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Bug fix and update in calculation of PSF zones #293

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afaisst merged 2 commits into from
Mar 26, 2026
Merged

Bug fix and update in calculation of PSF zones #293

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updated text and remove minus 1 in calculation of distance to PSF zon…
afaisst Mar 25, 2026
98d369d
small fixes: author, code-cell
afaisst Mar 26, 2026
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20 changes: 11 additions & 9 deletions tutorials/spherex/spherex_psf.md
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Original file line number Diff line number Diff line change
@@ -1,4 +1,10 @@
---
authors:
- name: Vandana Desai
- name: Jessica Krick
- name: Andreas Faisst
- name: "Brigitta Sipőcz"
- name: Troy Raen
jupytext:
text_representation:
extension: .md
Expand All @@ -9,12 +15,6 @@ kernelspec:
display_name: Python 3 (ipykernel)
language: python
name: python3
authors:
- name: Vandana Desai
- name: Jessica Krick
- name: Andreas Faisst
- name: Brigitta Sipőcz
- name: Troy Raen
---

# Understanding and Extracting the PSF Extension in a SPHEREx Cutout
Expand Down Expand Up @@ -576,10 +576,11 @@ for zone_id in xctr.keys():
```

Once we have created this dictionary with zone pixel coordinates, we can simply search for the closest zone center to the coordinates of interest.
For this we first add the distance between zone center coordinates and coordinates of interest to the table. (Note that the x,y coordinates of the PSF zone centers are in 1,1 convention, therefore we have to subtract 1 pixels.)
For this we first add the distance between zone center coordinates and coordinates of interest to the table.
Note that the zone pixel center coordinates are 0-based, while their _names_ in the header (for example `XCTR_n`) are 1-based.

```{code-cell} ipython3
tab["distance"] = np.sqrt((tab["x"]-1 - xpix_orig)**2 + (tab["y"]-1 - ypix_orig)**2)
tab["distance"] = np.sqrt((tab["x"] - xpix_orig)**2 + (tab["y"] - ypix_orig)**2)
```

Then we can sort the table and pick the closest zone to coordinates of interest.
Expand Down Expand Up @@ -630,8 +631,9 @@ To use this PSF for forward modeling or fitting, you must:

## About this notebook

**Updated:** 13 March 2026
**Updated:** 25 March 2026

**Contact:** Contact [IRSA Helpdesk](https://irsa.ipac.caltech.edu/docs/help_desk.html) with questions or problems.

**Runtime:** Approximately 30 seconds.