Timeline for Fitting PSF to an image to get total flux (Python)
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
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| Sep 23, 2018 at 15:20 | answer | added | Kornpob Bhirombhakdi | timeline score: 1 | |
| Sep 21, 2018 at 18:06 | comment | added | zephyr | Presumably you've already corrected your images for bias, flat field, etc. so drawing a bigger box shouldn't give you more flux (at least not a meaningful amount more). Generally only stars count as point sources, however, your asteroid in your case may be close enough to a point source, but either way, its irrelevant for the problem you're trying to solve. Although we're entering discussion territory and comments aren't meant for that. Please feel free to ask additional, new questions on this stack exchange to get more clarification. | |
| Sep 21, 2018 at 18:00 | comment | added | curious_cosmo | Also, sorry but how is an asteroid an extended source? (this term was unfamiliar to me until I looked it up just now) Wouldn't the angular size of an asteroid imaged by WISE be less than the telescope resolution, classifying it as a point source? | |
| Sep 21, 2018 at 17:56 | comment | added | curious_cosmo | When you say draw a box around the object, how does one choose the correct size of box? With a nonzero background and noise in the image, a bigger box would increase the flux even though the source doesn't extend further into the bigger box. | |
| Sep 21, 2018 at 17:41 | comment | added | zephyr | As Carl Witthoft answered, it doesn't make sense to apply a PSF to an extended source. Besides, even if this was a star, you wouldn't calculate flux by fitting a PSF to it first. You'd do exactly what I said and draw a box around your object and add up the values of the pixels in that box (although you can use the PSF to inform what your box should be for a point object). | |
| Sep 21, 2018 at 16:41 | comment | added | curious_cosmo | @zephyr Yes, but how is this accomplished by fitting a PSF to the image? | |
| Sep 21, 2018 at 14:36 | comment | added | zephyr | If you're looking for the total flux of the system, just draw a box around your image and add up the pixel values for every pixel in your box. That's all flux is. | |
| Sep 20, 2018 at 19:35 | answer | added | Carl Witthoft | timeline score: 2 | |
| Sep 20, 2018 at 18:10 | review | First posts | |||
| Sep 20, 2018 at 20:20 | |||||
| Sep 20, 2018 at 18:05 | history | asked | curious_cosmo | CC BY-SA 4.0 |