Unanswered Questions
100 questions with no upvoted or accepted answers
1
vote
0
answers
49
views
Space telescope spectroscopic data for stellar classification using Wien's law
My goal is to make a simple project which consists of classifying stars by applying Wien's displacement law.
I need public spectroscopic data about different stars from a space telescope, so that I ...
- 30.7k
1
vote
0
answers
87
views
How do you estimate standard deviation of sky from (Hubble) image
I'm working on a simulation project with Hubble data and I need the standard deviation of the sky in ADU per pixel. Sometimes I can obtain a fits file (e.g. hdfs image), open this with astropy, and ...
- 41
1
vote
0
answers
58
views
How do nuJ(nu) units work?
I'm working with (Nublado) Cloudy, which is essentially a spectral modelling tool for stellar matter. Using the software, I model my own stellar object and obtain its continuum.
According to Hazy, ...
- 156k
1
vote
0
answers
176
views
Photometry in SExtractor vs Python
I wanted to find stars in the dwarf Spheroidal (dSph) galaxy. I performed photometry using SExtractor and in Python using DaoStarFinder and other astropy packages. However, while extracting the ...
- 111
1
vote
0
answers
53
views
Determining the rotation curve of a galaxy via given spectroscopic data
Here is the data analysis question from IOAA-2011,
1. Weighing a galaxy: The image 8.2 shows a photograph of the spiral
galaxy NGC 7083, which lies at a distance of 40 Mpc, and image 8.3 a
fragment of ...
1
vote
0
answers
241
views
Split Multi-Extension fits file - fits.fz format
I have CFHT/MegaCam fits.fz file on which I want to do photometry. I want to split these large fits.fz file into separate CCD detector fits and then run Source Extractor on them for photometric ...
- 111
1
vote
0
answers
74
views
Effective gain when stacking N frame images
I am trying to understand how to derive the effective gain in [electrons / ADU] when stacking N frame images in different (summed, averaged, or medianed) ways. I found the effective gains for the ...
- 169
1
vote
0
answers
56
views
Magnitude cuts in different bands/surveys
I have data on around 142,000 galaxies. Some of these galaxies have apparent magnitude data in different bands. For example, many of my galaxies have SDSS PSF data in ugriz bands,GALEX FUV, GALEX NUV, ...
- 11
1
vote
0
answers
108
views
How has the rate of photon arrival from stars been estimated and then confirmed?
My understanding is that we can estimate the total energy emitted over a star’s entire spectrum and from that and the star’s measured spectrum estimate how many photons of a given wavelength we should ...
- 111
1
vote
0
answers
62
views
Angle to the line of sight
I don't understand this angle used in galaxy clustering. There is the line of sight and this angle to the line of sight which is not clear to me. Here is a transcript of a description from 1705.05442:
...
- 11
1
vote
0
answers
104
views
Errors in photometric magnitudes from SDSS DR16
I'm playing around with the data in the SDSS DR16, but the magnitudes have huge uncertainties:
...
- 2,620
1
vote
0
answers
104
views
What observational data was there that comet Leonard C/2021 A1 might have been dimming and/or breaking up?
Space.com's Comet Leonard, the brightest of the year, is fading and acting strange seems to be full of inexact language, like "something's wrong" and "unhealthy" and "goner&...
- 30.7k
1
vote
0
answers
61
views
Could we optically observe metallic hydrogen in space?
As many calculations have been done on whether metallic hydrogen is metastable or not in low-pressure environment, It occurred to me that by the fact that we have not observed any metallic hydrogen so ...
- 119
1
vote
0
answers
61
views
How to properly compare radio to optical/NIR images?
I mainly work with radio continuum data and recently I started working on some HST hydrogen recombination line datasets to compare with the radio data that I have, but I'm very confused about what is ...
- 11
1
vote
0
answers
46
views
Procedure to construct a spectral energy distribution and bolometric light curve of supernovae?
Can anyone check the logic of this proposed workflow and/or point me in the direction of a guide and example to check my work?
Proposed procedure to construct a spectral energy distribution and ...
- 30.7k