FORS_IMG_SCREEN_FLAT(7)

💅 fors_img_screen_flat(7) — the fors recipes glow-up

okay bestie, sit down, hydrate, because we're about to compute a master screen flat frame and it's genuinely iconic. this is fors_img_screen_flat from the FORS recipes section of the manual, and yes it's giving pipeline main character energy. 🎀

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✨ NAME ✨

fors_img_screen_flat — Compute master screen flat frame 🦋

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🌸 SYNOPSIS 🌸

esorex fors_img_screen_flat [OPTIONS] FILE.sof

that's it. that's the whole vibe. one recipe, one .sof file, all the options you could ever want. periodt. 💖

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👑 DESCRIPTION 👑

okay so here's the tea. 🍵

Once the bias has been subtracted (bias said not today), the input flat field frames get combined using whatever stack method you picked. then that combined frame gets normalised — meaning we divide it by its own large scale illumination trend. slay.

and how do we get that large scale trend, you ask? we apply a median filter with a large kernel. that's the move. 💅

but bestie, boundary effects are real and they are NOT cute. so the median filter is applied only to the specified region. no messy edges, no drama. 🙈

also, the overscan regions, if present, are removed from the result. bye, overscan. you will not be missed. ✨

📥 Input files (the ones you gotta bring)

• DO category: SCREEN_FLAT_IMG — Type: Raw — Explanation: Screen flat field — Required: Y 🔥
• DO category: MASTER_BIAS — Type: Raw — Explanation: Master bias — Required: Y 🔥

both are required, so like… no skipping. both or nothing, fr fr.

📤 Output files (the ones you get back)

• DO category: MASTER_SCREEN_FLAT_IMG — Data type: FITS image — Explanation: Master screen flat field 👑

one output, and it's the moment. the whole recipe was building to this. 🫶

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⭐ OPTIONS ⭐

every single flag, no gatekeeping:

• --stack_method <str> — the frames combination method (str; default: ´average´). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.stack_method [default = average]. 🎀
• --minrejection <int> — how many of the lowest values get rejected (int; default: 1). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.minrejection [default = 1]. 👇
• --maxrejection <int> — how many of the highest values get rejected (int; default: 1). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.maxrejection [default = 1]. 👆
• --klow <float> — low threshold in the ksigma method (float; default: 3.0). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.klow [default = 3.0]. 🌈
• --khigh <float> — high threshold in the ksigma method (float; default: 3.0). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.khigh [default = 3.0]. 🌈
• --kiter <int> — max number of iterations in the ksigma method (int; default: 999). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.kiter [default = 999]. 🔁
• --xradius <int> — median filter x radius, in unbinned pixels (int; default: 50). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.xradius [default = 50]. ↔️
• --yradius <int> — median filter y radius, in unbinned pixels (int; default: 50). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.yradius [default = 50]. ↕️
• --degree <int> — degree of the fitting polynomial (int; default: -1). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.degree [default = -1]. 📐
• --sampling <int> — sampling interval for fitting (int; default: 100). the full name of this option for the EsoRex configuration file is fors.fors_img_screen_flat.sampling [default = 100]. 📏

fun fact bestie: it is possible to create a configuration file containing these options, along with suitable default values. please refer to the details provided by the esorex --help command. iykyk. 🧚

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🔗 SEE ALSO 🔗

the full documentation for the fors pipeline can be downloaded as a PDF file using the following URL:

ftp://ftp.eso.org/pub/dfs/pipelines/fors/fors-pipeline-manual-4.9.pdf

an overview over the existing ESO pipelines can be found on the web page https://www.eso.org/sci/software/pipelines/. 🌍

basic documentation about the EsoRex program can be found at the esorex (1) man page.

and yes, it is possible to call the pipelines from python using the python-cpl package. see https://packages.python.org/python-cpl/index.html for further information. 🐍

the other recipes of the fors pipeline, aka the whole friend group, are:

fors_align_sky(7), fors_align_sky_lss(7), fors_bias(7), fors_calib(7), fors_config(7), fors_dark(7), fors_detect_objects(7), fors_detect_spectra(7), fors_extract(7), fors_extract_objects(7), fors_extract_slits(7), fors_flatfield(7), fors_img_science(7), fors_img_sky_flat(7), fors_normalise_flat(7), fors_photometry(7), fors_pmos_calib(7), fors_pmos_extract(7), fors_pmos_science(7), fors_remove_bias(7), fors_resample(7), fors_science(7), fors_spec_mflat(7), fors_subtract_sky(7), fors_subtract_sky_lss(7), fors_sumflux(7), fors_trace_flat(7), fors_wave_calib(7), fors_wave_calib_lss(7), fors_zeropoint(7)

that's the whole squad. 🫶✨

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📌 VERSION 📌

fors_img_screen_flat 5.5.7

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🖊️ AUTHOR 🖊️

Jonas M. Larsen <usd-help@eso.org> — thank you for your service, king. 👑

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😭 BUG REPORTS 😭

please report any problems to usd-help@eso.org. alternatively, you may send a report to the ESO User Support Department <usd-help@eso.org>. they're literally the same address, which is lowkey efficient of them ngl. 💀

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⚖️ LICENSE ⚖️

this file is currently part of the FORS Instrument Pipeline Copyright (C) 2002-2011 European Southern Observatory. 🌈

this program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

this program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. see the GNU General Public License for more details. 🫶

you should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

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and that's the whole page, bestie!! 💖 this little masterpiece is fors_img_screen_flat, version 5.5.7, hailing from the fors recipes corner of the manual world — and you read it all, which is honestly iconic of you. go stack some flats. 🎀✨🦋