UCD question: how to assign the wavelength-dependen (em) UCD word
Bo Milvang-Jensen
milvang at astro.ku.dk
Thu Mar 17 18:12:40 CET 2022
Dear Mireille and Semantics,
Thank you also for the reply to my "wavelength-dependent UCD question".
I am happy that you conclude that my selection process for this UCD word
is appropriate. And I note with interest your work on providing a fuller
description of the filter profiles.
Kind regards, Bo
On 3/8/22 9:44 PM, Mireille LOUYS wrote:
> Dear Bo, Dear Semantics,
> thanks for this interesting feedback.
>
>
> The SVO Filter profile service contains a lot of Filter descriptions
> and you can query what is stored with their search box :
> http://svo2.cab.inta-csic.es/theory/fps/index.php?id=Subaru/Suprime.IB505&&mode=search&search_facility=Subaru&search_instrument=Suprime&search_text=suprime#filter
>
> You see that many properties are recorded for a filter, much more than
> the UCD label you can assign on the photometric column.
>
> In the IVOA we can describe filters properties using the Photometry
> data model v1.0:
> https://www.ivoa.net/documents/PHOTDM/
> The way to provide more information to describe filters and
> calibration zero points at the top of a VOTable catalog was proposed
> in the
> PhotDM1.0 Appendix C.2 Photometric Data in Cone Search in the doc
> pointed above.
>
> The current update of this spec : PHOTDM1.1 is in progress and
> discussed in the community .
> You can see details on the revision process , people involved , etc,
> here :
>
> https://wiki.ivoa.net/twiki/bin/view/IVOA/PhotDM11RFC
>
> The goal is to set-up a mechanism to allow any filter and calibration
> information to be described in an annotation block at the beginning of
> a VOtable which in turn can be interpreted by a parser application
> based on a library.
>
> This work is in progress and will be shown at the next
> interoperability meeting (April) probably .
>
> Your example is up-to-the point and in sync with our current development.
>
> I hope we can show you examples of this representation for your
> filters in this syntax very soon.
>
> Best regards , Mireille.
>
> PS: So your selection process for ucd , based on the reference
> wavelength/frequency/energy, is appropriate. It is just that not all
> information can be wrapped in just one label.
>
> Le 02/03/2022 à 18:00, Bo Milvang-Jensen a écrit :
>> Dear Mireille and IVOA semantics list,
>>
>> Thank you for inviting me to send you my unsolved questions about
>> UCDs, I have two: one in this e-mail and one in the next
>>
>> Background: These questions have arisen while writing UCDs for the
>> around 1200 table columns in the COSMOS2020 catalogue, paper recently
>> published in Weaver+2022
>> (https://ui.adsabs.harvard.edu/abs/2022ApJS..258...11W/abstract),
>> before publication via ESO's Phase 3. The catalogue contains
>> photometry in around 40 photometric bands/filters, and photo-zs and
>> physical parameters (e.g. stellar mass) computed by two codes.
>>
>> My first question (i.e. this e-mail) concerns how to select the
>> wavelength-dependent (em) UCD word for a given photometric filter. I
>> have consulted the UCD1+ document, but the only guidance I found was
>> the short description for each UCD word, e.g. "Infrared between 1.0
>> and 1.5 micron". First, I am not sure I understand the motivation for
>> having overlapping words, as shown by this example:
>>
>> em Electromagnetic spectrum
>> em.IR Infrared part of the spectrum
>> em.IR.NIR Near-Infrared, 1-5 microns
>> em.IR.J Infrared between 1.0 and 1.5 micron
>>
>> My intuition is to select the most "specific" word (here em.IR.J),
>> but that could be wrong.
>>
>> Second, my main problem is that I do not know to select the most
>> appropriate em word. For each of my filters I know the central
>> wavelength and the full transmission curve. Some of my filters, e.g.
>> y and Y, have a transmission curve that transmits both below and
>> above 1 micron, which is one of the limits used in the descriptions
>> of the UCD words, so if one were to consider the full transmission
>> curve when selecting the em word, these filters could only be given
>> the very general word "em". I have made the choice of only using the
>> central wavelength when assigning the em word, not the full
>> transmission curve.
>>
>> Here is the full list of filters in COSMOS2020, with their central
>> wavelengths and widths (both in Angstrom), and with the UCD I
>> currently have assigned based on my two principles (most specific
>> word, and central wavelength) [see Weaver+2022 Fig. 2 for the filter
>> curves]:
>>
>> Label Description lam_cen width UCD
>> --------------------------------------------------------------------------
>>
>> GALEX_FUV GALEX FUV 1526 224 em.UV.100-200nm
>> GALEX_NUV GALEX NUV 2307 791 em.UV.200-300nm
>> CFHT_u CFHT/MegaCam u 3709 518 em.opt.U
>> CFHT_ustar CFHT/MegaCam u* 3858 598 em.opt.U
>> ACS_F814W HST/ACS F814W 8333 2511 em.opt.I
>> HSC_g Subaru/HSC HSC-SSP PDR2 g 4847 1383 em.opt.B
>> HSC_r Subaru/HSC HSC-SSP PDR2 r 6219 1547 em.opt.R
>> HSC_i Subaru/HSC HSC-SSP PDR2 i 7699 1471 em.opt.I
>> HSC_z Subaru/HSC HSC-SSP PDR2 z 8894 766 em.opt.I
>> HSC_y Subaru/HSC HSC-SSP PDR2 y 9761 786 em.opt.I
>> SC_B Subaru/SuprimeCam B 4488 892 em.opt.B
>> SC_gp Subaru/SuprimeCam g+ 4804 1265 em.opt.B
>> SC_V Subaru/SuprimeCam V 5487 954 em.opt.V
>> SC_rp Subaru/SuprimeCam r+ 6305 1376 em.opt.R
>> SC_ip Subaru/SuprimeCam i+ 7693 1497 em.opt.I
>> SC_zp Subaru/SuprimeCam z+ 8978 847 em.opt.I
>> SC_zpp Subaru/SuprimeCam z++ 9063 1335 em.opt.I
>> SC_IB427 Subaru/SuprimeCam IB427 4266 207 em.opt.B
>> SC_IB464 Subaru/SuprimeCam IB464 4635 218 em.opt.B
>> SC_IA484 Subaru/SuprimeCam IA484 4851 229 em.opt.B
>> SC_IB505 Subaru/SuprimeCam IB505 5064 231 em.opt.V
>> SC_IA527 Subaru/SuprimeCam IA527 5261 243 em.opt.V
>> SC_IB574 Subaru/SuprimeCam IB574 5766 273 em.opt.V
>> SC_IA624 Subaru/SuprimeCam IA624 6232 300 em.opt.R
>> SC_IA679 Subaru/SuprimeCam IA679 6780 336 em.opt.R
>> SC_IB709 Subaru/SuprimeCam IB709 7073 316 em.opt.R
>> SC_IA738 Subaru/SuprimeCam IA738 7361 324 em.opt.R
>> SC_IA767 Subaru/SuprimeCam IA767 7694 365 em.opt.I
>> SC_IB827 Subaru/SuprimeCam IB827 8243 343 em.opt.I
>> SC_NB711 Subaru/SuprimeCam NB711 7121 72 em.opt.R
>> SC_NB816 Subaru/SuprimeCam NB816 8150 120 em.opt.I
>> UVISTA_Y VISTA/VIRCAM UltraVISTA DR4 Y 10216 923 em.IR.J
>> UVISTA_J VISTA/VIRCAM UltraVISTA DR4 J 12525 1718 em.IR.J
>> UVISTA_H VISTA/VIRCAM UltraVISTA DR4 H 16466 2905 em.IR.H
>> UVISTA_Ks VISTA/VIRCAM UltraVISTA DR4 Ks 21557 3074 em.IR.K
>> UVISTA_NB118 VISTA/VIRCAM UltraVISTA DR4 NB118 11909 112 em.IR.J
>> IRAC_CH1 Spitzer/IRAC ch1 35686 7443 em.IR.3-4um
>> IRAC_CH2 Spitzer/IRAC ch2 45067 10119 em.IR.4-8um
>> IRAC_CH3 Spitzer/IRAC ch3 57788 14082 em.IR.4-8um
>> IRAC_CH4 Spitzer/IRAC ch4 79958 28796 em.IR.4-8um
>>
>> However, my ESO Phase 3 scientist Laura (in cc) thought it could be
>> misleading to assign em.IR.J to the Y and NB118 filters, but also
>> said that ESO needed to look into standardizing this. If my UCDs for
>> these two filters could be misleading, so could those for all the
>> intermediate bands (IA, IB), the other narrow bands, and the broad
>> bands that don't have a UCD with its name encoded (e.g. g, z).
>>
>> I would be interested in your view on this.
>>
>> Kind regards, Bo
>>
>> On 3/1/22 5:41 PM, Mireille LOUYS wrote:
>>> hi again ,
>>> please do not hesitate to send your questions to me , or to the ivoa
>>> semantics list in copy .
>>> this helps the community and maintainers like me to be aware of the
>>> trouble you may encounter.
>>>
>>> many thanks , Mireille
>>>
>>> Le 25/02/2022 à 16:59, Bo Milvang-Jensen a écrit :
>>>>
>>>> PS: I have a couple of other questions/problems with the UCD
>>>> standard that I would like to ask/report. What is the best channel?
>>>>
>>>> Kind regards, Bo
>>>
>
> --
> --
> Mireille Louys, MCF (Associate Professor)
> Centre de données CDS IPSEO, Images, Laboratoire Icube
> Observatoire de Strasbourg Telecom Physique Strasbourg
> 11 rue de l'Université 300, Bd Sebastien Brandt CS 10413
> F- 67000-STRASBOURG F-67412 ILLKIRCH Cedex
> Tel: +33 3 68 85 24 34
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ivoa.net/pipermail/semantics/attachments/20220317/1f60df17/attachment-0001.html>
More information about the semantics
mailing list