Where to observe in wicklow

7 years 8 months ago #95103 by albertw
Where to observe in wicklow was created by albertw
Hi,

I spent most of last night driving around wicklow taking lightmeter readings with an SQM-L. It was an excellent night, very steady, no clouds.

From a first glance at the data there are no real surprises but I thought I'd post about an initial look at the numbers, as it may have a factor in people choice of location for observing. Data is taken by pointing the meter at the zenith, it does not give an indication of brightness at the horizon.

The area covered was:


The brightest location in the search area (apart from ones near streetlights) was the Sugar Loaf car park at 20.58 magnitudes per square arcsecond (m/a^2). There is no straight conversion between those units to limiting magnitude, but it's is around 6. Dalkey by contrast is 19.6. The darkest was 21.30 near Tinahealy.

That does make a difference. The sky was notably darker in the 21+ areas than at the sugar loaf.

There does seem to be an absolute limit around wicklow of 21.2 to 21.3 - you won't find areas darker than this. I didn't go through the mountains much this time, but they are closer to dublin than Tinahealy so are unlikely to be darker.

The road by the GAA club in Roundwood registers 20.99. But you need to go beyond Laragh to get down to 21.2. Any of the higher altitude sights from Laragh south were over 21.2. But going any further south than Drumgoff.

The local towns and villages don't have an impact as much as I had suspected. 21.2+ readings were obtained near Tinahealy, Baltinglas, Donard. Though the SQM is looking at the zenith, due to low angle scatter proximity to streetlights will affect the horizon brightness.

It is not as dark in the valleys as on the hills. One location in Glenmalure registered brighter than the sugar loaf. This appeared due to a haze or mist that gathers in the valleys. Whether this holds for all valleys or is particular to Glenmalure with its very steep V shape I'll have to look into another night.

If anyone wants the raw data let me know. Also if anyone knows a good way to display this on some sort of contour map (preferably with python), please let me know!

Cheers,
~Al

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

Please Log in or Create an account to join the conversation.

7 years 8 months ago #95114 by Calibos
Replied by Calibos on topic Re: Where to observe in wicklow
Have to say, I'm not a huge fan of the Sugarloaf carpark tbh. I've only been there once with the SDAS and Meetup crew. Starts to get cramped very quickly. I guess The SDAS/Meetup events have been a victim of their own success. I am also a bit biased against it in that while a bowl shaped gravel carpark with no level flat areas is not a problem for tripods, its a bit of a problem for a dob.

Keith D.

16" Meade Lightbridge Truss Dobsonian with Servocat Tracking/GOTO
Ethos 3.7sx,6,8,10,13,17,21mm
Nagler 31mm

Please Log in or Create an account to join the conversation.

7 years 8 months ago #95115 by michael_murphy
Replied by michael_murphy on topic Re: Where to observe in wicklow
Trooperstown outside Laragh isn't too bad. It's flatter (but still gravel) and darker.
It also has the advantage of having a screen of trees to stop the wind.

Michael.

IFAS Secretary.

Please Log in or Create an account to join the conversation.

7 years 8 months ago #95117 by Calibos
Replied by Calibos on topic Re: Where to observe in wicklow
Forgot to say.....

Wow Al. Impressively comprehensive field trip and data gathering.

Insomnia? :D

Keith D.

16" Meade Lightbridge Truss Dobsonian with Servocat Tracking/GOTO
Ethos 3.7sx,6,8,10,13,17,21mm
Nagler 31mm

Please Log in or Create an account to join the conversation.

7 years 8 months ago #95124 by albertw
Replied by albertw on topic Re: Where to observe in wicklow
A large flask of very strong coffee!

The wicklow mountains have plenty to keep you alert at night as well, deer running across the road, rabbits sitting in the middle of the road staring at you, the radio mysteriously changing to Tipp FM late night country music :)

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

Please Log in or Create an account to join the conversation.

7 years 8 months ago #95125 by darragh
Replied by darragh on topic Re: Where to observe in wicklow
Al,

There is a number of open source GIS tools that are python based that can use a spatial enabled DB like PostGIS.
FeatureServer is probably the most relevant do take the point data and render it as a layer for use by OpenLayers or your other favourite JS GIS api.
FeatureServer is python based but from what I remember, there is very little you have to change to display non-spatial data in layer.

Darragh

GTalk: darragh.sherwin at gmail.com

The Colour Lab PhotoBlog
Nature and Landscape Photography
OffShoot Photography Society
The Photography Society for South Dublin

Please Log in or Create an account to join the conversation.

7 years 8 months ago - 7 years 8 months ago #95127 by albertw
Replied by albertw on topic Re: Where to observe in wicklow

albertw wrote: The local towns and villages don't have an impact as much as I had suspected. 21.2+ readings were obtained near Tinahealy, Baltinglas, Donard. Though the SQM is looking at the zenith, due to low angle scatter proximity to streetlights will affect the horizon brightness.


The only way to really quantify that is with an all sky image. Unfortunately I don't have a full frame DSLR with a wide fish eye lens (e.g. www.sigmaphoto.com/shop/8mm-f35-ex-dg-circular-fisheye-sigma ). On the off chance that anyone else does the standard settings are:

ISO: 1000
Aperture: fully open (f/3.5)
Shutter Speed: 180s (in places with more light pollution you will need a shorter exposure time, around 120s)
Focus: Manual, infinity

Camera should be mounted on a tripod and pointed at the zenith.

If you have the ability to take such images, from anywhere around the country not just Wicklow, then we'd appreciate getting the images for analysis.

Cheers,
~Al

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

Please Log in or Create an account to join the conversation.

Time to create page: 0.087 seconds
Powered by Kunena Forum