Questions tagged [data-analysis]

Analysis of data is a process of inspecting, cleaning, transforming, and modeling data with the goal of discovering useful information, suggesting conclusions, and supporting decision making.

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10
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2answers
278 views

How do you propagate asymmetric errors? (on the practical way to...)

I've used uncertainties's ufloatpackage to propagate uncertainties as I thought it's the standard way to do it. Now I want to ...
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0answers
55 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 ...
10
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1answer
1k views

What is sin i in this graph and why is it there?

This is some data presented in a lecture on exoplanets that depicts the distribution of the sizes of super-Earths in comparison to the mass of Jupiter. I would like to know what the argument of the ...
3
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1answer
70 views

How to plot 68% contours?

I am doing a grid search of omega_Matter vs Omega_dark_energy by iterating over ranges of both and determining the chi-squared to determine the optimal value of both for a LambdaCDM model. I have my ...
1
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1answer
27 views

How to handle empty tables returned by astroquery Nist.query() in Python?

I'm writing a code to extract wavelengths of certain species of atoms/ions in a given wavelength range using the Nist.query() command of the Python package ...
4
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1answer
123 views

Procedures to test an hypothesis

In the context of planet formation and with the intention of testing different migration and in situ formation scenarios, I'm wondering what are the standard procedures to test and rank different ...
6
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1answer
64 views

Why Nyquist Sampling Rate depends on Bandwidth and not max frequency?

Is the Nyquist sampling rate same for different bands if those bands have same bandwith? E.g. Would the Nyquist Sampling rate be same for 1000-1400 MHz band as for 100-500 MHz band because both the ...
4
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0answers
48 views

How does the Hubble Space Telescope measure the speed of the wind inside Jupiter's Great Red Spot?

Space.com's Jupiter's winds of change show increased storm speeds in Great Red Spot and Hubblesite.org's Hubble Shows Winds in Jupiter's Great Red Spot are Speeding Up both link to the recent open ...
2
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0answers
19 views

What are mag_a, mag_i, mag_z, a*, and sin_i * from the SDSS Moving Objects Data?

I'm currently working on the SDSS Moving Objects data sets and came across the column names mag_a, mag_i, mag_z, aprime, and sin_iprime. Can someone describe what these attributes mean, or where I can ...
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0answers
19 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 ...
4
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0answers
64 views

Obtaining the derived period of $\omega$ Canis Majoris

I have read these two papers: On the nature of the Be phenomenon I. The case of ω Canis Majoris Stellar and circumstellar activity of the Be star ω CMa II. Periodic line-profile variability In the ...
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0answers
18 views

Curated dataset of labelled images for NEO detection

I am looking for a dataset of images. Some images should contain NEO's (1 or more), others should not. With the dataset, there should also be an accompanying file, of which should contain 'labels'. ...
2
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1answer
58 views

Extracting specific star data from Gaia DR2?

I would like to extract all Gaia DR2 sources which have six-parameter solutions as well as their radial velocities and effective temperatures. Is this possible as DR2 only specifies that there are 1,...
2
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1answer
35 views

How to calculate an infrared SED from the specific intensities?

I have values of total infrared fluxes (SED) in literature expressed in Jy (Jansky) for galaxies. I want to assure that my infrared radial profiles of the same galaxies in MJy/sr (and other in Jy/...
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1answer
97 views

Why histogram does not look like the Gaussian curve?

I have data consisting of radial velocities and times (covering about 10 000 days). The radial velocity changes with a period. I tried to find out the period using Stellingwerf's method (it was ...
3
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1answer
233 views

What is z in this program?

Does z stad for the mass fraction of all the remaining chemical elements except helium and hydrogen, please? Source: https://github.com/chrysante87/pyterpol/wiki
3
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0answers
32 views

Solving the inverse problem - inspection

After solving the inverse problem*, how to investigate whether the solution is unique or not? When I check theoretical values and published values during the convergence and search for the lowest ...
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0answers
23 views

What is Euclidean fluence scaling in the context of bounding constraints on FRB all-sky rates? Would non-Euclidean scaling give a different answer?

The recent Chromatic periodic activity down to 120 MHz in a Fast Radio Burst contains two paragraphs in which X's are given "assuming an Euclidean fluence scaling". To me, a non-astronomer, ...
1
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0answers
25 views

Star Catalog with radius, luminosity, and spectra class?

I am looking for a star catalog (hopefully a .csv file) that contains radius, luminosity, and spectra class data for 1000+ stars. I have checked catalogs like the HIP, HD, and GAIA catalogs. I have ...
1
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1answer
44 views

Where do Astronomers usually get their wavelengths? Where do they turn to look up standard, accepted values for spectral features?

When identifying isolated observed spectral features or fitting complex observed spectra or even running complex numerical simulations, one needs a reliable, standard table of known wavelengths and ...
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0answers
36 views

How to find published data with the article?

How to find data published with an article, please? For instance, let us consider this paper. There are data products and the link to SIMBAD on the right. Then, the table with objects appears, but ...
7
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1answer
1k views

On what basis is the information about the distance and velocity of the Voyager probes determined?

Voyager 1 was the first-ever object to reach interstellar space on August 25, 2012 when it passed beyond the sun’s realm of plasma influence (the heliosphere)[...] (source) Although some of their ...
2
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2answers
85 views

How the data collected during 5 year DESI operation will be analyzed with regards to finding what dark energy really is?

Dark Energy Spectroscopic Instrument, or DESI at the end of it's 5 years operation will create the largest 3-D spectroscopic map of the universe. How the data collected during 5 year DESI operation ...
6
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1answer
526 views

Conventional units for astronomical object coordinates

I would like to know what the conventional units for identifying a celestial object (J2000.0) are. For instance, I am reading a paper in which they refer to object SDSSJ170013.70+400855.6; I am ...
3
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0answers
39 views

Estimate the shape of an object based on flux curve

Is there an aproximation to know the shape of a dust cloud,etc based on the magnitude/flux curves of stars they transit? Example, can I know if the shape is (at least in 2 dimensions) elliptical, ...
4
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1answer
101 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.....
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3answers
249 views

Role of power laws in astronomy?

I often see astronomers fitting data to power laws. What about power laws makes them so useful in astronomy? Why are so many astronomical observations well-fit by power laws? I know it's a relation ...
3
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1answer
63 views

Orbital resonances - expansion of disturbing function

I want to study the orbital resonance type 3:1 between an asteroid and Jupiter. For this purpose, I found the expansion of the disturbing function, $R$, in Celletti A., Stability and Chaos in ...
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0answers
22 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 ...
0
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1answer
81 views

Query with Gaia: I have a list of 1000+ source_id's. How do I find the associated stars and their data?

I have a table of around 1700 source id's from gaiadr2 (in csv format). I would like to see the data that Gaia has for each star in a new table. I'm really struggling to figure out how to do this ...
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0answers
53 views

Are sunspots named or individually tracked?

This is a follow-up question to How are the solar flares from May 23, 2021 extraordinary? which is about news of spaceweather.org. In the present question, I am curious solely about sun-spots and why ...
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0answers
30 views

Where to find all spectroscopic data about 28 CMa?

I am searching all available spectroscopic data (and particularly wavelength interval) of 28 CMa in the constellation Canis Majoris to measure radial velocities. Which database should I use?
2
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0answers
93 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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0answers
41 views

Kaggle dataset for Photo-Z estimation?

I would like to use the dataset for this kaggle but the competition was private, is closed and I have been unable to contact anyone directly. The challenge is machine learning for photo-z estimation ...
3
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0answers
46 views

Flickering and noise

I'm working with flickering measures from some stars. So, I take differential magnitudes, make a histogram and fit their standard deviation. My measure of flickering is the FWHM (full width at half ...
2
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1answer
67 views

Finding galaxy spectra in SDSS Catalog by object name

I am looking to find galaxy spectra of early type elliptical galaxies in the SDSS catalog by the objects name. See: https://dr12.sdss.org/advancedSearch. I dont know how to find out the PLATEID of my ...
1
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1answer
287 views

working with stellar spectra in fits format in python

Hey I am new to working with astronomical data in Python. I wanted to start working with stellar spectra and I am having trouble with the data. To get a first look I just wanted to plot a spectra (...
11
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2answers
296 views

Can automatic algorithms completely eliminate the impact of Starlink and other satellites?

According to a comment by user @J: With that said, other than aesthetics, machine vision algorithms are wildly more advanced today than in the past - strategies to remove passing satellites don't ...
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0answers
35 views

Can we identify planets, moons, and large asteroids in our solar system have a unique spectroscopy?

I'm looking to create a database of relatively consistent measurements for various cosmic bodies. Please inform if there's a way to gather reproducible signatures, with the same set of instruments to ...
4
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1answer
85 views

Accessing SDSS server SQL server via python

Is there a way to directly access any of the Sloan Digital Sky Survey servers via SQL via Python? Currently I have been able to run SQL queries from the website they provide (for example https://...
0
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2answers
41 views

Frequency analysis on Semiperiodic object(s) using Lomb-Scargle

So I already did a frequency analysis of the SRv-type's light curve using Period04. I already have the 'periodicities' of the object/star of choice which is quite hard since the latter/other periods ...
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0answers
172 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 ...
3
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0answers
104 views

What are some challenging astrophysics problems for which we have data available? [closed]

I am a Computer Science student, and I would like to pursue a PhD in the same area, by applying artificial intelligence techniques to astrophysics. Not being an astrophysicist, however, I was curious ...
0
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1answer
170 views

How to convert Proper Motion in RA & Dec to Galactic Coordinates

I'm trying to parse stellar data in the GAIA 2 release to galactic coordinates and am struggling with the velocity component. I've tried following online documentation and papers, but end up with ...
1
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2answers
200 views

Sample bias' contribution to "Planet 9" hypothesis, why was this not thoroughly addressed before?

Science Claim for giant 'Planet Nine' at Solar System's edge takes a hit arXiv No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects The brightness of distant solar system objects ...
0
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1answer
53 views

extracting visibility information from CASA measurement set

I am trying to export the UV wavelengths, visibilities and weights from a measurement set in CASA, but I haven't been able to find the right commands to do this. 'exportuvfits' might be what I am ...
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0answers
38 views

In what ways are neural net classifiers "better" than search algorithms for eclipsing star system searches? (1D time series, not images of cats)

Neural net classifiers are both "hot" and useful. TIC 168789840: A Sextuply-Eclipsing Sextuple Star System is quite an interesting read, and describes the use of one trained on a ...
4
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0answers
136 views

Time evolution data of the Great Red Spot on Jupiter?

Jupiter's Great Red Spot fascinates scientists for ages, so it does me. Where can I find a table (e.g. as CSV-file) with the time evolution of longitude, latitude, horizontal and vertical extension of ...
2
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1answer
43 views

SIMBAD TAP queries seem to indicate there are no distance measurements for a great many nearby stars, including Alpha Centauri or Barnard's Star

I'm attempting to create a map of all objects within 50LY, including main-sequence stars, binaries, planemos, etc. As such, I'm trying to do it all from first principles, building a micro-ETL to ...
3
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2answers
116 views

Do ASKAP and ALMA have "fast dump" interferometric modes? Can they see and perhaps report Fast Radio Bursts in real time?

Chatterjee et al 2017 The direct localization of a fast radio burst and its host nicely shows a VLA detection of a repeating FRB in 5 millisecond steps nicely demonstrating the dispersion slope ...

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