Recent Posts

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81
General Discussion / Report: Human Contrast Threshold and Astronomical Visibility
« Last post by admin on May 20, 2014, 05:48:27 pm »
Andrew Crumey has written a paper that you might be interested in:
  "Human Contrast Threshold and Astronomical Visibility" (accepted in
  MNRAS). It presents a model which gives visibility predictions somewhat
  different from the standard Hecht-Schaefer model, but in better
  agreement with the laboratory data (Blackwell, Knoll et al). In the
  conclusions, Andrew makes some proposals regarding sky quality
  indicators for public use.

  http://arxiv.org/abs/1405.4209
82
General Discussion / Overlay of different SQM measurements
« Last post by infographic_ch on March 02, 2014, 09:28:02 pm »
Dear all,
I am a GIS student. Currently, I am preparing a paper on the modelling of light pollution.
The approach is to measure night sky brightness with a SQM at various spots in an urban area.
e.g. close to a highway,  close to a primary street, etc.
For my model I have consider that each of those measurements can overlap.
I need to understand how individual SQM measurements add up if they overlap.
I am looking for a formula that applies for the combination of light sources measured in 'mags/arcsec2'.
Anyone is experienced in this field?
Thanks,
Stefan
83
General Discussion / Re: SQM-LU and INDI
« Last post by BPO on February 27, 2014, 08:47:37 pm »
Brilliant! INDI gets better every day.
84
Weatherproofing / Re: Drainage
« Last post by BPO on February 27, 2014, 08:39:11 pm »
Hi Anthony.

Thanks for the info. I was concerned I'd crack the plastic and have to buy new ones: Great for you, but not so good for me!

 ;D

Now that I know the plastic likely won't cause any problems, I have hole cutter bits that will do the job easily.

Also, the new holes will be covered by the foam already in the base of the enclosure.


Cheers,

Gary
85
Weatherproofing / Re: Drainage
« Last post by admin on February 27, 2014, 02:00:07 pm »
The base caps of both my SQM-LE enclosures have flexi-conduit connectors fitted, and I suspect they have raised rims internally which prevent any accumulated moisture in the enclosure from draining via the hole. How difficult is it to drill the plastic? Does it crack easily, or is it an easy job?

Thank you for your question Gary.

The white housing caps (and tube) are made of PVC. Here are some points below about how I deal with PVC:
  • It is a relatively soft plastic that does not crack easily. It might crack if stressed/cut at very low temperatures, but room temperature is warm enough to work with it without worrying too much about cracking.
  • The biggest problem I found with cutting PVC is that the cutting tool may grab too easily. I use a dulled drill-bit or hole-saw to prevent grabbing. You can either slightly round the sharp tip edges of the bit with a file, or purchase a special bit for plastic cutting to prevent grabbing (both of which would likely be overkill for your application). Cut at a slow speed, I use 570RPM. Occasionally clean out the excess shavings from the drill bit during use to prevent buildup which will cause the plastic to melt and bind easily.
  • I have also had great success with a carving knife. Carve small strips of the plastic to eventually get the shape you want. Box-cutter blades are too thin and sharp to work with nicely, but a pocket knife seems to work well.

If you are adding drain holes, make sure to cover the inside with a screen to prevent bugs crawling back up there.

Best wishes,
Anthony Tekatch
86
Weatherproofing / Re: Drainage
« Last post by BPO on February 27, 2014, 09:53:58 am »
Hi Anthony.

The base caps of both my SQM-LE enclosures have flexi-conduit connectors fitted, and I suspect they have raised rims internally which prevent any accumulated moisture in the enclosure from draining via the hole. How difficult is it to drill the plastic? Does it crack easily, or is it an easy job?


Cheers,

Gary Roberts
Benmore Peak Observatory
New Zealand
87
General Discussion / Reports
« Last post by admin on February 16, 2014, 07:55:23 pm »
Two new papers on light pollution have been published in a highly respected journal, the "Journal of Quantitative Spectroscopy and Radiative Transfer":
  • "Night sky photometry and spectroscopy performed at the Vienna University Observatory": Science Direct, arXiv.
  • "The night sky brightness at Potsdam-Babelsberg including overcast and moonlit conditions": Science Direct, arXiv.
88
General Discussion / SQM-LU and INDI
« Last post by ffernandez on January 14, 2014, 05:06:58 pm »
Hello,

  SQML-LU is now supported by INDI project (http://www.indilib.org/develop/indiforjava/i4jdrivers/sqm-lu-driver.html). Sergio Alonso main developer of "INDI for Java" project  has created this driver.
 
  Soon, we'll be able to announce a new version  of Maroc (http://www.luz-cero.es/maroc) with INDI support. Any INDI compatible mount will be controlled by Maroc and also SQM-LU readings will be request using INDI protocol.
89
Connected meters (SQM-LE/LU/LR/DL) / SQM Reader Pro 2 software released
« Last post by knightware on September 24, 2013, 11:21:04 am »
Knightware is pleased to announce the release of SQM Reader Pro 2 software. SQM Reader Pro 2 reads sky darkness data from connected Sky Quality Meters automatically and continuously, displays and graphs data, stores data in files and transfers it to an FTP server and post processing scripts, batch files and programs. Readings can be submitted automatically to a live SQM Readings Map web page at http://www.knightware.biz/community/public/sqm2/sqm_map.php.

Readings may be stored in 2 data file formats, including the new Skyglow Observation Standard Format (see Skyglow Standard web page at http://www.darksky.org/night-sky-conservation/248).  The standard format allows data to be shared with dark sky researchers around the world. Data files in both formats (plus Unihedron Device Manager format) may also be re-opened and processed with SQM Reader Pro 2 at a later time.

SQM Reader Pro 2 operates on Windows 8, 7, Vista and XP.  It supports reading SQM models LE (Ethernet), LU and LU-DL (USB) and LR (RS-232). It includes thorough documentation, online product support and online product updates. For full product description, please see http://www.knightware.biz/sqm .

Pricing and Availability
SQM Reader Pro is available by digital delivery ($50) and on CD ($58.95) directly from Knightware at http://www.knightware.biz.
90
General Discussion / Tripod adaptors
« Last post by admin on July 30, 2013, 08:18:04 pm »
Tripod adaptors are now available for our meters:

Example
Kit
SQM
SQM-L
SQM-LE/LU/LR
SQM-LU-DL

This will help in consistently positioning the meter at various angles for detailed repetitive studies.

The kit includes one tripod adaptor, 3D-printed in ABS or PLA, and two longer screws (to replace two short screws already in the meter).

More details and ordering links can be found here.
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