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Open a Discussion / Re: Meteo sensor
« Last post by Pawel Lejba on June 21, 2017, 11:26:13 AM »
Thanks !
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Open a Discussion / Re: Meteo sensor
« Last post by pywang on June 19, 2017, 01:43:27 PM »
In Graz, we have:

1) MET3A from Paroscientific, delivering all 3 meteorological parameters for standard ranging, since long time;

2) PTU301 from Vaisala, bought in 2015, for SP-Dart (hopefully you know what is SP-Dart  :D)

We made a 4-days pressure data comparison between MET3A and PTU301, 1 sample /minute, we got::

----Average of differences= 0.062 mBar (MET3A< PTU301 )
----RMS of differences       = 0.044 mBar

In addition, we have another barometer also from Paroscientific (Model 740-16B) in our laser room.
The difference between MET3A and 740-16B is checked always when starting a pass, and a difference of > 0.3 mbar will be reported as a warning, just to avoid any hardware/software/artificial accidents.

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In 2015, we also made a market investigation:

1) Paroscientific provides MET4(~8.3k Euros) and MET4A (with fan-aspired, (~9,0k Euros)
2) Vaisala PTU301, about 2.6k Euros excl. tax
3) Climatronics(USA), ALLinONE (even include wind info.), about 2.5k dollors. Needs to be checked / tested.

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By the way, please remember that SLR expects the pressure value at the system invariant point (crossing of Az /EL axis in the telescope).

Graz has measured the pressure difference between this system invariant point and the location of the sensor; this difference (a constant value) is applied to all  measurements of  air pressure.
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Open a Discussion / Meteo sensor
« Last post by Pawel Lejba on June 16, 2017, 10:57:31 AM »
Dear Colleagues,

Borowiec plan to exchange the meteo station. What would you recommend to us ? We have an experience with Vaisala. What is a price of your professional meteo sensor you are using ? I will be very gratefull for any replies.

Kind regards,
Pawel
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Open a Discussion / Re: Tracking CZ-2C rocket bodies with NORMAL laser
« Last post by Pawel Lejba on June 16, 2017, 10:50:33 AM »
Hi,
Dear Zhipeng,

Borowiec tracks regulary (since January 1, 2017) two CZ2C targets, 28480 and 31114. They give us very interesting results.

Kind regards,
Pawel
5
Lasers / Start Diodes - What is best?
« Last post by Matt Wilkinson on May 04, 2017, 09:46:01 AM »
Hi all

What start diode setups are stations currently using in their lasers to detect laser fires and trigger a timer start? I'll go and find the details of the Herstmonceux diode and post it here, but i know we use a rather cheap diode in to a threshold discriminator.  Is there anything better out there anyone could recommend? Are people satisfied with their start diodes?

When we moved to kHz SLR and lower energy pulses (from 20mJ to 1mJ), the threshold for a start had to be dropped considerably.  And so alignment is critical.  If it is not optimised we can get large RMS values in our calibrations.

Matt
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Hi all

From about the beginning of 2017, the team at the SGF noticed some increased instability in our terrestrial range calibration values at the level of 2-3 mm.  It was particularly clear on the first calibration of the day being a low value and so we learnt to take at least two calibrations before starting an observing duty.

2 weeks ago we also saw an increase in the RMS of the calibrations and some periodic behaviour in the calibration range values.  We consequently took the kHz laser offline and began using our older 10Hz laser, which had very stable calibration values and RMS.

After some investigation and discussion with High-Q, the team found that the flow rate of the cooling water was much lower than it should have been.  The water used is a reservoir of distilled water, but after 10 years of use something had built up to block the waterways.

Temperatures in the laser bed were not being kept at a stabilised constant, causing energy fluctuations and range errors from the start diode. The temperature would change when the laser began firing after being off for a period (20+ minutes). It would stabilise after approximately 10 minutes, during which time calibration range differences were seen.

Running the flow backwards and using a descaler (Durgol was recommended) brought the flowrate up to specification levels.  Setting the best operating temperature removed the signals in the range values and now the calibration RMS and repeatability are now within acceptable levels.

Needless to say, we will be checking the flowrate more often from now on.

Matt
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Telescopes / Re: CCTV/ICCD/EMCCD cameras for tracking
« Last post by Matt Wilkinson on February 22, 2017, 03:23:26 PM »
Hi Kalvis

I've been testing one of these cameras https://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=4024, which are rebranded uEye cameras from IDS https://en.ids-imaging.com/home.html (more to choose from at IDS site!).

It is very adaptable and affordable with an extensive API with example software. If you don't need a top of the range camera, these could be worth a look, depending on the job you have in mind.

Matt
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Open a Discussion / Site Log
« Last post by CurtisEmerson on February 21, 2017, 06:40:04 PM »
I notice in the ILRS site log fields exist to identify Model and Manufacturer for:

Tracking Camera
Detector
Signal Processing
Time of Flight Observ.
Frequency Standard
GPS Timing Rcvr
Meteorological Instrumentation


but not for:

Laser
Receiving Telescope
Xmitting Telescope
Calibration Target
Aircraft Detection
Collocated Permanent Geodetic Systems (which would be identified in their own site logs).

Just an historical anomaly, or is vendor/model information useful for some but not others?
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Telescopes / Re: CCTV/ICCD/EMCCD cameras for tracking
« Last post by danielhampf on January 31, 2017, 12:56:46 PM »
Dear Kalvis,
we have been using the Andor Zyla sCMOS camera for about 3 years now and are quite happy with it. It comes as camera link or USB3 version, of which the latter was much more practical to use (we have 3 of these now, 2 USB and one older CL). To your questions:
1) Programming API is pretty good in my opinion, it's a C library that also exists in a precompiled form. I imported the DLL to python and went on from there.
2) There are a number of trigger options, which should enable you to do what you want. E.g. you can trigger via TTL input. The shutter is fully electronical, global or rolling. The camera is also pretty fast, up to some 50 Hz or so if you really push it hard.
3) Pixel size is 5,5 um, the sensor is 2560 x 2160 pixels, which gives us (at 3m focal length) a FoV of 0.3 deg and a scale of 0.5 arcsec per pixel. Pretty useful. And it's cmount.
4) No problems whatsoever so far in rather harsh outdoor conditions. The camera is also rather small and lightweight, which is also nice.
I can also mention that we tested two other cameras that were less useful in this context: First a FLI astro-CCD that had a gigantic chip and thus FoV, but a slow shutter and readout, so you could only take one picture every five seconds or so, and the timing was not accurate either (otherwise very good camera). And an Andor iXon emCCD which is very sensitive, but the camera is somewhat bulky and heavy and the chip is rather small. Unless you expect very low light levels I do not see much point in using any emCCD at the moment.
Ah, and maybe good to know: You'd pay something like eight to ten thousand Euro for it. Maybe a bit expensive for your needs, don't know.
If you need a rather cheap, reliable camera, I can recommend pretty much everything from PointGrey. Sturdy industrial cameras with a good interface, high frame rates, small size, cmount, ethernet or USB connection. Not very sensitive and not very large chip though. We use them for beam monitoring and occasionally on our transmitter telescope.
Hope that helps somewhat...
Daniel
10
In-Sky Safety / Re: On telescope camera for plane spotting
« Last post by Matt Wilkinson on January 31, 2017, 12:20:20 PM »
Hi Kalvis

That's quite a narrow FOV.  We are wondering here @Hx what would be the best approach, either to use a wider image to spot approaching planes and take action when necessary or to have a narrower field to immediately shutoff when any plane like object appears in the frame (perhaps using a comparison to an earlier frame).

We've not tested our camera at night yet.

Matt
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