Questions tagged [python]

Questions about using the Python programming language to solve astronomical problems. General questions about Python are off-topic but might be asked on Stack Overflow.

41 questions with no upvoted or accepted answers
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243 views

Generate probability skymap

I am trying to generate skymaps for a set of Fermi GBM triggers, containing the probability that a trigger originated in a given part of the sky. For each trigger, I have access to the RA, dec, error ...
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22 views

How to find x-values of fourier-transformed correlation functions in velocity space?

I am trying to extract the kinematic parameters (rotation velocity, velocity dispersion, ...) of an elliptical galaxy by extracting the kinematical broadening function using the FCQ-Algortihm first ...
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66 views

How to remove redshift from galaxy spectra in Python?

Hello I extracted a spectrum from the central region of the 2D spectrum of the major axis from NGC 4697 (I just took a central row in the 2D data set, see this question for more information: How to ...
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195 views

Issues in dimensions and slicing while plotting contours over a FITS Image in Astronomical Plotting Library in python (APLpy)

I have been trying to plot the contours of a FITS image over itself in APLpy. The image was created in AIPS, and has dimensions (1024,1024,1,1), viz., right ascension (RA--SIN), declination (DEC--SIN),...
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135 views

How do I plot field of view of an earth-based observatory in Galactic Coordinates?

I would like to plot in Galactic Coordinate the sky field-of-view of an earth-based observatory (e.g. MAGIC). Something like this from Liu et 2016. I already know how plot source positions on a 2D ...
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43 views

Is there a tool to convert N-body RAMSES simulation file formats to GADGET 2 format in Python?

I am looking for a way to convert RAMSES files to GADGET-2 binary files because I want to use the package SimSpin (https://github.com/kateharborne/SimSpin/blob/master/R/make_simspin_file.R) which is ...
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63 views

How to calculate orbital velocity of binary star?

I am trying to simulate the Alpha Centauri AB System. I built the simulation, it works flawlessly when trying to simulate our solar system, and I am now trying to simulate the AB System. I found all ...
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18 views

reference frames-healpix: projection parameters for smooth continuous tiles on a sky map

I am working on a newly completed survey which uses healpix fits files on 1/8th of the sky. I would like to set a flat skymap which covers the entire sky but it seems this will create artifacts and ...
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32 views

healpix: creating isometric tiles for flat map of survey

I am currently tasked with creating a visual of a recently completed survey which is in HEALPix1 format. I am also required to use the DSS and Planck skymaps also in HEALPix, and would like to flatten ...
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105 views

Logarithmic rebinning and continuum removal of stellar spectra

I am trying to learn how to derive the line of sight velocity distributions from galaxy spectrum to extract kinematical parameters like rotational velocity and velocity dispersion. Therefore I need to ...
2
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71 views

Using the 'exoplanet' module to fit a radial velocity curve for a binary star system

As part of a project, I am trying to fit a radial velocity curve using the tutorial for the binary star system (EBLM J0608-59) My code is quite similar to the tutorial, but as it is only one body ...
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52 views

Should I fit a function to this lightcurve?

I am creating a light curve for the duration of a binary system in order to find out the duration of the eclipse. I am unsure as to whether to fit a function to the data (is it appropriate) as by ...
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48 views

Detect sources near image edge with python photutils

As my question suggests, I 'm trying to use a python library photutils in order to detect sources from MUSE cube. MUSE (Multi Unit Spectroscopic Explorer) is an ...
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60 views

PHOEBE 2.2 Documentation, components and semi-major axis definitions

I'm looking at PHOEBE 2.2 Documentation, specifically at a tutorial about constraints What are Constraints? Constraints live in their own context of the Bundle, and many are created by default - ...
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115 views

How are small objects automatically identified and their locations determined in digital images?

I have a large quantity of old digital images of low energy electron diffraction (LEED) patterns that I must process to identify and locate small, sometimes elongated gaussian-like blobs of a few ...
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137 views

Covariance matrix not calculated when fitting gaussians?

So I am using Astropy's basic models.Gaussian1D model and a fitter = fitting.LevMarLSQfitter() to fit 3 Gaussian pulses with some added random noise. The fit is good, but when I type fitter.fit_info, ...
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61 views

How would I code to find the seeing of a binary star system in python?

I have fit images of binary systems and want a program that will help determine which ones are highest quality, the seeing. The simplest way is apparently to equate it to the FWHM of the Gaussian of ...
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256 views

How to "slice" a fits table in astropy?

I have imported my fits table, hdul0, into python. I'm using astropy.table. I opened it with hdul0 = fits.open('filename'). hdul0data = Table(hdul0[1].data) I ...
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230 views

Comoving distance between two points [(RA1, Dec1, z1) and (RA2, Dec2, z2)]

I have Redshift (z), RA and Dec positions for two points in a galaxy catalogue (say P1 = [<...
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88 views

Efficiently calculating power spectra from galaxy catalogs

I am dealing with a problem which requires calculating either the correlation function or the power spectrum. At times, the 2-point-correlator seems the better route, at others, the PS. Right now I am ...
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467 views

Coordinates reduction python

How can I calculate position (alt, az) of star for observer at some station (longitude, latitude) on specific date and time? I need full coordinates reduction with all elements included in calculation ...
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40 views

how to plot Gauss-Hermite moment maps from arrays of star velocity values in Python?

I want to calculate Gauss-Hermite moments, such as h1,h2, h3, h4 moments from the values in an array of numbers which represent velocity distribution of stars in a galaxy. How would I fit a curve to ...
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30 views

Simulating Light Curve with the Timmer & Koenig method in Python

How to simulate the light curve using the Timmer & Koenig method in python with error bars in each counts generated by that method. I have used astro ML but I doesn't show the error in the counts. ...
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62 views

How to quickly loop through many small fits files for data analysis?

I need to extract information from a few columns in ~20k different fits files with python. Each file is relatively small, ~0.2MB. I have been doing this so far with a loop and ...
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21 views

How to calculate S/N in galaxy absorption spectra?

I want to calculate the S/N of an galaxy absorption spectrum. I therefore chose a part of the spectrum which contains very little to none absorption features and should be only made up of noise and ...
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23 views

Filtering local region in SIMBAD

I am completely new to astrophysics and currently writing a paper on Cepheid variables for high school physics. I would like to filter out all Cepheid variables in the local system which I would ...
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206 views

Schechter Luminosity Function fitting plot of galaxies

I would like to plot the Schechter Luminosity function of galaxies. Here is my data(I have the Luminosity L[Ha] in erg/s). I would like to plot like this figure from this paper. In this paper, they ...
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52 views

Using lightkurve to identify a planet

I have gotten LightKurve to work and plot a lightcurve to allow for the identification of possible transits. However is there a way I can get it to run and tell me if there is a possible transit in ...
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174 views

Wavelength Calibration in Python - Line Identification algorithm

I was asked to develop a data reduction pipeline for a telescope and am facing a problem. I have the standard lamp spectra and need to identify the emission lines in order to find a wavelength ...
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288 views

Python interface for DMK 23U274 USB camera for astrophotography

I have access to a monochrome USB camera (DMK 23U274, The Imaging Source) and I'd like to record focal plane images from a small telescope with a python script that would control it by setting ...
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137 views

Three Body Problem

I tried to solve the three body problem numerically. While after 1000 time steps the system looks stable (See Fig.1) it is completely unstable after 10000 time steps (See Fig.2). Is that an intrinsic ...
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375 views

To show perihelion precession motion of Mercury in Python with matplotlib

I'm trying to make it more general code so I can trace even a parabola or hyperbola for $e=1, E=0$ and $e>1, E>0$ respectively. And after achieving that general code I want to make the same code ...
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33 views

How can I get the fluxes of fetch_imaging_sample? - astroML

I'm working with astroML in Python and I need to get the fluxes from the magnitudes in r band of fetch_imaging_sample(). ...
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125 views

Plotting GAIA barycentric radial velocity data with python

Does anybody know of a good tutorial on how to use python and astropy to generate plots of GAIA, RAVE or any other database of barycentric (heliocentric) radial velocity data of stars in our galaxy? ...
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502 views

Plot an AltAz grid over a square grid of RADec points

first post here. As I'm new, StackExchange won't let create or use the wcsaxes tag. wcsaxes looks like the most appropriate tool for the job, but astropy is closely related. I think the title says ...
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13 views

Power Spectral Response Method

Can any one suggest me how we can apply the power spectral response method to calculate the best fit spectral index in python ? And plot the probability vs spectral index ?? Or any reference to ...
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29 views

Why can I not get pymultinest running and what's the best way to generate CMD with coding?

I recently downloaded the isochrones environment for Python, and I installed pymultinest for sure, but when I import it in Jupyter Notebook it always says 'ERROR:root:Internal Python error in the ...
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41 views

Are there python packages to calculate mean line of sight velocity, linewidth and other distributions from galaxy simulation snapshots?

Does anyone know of any packages/functions in packages that can give mean line of sight velocities (losv) from a simulation snapshot (from the spatial and velocity coordinates or directly from the ...
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31 views

What is the formula to input date, time and longitude. Where I can get latitude of the civil twilight back?

I am making a watch app, where I need to know where there is currently sun, and where it's not. I need to have some sort of formula/function to insert: date, time and longitude, and get back the ...
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23 views

How to create synthetic galaxy spectrum by broadening stellar spectra with a gaussian

I am trying to create a synthetic galaxy spectrum, by convolving a gaussian-velocity-distribution f(v) with my stellar spectra S. I have already logarithmically rebinned the spectrum and removed the ...
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164 views

Smoothing an SED with binning

I have an (observed) SED of a galaxy, and am attempting to match model SEDs to it. To do this I need to be able to see its shape better, which would involve some sort of smoothing of the spectrum. I ...