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Unanswered Questions

132 questions with no upvoted or accepted answers
0 votes
0 answers
60 views

Crop a FITS file in shape of another

I have a FITS file, let us say file A. I have another FITS file, file B. File B has a smaller footprint than file A. I want to crop file A in shape of file B. How do I go about doing that?
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50 views

calculating mass of galaxy from luminosity

A very elementary question, just to make sure I got this thing right. Suppose we are given that the mass to luminosity ratio of a galaxy is $2 \frac{M_{\odot}}{L_{\odot}}$. Let us say, that the ...
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50 views

What are the primary astrophysical implications of a proposed mass of about 11 M⊙ for the SN 2023ixf progenitor?

The abstract of the arXiv preprint SN 2023ixf in Messier 101: A Variable Red Supergiant as the Progenitor Candidate to a Type II Supernova (itself recently "discovered" in the observatory) ...
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42 views

Trying to understand how to properly implement this equation to a healpix map

So i am working on reproducing a paper (Secrest, N. J., von Hausegger, S., Rameez, M., Mohayaee, R., Sarkar, S., & Colin, J. (2021). A test of the cosmological principle with quasars. The ...
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52 views

What is the force that drives electrons along the magnetic filaments of galaxies?

"Milky Way's mysterious filaments have 'older, distant cousins'" https://www.techexplorist.com/milky-ways-mysterious-filaments-older-distant-cousins/54966/?amp=1 Quote from article: "...
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55 views

Convert from magnetic coordinates to true coordinates

I am working with the IGRF (International Geomagnetic Reference Field) model and from a journal article found here, I am able to compute the earth's magnetic field at any point in spherical ...
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166 views

How much would you weigh at the equator of the fastest spinning pulsar?

Assuming you have a mass of 70 kg, what would your weight be on the equator of PSR J1748−2446ad?
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37 views

What is sonic transition of an astrophysical fluid?

My notes mention sonic transition of a fluid. Is it where the speed of the fluid elements cross the speed of sound in the medium they are located?
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114 views

Where can I find galaxy spectra (in the form of FITS files)?

I know there's SDSS and I tried searching for the spectra through the navigate and explore tool under CAS as well as by using RA/Dec coordinates under SAS, but every single time it comes out with 0 ...
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82 views

Setting specific CENTER coordinates coordinate in SWARP

The SWARP Documentation specifies that we first set the CENTER_TYPE to MANUAL and then in the CENTER parameter we specify either one of the equatorial coordinates (RA, Dec). This is specified in the ...
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88 views

What was the energy/wavelength/frequency of the CMB when first emitted/released?

Given the z redshift of 1089, and the temperature difference between then and now of about 1089, I tried scaling the ev, freq. and wavelength by 1089.... Is that right? I get a freq. of about 240 ...
-6 votes
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66 views

Answer this or don't downvote

Otherwise you'll be showing your complete ignorance in the matter and contempt for the truth. If the scale factor as a function of time represents or is equal to the average distance between the ...

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