All Questions
Tagged with python observational-astronomy
28 questions
2
votes
0
answers
53
views
How to convert .exp files from NRAO VLA Archive to .fits format
I recently downloaded some observational data files from the NRAO VLA Archive, and they have the extension .exp. These are old observations. I need to convert these files to .fits format for further ...
1
vote
0
answers
49
views
Tiling the sky with astropy-healpix
I have a bunch of files containing sources with galactic l and b values. What I want is to redistribute the sources such that each new file contain sources that fall within 15 degrees of a central l,b ...
8
votes
1
answer
346
views
Attempting to plot solar terminator using Python and Skyfield library
Problem
I would like to plot the small circle defining the visible portion of Earth for an observer at position $P$ away from the Earth, on a 2D map. In the case of the Sun, this would be the solar ...
- 331
2
votes
1
answer
72
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Help with simulating long-term orbital dynamics of exoplanetary systems using Rebound
I am a junior in high school working on an independent research project and I need help because I've reached the limits of my knowledge. My goal is to simulate the long-term orbital dynamics of ...
- 31
1
vote
0
answers
27
views
Obtaining Transit Spectrum for Celestial Bodies Using JWST NIRSPEC
I've recently been tasked with obtaining transit spectrum data for some fascinating celestial bodies, including Ceres, Enceladus, Ganymede, Io, and Titan. The goal is to compare their transit spectra ...
2
votes
0
answers
101
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How can I compute reasonable errors on my Gaussian fits to the observed strong optical lines of interest?
I'm fitting Gaussians to optical lines spanning from H-beta to Sulfur using Astropy's Gaussian (https://docs.astropy.org/en/latest/api/astropy.modeling.functional_models.Gaussian1D.html) model with a ...
- 1,111
3
votes
2
answers
151
views
How to construct optimal Wiener Filter?
I am trying to construct a Wiener Filter, to filter the ratio of the peak from the cross-correlation function, between a galaxy spectra and a template spectra, with the peak of the auto-correlation ...
- 849
0
votes
1
answer
160
views
2D Galaxy Spectrum taken by long-slit-spectrograph
I have the 2D data (shape(1125,2058) taken by a long slit spectrograph, which looks as follows:
The y-axis corresponds to the distance from the center, where the center is at the most bright green ...
- 849
4
votes
0
answers
99
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Keyerror: 0 while using astropy SkyCoord
I am facing a problem while using SkyCoord from astropy library. The scenario is as below,
I have read the data from a fits file into a pandas dataframe.
I have applied several quality cuts to the ...
- 173
1
vote
0
answers
137
views
Can this ppxf fit work?
I am trying to do kinematical analysis of spectra using ppxf-algorithm from Capellari. The velocity dispersion I get seems to be to high and I am not sure what the reason could be. On the website of ...
- 849
1
vote
0
answers
64
views
How to plot matplotlib plots as tables in python(hdf5 tables)
I have extracted the data from a fits file and plotted a spectra.i need to do the same for multiple fits files .how can I store the resultant spectra's as a hdf5 table or fits table?
And which ...
- 79
2
votes
1
answer
149
views
How to fit LOSVD of a galaxy with gauss hermite parametrization
I have recovered the following LOSVD from an elliptical galaxy, that I now want to fit a gauss-hermite-parametrization to and derive the kinematical parameters rotational velocity, velocity dispersion ...
- 849
3
votes
0
answers
87
views
S/N binning of 2D spectral galactic data
I have the 2D spectrum of the ellipical galaxy NGC 4697 taken by a long slit spectrograph. The x-direction (horizontal) corresponds to wavelength and the y-direction (vertical) corresponds to distance ...
- 849
2
votes
0
answers
450
views
How to subtract background correctly?
I want to perform sky background estimation and subtraction.
To do that, I am adopting some libraries in python, i.e. photutils which does have *some support for background estimation.
However, I ...
- 31
4
votes
1
answer
2k
views
Query Gaia by star name
I am attempting to query Gaia programmatically in python to get certain properties for specific stars. I can write a query which obtains some properties, but only for all stars, not a set of stars or ...
1
vote
1
answer
581
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 ...
- 849
3
votes
0
answers
30
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 ...
- 849
5
votes
1
answer
482
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 ...
- 849
5
votes
1
answer
382
views
How to extract galaxy spectra for different radii in Python for spectra taken by long slit spectrograph?
I am trying to extract the kinematics from the elliptical galaxy NGC 4697 using the Fourier Correlation Quotient (FCQ) algorithm described by Bender (http://adsabs.harvard.edu/full/1990A%26A...229.....
- 849
1
vote
1
answer
156
views
Derive LOSVD from galaxy spectrum, using fourier method
I am trying to implement a programm, that derives the kinematics (specifically the kinematic parameters: mean rotation velocity, velocity, dispersion, hermite coefficients h3 and h4) from an ...
- 849
-1
votes
2
answers
799
views
Calculate exact date and time from position of the sun - 88° degrees
I am currently working on an astrology project and need to figure out the exact date and time based on the sun's position of birth - 88° degree (approx. 89 days) before the moment of birth.
I am using ...
2
votes
0
answers
573
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 ...
- 849
2
votes
2
answers
203
views
Technique for folding sparse event data in order to detect an underlying periodicity?
@JamesK's answer to When will the next transit of Earth be visible from Mars? Was the last one really on May 11, 1984? lists dates of 18 transits which I've converted to days since 1500-Jan-01 as
<...
- 30.7k
17
votes
2
answers
4k
views
Why does the Fourier transform of this CMB image have a hole in it?
The BBC's Desert telescope takes aim at ageing our Universe contains the image below of the Cosmic Microwave Background from the Atacama Cosmology Telescope or ACT. It looks like this is plotted with ...
- 30.7k
3
votes
0
answers
106
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 ...
- 131
2
votes
0
answers
161
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 ...
- 30.7k
2
votes
2
answers
644
views
How to do logarithmic wavelength binning (in Python) in order to find redshift?
In Tonry and Davis (1979), p.1513, they formulated a cross-correlation method for extracting velocity redshifts:
Theory of Correlation Analysis
a) Introduction
Let $g(n)$ be the spectrum of a galaxy ...
- 43
2
votes
2
answers
830
views
Converting FITS (NuSTAR) coordinates to WCS
I'm trying to convert some pixel coordinates I have into WCS coordinates, ideally into a WCS region for use in some further analysis.
So far I've been able to load and parse a NuSTAR FITS file, do ...
- 21