Aurora activity

Despite still being in the dregs of the solar cycle the aurora occasionally really activates, and it's doing so right now. While it's daytime here in North America, the aurora is detectable by the way it distorts radio signals, producing a warbling effect on ionospherically bounced waves. The enhanced ionization also provides the ability to bounce much higher frequency radio signals than is usual, although everything is still subject to that pesky warbling.

Current observed aurora here via a NOAA satellite--it takes some time to refresh in orbit.

Spaceweather.com will have updates at some point soon; they are usually on the ball with sightings of neat events.
See the aurora forecast at UAF; which is useful, although long-term forecasts are always tough.

This alert was brought to my attention by the DXrobot, which monitors radio amateur's contacts for notes about unusual VHF radio conditions. Click here for the arcane info.

P.S. It would seem unlikely for this to be an "event" for Chicago city folk--the moon is out, light pollution is as bad as ever, clouds are coming in, and sometimes these events are short-lived.

Updates: Tesla coil and light bulb

Updates.

I tried to help Igor out on his Tesla coil. It's a traditional spark-gap variety coil. The problem was the secondary kept arcing over to the primary or elsewhere from near the bottom, nowhere near the top, and we didn't see any streamers or such from the top. Nothing we tried would insulate the primary from the secondary--styrofoam, electrical tape, plastic cups. When we changed where we connected to the primary the sparks would change their behavior--sometimes we would get a single spark or sometimes we would get what we think was called "racing sparks"--the ones that jump a few inches on the secondary. Also we tried grounding, although we were up on a third story. All this, plus the fun of a spark gap that literally was too loud to operate. Bang-bang-bang! We need to enclose the spark gap in something to absorb the sound, but to do that would mean we'd also have to set up an air flow via a fan to break the arc. No photos of this work.

The other is a revisit to a Scav Hunt item, a homemade light bulb. This was a success on our part. We used a 0.5mm mechanical pencil lead, connected it to a pair of 6V latern batteries wired in series, giving 12V. The filament was enclosed in a Snapple bottle with wire passed through a hole in the cap sealed with hot glue. To remove oxygen in the air we lit a match or two in the bottle until it went out and sealed quickly. This bulb had a nice ruddy glow to it. We only ran it for thirty seconds or so before it was passed on for the judges to see. I don't know where it is now, so I decided to make another one. The basics were the same except for the power source. I used a 15V AC 1A power supply. I put the filament in a Starbucks glass container that I had worries about being airtight enough. This time it lit nicely, but within ten seconds one side of the graphite became brighter. A post-mortem showed it got brighter because the lead got narrower, and more power was dissipated there, increasing the erosion. It got brighter and brighter and then narrowed to nothing, when it broke.


Graphite filament assembly


Light bulb lit


Lightbulb movie -- Click to play -- sorry for the poor aspect ratio

Space Shuttle and ISS space station visibility this week in Chicago

UPDATE 7/06/2009: Here's the current set of passes.

It's June, the day is nearly as long as it gets, and at night the sunlight streams over the north pole and lights up many low earth orbit satellites even in the middle of the night above Chicago. The International Space Station and the Space Shuttle are well aligned to be visible all this week for Chicago.

See the schedule here at Heavens-Above;

Date	Mag	Starts			Max. altitude			Ends
		Time	Alt.	Az.	Time	Alt.	Az.	Time	Alt.	Az.
2 Jun	0.1	21:26:21	10	NNW	21:28:30	19	NNE	21:30:39	10	ENE
2 Jun	-0.9	23:00:58	10	WNW	23:02:49	35	WNW	23:02:49	35	WNW
3 Jun	-1.1	21:48:13	10	NW	21:50:55	34	NNE	21:52:32	19	E
3 Jun	0.6	23:23:28	10	W	23:23:51	12	W	23:23:51	12	W
4 Jun	0.0	20:35:37	10	NNW	20:37:44	18	NNE	20:39:51	10	ENE
4 Jun	-2.5	22:10:13	10	NW	22:13:06	84	SW	22:13:35	58	SE
5 Jun	-1.0	20:57:26	10	NW	21:00:06	33	NNE	21:02:45	10	E
5 Jun	-0.7	22:32:38	10	WNW	22:34:39	24	WSW	22:34:39	24	WSW
6 Jun	-2.4	21:19:21	10	NW	21:22:15	89	WSW	21:24:26	16	SE
7 Jun	-0.8	21:41:41	10	WNW	21:44:11	26	SW	21:45:33	18	S
9 Jun	-0.8	20:50:39	10	WNW	20:53:12	28	SW	20:55:44	10	SSE

For the next few nights you can see the ISS and Shuttle twice in one evening; literally, on the next orbit.


UPDATE 5/13/2009: Looking for the current Shuttle passes?

Re: Even more awesome Mars images?

As rumored, here's the awesome Mars Phoenix image. An image later in the descent as the spacecraft nears the surface. Heimdall crater is within twenty kilometers of the landing site but just in the background in the image (You can't see it from the landing site).




Via Planetary Society Blog.

P.S. Also see the image of Phoenix on the ground at HiRISE blog. Heck, see the full image to see the parachute and heat shield as well.

Sudden cold front temperature change

A fantastic wind shift and cold front passage last night dropped temperatures by twenty degrees Fahrenheit in the course of a few minutes. As is common here, the cold front used the lake as an expressway south to accelerate and end an otherwise warm and humid Memorial Day. As experienced by me, a quiet warm night suddenly grew loud as the trees shook, then a blast of cold air blew through my open windows in a gust. Another account.

This data is from the Ryerson weather station.
--Timestamp--- Temp Humid Dewpt Wind HiWind WindDir
20080526 19:30 80.6 57 63.9 8 18 247
20080526 20:00 79.8 58 63.7 6 15 247
20080526 20:30 79.0 61 64.4 5 13 270
20080526 21:00 78.2 63 64.6 4 13 247
20080526 21:30 77.6 66 65.3 5 11 247
20080526 22:00 76.8 67 65.0 5 11 247
20080526 22:30 76.1 69 65.2 4 11 270
20080526 23:00 54.3 73 45.8 10 35 270
20080526 23:30 51.9 78 45.3 18 41 0
20080526 24:00 48.8 82 43.6 18 33 0


One of the few storms that popped up on the warm side earlier that evening
Is this cloud from the cold air bumping the warm humid air up and out of the way?

Even more awesome Mars images?

You've seen the amazing image of Phoenix descending in the Martian atmosphere as taken from MRO's HiRISE. (As Emily Lakdawalla puts it: "OMG!! Parachute!!!! Photo !!!!!" You might have seen the first false-color images. But now there is a rumor about another HiRISE image of Phoenix while it was still descending in front of Heimdall Crater.

Is this that image? Not spectacular enough after the first image.

One hour to Phoenix Mars Landing

One hour to go.

The newest supernova in the Milky Way

The last supernova in the galaxy was Kepler's star of 1604 in Ophiuchus. Or was it? You'd expect a supernova in a barred spiral of our size every 50-100 years. We haven't seen any, and it's because of that pesky dust in the way, blocking our optical view. But it looks like follow-up x-ray work from Chandra has found evidence of a 150-year old supernova in Sagittarius!


X-rays in orange, radio in blue. Reminds me of the firefox logo.

It looks like the impetus for revisiting the radio work in 1985 was that the x-rays detected by Chandra were significantly outside the 1985 radio contours implying rapid expansion. See the paper here.

P.S. Tip to General Carlessness and Bad Astronomer

Adventures in large format digital photography: part 5

I got the camera working again, kinda of. It doesn't work with TWAIN enabled stuff. It will work just fine using Vuescan on Windows and XSane on Ubuntu. Exposures are weird with Vuescan--I seemingly lost 3 stops of speed with it.

I also dremeled open the highly vignetting slot that previously limited the images to that narrow vertical view. I can now scan 7x11 inches. (Somehow I lost an inch and a half--the sensor is dead below 7 inches). There is also a band of vignetting and/or low sensitivity right across the central-top of the frame.

Kaguya: Color on the Moon

I was perusing (as best as possible without reading Japanese) the currently released images of the Moon from the Japanese spacecraft Kaguya when I encountered this one. You nearly forget all the images are in color when all you are looking at is the nearly monochrome Moon.

Click to enlarge to HDTV resolution

The bad idea of a gas tax holiday

Tom Friedman points out the obvious stupidity of McCain's and Clinton's idea of a gas tax holiday for the summer.

Broke the camera

In my attempt to remove the prominent vignetting which restricts the scanned area to 5x8 inches, I broke the camera. This was to be expected, as it has happened every time I try to do it (or at least soon thereafter). I can only hope the problem is a physical gearing issue, which means I might be able to fix it. And I hope it does, as I'd love to take it out west and south and other places...

Rockefeller Chapel, Reynolds Club, and Flowers

The light was rapidly falling last evening and this was my last image, with a full open aperture, but it was still underexposed by about a stop. Expressed in other terms, a film camera with 100ASA film would expose for this for about one second at f/8. Autoleveled and hue adjusted in photoshop. See the original here. This also was the first outing of the camera with a coat of black paint in the interior, an additional baffle on the top to handle light when doing macro work, and I added a shoulder strap with some eyelets (one broke on the trip). Remind me to stick some teflon strips or wax the bottom of the inner box--it's getting too hard to move to focus.


A color image, underexposed. The lightest of breezes moved the daffodils a touch between exposures. The flowers were just over 4 feet away.

CF Torchiere replacement

Compact Fluorescents are all hot right now. And it's Earth Week.

I bought a floor lamp from Home Depot that used a single standard bulb and didn't have any fancy dimmer system: it just had a hi/lo switch (I'm still not sure what it does with it--the CFLs flicker on the low setting, so I quickly turn the lamp to high when flipping the switch. It could be a simple rectifier to provide 50% of the power). I then bought three lamp socket splitters. These screw into a standard lamp socket and provide two sockets. So, with three splitters, a single socket becomes four. This is OK because the CFLs use so much less power--with four of them, I'm only using 100W, and the floor lamp suggests using a 150W standard bulb. The sockets themselves are rated higher, so I think the 150W max is for thermal/fire issues (high wattage bulbs can start fires if drapery or other flammables fall on them).



Taking pictures of lighting fixtures is hard--either the fixture looks dim and the room dark, or the fixture is overexposed.



If you think the color temperature is off, you can adjust by using different color CF bulbs. Here was an experiment with a 2:1 warm:daylight ratio.


an even ratio between warm and daylight. This was too cool for evening use. The color is way exaggerated here--the yellow bulbs are nearly white to the eye.


The color of the photographs is too strong--your eye does not see such strong color in the fixture.

In any case, I made this fixture 100% n:vision 100W soft white bulbs, and use it all the time. I have a second fixture where I replaced the dimmer switch with a standard push switch (it's tough to find a switch that fits in small diameter torchieres) so I could use compact fluorescents in it. I put 3 GE 100W daylight bulbs in the latter fixture and use it only during the day.

Now the caveat: the splitters stick the bulbs higher than where an incandescent would be in the fixture. Ideally the rim of the lamp shade would be a touch higher, but I've yet experimented with the right material to make one. Doing so would improve the fixture and reduce glare from it.

The end result is I've increased the lighting in my otherwise dark apartment (north facing windows on the first floor) and decreased my lighting energy usage by 50%, even more on average since I don't use the second fixture at night. I'm already being paid back on my electricity bill: some $10 a month less.

Weather on campus

The Ryerson Astronomical Society got SG funding for a weather station on campus, to get accurate weather data (which is really important in the spring with lake breezes freezing the lakefront while Midway is warm). We finally overcame all obstacles last night and have the station live at http://sagan.uchicago.edu/. I believe we have other delivery vectors to set up, so it can be seen at the Reynold's Club TV screen and such.