6 July 2006
Yesterday I went through my reproductuin antique star chart cards to identify all of the obsolete constellations on them with the aim of starting to find those missing figures in the sky (I am optimistic that someday the clouds will part and we will be able to see the sky again). While searching the web for information on the obsolete constellations I came across a site that has information on the cards and scanned copies of them.
Today I checked at the library to see if the August issue of Sky & Telescope had arrived yet so I can start getting dates for upcoming Jupiter events. The same issue I have been seeing there for a while was still there. I picked it up to look at the tables thinking perhaps this was the issue I needed and I haven’t realized it all this time but that wasn”t the case.
On opening the magazine it fell to the beginning of a story about the star charts of John Flamsteed. In the article they show pictures of several other star atlases and I happened to have my star cards with me so compared them to the various samples in the article. The illustrations on my cards bear some resemblance to those of Flamsteed but are more similar to the French edition of the Flamsteed atlas published by Jean Fortin in 1776. The major difference between the cards and the atlases is that the cards lack the coordinate grid contained in all of the atlases.
A few observations on the Flamsteed atlas (based on one plate).
- the stars are depicted by various sizes of circles, or squashed circles, relative to their brightness
- the atlas uses both the RA/Dec and Alt/Az grids
- there are no dividing lines between the constellations
- Orion’s sword has a handle and hilt but no blade so it looks more like a penis than it does a sword
Notes on the history of celestial cartography
- first sky chart by Albrecht Durer in 1515
- depicted stars as seen from outside the universe
- used a polar grid system based on Ptolemy’s catalog
- first sky chart as seen from earth by Alessandro Picolomini in 1540
- brighter stard had larger symbols
- stars identified with Roman letters
- atlas based on Copernicus’ observations by Giovanni Gallucci in 1588
- trapezoidal projection
- ”latitude” lines parallel
- ”longitude” lines straight but converge to top of bottom
- trapezoidal projection
- Uranometria published by John Bayer in 1603
- based on Tycho Brahe’s observations
- calibrated trapezoid projection
- bright stars labeled with Greek letters
- star patterns as seen from earth but depictions from the rear
- classical star location descriptions appeared backwards
- Uranographia by Johannes Hevelius, published after his death by his wife in 1690
- calibrated trapezoidal projection
- based on Hevelius’ own observations
- star patterns as from outside the solar system, depictions matched
- also made a Moon atlas
- based on Flamsteed’s own observations from the Royal Observatory, London
- star locations and figure depictions agreed with classical descriptions
- first use of the RA/Dec grid system in an atlas
- contains a secondary grid system based on the ecliptic
- sinusoidal projection minimizes distortion
- parallels are equidistant straight lines; meridians curve toward straight central meridian
- smaller version (7”x9” vs 20’x24’) of Flamsteed’s atlas
- used by Charles Messier
- new charts included new stars
- conic projection
- 100 constellations, 17,000 stars
| Observing Location | TotL | ||||
|---|---|---|---|---|---|
| Observational Period | 2100-2315 EDT | ||||
| Atmospheric Conditions | When I arrived it was partly to mostlly cloudy but then it started to clear off as all of the weather forecasts I had checked said it would, save CSC. They had it being partly cloudy around sunset then becoming totally cloudy for the rest of the night. Kin arrived in time to comment on how transparent the air was between the clouds. Shortly thereafter he was packing up as the sky was totally overcast and showing no sign that it was going to break up. It didn't. It turns out CSC had the best forecast for tonight. At one point I felt a few drops of rain and just before leaving Kin felt the same. It was basically virga.
| ||||
| Instruments | SAR: Coulter CT-100 -Charlie
Conditions went south before I even took the scope out of my pack. Canon 15x50 IS binocular - Charlie I was having trouble with the binocular again tonight. I couldn’t get it to focus on anything and the stars all had three tails. I was worried that I might have banged it although I didn't remember having done so. I tried turning on the image stabilization to see if that would change anything and found that the IS batteries were dead. The IS switch must have been turned on repeatedly in my bag. I replaced the batteries and the problem has disappeared. Celestron 10x50 binocular - Kin | ||||
| Observing Party | Charlie Ridgway
Kin Lee |
| Target | Jupiter |
|---|---|
| Constellation | Vir |
| Category | Planet |
| Time | 20060706.2150 EDT |
| Comments | The Moon, Jupiter and Spica are forming a large arc or a flat triangle.
Two moons (Callisto and Europa) were on the left side of the planet and one (Ganymede and Io) on the right. Io was very close to the planet. TYC 5575-00473-1 was above Ganymede and would have easily been taken as a moon as it appeared about the same brightness. TYC 5575-00164-1 was farther away at 4:00 but also would be mistaken for a moon by the untrained observer. |
| Target | Moon |
|---|---|
| Constellation | Lib |
| Category | Lunar |
| Time | 20060706.2155 EDT |
| Comments | The moon was looking very nice but I didn't have time to really study it.
There were a lot of faint rays coming off of Copernicus. Rays were also seen leaving Tycho and although brighter they were not as impressive as those around Copernicous. Sinus Iridum, Plato and the area between them looked like three scalloped indentations on the edge of Mare Imbrium. Mare Nubium had just come off the terminator and looked very nice. Tonight would have been a good night to have used SAR with the Barlow if it hadn't clouded over. |
posted by Charlie at 12:03
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