How to add photometry from UKIRTS/WFCAM

[pjchen3]

Hi Joris,
I am a new user of speedyfit. Could you please advise on how to incorporate JHK photometry from UKIRT/WFCAM into the fitting? The object is not included in existing Vizier catalogs such as UKIDSS-DR7, but I have extracted the photometry directly from images.

[vosjo]

Hi,
You can add your photometry directly to the photometry file. Just make sure that you provide the flux and flux error in units of "erg/s/cm2/AA". For a bit more info on the photometry file: https://speedyfit.readthedocs.io/en/latest/userguide/photometry_file.html

Let me know if you need more info.

[pjchen3]

Thank you for the reply.
I tried adding the flux and flux error to the photometry file using the following format:
| WFCAM.J | flux | flux error |

However, when I ran the command, it returned: “Passband WFCAM.J missing from table”.

[vosjo]

Hi,
You will have to add those bands to the integrated grids you want to use because WFCAM is not included by default. Speedyfit has the transmission curves for WFCAM included in the package. So you do have everything you need to make a new integrated grid with WFCAM included. To do this. Look in the source code of speedyfit. There is a file called integrate_grid.py At the very bottom of the file there is a section like this:

if __name__=="__main__":

    responses = ['GALEX', 'IUE', 'STROMGREN', 'JOHNSON', 'GAIA3E', 'GAIA2', 'SKYMAPPER', 'APASS', 'SDSS', '2MASS', 'WISE']
    evbs = np.r_[0:1.02:0.05]

    # Kurucz
    calc_integrated_grid(threads=6, ebvs=evbs, law='fitzpatrick2004', Rv=3.1,
                         responses=responses, grid='kurucz')

Add the grid you want to the responses list:
responses = ['GALEX', 'IUE', 'STROMGREN', 'JOHNSON', 'GAIA3E', 'GAIA2', 'SKYMAPPER', 'APASS', 'SDSS', '2MASS', 'WISE', 'WFCAM']

Then run that script and it will make a new integrated grid that you can use. This will take quite a lot of time depending on the computer you are running it on.

[pjchen3]

Many thanks!

[pjchen3]

Hi Joris,
I added commands to the code (lines 196 and 206 of “plotting.py”) to save the synthetic model and flux values. I then tried to recalculate the flux values from the synthetic model using the “synthetic_flux()” function in “filters.py.” However, I noticed that the recalculated flux values are consistently slightly smaller than those returned by the algorithm, and I haven’t been able to identify the cause. Could you please help me understand what might be causing this discrepancy?

In the attached image, the red crosses represent the synthetic fluxes returned by the algorithm, while the blue crosses represent the flux values I recalculated. Observed fluxes from SDSS are marked with green circles.

[vosjo]

Hi, I need to see some code to comment on this. Can you send a minimum viable example please?

…

On Tue, 14 Jan 2025 at 09:50, pjchen3 ***@***.***> wrote: Hi Joris, I added commands to the code (lines 196 and 206 of “plotting.py”) to save the synthetic model and flux values. I then tried to recalculate the flux values from the synthetic model using the “synthetic_flux()” function in “filters.py.” However, I noticed that the recalculated flux values are consistently slightly smaller than those returned by the algorithm, and I haven’t been able to identify the cause. Could you please help me understand what might be causing this discrepancy? In the attached image, the red crosses represent the synthetic fluxes returned by the algorithm, while the blue crosses represent the flux values I recalculated. Observed fluxes from SDSS are marked with green circles. Screenshot.2025-01-14.at.16.46.28.png (view on web) <https://github.com/user-attachments/assets/88972eea-5cb7-4014-ad96-6adbc932c96c> — Reply to this email directly, view it on GitHub <#15 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AASU63FBK7VT5TU6VMKQYIT2KTFUBAVCNFSM6AAAAABVBIJVUKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKOBZGM2DENZRGY> . You are receiving this because you modified the open/close state.Message ID: ***@***.***>

-- m.v.g. Joris Vos

[pjchen3]

Thank you for the reply. We might consider using the case of HIP_4618 (with constraints) from https://speedyfit.readthedocs.io/en/stable/userguide/quickstart.html.
Below is the code I used to calculate the synthetic flux in the 2MASS J band (utilizing the transmission curve in the package) from the synthetic spectrum (file “binary_model.txt”) returned by the algorithm:

wave = wave_model # synthetic spectrum from the file "binary_model.txt"
flux = flux_model # synthetic spectrum from the file "binary_model.txt"
waver, transr = np.loadtxt('path_to_the_transmission_curve/2MASS_J.txt', unpack=True)
region = ((waver[0] - 0.4 * waver[0]) <= wave) & (wave <= (2 * waver[-1]))

wave_ = wave[region]
flux_ = flux[region]

if (np.searchsorted(wave_, waver[-1]) - np.searchsorted(wave_, waver[0])) < 5:
    wave__ = np.sort(np.hstack([wave_, waver]))
    flux_ = np.interp(wave__, wave_, flux_)
    wave_ = wave__

# -- interpolate response curve onto model grid
transr = np.interp(wave_, waver, transr, left=0, right=0)

# -- integrated flux: different for bolometers and CCDs
# -- WE WORK IN FLAMBDA
F_band = np.trapz(flux_ * transr * wave_, x=wave_) / np.trapz(transr * wave_, x=wave_)

print("Flux in J band: {:.4e} erg/s/cm^2/Å".format(F_band))

The synthetic flux (file “synthetic_flux.txt”) returned by the algorithm in the 2MASS J band is approximately 1.398e-12, while I obtained a value of 1.474e-12 using the code above.
binary_model.txt
synthetic_flux.txt

[vosjo]

Hi, I can't immediately see the issue. I will try to look at this in more detail asap. But I am a bit busy right now with my full time job.

…

On Tue, 14 Jan 2025 at 17:45, pjchen3 ***@***.***> wrote: Thank you for the reply. We might consider using the case of HIP_4618 (with constraints) from https://speedyfit.readthedocs.io/en/stable/userguide/quickstart.html <http://url>. Below is the code I used to calculate the synthetic flux in the 2MASS J band (utilizing the transmission curve in the package) from the synthetic spectrum (file “binary_model.txt”) returned by the algorithm: wave = wave_model # synthetic spectrum from the file "binary_model.txt" flux = flux_model # synthetic spectrum from the file "binary_model.txt" waver, transr = np.loadtxt('path_to_the_transmission_curve/2MASS_J.txt', unpack=True) region = ((waver[0] - 0.4 * waver[0]) <= wave) & (wave <= (2 * waver[-1])) wave_ = wave[region] flux_ = flux[region] if (np.searchsorted(wave_, waver[-1]) - np.searchsorted(wave_, waver[0])) < 5: wave__ = np.sort(np.hstack([wave_, waver])) flux_ = np.interp(wave__, wave_, flux_) wave_ = wave__ # -- interpolate response curve onto model grid transr = np.interp(wave_, waver, transr, left=0, right=0) # -- integrated flux: different for bolometers and CCDs # -- WE WORK IN FLAMBDA F_band = np.trapz(flux_ * transr * wave_, x=wave_) / np.trapz(transr * wave_, x=wave_) print("Flux in J band: {:.4e} erg/s/cm^2/Å".format(F_band)) The synthetic flux (file “synthetic_flux.txt”) returned by the algorithm in the 2MASS J band is approximately 1.398e-12, while I obtained a value of 1.474e-12 using the code above. binary_model.txt <https://github.com/user-attachments/files/18413333/binary_model.txt> synthetic_flux.txt <https://github.com/user-attachments/files/18413334/synthetic_flux.txt> — Reply to this email directly, view it on GitHub <#15 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AASU63HWFFM3UDSAM2T3BKT2KU5JXAVCNFSM6AAAAABVBIJVUKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKOJQGUYTOOBRGE> . You are receiving this because you modified the open/close state.Message ID: ***@***.***>

-- m.v.g. Joris Vos