Bortle Scale Survey for Stellarium Based Project

7 years 10 months ago #94395 by pdempsey
I'm currently working on a small project in Stellarium , and am looking for Bortle scale estimates from around Ireland (or anywhere you're visting :-) ). I'm hosting a survey on http://www.dasurvey.com/n/irishlightpollutionsurvey/ and would appreciate continuous submission of data.

This will be a long term project, requiring regular inputs throughout the year, but depending on the responses I hope to post updates here every 6 months in the form of a map.

Please feel free to provide feedback on the survey format, and consider sending the link on to anyone who would be interested or could help.

Thanks
Paul :)

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7 years 10 months ago - 7 years 10 months ago #94396 by dave_lillis
Hi,
that looks quiet interesting, worth caring out !
would it be ok with you if i put up a link to your site on our club website?

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor

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7 years 10 months ago - 7 years 10 months ago #94398 by pdempsey
Hi Dave,
It's purely naked eye based estimates. The astronomical objects that are used in this test are M31 (the Andromeda Galaxy), M33 (the Triangulum Galaxy), M4 (a globular cluster in Scorpius), M5 (a globular cluster in Serpens), M15 (a globular cluster in Pegasus), and M22 (a globular cluster in Sagittarius). The Bortle Scale can be estimated on a clear night as follows:
ScaleRequired Observations
1M33 seen with direct vision. Saggittarius & Scorpius regions of Milky Way cast a shadow.
2M33 easily seen and Milky Way has detailed structure.
3M4, M5, M15 or M22 and be seen distinctly.
4M33 can barely be seen, with averted vision.
5Zodiacal light can be seen on the very best nights in spring/autumn.
6The Milky Way can be seen overhead.
7Can see all seven main stars of Ursa Minor.
8Can barely see M31.
9Can't even see M31.

The more estimates by different people in different locations will allow me build up a decent map. More details are available here: http://www.novac.com/lp/def.php and http://en.wikipedia.org/wiki/Bortle_Dark-Sky_Scale . Most dark sky preseves have a bortel index of 2 ( http://en.wikipedia.org/wiki/Dark-sky_preserve ).

Observations can be taken from anywhere from city centres to isolated mountain tops, or even on a ship!

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7 years 10 months ago - 7 years 10 months ago #94399 by pdempsey
Feel free to link to it from anywhere. Initially hoping to cover Ireland well, but if anyone in any other region is interested it's easy to setup different surveys.

If linking please passing on link please use www.dasurvey.com/n/irishlightpollutionsurvey/ , or bit.ly/MCPCcA for tweets etc., and not the address that appears in your browser, as that page is a unique instance of the questionnaire for each submission.

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7 years 10 months ago #94401 by albertw
Hi Paul,

You might also want to check out mydarksky.com/home.aspx who have a database of light pollution readings. Ireland is pretty sparse at the moment apart from one survey in Kerry but we'll be updating more data there in the autumn.

The globe at night project also should have similar estimations to what you are looking for for Ireland.

A couple of points about the questionnaire from having looked at results from these before.
- Get people to specify an exact date. Otherwise they will need to state the sun's altitude (to verify its after astronomical twilight) and moon altitude, and phase.
- Specify whether they should use Summer time or UTC. At least give an option to specify which.
The above two points are necessary to be able to factor in the influence of the twilight and moon, otherwise the readings can be useless.
- Weather. This can be very subjective, but some indication of mist and cloud would is useful.
- Seeing - again subjective, especially for non amateur astronomer.
You could hope to eliminate some of those issues statistically, but even the most well publicised surveys like this rarely get sufficient data to get more than a broad idea of light pollution and dark skies.

Finally, it would be great if you could share your results with us and particular Dr. Brian Espey in TCD who co-ordinates light pollution/dark sky measurement.

Cheers,
~Albert
International Dark SKy Association - Ireland

Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/
The following user(s) said Thank You: pdempsey

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7 years 10 months ago #94404 by pdempsey
Thanks Albert,

I've edited the time and date fields as suggested, and added optional weather and seeing fields. I was going to take a statistical approach, but that'll depend on the amount of data. I'm hoping the fact it's a structured naked eye test will improve responses. The Bortel scale is built into Stellarium, which is the reason for that choice. My focus is on the areas around historical observatories in Ireland, but I'll shared data with any interested parties, minus names and email addresses, but moderate noise will be added to GPS coordinates to protect anyone who may have reported from their homes (like me!!).

Cheers,
Paul

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7 years 10 months ago #94406 by albertw
Hi,

pdempsey wrote: I've edited the time and date fields as suggested, and added optional weather and seeing fields. I was going to take a statistical approach, but that'll depend on the amount of data. I'm hoping the fact it's a structured naked eye test will improve responses. The Bortel scale is built into Stellarium, which is the reason for that choice. My focus is on the areas around historical observatories in Ireland, but I'll shared data with any interested parties, minus names and email addresses, but moderate noise will be added to GPS coordinates to protect anyone who may have reported from their homes (like me!!).


Good luck with it, I haven't seen a survey using those examples of the Bortle scale before. Hopefully that will improve the response among the amateur astronomers, the more traditional 'count the stars' approach works well getting the public and schools involved, but not so well with amateur astronomers!

Rough GPS locations is fine. Fine grained gives little benefit unless you really are looking for sources of light pollution.

TCD have been working on a datalogging meter that can be left in-situ on a site and will record the sky brightness (like the SQM datalogger), which potentially is something that could be installed at the historical observatories if there was funding. That could potentially then be used to calibrate the readings from observers at a distance from the site, to account for moisture in the air etc.

I'll post the link to your survey on our website.

Best Wishes,
~Al

Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/

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7 years 10 months ago #94485 by eansbro
Paul,

I submitted a report to the light pollution survey but I forgot to move the location cursur to my location.
So I have resubmitted again with the correct location and the same report. I think it was off by 100kms.
I also made a mistake in the Bortle scale readings. It should have read 1 and not 2.
The reason for the mistake is that most of the readings are Bortle 2 or 3 on my list. A March 22/23 , 2008 reading was a very rare exception of Bortle scale 1

Using the Cinzano Sky Brightness Map, my location is in the grey area which has a rating of 2 on the Bortle scale. ie.limiting magnitude of 7.1-7.5. I have been taking historical records of light pollution since 2003. For example, an exceptional record on sky brightness was achieved on March 22/23, 2008 when a reading of 21.74, taken at my location using a Sky Quality Meter (SQM) from Unihedron at in v. This exceptional reading was simultaneously monitored with to a 1.5 arc second reading of transparency taken by the STV camera/lens.. The SQM that is used is the original version that is manually operated. Routine measurements have taken every clear night with readings on average of 21.55 +/-0.5 since 2003. These measurements are taken at ~20 degrees from zenith with a Moonless sky.

The apparent sky brightness is between 2% and 15% brighter than the natural background. I have taken light bubble images generated by a series of photographs taken with a wide-angle lens on December 12/13, 2007. The images are stitched together to form a panoramic view. In 2007, I was concerned that the ever increasing developments and subsequent electrification from distant towns may effect the present dark location. However, with the halting of commercial developments in late 2007, the future looks good for the lack of light pollution for the next few years in the present location. There has been no increase in light pollution since 2007. Hooray! Economic crisis has some its benefits to astronomy

I hope this additional info may be useful in your research.

Eamonn

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7 years 10 months ago #94487 by pdempsey
Thanks Eamonn,

I deleted your original submission. I might be in contact over the autumn/winter to try to convince you to take some readings in, and on the outskirts of, some nearby towns and villages :)

Cheers,
Paul

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7 years 10 months ago #94488 by eansbro
Paul,

Do you want naked eye readings manually based on the Bortle scale for your new survey? Or do you want Sky Quality Meter (SQM Unihedron))readings? Or both?

Eamonn

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7 years 10 months ago #94492 by pdempsey
Either or. I'll be able to filter. If you have a existing data you can just mail it to me (paul.dempsey --at-- dazult.com). It's part of a project aimed more at the general public than serious astronomers, again using astronomy as a gateway to other sciences, so coverage is more important than accuracy; hence the naked eye instructions are provided on the survey page. To get the coverage I'm hoping to convince the college astronomy societies to do some naked eye readings when they start back in October, but sure we'll see how that goes.

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7 years 10 months ago #94505 by eansbro
Paul,

I have about 5400 readings recorded over the years in both Bortle Scale and "seeing" in arc seconds.
These readings were taken simultaneously. The seeing data is very accurate to +/-0.1 arc sec.
There are at least 100+ files of data. It may be easier just to send you the Bortle scale data only.

Eamonn

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