<p>If you want a bolometric light curve from photometric points, you don't need to reconstruct its SED inside the range you already have data points. Use effective central wavelength of each band with its magnitude. Do trapezoid. This is an approximation, but it is better than reconstructing the SED that makes you rely more on assumptions for most circumstances, especially that you have UBVRI.</p>

<p>If, under some circumstances, you really need some more data points in between, or you really want a SED, blackbody is the first-order approximation, and is commonly used in SNe (at young ages). Less known issue in optical VBRI. There might be some issues with U like UV excess/suppressed. In this case, just fit the data to a blackbody.</p>

CC BY-SA 4.0
2018-11-17T15:38:51.677Z
2018-11-17T15:38:51.677Z
Kornpob Bhirombhakdi
<p>Could anyone point me to some manual or tutorial, possibly step-by-step one, on reconstruction of (quasi-) bolometric light curve using UBVRI-photometry data?</p>

<p>Both links and names are fine for me.</p>

CC BY-SA 4.0
2018-11-17T12:14:00.343Z
The task is simple. You integrate the SED (i.e., wavelength (or frequency) VS fluxes). In case of data points, you sum for area under the curve discretely, with or without inter/exterpolating the missing points. Another way, model the data with any known SED function, mostly blackbody, and integrate the fit model. For a blackbody, it is Stefan-Boltzmann.
Kornpob Bhirombhakdi
CC BY-SA 4.0
2018-11-17T12:29:23.160Z
But what I am asking is how do I reconstruct SED for those epochs where I have no spectral data. I know that it can be done somehow using UBVRI magnitudes, but cannot find detailed explaiation.
Tajimura
CC BY-SA 4.0
2018-11-17T13:53:43.633Z
Are you talking about the edges longer than I and shorter than U?
Kornpob Bhirombhakdi
CC BY-SA 4.0
2018-11-17T15:14:51.280Z
No. Just imagine the situation: you have values (apparent magnitudes) in 5 bands – from U to I and each of those values is not the real "point-value" at some frequency, but integral over the passband. And you have to reconstruct the full spectrum to use it to get bolometric lightcurve.
Tajimura
<supernova><photometry><resource-request><light-curve>
Comprehensible full manual for bolometric light curve reconstruction
Tajimura
# Comprehensible full manual for bolometric light curve reconstruction

(Asked by: username_0 on 2018-11-17)

Could anyone point me to some manual or tutorial, possibly step-by-step one, on reconstruction of (quasi-) bolometric light curve using UBVRI-photometry data?

Both links and names are fine for me.

**Tags:** supernova, photometry, resource-request, light-curve
> **Comments:**
> **username_1**: The task is simple. You integrate the SED (i.e., wavelength (or frequency) VS fluxes). In case of data points, you sum for area under the curve discretely, with or without inter/exterpolating the missing points. Another way, model the data with any known SED function, mostly blackbody, and integrate the fit model. For a blackbody, it is Stefan-Boltzmann.  
> **username_0**: But what I am asking is how do I reconstruct SED for those epochs where I have no spectral data. I know that it can be done somehow using UBVRI magnitudes, but cannot find detailed explaiation.  
> **username_1**: Are you talking about the edges longer than I and shorter than U?  
> **username_0**: No. Just imagine the situation: you have values (apparent magnitudes) in 5 bands – from U to I and each of those values is not the real "point-value" at some frequency, but integral over the passband. And you have to reconstruct the full spectrum to use it to get bolometric lightcurve.  

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## 1 answers

### Answer by username_1 on 2018-11-17. Score: 2

If you want a bolometric light curve from photometric points, you don't need to reconstruct its SED inside the range you already have data points. Use effective central wavelength of each band with its magnitude. Do trapezoid. This is an approximation, but it is better than reconstructing the SED that makes you rely more on assumptions for most circumstances, especially that you have UBVRI.

If, under some circumstances, you really need some more data points in between, or you really want a SED, blackbody is the first-order approximation, and is commonly used in SNe (at young ages). Less known issue in optical VBRI. There might be some issues with U like UV excess/suppressed. In this case, just fit the data to a blackbody.


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