Saturday, July 30, 2005

Bad time to be away

Brown's team, afraid of being upstaged by someone else, dropped the bomb in announcing 2003 UB313 -- and finally found the big one. Bigger than Pluto. It had to happen.

Thursday, July 28, 2005

Huge new Kuiper Belt Object / Transneptunian Object?

2003 EL61. A Spanish survey claims to have found a mid 17th magnitude object with a proper motion consistent with a TNO at 51 AU distance, and have images of it from 2002 and 2003.

Their web site

According to our best orbit fit and using regular assumptions on phase angle
correction, the H value es around 0.3. Unfortunately we do not know the
geometric albedo but if below 0.25 (which is the case of all TNOs for which an
albedo has been measured except Pluto), the object would be larger than Pluto.
However, it may well happen that this object is abnormally bright (with a very
high albedo), like Pluto. So, depending on the albedo, this object might be sort
of a Pluto's brother or Pluto's father...

This object is beyond Pluto and almost reachable by most amateurs, which is the
reason why we write here!. It is observable right after sunset for a while at a
reasonable elevation. Maybe some decent science can still come out of your

Time will tell if it is a legitimate huge find. The size/population numbers have always indicated that there should probably be at least one more Pluto-size object out there, and I always believed someone would find it. Early KBO papers after the discovery by Jewitt and Luu of 1992 QB1 discussed the size distribution with Pluto at the top and kept the option open of other big ones.

Saturday, July 23, 2005

Completed projects and stuff to do.

I realized after seeing this that I have failed to remember to write up completed projects of the past. So some brainstorming about what's been done is appropriate.

Solar Spectroscope design
Digital setting circles on Ryerson telescope
Long-term office radiation -- just finished a long series at work 9.3microRads/hr.

stuff to do
humidity project
lightning detector
VLF radio on computer
coffee can furnace (finally a place to use those huge aluminum backplanes on hard drives)
light pollution sensor
fabric dyes (coffee, mulberry)

Tuesday, July 19, 2005

Linking to other blogs

Do people generate hits by linking to other people's blogs? I.e., the almost required links on the right of every blog?

Disassembling printers can be useful

I actually used knowledge gained from taking apart those inkjet printers to actually fix a big expensive inkjet at work today! Seems someone created a paper jam that jammed up into the path of the speeding ink carriage, knocking it off the drive belt.

Friday, July 08, 2005

Inkjet printer technology

I disassembled a broken Epson C80 inkjet printer the other day. They nearly always clog if you don't use them constantly, if you use them constantly but have low humidity, or if you look at them the wrong way. It was a useful exercise, and I learned a few things about the state of printer engineering and how things change over time.

The engineers have decided that the principle of "imprecise positioning with a cheap motor, but with feedback", is a better/faster/cheaper approach than "precise positioning, assume the motor goes where commanded". Instead of stepper motors, with their high torque and their ability to hold them at a defined angle, they used standard DC motors, and read what they're doing via optical encoders, both rotary and linear, on the axles they move (aka servos). In the telescope world, most people prefer to use steppers for positioning. is a full overview of steppers. I got into learning about motors from the king of converting telescopes into computer-controlled monsters: Mel Bartels

You can tell you have a stepper in your hand if the motor has four or more wires going into it. When you turn the shaft of them, they should feel like they move into defined positions as you rotate it.

I've taken apart a number of inkjet printers, starting with old HP Deskjets from 1990. They used encoders and standard motors too, but the printer was designed to last. Canon Bubblejets from the mid-90's used steppers; and I had always assumed all printers would from now on. The HP Deskjets also used a Z80 CPU; I'd always loved that an ancient processor was still being used in embedded stuff. Keith tells me it's a great processor.

In addition to the DC motors I get some encoders, a beautiful aluminum heatsink, and a 1/3Farad backup capacitor. I would have had a huge absorptive sponge too, but it was full of ink.

Thursday, July 07, 2005

Steven is (or was) here

The TERRA satellite rocks. Steven is in the Yucatan in Mexico. I grabbed an image from TERRA taken on June 30th. The linked file is a huge crop from a even bigger image.