Limb Darkening Coefficients Calculation: Understanding Bandpass Selection

[natski]

Hi everyone,

I found some useful code to predict limb darkening coefficients on http://www.fiu.edu/~vanhamme/limdark.htm. I understand all of the inputs to this program except the selection of 'bandpass'.

I am assuming that anyone bandpass refers to a range fo wavelengths for which the calculation of the limb darkening coefficients will be valid. Can someone please just first confirm that this interpretation is correct?

Secondly, the author uses names such as Hipparcos, Tycho B and V bands which don't really mean anything to me, so I need some kind of catalogue or index which gives the corresponding wavelength values in S.I. for each bandpass name. If anyone knows what these names refer to or a good online catalogue or something, please please post it!

Thanks in advance,
Natski

 

[chemisttree]

Hi everyone,

I found some useful code to predict limb darkening coefficients on http://www.fiu.edu/~vanhamme/limdark.htm. I understand all of the inputs to this program except the selection of 'bandpass'.

I am assuming that anyone bandpass refers to a range fo wavelengths for which the calculation of the limb darkening coefficients will be valid. Can someone please just first confirm that this interpretation is correct?

Secondly, the author uses names such as Hipparcos, Tycho B and V bands which don't really mean anything to me, so I need some kind of catalogue or index which gives the corresponding wavelength values in S.I. for each bandpass name. If anyone knows what these names refer to or a good online catalogue or something, please please post it!

Thanks in advance,
Natski

Hipparcos was a satellite launched in 1989 that returned parallax and astrometric data on roughly 120,000 objects with high precision. The list of objects are known as the Hipparcos list. Another list of less precise measurements, known as the Tycho list contains about a million objects. I've only seen Tycho 1 and Tycho 2 used to describe this data... perhaps the Tycho B list is the Tycho 2? The V band refers to the bandpass of wavelengths measured, in this case it means the green-yellow (visible) portion of the spectrum.

Color index
the catalog

 

[natski]

Two fo the most commonly quoted bandpass systems seem to be Stromgren uvby Johnson UBV. I cannot find any actual values for the wavelength passes though despite a couple of hours of heavy Googlage... any ideas??

 

[natski]

I found http://www.aavso.org/pipermail/aavso-photometry/2003-December/000111.html which explains the Stromgren system... just need to find Johnson UBV now...

 

[chemisttree]

try this. especially reference #1.

A review article for you.

STANDARD PHOTOMETRIC SYSTEMS
Michael S. Bessell
Annual Review of Astronomy and Astrophysics, September 2005, Vol. 43, Pages 293-336
(doi: 10.1146/annurev.astro.41.082801.100251)

 

[natski]

Yup, thank-you very much chemisttree

 

[natski]

Does anyone know what wavelengths the near-infrared bands R, I, J, H & K correspond to?

 

[FTL_Diesel]

Hi Natski,

R: 500-776nm
I: 648-746nm
J: 1007-1433nm
H: 1323-1937nm
K: 1800-2580nm

More or less; I just pulled this out of a fortran code I have, but the exactness of the bounds seems circumspect to me. If you can get a copy of Allen's Astrophysical Quantities, I bet that'll have the wavelength range for these bandpasses.

As an aside, a more recent set of limb-darkening coefficients can be found in Claret (2000) (http://adsabs.harvard.edu/abs/2000A&A...363.1081C), if you're interested.

Can I ask, having seen all your posts, what exactly it is that you're doing?

 

[Chronos]

Good question, FTL. It's an ATM trojan horse.

 

[natski]

I can't really go into too much detail because this is the world wide web afterall. I'm doing some modelling and just needed to correct some code I got provided with many unfamiliar aspects to it. I was basically trying to change the code from quadratic to Claret-style limb darkening.

 

[FTL_Diesel]

Good question, FTL. It's an ATM trojan horse.

ATM?

 

[Chronos]

An "Against The Mainstream" conjecture. This model was refuted about a century ago.

 

[chemisttree]

OK, I'll bite... What theory are you referring to?