# Astropy **URL:** https://community.openastronomy.org/c/astropy/8.md?page=1 [Latest](https://community.openastronomy.org/latest.md) · [Categories](https://community.openastronomy.org/categories.md) · [Tags](https://community.openastronomy.org/tags.md) **Page:** 2 --- ## [How can I locally backup downloaded data files?](https://community.openastronomy.org/t/how-can-i-locally-backup-downloaded-data-files/1192)
**Author:** [@msmcconnell](https://community.openastronomy.org/u/msmcconnell)\ **Replies:** 7\ **Last updated:** [January 31, 2025, 1:30pm UTC](https://community.openastronomy.org/t/how-can-i-locally-backup-downloaded-data-files/1192 "2025-01-31T13:30:38Z")
When I first run some of Astropy’s functions it will trigger downloads of data such as https://datacenter.iers.org/data/9/finals2000A.all These downloads can occasionally fail. I would like to have local copies instead … --- ## [Editing header of compressed image HDU without recompressing](https://community.openastronomy.org/t/editing-header-of-compressed-image-hdu-without-recompressing/1189)
**Author:** [@rknop](https://community.openastronomy.org/u/rknop)\ **Replies:** 1\ **Last updated:** [January 27, 2025, 8:16am UTC](https://community.openastronomy.org/t/editing-header-of-compressed-image-hdu-without-recompressing/1189 "2025-01-27T08:16:53Z")
I recently updated to astropy 7. Previously, using astropy 5, I had code that opened a fits file with mode “update” and replaced the header of a compressed image extension, but did not change the data. (The compressed … --- ## [Code to Calculate Velocity from GAIA DR3 Data](https://community.openastronomy.org/t/code-to-calculate-velocity-from-gaia-dr3-data/1182)
**Author:** [@Strueb](https://community.openastronomy.org/u/Strueb)\ **Replies:** 2\ **Last updated:** [January 17, 2025, 10:15pm UTC](https://community.openastronomy.org/t/code-to-calculate-velocity-from-gaia-dr3-data/1182 "2025-01-17T22:15:35Z")
I am working to calculate and plot velocity vs distance for large GAIA DR3 data sets. Are there any efficient code blocks in Astropy to help with this or do I need to code it step by step? I am working with ra, dec, para… --- ## [Announcing Astropy Coordination Committee Election: December 2024](https://community.openastronomy.org/t/announcing-astropy-coordination-committee-election-december-2024/1139)
**Author:** [@ceb8](https://community.openastronomy.org/u/ceb8)\ **Replies:** 1\ **Last updated:** [January 8, 2025, 3:58pm UTC](https://community.openastronomy.org/t/announcing-astropy-coordination-committee-election-december-2024/1139 "2025-01-08T15:58:13Z")
The next Astropy Coordination Committee (CoCo) election will begin on December 2, 2024. One seat is available as Kelle Cruz’s 3-year term is coming to an end. The new member will serve 3-year term. More details about the… --- ## [Pre-commit failed tests](https://community.openastronomy.org/t/pre-commit-failed-tests/1149)
**Author:** [@zerosumhippo](https://community.openastronomy.org/u/zerosumhippo)\ **Replies:** 1\ **Last updated:** [January 4, 2025, 6:23pm UTC](https://community.openastronomy.org/t/pre-commit-failed-tests/1149 "2025-01-04T18:23:52Z")
Hello, I’m trying to add a simple change to documentation related to issue #16624. I’m just trying to removed the three paragraphs about affiliated packages in astropy/docs/development/codeguide.rst and replace them wi… --- ## [How to plot the sky using the curved grid from equatorial coordinates](https://community.openastronomy.org/t/how-to-plot-the-sky-using-the-curved-grid-from-equatorial-coordinates/1058)
**Author:** [@neowise](https://community.openastronomy.org/u/neowise)\ **Replies:** 6\ **Last updated:** [December 22, 2024, 3:04pm UTC](https://community.openastronomy.org/t/how-to-plot-the-sky-using-the-curved-grid-from-equatorial-coordinates/1058 "2024-12-22T15:04:52Z")
Hi! I’m new here, so it’s my first question in the forum. I’m trying to generate star charts (or maps) with the equatorial coordinates system (RAJ2000 and DEJ2000), where the parallels and meridians are curved. Like it … --- ## [TypeError in match\_coordinates\_sky](https://community.openastronomy.org/t/typeerror-in-match-coordinates-sky/762)
**Author:** [@KCook3824](https://community.openastronomy.org/u/KCook3824)\ **Replies:** 1\ **Last updated:** [December 5, 2024, 10:36pm UTC](https://community.openastronomy.org/t/typeerror-in-match-coordinates-sky/762 "2024-12-05T22:36:16Z")
Hello all, I’ve been using match\_coordinates\_sky for awhile now with no issues in Jupyter Notebook. Suddenly (I’ll detail that a bit below in case it is helpful to anyone), my code started to give the following error: … --- ## [2024 CoCo Election: Aarya Patil](https://community.openastronomy.org/t/2024-coco-election-aarya-patil/1159)
**Author:** [@aaryapatil](https://community.openastronomy.org/u/aaryapatil)\ **Replies:** 0\ **Last updated:** [November 29, 2024, 7:58pm UTC](https://community.openastronomy.org/t/2024-coco-election-aarya-patil/1159 "2024-11-29T19:58:27Z")
I am honored to be nominated for membership on the Astropy Coordination Committee (CoCo). Currently, I serve as a Finance Committee member for the Astropy Project and as an LSST Discovery Alliance Catalyst Fellow at the… --- ## [Manually set the ticklabels of \`CoordinateHelper\`](https://community.openastronomy.org/t/manually-set-the-ticklabels-of-coordinatehelper/1151)
**Author:** [@yjzhu-solar](https://community.openastronomy.org/u/yjzhu-solar)\ **Replies:** 1\ **Last updated:** [November 27, 2024, 1:36am UTC](https://community.openastronomy.org/t/manually-set-the-ticklabels-of-coordinatehelper/1151 "2024-11-27T01:36:54Z")
Are there any ways to manually set the tick labels of Coordinate Helper? I tried ax.coords\[2\].set\_ticklabel(text=\['1','2','3'\]) or directly accessing ax.coords\[2\].ticklabels.text\['t'\] = \['1','2','3'\] Both failed. --- ## [2024 CoCo Election: Eero Vaher](https://community.openastronomy.org/t/2024-coco-election-eero-vaher/1156)
**Author:** [@eerovaher](https://community.openastronomy.org/u/eerovaher)\ **Replies:** 0\ **Last updated:** [November 27, 2024, 1:05am UTC](https://community.openastronomy.org/t/2024-coco-election-eero-vaher/1156 "2024-11-27T01:05:43Z")
I am announcing my participation in the 2024 Astropy Coordination Committee election. Although I have been a maintainer for astropy.coordinates for a couple of years by now, I am still a relative newcomer to the project… --- ## [Pytest error: unrecognized arguments: --doctest-rst](https://community.openastronomy.org/t/pytest-error-unrecognized-arguments-doctest-rst/1138)
**Author:** [@zerosumhippo](https://community.openastronomy.org/u/zerosumhippo)\ **Replies:** 3\ **Last updated:** [November 1, 2024, 5:05pm UTC](https://community.openastronomy.org/t/pytest-error-unrecognized-arguments-doctest-rst/1138 "2024-11-01T17:05:32Z")
Hello, I am running through the setup instructions for contributing to Astropy here and just got to the point where I’m trying to test astropy/coordinates. I am running pytest astropy\\coordinates in a Miniforge prompt … --- ## [Error using cosmology.distmod](https://community.openastronomy.org/t/error-using-cosmology-distmod/617)
**Author:** [@shram222](https://community.openastronomy.org/u/shram222)\ **Replies:** 2\ **Last updated:** [October 22, 2024, 2:15pm UTC](https://community.openastronomy.org/t/error-using-cosmology-distmod/617 "2024-10-22T14:15:31Z")
Hello, A while ago I completed a project during which I briefly used Astropy, in particular, cosmology.distmod(redshift).value into which I inputted redshifts in the form of a Pandas Series. This code, run on my old wi… --- ## [Órbita -trajectory calculation](https://community.openastronomy.org/t/orbita-trajectory-calculation/1117)
**Author:** [@Eduardodelpinotoro](https://community.openastronomy.org/u/Eduardodelpinotoro)\ **Replies:** 0\ **Last updated:** [September 21, 2024, 7:36am UTC](https://community.openastronomy.org/t/orbita-trajectory-calculation/1117 "2024-09-21T07:36:18Z")
Hello, I have created a tool in Python code using the Google Colab notebook to enter the coordinates of some object in the sky that has not yet been identified to calculate its trajectory and parameters. The results are … --- ## [Converting fits.hdu.compressed.CompImageHDU to fits.hdu.Image.ImageHDU](https://community.openastronomy.org/t/converting-fits-hdu-compressed-compimagehdu-to-fits-hdu-image-imagehdu/1114)
**Author:** [@Danmcl77](https://community.openastronomy.org/u/Danmcl77)\ **Replies:** 0\ **Last updated:** [September 15, 2024, 3:32pm UTC](https://community.openastronomy.org/t/converting-fits-hdu-compressed-compimagehdu-to-fits-hdu-image-imagehdu/1114 "2024-09-15T15:32:19Z")
Hi there, I’m currently trying to use PS1 image data to make a tricolour image of NGC 160 using the make\_lupten\_rgb function and I’m running into some difficulty re: getting the image data from a compressed HDU image to… --- ## [Add "+" sign for positive values in Declination](https://community.openastronomy.org/t/add-sign-for-positive-values-in-declination/1105)
**Author:** [@neowise](https://community.openastronomy.org/u/neowise)\ **Replies:** 3\ **Last updated:** [September 11, 2024, 2:04pm UTC](https://community.openastronomy.org/t/add-sign-for-positive-values-in-declination/1105 "2024-09-11T14:04:28Z")
I wish to add the plus sign (“+”) for the positive values in the Declination axis (Y). I tried a lot of solutions. The method set\_major\_formatter seems very limited, it only allows a small usecase. It’s crazy because it’… --- ## [Get parallax and parallax error by id in Simbad](https://community.openastronomy.org/t/get-parallax-and-parallax-error-by-id-in-simbad/1100)
**Author:** [@B612](https://community.openastronomy.org/u/B612)\ **Replies:** 0\ **Last updated:** [September 1, 2024, 9:44am UTC](https://community.openastronomy.org/t/get-parallax-and-parallax-error-by-id-in-simbad/1100 "2024-09-01T09:44:54Z")
Hi. How can I search for parallax and parallax error by the Gaia DR3 designation of a star using Astropy? I searched for the Gaia DR3 id of a star HIP 79672. The code is: from astroquery.simbad import Simbad tab = Sim… --- ## [Writing a sextractor formatted ascii table in AstroPy](https://community.openastronomy.org/t/writing-a-sextractor-formatted-ascii-table-in-astropy/1095)
**Author:** [@cduston44](https://community.openastronomy.org/u/cduston44)\ **Replies:** 0\ **Last updated:** [August 26, 2024, 9:01pm UTC](https://community.openastronomy.org/t/writing-a-sextractor-formatted-ascii-table-in-astropy/1095 "2024-08-26T21:01:25Z")
I am trying to write a function to clean catalog files that are output from sextractor. The sextractor catalog creation command and the initial ascii read command seem fine: cat\_sci = ascii.read('sci\_match.cat',format='… --- ## [Hiding ticks and labels with a specified value](https://community.openastronomy.org/t/hiding-ticks-and-labels-with-a-specified-value/1072)
**Author:** [@neowise](https://community.openastronomy.org/u/neowise)\ **Replies:** 1\ **Last updated:** [August 11, 2024, 10:27pm UTC](https://community.openastronomy.org/t/hiding-ticks-and-labels-with-a-specified-value/1072 "2024-08-11T22:27:23Z")
Hi! Is it possible to hide ticks and labels with a specified value? Is it even possible iterate between the values? I need to modify two things of my plot: The first one is that a label with 0h and another with 24h appe… --- ## [How to change the type of WCS axis](https://community.openastronomy.org/t/how-to-change-the-type-of-wcs-axis/1057)
**Author:** [@Firestar](https://community.openastronomy.org/u/Firestar)\ **Replies:** 0\ **Last updated:** [July 23, 2024, 11:31am UTC](https://community.openastronomy.org/t/how-to-change-the-type-of-wcs-axis/1057 "2024-07-23T11:31:15Z")
I want to read a FITS file from https://hiverse.alkaidos.cn/ (you can download any one to reproduce this) But it returns: from spectral\_cube import SpectralCube as sc file = "00\_DEC\_-13.0\_-3.0\_\_06\_RA\_60.0\_70.0\_\_-600kms… --- ## [Changes to astroquery.ipac.ned?](https://community.openastronomy.org/t/changes-to-astroquery-ipac-ned/1052)
**Author:** [@p41nk1ll3r](https://community.openastronomy.org/u/p41nk1ll3r)\ **Replies:** 0\ **Last updated:** [July 16, 2024, 11:22pm UTC](https://community.openastronomy.org/t/changes-to-astroquery-ipac-ned/1052 "2024-07-16T23:22:06Z")
Hello, I’m experiencing an issue lately with the NED queries.I used to be able to fetch table data using whichever name an object is known by, but now I have to input the name preferred by NED. Example: from astroquery.… --- ## [KeyError: "Keyword 'CTYPE3' not found."](https://community.openastronomy.org/t/keyerror-keyword-ctype3-not-found/1037)
**Author:** [@codeNick7](https://community.openastronomy.org/u/codeNick7)\ **Replies:** 3\ **Last updated:** [July 11, 2024, 6:49pm UTC](https://community.openastronomy.org/t/keyerror-keyword-ctype3-not-found/1037 "2024-07-11T18:49:25Z")
Hi, I am new here. Trying spectrography using fits files for the first time. I have: python 3.9.6. and using the following code to read a fits file and plot it. I am getting the following error. Could you please help? … --- ## [Which utc to ut1 conversion is correct? Time.ut1 vs utc+get\_delta\_ut1\_utc()](https://community.openastronomy.org/t/which-utc-to-ut1-conversion-is-correct-time-ut1-vs-utc-get-delta-ut1-utc/1034)
**Author:** [@msmcconnell](https://community.openastronomy.org/u/msmcconnell)\ **Replies:** 2\ **Last updated:** [July 8, 2024, 1:00pm UTC](https://community.openastronomy.org/t/which-utc-to-ut1-conversion-is-correct-time-ut1-vs-utc-get-delta-ut1-utc/1034 "2024-07-08T13:00:28Z")
I’m trying to get a timestamp reported by my linux computer into UT1. My understanding is that for this distribution calling python’s time.time() gives me the unix time (the number of seconds ignoring leap seconds since … --- ## [Astroquery - Splatalogue not working](https://community.openastronomy.org/t/astroquery-splatalogue-not-working/1032)
**Author:** [@luke\_keyte](https://community.openastronomy.org/u/luke_keyte)\ **Replies:** 0\ **Last updated:** [July 2, 2024, 3:00pm UTC](https://community.openastronomy.org/t/astroquery-splatalogue-not-working/1032 "2024-07-02T15:00:08Z")
I am trying to use astroquery to access Splatalogue. Following the example in the documentation, I get an error: CO1to0 = Splatalogue.query\_lines(115.271u.GHz, 115.273u.GHz) \>\>\> CO1to0.pprint(max\_width=200) Inconsisten… --- ## [The return value of ra.to\_string(sep='hms') is incorrect](https://community.openastronomy.org/t/the-return-value-of-ra-to-string-sep-hms-is-incorrect/1029)
**Author:** [@ccc](https://community.openastronomy.org/u/ccc)\ **Replies:** 0\ **Last updated:** [June 30, 2024, 9:24am UTC](https://community.openastronomy.org/t/the-return-value-of-ra-to-string-sep-hms-is-incorrect/1029 "2024-06-30T09:24:07Z")
from astropy.coordinates import SkyCoord c = SkyCoord('15h34m57.1s +23d30m11s',frame='icrs',equinox='J2000') print(c.ra.to\_string(sep='hms')) The output result is like this, which is obviously incorrect. 233h44m16.5s I… --- ## [Tidal Forces in Astropy](https://community.openastronomy.org/t/tidal-forces-in-astropy/1022)
**Author:** [@Nick](https://community.openastronomy.org/u/Nick)\ **Replies:** 0\ **Last updated:** [June 23, 2024, 5:57pm UTC](https://community.openastronomy.org/t/tidal-forces-in-astropy/1022 "2024-06-23T17:57:25Z")
I want to write a small script that calculates the changes in acceleration due to gravity, taking into account tidal force, to look at errors in a pendulum So for a given location on the earth, you have a force due to t… --- ## [Creating a header of matched catalogs](https://community.openastronomy.org/t/creating-a-header-of-matched-catalogs/1015)
**Author:** [@lifemannequin](https://community.openastronomy.org/u/lifemannequin)\ **Replies:** 0\ **Last updated:** [June 17, 2024, 11:27am UTC](https://community.openastronomy.org/t/creating-a-header-of-matched-catalogs/1015 "2024-06-17T11:27:10Z")
I used the function match\_to\_catalog\_sky to match two catalogs. I want to save the new matched catalog with the headers of the 2 catalogs plus the match\_id and match\_d2d columns. The matching is done : #Finds the closes… --- ## [Help regarding cross-matching catalogs! Separation and match\_catalog\_sky](https://community.openastronomy.org/t/help-regarding-cross-matching-catalogs-separation-and-match-catalog-sky/1014)
**Author:** [@lifemannequin](https://community.openastronomy.org/u/lifemannequin)\ **Replies:** 0\ **Last updated:** [June 13, 2024, 1:16pm UTC](https://community.openastronomy.org/t/help-regarding-cross-matching-catalogs-separation-and-match-catalog-sky/1014 "2024-06-13T13:16:41Z")
I am trying to crossmatch the latest Fermi LAT catalog to an sdss catalog. I found tsuji et al. 2021 where they create a distance profile and use it to decide the cutoff. I did it by using a separation function in astrop… --- ## [Static reference frame](https://community.openastronomy.org/t/static-reference-frame/989)
**Author:** [@Angelo](https://community.openastronomy.org/u/Angelo)\ **Replies:** 0\ **Last updated:** [June 3, 2024, 6:35am UTC](https://community.openastronomy.org/t/static-reference-frame/989 "2024-06-03T06:35:27Z")
Hi, I would like to compute the pointing (azimuth and elevation) between two earth station starting form their known WGS84 positions. I was trying by using the AltAz reference, SkyCoord and trasfrom\_to but the pointing … --- ## [Trouble with ICRS/TEME conversions](https://community.openastronomy.org/t/trouble-with-icrs-teme-conversions/987)
**Author:** [@noaahhh](https://community.openastronomy.org/u/noaahhh)\ **Replies:** 0\ **Last updated:** [May 28, 2024, 8:50pm UTC](https://community.openastronomy.org/t/trouble-with-icrs-teme-conversions/987 "2024-05-28T20:50:00Z")
I’m trying to do some conversions between the ICRS and TEME reference frames. I need to get a direction cosine matrix (DCM) relating the two frames. The trouble I’m having is that the matrices I get are not orthogonal. f… --- ## [PySynphot Example](https://community.openastronomy.org/t/pysynphot-example/977)
**Author:** [@Arwen7](https://community.openastronomy.org/u/Arwen7)\ **Replies:** 0\ **Last updated:** [May 6, 2024, 9:42pm UTC](https://community.openastronomy.org/t/pysynphot-example/977 "2024-05-06T21:42:23Z")
I am trying to use the Phoenix Stellar models, but would like to resample/rebin the models to a lower resolution. I have been trying to use the pysynphot package but I am having trouble figuring out how to first make su… [Previous page](https://community.openastronomy.org/c/astropy/8.md) [Next page](https://community.openastronomy.org/c/astropy/8.md?page=2)