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General Astronomy >> Light Pollution

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Nop
Vendor (iPushto)


Reged: 02/12/06

Loc: Netherlands, Valkenburg
Dark Sky Meter Live map now online
      #5898973 - 06/03/13 03:06 AM

Dear all,
Our Dark Sky Meter map is online. The map contains all valid night sky measurements made with the Dark Sky Meter for iPhone. It's fully automated.
Feel free to explore
http://www.darkskymeter.com/map/
Regards
Norbert

PS Note that this is a 'semi-live' map. All the data is refreshed every hour.


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cuivienor
professor emeritus


Reged: 10/07/10

Loc: Tokyo, Japan
Re: Dark Sky Meter Live map now online new [Re: Nop]
      #5899016 - 06/03/13 04:18 AM

Hi Nop,

This is excellent! Thank you, I'm already waiting for some new neat data in Tokyo - now if the app can also measure the frequency of light pollution, maybe we could find cities where phase of the streetlights is the same, and this skyglow peaks could be filtered out by blocking out light at the peaks

OK the above was a bit "out there", some on a more feasible angle, I think this app could also turn into a great way to find nice observation places - my understanding is that locations are rounded to 800 meters. Wouldn't it be a good idea to allow users to disclose the exact location (from a public park for example) should they chose to do so? This would turn into a great dictionary of observation sites.

This would be particularly useful for city dwellers like me, in Tokyo, to know where we could travel by train to which park to get the best skies possible! Under that mode, if submitters could also rate their location (streetlights, public lights, etc.) it would make it even more powerful.

Yannick


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dcbrown73
member


Reged: 06/23/12

Loc: Lower Connecticut
Re: Dark Sky Meter Live map now online new [Re: cuivienor]
      #5899216 - 06/03/13 09:09 AM

Pretty cool. Though, I'm an Android guy. I don't have any iOS devices.

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REC
Post Laureate
*****

Reged: 10/20/10

Loc: NC
Re: Dark Sky Meter Live map now online new [Re: Nop]
      #5899239 - 06/03/13 09:25 AM

Oh, that's cool. Just saw my post of 18.42 here in Gastonia, NC.

Bob


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pfile
Post Laureate


Reged: 06/14/09

Re: Dark Sky Meter Live map now online new [Re: REC]
      #5899881 - 06/03/13 02:40 PM

i wish you would fuzz the locations on the map a little bit... bit of a privacy concern.

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Nop
Vendor (iPushto)


Reged: 02/12/06

Loc: Netherlands, Valkenburg
Re: Dark Sky Meter Live map now online new [Re: pfile]
      #5901072 - 06/04/13 02:33 AM

Thanks!
A quick note on location:

- The locations are rounded (about 110 meters for privacy reasons.
- Uploading is not obligatory. The app doesn't do any 'sneaky uploading':) . So you are in control.
- If you don't want your location on the map. Simply erase it from the 'My Data' menu (swipe and delete)


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Qwickdraw
Pooh-Bah
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Dark Sky Meter Live map now online new [Re: Nop]
      #5901161 - 06/04/13 05:43 AM

It would be nice if the moon phase could somehow be calculated out of the number so that all locations show actual LP factors regardless of moon phase.

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Nop
Vendor (iPushto)


Reged: 02/12/06

Loc: Netherlands, Valkenburg
Re: Dark Sky Meter Live map now online new [Re: Qwickdraw]
      #5901206 - 06/04/13 07:16 AM

Yes, we are discussing that. But, it is and will be an estimated result. There's a lot of side effects measuring with moon (dirty sensor, bad transparency etc).

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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: Dark Sky Meter Live map now online new [Re: Nop]
      #5901398 - 06/04/13 10:03 AM

If I uncheck the markers for data that appears less useable, there's not much left. Wrong/no time, low angle, clouds...you're getting many more less useful readings than useful ones. Any way to imrpove those percentages?

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Nop
Vendor (iPushto)


Reged: 02/12/06

Loc: Netherlands, Valkenburg
Re: Dark Sky Meter Live map now online new [Re: derangedhermit]
      #5903228 - 06/05/13 04:58 AM

@derangedhermit
It will need some time. Keep in mind that the app is released only 2 months ago and for the Northern hemisphere the nights are getting shorter. Here in Europe the weather has been terrible. So there's a lack of good readings. I'll expect to have a good number of readings coming this fall and more amateur astronomers will provide useful SQM measurements. And I hope we get a lot of users on the southern hemisphere.
With over 2000 downloads worldwide (lite+pro) the app has a good potential.


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: Dark Sky Meter Live map now online new [Re: Nop]
      #5903404 - 06/05/13 08:38 AM

I know it will. I hope the app or server provides feedback to users about no/wrong time, pointing angle - whatever it can to improve the readings.

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audioaficionado
professor emeritus


Reged: 05/24/12

Loc: Medford, Orygun, USA
Re: Dark Sky Meter Live map now online new [Re: derangedhermit]
      #5908261 - 06/07/13 04:09 PM

Quote:

Dark Sky Meter for iPhone




There are also a lot of Android phone users who could be recruited to add more data points.


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Dark Sky Scott
super member


Reged: 01/06/12

Loc: Tucson, Arizona
Re: Dark Sky Meter Live map now online new [Re: audioaficionado]
      #5908673 - 06/07/13 07:59 PM

Android phones have a lot of variability in their cameras. A different app was developed for them. Check it out here:
https://play.google.com/store/apps/details?id=com.cosalux.welovestars


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StarDaddy
member


Reged: 05/10/13

Loc: Eastern Shore, Maryland
Re: Dark Sky Meter Live map now online new [Re: pfile]
      #5921155 - 06/14/13 07:57 PM

Quote:

i wish you would fuzz the locations on the map a little bit... bit of a privacy concern.




=========

Don't worry my friend, the NSA knows exactly where you are! (and the fact that we are having this correspondence)


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Mauro Da Lio
professor emeritus


Reged: 09/12/04

Re: Dark Sky Meter Live map now online new [Re: StarDaddy]
      #6006323 - 08/04/13 05:31 PM

I have installed the Pro version yesterday. Here is a comparison with a "hardware" SQM.

a) Today at my home.
I took 5 SQM readings, which were: 18.88, 18.89, 18.87, 18.87, 18.87. Mean 18.876 and SD < 0.01
I took 5 Dark Sky Meter readings which were: 18.78, 18.82, 18.73, 18.75, 18.84. Mean 18.784, SD 0.046.
The difference between the two means is less than 0.1mpsas, ie less than the claimed accuracy of standard SQM (mine is a little bit optimistic). HOWEVER the repeatability of the Dark Sky Meter is nearly 5 times worse.

b) Yesterday at dark site.
The SQM was averaging at 21.6, with deviations of the order of 0.1. But the DSM, in such low lights, had very large fluctuations, from 21.4 to 22.2 (nearly one magnitude).

It seems that in low lights (ie what is more interesting for me) the DSM is loosing accuracy.

Hopefully tomorrow I will be on a dark site again and I will record carefully the readings of both.

Edited by Mauro Da Lio (08/04/13 05:32 PM)


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: Dark Sky Meter Live map now online new [Re: Mauro Da Lio]
      #6006390 - 08/04/13 06:21 PM

Mauro: is the close agreement with the SQM after you "calibrated" the app against the SQM? Is the SQM the narrower FOV version, or the original?

Also, very good information, thank you; and I look forward to your further tests.


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Mauro Da Lio
professor emeritus


Reged: 09/12/04

Re: Dark Sky Meter Live map now online new [Re: derangedhermit]
      #6007106 - 08/05/13 06:35 AM

No, I did no particular calibration. My SQM is on average 0.1 mg optimistic and is the standard version. However the sky at my home is pretty uniformly polluted so the difference in the FOV is in influential.

However, despite the agreement at ~SQM 19, there is no longer agreement above SQM 21, and, what is worse, the DSM gives non repeatable readings.


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Tony Flanders
Postmaster
*****

Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Dark Sky Meter Live map now online [Re: Mauro Da Lio]
      #6007304 - 08/05/13 09:50 AM

Quote:

However, despite the agreement at ~SQM 19, there is no longer agreement above SQM 21, and, what is worse, the DSM gives non repeatable readings.




That's exactly what I would expect. The DSM has to rely on the built-in camera, which is designed for compactness and high pixel count -- precisely the qualities that make a camera work poorly at low light levels. On the whole, it's amazing that it works as well as it does.


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Mauro Da Lio
professor emeritus


Reged: 09/12/04

Re: Dark Sky Meter Live map now online [Re: Tony Flanders]
      #6008826 - 08/06/13 05:31 AM

This is quite obvious. There is no detail about how the sensor data are processed, but I believe that by lumping all the pixel together one may reduce noise and increase signal. After all the CCD of the iPhone is similar in size to the sensor element of the SQM. So it looks to me that a clever processing might obtain similar results.

Use in Dark sites is important. Moreover another useful feature might be that of collecting readings at intervals the whole night and producing a chart (similar to the SQM-LE).

Edited by Mauro Da Lio (08/06/13 05:32 AM)


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derangedhermit
Pooh-Bah


Reged: 10/07/09

Loc: USA
Re: Dark Sky Meter Live map now online new [Re: Mauro Da Lio]
      #6010093 - 08/06/13 06:46 PM

Mauro, the phone gets *hot* inside, the SQM does not. The heat you know makes a lot of noise in the image.

Kill all the unneeded apps and services, see if there is a way to turn off the mobile radio hardware (big problem), turn off the display hardware (big problem), etc. Wrap a cold pack around it and let it chill.

It may help in both variance and going deeper.


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