Questions tagged [fits-header]

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Compute rotation angle of fits image

I have a fits image and the header has the keys PC1_1, PC1_2, PC2_1, PC2_2. I want to compute the angle by which my image is rotated so that North will be up. I use the formula below: angle = np....
Sketos's user avatar
  • 31
1 vote
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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 ...
Abhinna Sundar's user avatar
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How to reproject a fits file using MontagePy

I am fairly new to image reprojection so I am trying to use MontagePy to go from a bigger fits file to its smaller subsection (which is in a different observation, therefore header) but the output ...
mattcarv's user avatar
2 votes
1 answer

How to slice WCS in a FITS file?

I have three WCS axes in a FITS image. I want to slice the axes and use only the first one. Note that though there are three axes, the WCS is superimposable. So there is no worry about a shift in WCS ...
SlightDecoy's user avatar
3 votes
1 answer

Frequency coverage for first spectral channel of .fits cube?

A .fits cube has 3 dimensions, where the 1st axis is RA, 2nd axis is Declination and 3rd axis is frequency. My question is rather simple, but causing pain none-the-less. Given a .fits cube, what is ...
simonp2207's user avatar
4 votes
1 answer

How can I replicate AstroImageJ's pixel to RA/Dec algorithm in my own code?

EDIT: solved, thanks to Eric Jensen's suggestion (in a comment on his answer) that I include the correction to my right ascension value as a function of my declination. All other comments were helpful ...
Conor W's user avatar
  • 43
2 votes
1 answer

How to use Astropy to edit a keyword (not value) in batches of FITS file headers to be used in AstroimageJ (AIJ)? (summer undergrad research project)

I would be so grateful if someone could help me. I am stuck for over a week now trying to find some way to use Astropy to write some small code to edit one keyword in batches of FITS file headers so ...
strange_octopi's user avatar
4 votes
1 answer

align an image to celestial North

I'm producing images from FITS files, But most of my images aren't aligned to the celestial north. I would expect there to be a simple library, or even an astropy command to make the alignment of the ...
Kipod23's user avatar
  • 41
2 votes
2 answers

How to invert fits headers order (primary/secondary)?

I have an image from Hubble telescope with two headers and this creates a problem because my program expects the NAXIS, NAXIS1, NAXIS2 in the first header, but in this image case, this info is in the ...
Igor Kolesnikov's user avatar
-1 votes
1 answer

Cannot plot Kepler FITS files with topcat in Windows

This is a continuation of my earlier question here. I was able to find Kepler data. Now I wanted to plot the data using Topcat. But when I tried to plot the data, I received error. Below is the error ...
Mr Learner's user avatar
2 votes
1 answer

Align multiple fits images without WCS for future aperture photometry analysis

Recently I have got a bunch of raw fits images (2048x2048 pixels) of the same sky region without WCS to process in iraf. However, those images are not well-aligned. There would be around 4~5 pixels' ...
march_happy's user avatar
1 vote
1 answer

CoRoT FITS files read error

I downloaded fits file using wget script from I am not able to view the file. I tried atsromagic and DS9 . After File->Open ...
qqqqq's user avatar
  • 163
4 votes
1 answer

Fits file re-alignment

I would like to re-align an image using a reference image (taken from GAIA). I am aware of the software Koords developed by the Karma team: ...
Carter Rhea's user avatar
1 vote
1 answer

In sky surveys, what does inverse variation really mean? How do we use inverse variation to remove noise?

I am trying to work on data from a .fits file and it has an IVAR header. How can I use inverse variation information along with the actual signal data to get better results or reduce noise?
Anks_Eagle's user avatar
2 votes
2 answers

Python: Find brightest pixel in fits-file and ignore brighter artefacts

I have 4000 fits-files images from SPITZER, each containing the same star over a time period. Each image is a photmetry cube of 32 pixel * 32 pixel * 64 consequent time frames. I need to look through ...
NeStack's user avatar
  • 313
5 votes
0 answers

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 ...
Mike's user avatar
  • 51
2 votes
2 answers

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 ...
Robert Rosca's user avatar
1 vote
2 answers

Problems with FITS headers

I'm working with some NEOWISE images that seem to have incomplete header tags. I've been advised by the SAO (because I'm using DS9 to view them) that I have "a partial PC matrix defined, yet it does ...
Jim421616's user avatar
  • 2,404