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##### Activity
Ghosha
@gekaremi
Is there an easy way to make the coordinate (angle) periodic (2pi)? This is a pendulum-like problem, and with some parameters at some points in time the body rotates, and with some it only librates/swings
It is clear that it is possible to apply mod2pi to a solution, but this is not always convenient.
matrixbot wildlander on Freenode says goodbye: see you in the next! o/
matrixbot
@matrixbot
kerel on Freenode lbracher: I can recommend the method twoline2rv from sgp4 to read the TLE and then skyfield, poliastro or sgp4 to propagate around the orbit. To determine the perigee you could then use the optimization functions from SciPy. I don't think there is a method which directly returns the next perigee.
matrixbot
@matrixbot
lbracher on Freenode kerel, thank you! I'll try those!
matrixbot
@matrixbot
kerel on Freenode lbracher: Here is an example for propagation with sgp4: https://gitlab.com/kerel-fs/jupyter-notebooks/blob/master/beresheet/Beresheet.ipynb
kerel on Freenode If you implement a method for next perigee I would be interested as well (might use it to follow Beresheet :D).
kerel on Freenode (only cell In[9] is relevant here)
matrixbot
@matrixbot
lbracher on Freenode kerel, thank you! :)
Ghosha
@gekaremi
oh sorry, the past message was meant for another chat.
matrixbot
@matrixbot
mithrison on Freenode hey
mithrison on Freenode what’s exactly this framework for?
matrixbot
@matrixbot
SuperMcFreaky on Freenode Hi All. I've got a question about handling FITS files with io.fits
SuperMcFreaky on Freenode Is there a way to convert a PrimaryHDU object to an ImageHDU object?
SuperMcFreaky on Freenode I can do i = fits.ImageHDU(primary.data, header=primary.header)
SuperMcFreaky on Freenode and that works, but it copies the data into memory, which can be a real problem in my case
matrixbot
@matrixbot
astrofrog (@slack_astropy_U07529085:openastronomy.org) Just to check, why do you need to do this?
matrixbot
@matrixbot
SuperMcFreaky on Freenode I have a large collection of single-HDU FITS files that get collected into a custom data object
SuperMcFreaky on Freenode for debugging purposes it is sometimes useful to write this aggregate object as a single FITS file
SuperMcFreaky on Freenode and an HDUList with all PrimaryHDUs produces a non-compliant FITS file
SuperMcFreaky on Freenode it won't even write unless I set output_verify='ignore|warn" in the call to .writeto()
astrofrog (@slack_astropy_U07529085:openastronomy.org) interesting, I would have thought an HDUList of PrimaryHDU would do the right thing
astrofrog (@slack_astropy_U07529085:openastronomy.org) it might be worth opening an issue in the GitHub repo to ask whether astropy could be smarter about auto-converting to ImageHDU when writing, we definitely shouldn't be writing files that don't comply with the standard
astrofrog (@slack_astropy_U07529085:openastronomy.org) I'm not sure how to avoid the copy, if you join the astropy Slack team there is a #fits channel where you could ask
SuperMcFreaky on Freenode well, it won't do that unless I tell it that I'm OK with a non-standard file
matrixbot
@matrixbot
SuperMcFreaky on Freenode ok, I had thought about opening an issue on GitHub but I figured I'd check here first to make sure I wasn't missing something obvious
SuperMcFreaky on Freenode I feel like the capability should/could be there because io.fits already is really good about using memmap, etc.
SuperMcFreaky on Freenode for example, if I open 1000 files with large ImageHDUs and put them together in a new HDUList and write that to disk then they data never enters memory
SuperMcFreaky on Freenode which is exactly what I want, except for PrimaryHDUs
saimn I don't think that the data is copied if it is a numpy array, but maybe it needs to be copied because it is memmmaped
matrixbot
@matrixbot
@saimn:matrix.org was kicked by @appservice-irc:matrix.org ("30 day idle timeout.").
Anne Archibald
@aarchiba
anyone have any idea why I might not be able to make files or directories readonly under CircleCI? It's 32-bit but it's Linux and I'm using chmod. (And it works on my machine and Travis Linux.)
wait, is CircleCI running astropy as root? really?
matrixbot
@matrixbot
Cadair (@cadair:cadair.com) yeah that's pretty common
Cadair (@cadair:cadair.com) it's all containers in VMs etc
Anne Archibald
@aarchiba
well that'll do it I guess. any good ways for root to temporarily make it impossible to write to a directory?
matrixbot
@matrixbot
@cadair:openastronomy.org was kicked by @appservice-irc:matrix.org ("User has been idle for 30+ days.").
matrixbot
@matrixbot
@slackbot:openastronomy.org was kicked by @appservice-irc:matrix.org ("User has been idle for 30+ days.").
Santam Roy Choudhury
@SantamRC
How to install astropy?... I am getting this
matrixbot
@matrixbot
astrofrog Cadair: what's the URL for the openastronomy matrix server? (to log in to Riot)
Cadair (@cadair:cadair.com) openastronomy.modular.im
astrofrog I got logged out due to a corrupt session (think I ran out of disk space)
Cadair (@cadair:cadair.com) oh 😕
matrixbot
@matrixbot
Peanut on Freenode Hi everyone - I'm trying to plot a few stars, in RA and Dec. I keep running into how to initialize a useful WCS without having a FITS file. Does anyone have suggestions please?
matrixbot
@matrixbot
@slack_astropy_U78DGPA6M:openastronomy.org was kicked by @appservice-irc:matrix.org ("User has been idle for 30+ days.").
@slack_astropy_U7WT8K0BV:openastronomy.org was kicked by @appservice-irc:matrix.org ("User has been idle for 30+ days.").
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matrixbot
@matrixbot
nitin_k I have a small query... When we create a cartesian coordinate, can all the three coordinates be of different units in astropy?
matrixbot
@matrixbot
amaurea on Freenode In relatively recent versions of astropy (at least on my laptop) wcs.WCS(naxis=2) results in an annoying warning being printed every time: WARNING: FITSFixedWarning: 'datfix' made the change 'Set DATE-REF to '1858-11-17' from MJD-REF'. [astropy.wcs.wcs]