<p><strong>First of all hello, I am new to this forum and I apologize in advance if I am wrong.</strong> <br/>
I am doing open cluster observations and as a result of these observations I am trying to find the conversion coefficients for UBVRI filters to the standard photometric system. I need to write a code in python using &quot;curve fit&quot; and error codes, but I am not very proficient.<br/>
The equations I need to use are in the photo. If you want to look at it additionally, you can look at the article written by Janes et al. <strong><a href="https://iopscience.iop.org/article/10.1088/0004-6256/145/1/7#aj450229r21" rel="nofollow noreferrer">Link</a></strong><br/>
<a href="https://i.sstatic.net/aOWZT.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/aOWZT.png" alt="enter image description here" /></a><br/></p>
<p>I made my observations of 17 standard fields selected from Landolt (2009) with the telescope. After downloading my fits images with information such as air mass (X), luminosities, etc., I registered them in a database. The atmospheric extinction and conversion coefficients to the standard photometric system and the nightly constants calculated in a previous project at the telescope we observed are given in the photo below.<br/></p>
<p><a href="https://i.sstatic.net/slJVC.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/slJVC.png" alt="atmospheric" /></a></p>
<p>I aim to find new coefficients by using the coefficients in the photo, the database I obtained by reducing the coefficients from the fits images and the luminosities of Landolt Standard Stars in the literature.</p>
<p>For example <span class="math-container">$$ v=V+\alpha_{bv}\ (B-V)+k_v\ X_v+C_{bv} $$</span> in this equation: I have the UBVRI luminosities and air masses from my standard field observations, so V , (B-V) and X are known. alpha_bv, k_v and C_bv will be taken from the table I provided and used in the curve fit. We can write them down by defining a p0. For example, if we define <span class="math-container">$$ \alpha_{bv}=-0.021 , k_b=0.238 , C_{bv} =-0.901 $$</span> in a p0 list, it can make our job easier when using curve_fit.<br/></p>
<p>I want to call the database in python where I added the data I got with the reduction and after extracting my data, I want to calculate the same data and its errors with curve fit using the data given in the table above?<br/></p>
<p>I would be very grateful if there is someone who can help me even briefly on this subject. <strong>Thank you.</strong></p>

CC BY-SA 4.0
2023-08-08T04:48:38.170Z
We're going to need a little more information. What are the open cluster observations you are trying to transform, where did they come from (are they your own data or are you replicating another dataset/paper) and what else do you have ? $X$ in the above is the airmass and the $k_v$ etc are the extinction coefficients - fitting these normally needs observations of standard stars of known mags. over a range of airmass (inverse altitude basically; 1.0 is the zenith, 2 is 30deg altitude). If you can edit and add some details this will makes things easier
astrosnapper
CC BY-SA 4.0
2023-08-08T09:36:04.440Z
Thank you for the return. I have corrected my question again and added the new information.
houst
CC BY-SA 4.0
2023-08-08T11:00:48.583Z
I still don't see a question here.
ProfRob
CC BY-SA 4.0
2023-08-08T11:25:24.717Z
Hi Rob, I think I asked my question clearly. If I need to ask again briefly, I want to find the new values of the above equations using curve_fit with a function.
houst
CC BY-SA 4.0
2023-08-08T12:24:38.577Z
@houst in the mean time, can you add a sentence that ends with a question mark that is an actual question to which proper Stack Exchange answers can be posted? *Thanks!*
uhoh
CC BY-SA 4.0
2023-08-08T12:27:44.030Z
@ProfRob I just got the notification again. I guess I didn't get a notification because I didn't tag you, so I'm commenting again. I'm sorry.
houst
CC BY-SA 4.0
2023-08-08T12:27:55.873Z
@astrosnapper I just got the notification again. I guess I didn't get a notification because I didn't tag you, so I'm commenting again. I'm sorry.
houst
CC BY-SA 4.0
2023-08-08T13:27:32.787Z
I still don't get it. You describe a procedure - "I want to... " (which souds fine) and then just end it with a question mark. Is the question - "does this procedure sound like the right thing to do"? Or what?
ProfRob
CC BY-SA 4.0
2023-08-08T16:28:14.893Z
@ProfRob I cannot solve my work without using the equation given by Janes et al. I am trying to calculate the coefficients in nightly observations and I am trying to run this procedure in python and get output. I apologize my English is a bit bad.
houst
<python><star-cluster><standards>
PYTHON calculation of conversion coefficients for UBVRI filters to standard photometric system
houst
# PYTHON calculation of conversion coefficients for UBVRI filters to standard photometric system

(Asked by: username_0 on 2023-08-07)

**First of all hello, I am new to this forum and I apologize in advance if I am wrong.**   
I am doing open cluster observations and as a result of these observations I am trying to find the conversion coefficients for UBVRI filters to the standard photometric system. I need to write a code in python using "curve fit" and error codes, but I am not very proficient.  
The equations I need to use are in the photo. If you want to look at it additionally, you can look at the article written by Janes et al. **[Link](https://iopscience.iop.org/article/10.1088/0004-6256/145/1/7#aj450229r21)**  
[![enter image description here](https://i.sstatic.net/aOWZT.png)](https://i.sstatic.net/aOWZT.png)

I made my observations of 17 standard fields selected from Landolt (2009) with the telescope. After downloading my fits images with information such as air mass (X), luminosities, etc., I registered them in a database. The atmospheric extinction and conversion coefficients to the standard photometric system and the nightly constants calculated in a previous project at the telescope we observed are given in the photo below.

[![atmospheric](https://i.sstatic.net/slJVC.png)](https://i.sstatic.net/slJVC.png)

I aim to find new coefficients by using the coefficients in the photo, the database I obtained by reducing the coefficients from the fits images and the luminosities of Landolt Standard Stars in the literature.

For example $$ v=V+\alpha\_{bv}\ (B-V)+k\_v\ X\_v+C\_{bv} $$ in this equation: I have the UBVRI luminosities and air masses from my standard field observations, so V , (B-V) and X are known. alpha\_bv, k\_v and C\_bv will be taken from the table I provided and used in the curve fit. We can write them down by defining a p0. For example, if we define $$ \alpha\_{bv}=-0.021 , k\_b=0.238 , C\_{bv} =-0.901 $$ in a p0 list, it can make our job easier when using curve\_fit.

I want to call the database in python where I added the data I got with the reduction and after extracting my data, I want to calculate the same data and its errors with curve fit using the data given in the table above?

I would be very grateful if there is someone who can help me even briefly on this subject. **Thank you.**

**Tags:** python, star-cluster, standards
> **Comments:**
> **username_1**: We're going to need a little more information. What are the open cluster observations you are trying to transform, where did they come from (are they your own data or are you replicating another dataset/paper) and what else do you have ? $X$ in the above is the airmass and the $k_v$ etc are the extinction coefficients - fitting these normally needs observations of standard stars of known mags. over a range of airmass (inverse altitude basically; 1.0 is the zenith, 2 is 30deg altitude). If you can edit and add some details this will makes things easier  
> **username_0**: Thank you for the return. I have corrected my question again and added the new information.  
> **username_2**: I still don't see a question here.  
> **username_0**: Hi Rob, I think I asked my question clearly. If I need to ask again briefly, I want to find the new values of the above equations using curve_fit with a function.  
> **username_3**: @houst in the mean time, can you add a sentence that ends with a question mark that is an actual question to which proper Stack Exchange answers can be posted? *Thanks!*  
> **username_0**: @ProfRob I just got the notification again. I guess I didn't get a notification because I didn't tag you, so I'm commenting again. I'm sorry.  
> **username_0**: @astrosnapper I just got the notification again. I guess I didn't get a notification because I didn't tag you, so I'm commenting again. I'm sorry.  
> **username_2**: I still don't get it. You describe a procedure - "I want to... " (which souds fine) and then just end it with a question mark. Is the question - "does this procedure sound like the right thing to do"? Or what?  
> **username_0**: @ProfRob I cannot solve my work without using the equation given by Janes et al. I am trying to calculate the coefficients in nightly observations and I am trying to run this procedure in python and get output. I apologize my English is a bit bad.  

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## 0 answers

