MSHRINKHDR(1)

📦 version 6.1, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

✨ MSHRINKHDR ✨

okay bestie, welcome to the Montage manual page for mShrinkHdr — she makes a FITS header from a template, but at a different pixel scale. tiny header, big dreams. 💅

🎀 NAME 🎀

mShrinkHdr — make a FITS header from a template with a different pixel scale. periodt.

🦋 SYNOPSIS 🦋

mShrinkHdr [-d][-s scale] template.hdr shrunken.hdr

💖 DESCRIPTION 💖

so. there are two ways to generate "thumbnail" images, and we need to talk about them.

  1. Build a full-resolution mosaic, then shrink it down using mShrink to whatever scale you actually want. cute in theory, but this can be costly if you don't want the full-res image — or like, don't want it yet.
  2. Mosaic at the scale of the thumbnail itself. much faster, no notes.

and like, why would you even do option 2? one very valid reason: to evaluate whether the full-resolution mosaic is worth building at all. vibe check first, spend the compute later. 💀

mShrinkHdr is a simple little utility that takes a FITS header template (the kind that might come out of mMakeHdr or mHdr) and makes a new one at a different pixel scale. the default scale for this new header is 200 pixels, though you can override it with literally any value you want. she's flexible like that. 🫶

🌸 OPTIONS 🌸

  • -d — turn on debugging. she'll be extra chatty about what she's doing.
  • -s scale — set the size in pixels of the larger axis. yes, the larger one. 👑

🎀 ARGUMENTS 🎀

  • template.hdr — the original FITS header template. the blueprint. the moment.
  • shrunken.hdr — the "thumbnail" FITS header template. the glow-down. ✨

💜 RESULT 💜

if it works, you get a brand-new FITS header template with a size and pixel scale that's appropriate for making a thumbnail mosaic. slay. 🔥

😭 MESSAGES 😭

the girl can be dramatic sometimes. here's what she might yell:

ERROR  Cannot open output template file
ERROR  Bad template: filename
ERROR  Output wcsinit() failed.

🌈 EXAMPLES 🌈

$ mShrinkHdr region.hdr thumbnail.hdr
       [struct stat="OK"]

look at that [struct stat="OK"]. we love a clean run. 💖

💀 BUGS 💀

okay, deep breaths, this is the part where we're honest.

  • the drizzle algorithm has been implemented but has not been tested in this release. so like... it's there. it exists. do with that information what you will. 🙈
  • if a header template contains carriage returns (i.e., it was created or modified on a Windows machine), the cfitsio library will be unable to read it properly. that gives you this error:
[struct stat="ERROR", status=207, msg="illegal character in keyword"]

so yeah. watch out for that.

  • for the background correction algorithms, it is best if the area described in the header template completely encloses all of the input images in their entirety. if parts of the input images are "chopped off" by the header template, the background correction will be affected. 😭 we recommend you use an expanded header for the reprojection and background modeling steps, then return to the originally desired header size for the final coaddition. also, the default background matching assumes there are no non-linear background variations in the individual images — and therefore none in the overlap differences. if there's any uncertainty about that, it's safer to turn on the "level only" background matching (that's the -l flag in mBgModel). better safe than sorry, bestie. 🫶

2001-2015 California Institute of Technology, Pasadena, California

if your research uses Montage, please include the following acknowledgement:

"This research made use of Montage. It is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration's Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology."

the Montage distribution includes an adaptation of the MOPEX algorithm developed at the Spitzer Science Center.

and that's the whole page, bestie. 💅 this was Montage 5, dated Dec 2016 — catch you in the next manual, mwah. 🎀🦋✨

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