Re: IOD Format - Please, some help with a few questions (applied to Starlink observations)

From: Chris Lewicki via Seesat-l <seesat-l_at_satobs.org>
Date: Fri, 22 May 2020 16:52:57 -0700
> 
>> 4) the "Angle format code" I use 2 because I saw a few more of you using
>> it. Does it make a difference?
> 
> No, this does not really make a difference. If you are referencing
> positions with astrometry.net, use the RA/Dec formats, so either 1, 2,
> 3 or 7.

Andrea,

As Cees indicates, any format will do, but some formats allow more precision than others, due to the fixed-column format and the ability to represent combined significant figures.  My analyses of the IOD angle formats was as follows (listed as best to worst):

Format	Type	RA/AZ	DEC/EL	MX units of arc	RA/DEC Precision	AZ/EL Precision	Precision Sum	Least Squares	Precision (mas)	X Times worse
6:	AZ/EL	DDDdddd	DDdddd	degrees	1.00E-04	1.00E-04	2.00E-04	1.41E-04	509	1.00
5:	AZ/EL	DDDMMmm	DDMMmm	minutes	1.67E-04	1.67E-04	3.33E-04	2.36E-04	849	1.67
3:	RA/DEC	HHMMmmm	DDdddd	degrees	2.50E-04	1.00E-04	3.50E-04	2.69E-04	969	1.90
2:	RA/DEC	HHMMmmm	DDMMmm	minutes	2.50E-04	1.67E-04	4.17E-04	3.00E-04	1,082	2.12
4:	AZ/EL	DDDMMSS	DDMMSS	seconds	2.78E-04	2.78E-04	5.56E-04	3.93E-04	1,414	2.78
7:	RA/DEC	HHMMSSs	DDdddd	degrees	4.17E-04	1.00E-04	5.17E-04	4.28E-04	1,543	3.03
1:	RA/DEC	HHMMSSs	DDMMSS	seconds	4.17E-04	2.78E-04	6.94E-04	5.01E-04	1,803	3.54

Also, as Marco indicated, his windows software can help you format an IOD.  If you don’t easily have access to windows you can use this online dynamic form at TruSat.org <http://trusat.org/> (you can copy the resulting IOD string if you don’t want to register there)

https://trusat.org/submit/single <https://trusat.org/submit/single>


-Chris
_at_interplanetary



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Received on Fri May 22 2020 - 18:54:04 UTC

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