, I decided to use the 10 in. Dob. I let the tube cool outside for a few minutes while I bundled up (the temperature was just below freezing). After setting it up on the sidewalk in front of my house I scanned the sky around Perseus for the comet. It took a few minutes to find it; oddly enough, it seemed easier to see through the binocs than through the scope. I suppose the extra magnification spread it around enough so that it appeared very indistinct even using the 35 mm eyepiece. It had a very low surface brightness and it appeared as a wispy gray ghost that occupied nearly the entire field of view.

For comparison, I also located M31; it was nearly straight up so I had to crane my neck to use the spotter. I could now see that Comet Holmes had a lower surface brightness than M31.

Before calling it a night, I noticed that Mars was rising; it had been growing noticeably brighter lately so I took a quick look. I could make out a distinct orange disk, but not much surface detail was visible. I’ll have to give it another look sometime when it is higher in the sky.

November 5, 2007

Tweaking the theme

Filed under: Uncategorized, meta — nick @ 2:38 am

4 November 2007

After a lot of messing around with the CSS for this blog, I think I finally got it to look something close to the way I wanted it, with only some minor glitches.

November 3, 2007

Comet Holmes

Filed under: Comet Holmes, Observing — nick @ 4:02 am

2 November 2007: Comet Holmes

This was my third night that I observed comet 17P/ Holmes (The first two observations were on Oct 28 and Oct 29). Around 10:30 pm I went outside to look at the sky. It was pretty clear; some scattered clouds were about, and the seeing was medium quality as the air seemed a bit hazy. Comet Holmes was still easily visible, not noticeably dimmer than before. I could definitely see it as a “fuzzy” object tonight.

I decided to get out the 4.5 in Dob tonight instead of the big one, since I planned on just a quick look. I quickly set the scope on on a small table in the driveway and found the comet quickly. It was definitely dimmer looking than before, but then this scope has only about a fifth if the light gathering ability of the 10 in. Nevertheless, it seemed a litter bigger than before; I estimate it was about a sixth of the angular field of view using my 25 mm eyepiece (calculated total field of view should be about 1.39°). The nucleus was not apparent at all; I thought I might have seen it using averted vision (or perhaps it was just “averted imagination”).

Before I went back inside I took look at Albireo (shining like a pair of blue and gold gems—always a fun object) and the Pleiades (nice but too big to be a good telescope object, at least with my equipment).

As to comparing the the two telescopes over the last few days, there are a couple of points. First, aperture wins, as the saying goes. Bigger glass makes for better views. However, the small Dob is very light and easy to set up and get to viewing; it’s a really fun scope for that reason. It’s pity I don’t use it more often, and if I had better skies, I might.

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