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Messages - pywang

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Telescopes / Anti-reflection coating for flat glass
« on: December 15, 2022, 12:25:12 PM »
Hi all,

In front of our Cassegrain telescope there is a protecting flat glass.
After celebrating its 40 years birthday we are thinking about re-coating it.
It has a size of 50 cm in diameter and 1 cm in thickness, and we need broadband anti-reflection coating on its both sides.
Does anybody have good experiences with some companies?
Thanks in advance!

best regard, Peiyuan Wang from SLR Graz

Lasers / Laser Profiling paper
« on: June 10, 2022, 11:38:15 AM »

Former time it was very common to use a kind of special paper (e.g. Kodak Linograph 1895) to check the dye laser profile.
Does anybody know how/where to order such paper now?
Or any alternatives?
Is Baryta coated paper applicable?


Peiyuan Wang

Data and Software Questions / COSPAR ID to ILRS format
« on: February 04, 2021, 03:14:50 PM »
Hello everybody,

Now I have a problem regarding converting COSPAR Int'l Code to ILRS format.
For a normal case it is easy, eg. "2009-005A" to “0900501”
But when having "2020-061AX", how then?
Second, is it correct that only 'O', ‘L’ and ‘I’ are omitted in COSPAR#, not more?

I put the discussing with Randy (I hope that is Okay for him) below, and there are some hits but not 100% solve my problem.

thanks in advance and best regards,
Wang Peiyuan

Hi Wang,

It's good to hear from you!

As you may know, the COSPAR ID to ILRS ID conversion algorithm is in the CRD and CPF manuals. I include it below. That explains the conversion, although there have been some exceptions over the years. The "i" is not used, as I understand it, because of its similar appearance to lower case "L" and the number "1". The letter "o" is apparently also not used because it looks like zero. Unfortunately, I don't have any source documentation on the COSPAR ID. I am cc-ing this message to Carey Noll and Julie Horvath, who have worked with the COSPAR ID more than I have.

As far as the debris data is concerned,  i.e., data that the ILRS analysts will never see, the ILRS ID could be set to "na" and the COSPAR ID could be included in a "00" comment record. You would still have the NORAD ID to identify the target, which should exist for all debris. (How much of the debris actually has a COSPAR ID? If stations are tracking rocket upper stages, farings, etc., do they have anything but a NORAD number?)

I am reluctant to say "use the COSPAR ID", because the ILRS ID is all numbers and the COSPAR-ID is numbers+letters+ "-". That could break current reading routines. The all-numeric solution you suggest might be a better idea, although that would have to be documented in the manual, too, and it is a bit clumsy. We could have a broader discussion in the DFPSG or the CB about changing the CRD manual so that the COSPAR ID could replace the ILRS ID for debris data only. You are right that this discussion would have been easier a year ago.  :-)

Take care,

COSPAR ID to ILRS Satellite Identification Algorithm:
YYYY is the four-digit year of when the launch vehicle was put in orbit
XXX is the sequential launch vehicle number for that year
A is the alpha numeric sequence number within a launch
Example: LAGEOS-1 COSPAR ID is 1976-039A
Explanation: LAGEOS-1 launch vehicle was placed in orbit in 1976; was the 39th launch in that year; and LAGEOS-1
was the first object injected into orbit from this launch.
ILRS Satellite Identification Format: (YYXXXAA), based on the COSPAR ID
YY is the two-digit year of when the launch vehicle was put in orbit
XXX is the sequential launch vehicle number for that year
AA is the numeric sequence number within a launch
Example: LAGEOS-1 ILRS Satellite ID is 7603901
-----------------------    Randy Ricklefs    ------------------------
      Center for Space Research,  The University of Texas at Austin
                            Austin TX 78712

Sent: Friday, February 14, 2020 2:32 AM
To: Ricklefs, Randall L <>
Subject: COSPAR ID convert to ILRS
Hello Randy,
Some question about COSPAR ID.
As you know LAGEOS-1 ILRS Satellite ID is 7603901 relating to COSPAR ID 1976-039A.
But how to convert targets ID like a decaded debris 1993-036ASU to ILRS ID, 93036011820 or something else?
,there A-01, S-18, U-20
Why S-18 not S-19? Because I found the letter “I” is not used in COSPAR ID
And I don’t know if any other letter also not used. :)
A example of S-NET serial, no “I” used.
43186 S-NET D  2018-014G
43187 S-NET B  2018-014H
43188 S-NET A  2018-014J
43189 S-NET C  2018-014K
I could not find the specification of COSPAR ID, and do you have it?
Do you see any chance that in CRD ver2, we just use COSPAR ID instead of ILRS format?  -- sorry a little too late.
Thanks in advance!!

Station Equipment Questions / Re: Meteorological station
« on: May 25, 2018, 06:46:42 AM »
In Graz, we are using  MET3A from Paroscientific.

And another pressure sensor--740-16B . Because pressure is the most critical met parameter, the 2 pressure sensor data are compared after each reading; a warning mesage is issued if the difference is > 0.3 hPa. Both are setup at different altitudes (not on the same as the reference point), and values are corrected to our invariant point.

All met devices are read by a dedicated PC in 1 Minute intervals. Any program in need for met data is accessing this data.

Unfortunately, since I am here(almost 4 years) never heard about somebody made any calibration.

Open a Discussion / Re: Meteo sensor
« 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.


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.


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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