NavList:

   

Reply

George H, you wrote:
"That was the claim that presumably Frank is repeating, as he has linked our 
attention to it once again. Does he still maintain those words?"

As I said to you back then, George, the pointing accuracy is not a critical 
matter. I said this to you again and again and again. I linked to that post 
to repeat my point about using this technology to boost celestial navigation 
education. It's going to be revolutionary. The number of people who can 
identify the brightest two dozen stars on any night may be ten times higher 
in two years than it is today (and I don't mean people who can point their 
phones, click a button, and read the screen... I mean people who have done 
that enough times that they can walk down a street and say "Oh look... that's 
Vega... I learned that from my phone last week").

And you wrote:
"At the time, I expressed my usual scepticism. It seemed too good to be true. 
It was. Being entirely dependent on the local magnetic field, its pointing 
accuracy could be no better than the local magnetic field was. The ensuing
discussion flows under the threadname "learn the stars, by phone"."

Yes, alas, there were quite a few pointless posts in that thread distracting 
from the original subject. That original subject must really bug you, George. 
Is the very thought that ordinary people, mostly young people, might be able 
to learn the names of the navigational stars from a mobile phone somehow 
discomforting to you? You appear to be obsessed with pointing accuracy. So 
let me repeat, POINTING ACCURACY IS NOT A MAJOR CONCERN FOR THIS APPLICATION. 
Sorry to yell at you, George, but you do sometimes need it.

And you wrote:
"On investigation, it turned out that Celestron had quickly relaxed that spec 
to a pointing precision of 0.5 to  "2 to 3 degrees", interpreted as 3 degrees 
by a Celestron distributor."

And just a reminder, George, you have still not even bothered to define 
"pointing precision". How strange to worry so much over something that you 
have not defined...

And you wrote:
"We were assured that the instrument could detect the presence of local 
magnetic material, and give a warning, before significant error occurred. 
That seemed unlikely; see recent results, below."

It can do so, yes. Does it do it perfectly? No. Why should it?? Any child can 
break a toy. And sadly, many children can only think of demonstrating that 
talent when presented with a new toy. The SkyScout does indeed give a warning 
under many circumstances. That it is not perfect is to be expected, and it's 
hardly worth mentioning. Have you once again confused an educational 
observing tool with a measuring instrument??

And more:
"So that implied that the pointing could be off-axis by 3 degrees, and the 
instrument could still meet its revised spec., a target width 6 degrees 
across (about 3 fingers at arm's length). Celestron claimed that their 
database included 50,000 sky objects: that target might contain 34 of them."

Wow. You really are very confused by the purpose of this machine, aren't you? 
Let's take two examples from this database (actually from a similar database 
on a mobile phone version of this idea but almost certainly included in the 
Skyscout database): the star Vega and the "center of the Milky Way". The 
first object is one of the very brightest stars in the night sky. The second 
is quite invisible from the Earth in optical wavelengths. 

Including the first object, Vega, in the database is an obvious choice. It's 
there because a backyard observer might well point the device at "that bright 
star up there" and click the "Identify" button. Now it's possible, just 
barely possible, that some very bad software designer would ask the software 
to start with the faintest object in the database near the pointing location 
and indicate that object as the identity of the bright star in the sky. And 
in that case, the pointing accuracy would be terribly important, and your 
point would be made. But guess what, George -- people aren't idiots. The 
software starts with (or appears to start with) the brightest object in the 
indicated direction when it is in Identify mode. 

Why is the center of the Milky Way in the database? We can't see it. This 
object falls into the second type of functionality found in the SkyScout and 
similar devices. That's the "Show me" mode. You select an object, like this 
one, from the database on-screen and then you hit the "Show me" button 
(whatever its equivalent is on Skyscout). It then responds with arrows which 
will guide you to that part of the sky until that spot in Sagittarius is more 
or less centered in the field of view. The software can then tell you "all 
about" the center of the Milky Way. It's educational, and it's very 
entertaining for many people to know that they are looking right at it even 
though it's just a blank patch of sky. It's literally like a planetarium show 
in the palm of your hand.

And you wrote:
"In the absence of any magnetic perturbation, no doubt that instrument, or 
some sort of fancy-phone that works the same way, might do a reasonable job 
in pointing precision"

Fine. That's all that's required. Let me repeat that a little louder for you: 
THAT IS ALL THAT'S REQUIRED. 

And you wrote:
"though not, unfortunately, in a moving envirenment at sea or on land."

Certainly not with current implementations of this technology. To deal with 
accelerations would require a more sophisticated inertial system if such 
functionality was really desirable. And if I did not see people playing "Wii 
Bowling" every night in local bars, I might contend that the possibility of 
miniature inertial motion analysis in a handheld device was science fiction, 
something for the 22nd century, not this one. But they do. That said, WHY 
WOULD YOU CARE? Why would operation in a "moving environment" be desirable? 
What difference does it make that you can't do this while flying down the 
parkway in your car and accelerating around curves? Is that really an 
important environment for learning the names of the stars and, perhaps, 
pointing out the location of the center of the Milky Way??

And here's George's big coup de grace for this technology:
"With a firm footing in the open air, away from vehicles, steel-framed 
buildings, a pyrites seam, or steel-framed spectacles, it might be fine as 
long as the magnetic mapping gets updated periodically. Elsewhere, how can a 
user be sure that it's unaffected, in a world that's rife with iron and 
steel?
Not by relying on the indicator that warns of the presence of magnetic 
material. An attempt, not by me, to try fooling it, showed that it was 
possible, with care,  to approach a Skyscout, from East or West, with a small 
magnet held horizontally, to within 10 cm, and thereby twist the indicated 
azimuth by all of 50 degrees, before it indicated presence of magnetic 
material!"

LOL. It's a good thing we have you here, George, to keep us from putting 
magnetic compasses in our mobile phones. Those engineers at Apple, Motorola, 
Nokia, and the others owe you a debt of gratitude. You have proved that the 
software which they have running on their phones using magnetic compass data 
cannot possibly be running on their phones using magnetic compass data. It 
cannot be. I presume that reality, having been observed by you, has now 
collapsed into an eigenstate where such devices and such software no longer 
exist. Poof!

Or maybe not. Maybe reality is what it is, and the problems you feel you've 
found simply aren't relevant to "useful" functionality. Do you suppose that's 
possible, George?? As for being able to "break" the behavior of the Skyscout 
by carefully bringing a magnet up to it, well, yes, you can break any toy. 
Does that mean you could never find any pleasure in using one, knowing that 
it is imperfect and capable of being fooled?? Do you contend that no one 
could learn the stars this way because some gremlin might be sneaking up on 
them with a magnet?? 

George, you wrote:
"In his recent posting, Frank appears to be rowing back from magnetics"

Not in the slightest. Please do not put words in my mouth. The mobile phones 
using GPS positions and magnetic compasses to point the user to astronomical 
objects using specialty software currently EXIST. Why would I be "rowing 
back" from reality?

And you quoted me saying that the technology 
"generally implies a built-in magnetic compass. There's a way around this in 
major cities if you use some sophisticated processing (which can occur 
server-side) to take the image, the GPS (or wifi) location data and then 
figure out direction based on the buildings seen and maybe even using shadows 
if it's daytime. That combined with the simple inertial sensors in many 
phones would yield orientation without a magnetic compass."

Yes, I was pointing out that it might be possible to do some of this 
"augmented reality" stuff that they've been talking about by turning the 
tables. Rather than using the compass to get direction, we could use 
astronomical cues or obvious landmarks to get direction. Shadows are rather 
easily defined in photos in urban environments. If the phone knows the 
location and date and can detect a long shadow pointing in a particular 
direction, then it can get orientation EVEN WITHOUT a built-in compass. This 
would require a fair amount of image processing using the camera's live video 
which poses certain privacy and security issues (!!!) so that may be a long 
time in coming (read five years instead of two).

And George, you concluded:
"Is Frank really serious? In what circumstances could such technology 
conceivably aid a viewer of the night sky? We've had many absurdities on 
Navlist, but this one ranks near the best."

George, for the life of me, I cannot fathom how you become so confused by the 
things I say. Do you REALLY have such trouble reading my sentences? Or are 
you just trolling (in this case, "trolling" means posting absurdities just 
for the fun of being annoying)?

-FER





--~--~---------~--~----~------------~-------~--~----~
NavList message boards: www.fer3.com/arc
Or post by email to: NavList@fer3.com
To , email NavList+@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply