>>> d = Time('2019-06-21T10:00:00')
>>> d.to_value('iso', subfmt='date')
Traceback (most recent call last):
  File " stdin ", line 1, in  module 
  File "/usr/lib/python3.8/site-packages/astropy/time/core.py", line 993, in to_value
    value = tm._shaped_like_input(tm._time.to_value(
TypeError: to_value() got an unexpected keyword argument 'out_subfmt'

In reply to@slack_astropy_U75NUJ99P:openastronomy.org
If you wanted to measure the FWHM of stars in an image with astropy tools, how would you go about it? It doesn't look like photutils can do this, as it expects that you know the PSF a priori.

In reply to@slack_astropy_U8EC16YE4:openastronomy.org
We have been using sextractor. Just in case you were thinking Gemini might have the answer...

In reply to@slack_astropy_U76R9NRLP:openastronomy.org
Look into the source detection or segmentation functionalities in photutils. I don't have an easy access atm to the docs, but as I recall a recent discussion with Larry, we do have functionality that returns 2d parameterisation of the fitted ellipses. Using that you may come up with a fwhm like value.

In reply to@slack_astropy_U76R9NRLP:openastronomy.org
Also, the epsf functionality might be relevant too

In reply to@slack_astropy_U75NUJ99P:openastronomy.org
The goal is to write some automated focusing code for a student observatory. I’m surprised there isn’t a greater need for “auto-PSF” code for just this purpose. Does everybody just focus manually, or what?

In reply to@slack_astropy_U76R9NRLP:openastronomy.org
I suppose focusing is part of TCS and that may be less python based than pipelines, etc 🤷‍♀️

ValueError: an astropy.io.fits.HDUList is required for Lookup table distortion.
I am using reproject version 0.6, and astropy both versions (3.2.3 and 4.0).
Information about the images: One image is from HST/WFC3 and second one is from HST/ACS.  

In reply to@slack_astropy_U76R9NRLP:openastronomy.org
But even then, it shouldn't take many lines to build something from using the photutils segmentation code

In reply to@slack_astropy_U7NCAGGJV:openastronomy.org
For focusing a telescope automatically, it is usually more robust to measure the Half-Flux Diameter. See https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=2ahUKEwig-9Ghi4jnAhUQShUIHXpOBbYQFjAIegQICBAB&url=http%3A%2F%2Fsolo.dc3.com%2Far%2FRefDocs%2FWeber-Brady_FocusMax.doc&usg=AOvVaw06Zs7KyEuiYuNxmcIlcu25 for more details of a solid algorithm for automated focusing. Measuring the HFD with photutils is possible; just perform photometry with a range of aperture sizes and use interpolation to find the aperture size that contains half the flux. However it’s easier with sep (a python port of sextractor) which has this functionality built in... bkg = sep.Background(data)

In reply toundefined

In reply toundefined

In reply to@slack_astropy_U7NCAGGJV:openastronomy.org
sorry - keep hitting return by mistake - let's try again bkg = sep.Background(data) bkg.subfrom(data) objects = sep.extract(data, threshold_in_sigma, bkg.globalrms, clean=True) hfr, mask = sep.flux_radius(data, objects['x'], objects['y'], 40 np.ones_like(objects['x']), 0.5, normflux=objects['cflux']) hfd = 2 np.median(hfr[mask])

In reply to@slack_astropy_UE3AMRPL1:openastronomy.org
I was recently discussing about having a focus calculator as part of an affiliated/coordinated package

In reply to@slack_astropy_UE3AMRPL1:openastronomy.org
I have created this package https://github.com/soar-telescope/goodman_focus

In reply to@slack_astropy_USEH4N9FT:openastronomy.org
Hi. I am trying to align two images I downloaded from MAST HST portal. For this, I am using astropy-reproject package. However, I am running into an error, every time I use reproject, despite providing the WCS information. Following is the error:

ValueError: an astropy.io.fits.HDUList is required for Lookup table distortion.
I am using reproject version 0.6, and astropy both versions (3.2.3 and 4.0).
Information about the images: One image is from HST/WFC3 and second one is from HST/ACS.  

Here's the google drive link where my images and code are: https://drive.google.com/open?id=1SRZ9Evb1NgF_yJmQdLCw5soO929lT204

In reply to@slack_astropy_UE3AMRPL1:openastronomy.org
which is relatively simple, though since the Goodman HTS is an Imaging Spectrograph, focus is calculated using the image of a slit, not stars in 2D

In reply to@slack_astropy_U763FSX37:openastronomy.org
I’ve sent a reply to the Astropy mailing list. The key points are: 1. Construct input and output WCSs explicitly, passing HDULists as an additional argument so that the distortion information is properly picked up from the input FITS files. 2. When calling reproject_interp, pass as the first argument a tuple of (array, WCS) and specify the shape_out argument.