Plotting local AltAz on series of images with WCS solved by nova.astrometry.net

[Adam Smith]

Hi all,

I'm having difficulty doing a series of tasks that at first seemed straight forward to me.

I have a static camera that takes sky images, but I would like, for sky identification purposes, to plot local azimuth and altitude over top of a series of color images using the WCS from a solved image. I have all the local data (lat/long, time, elevation, pressure, temp, etc) to convert to an alt/az grid that I presume with be rather simple to plot over top of several images.

But, I've been having a LOT of trouble doing that with astropy in an effective and reliable way. I've been able to take WCS info to output alt/az values for pixel positions that I give it, and that's about it before my laptop crashed with much of my files unrecoverable (sigh..).

Anybody have experience with anything like this that is able to help?

Thanks so much in advance!

-Adam

[Dustin Lang]

Hi,

If you want to plot an Alt,Az grid, then don't you want to go:

- set Alt = 30 degrees

- set Az = a range of values from 0 to 360

- convert Alt, Az to RA,Dec using astropy

- convert RA,Dec to pixel x,y using the WCS

- plot those x,y positions on the image

repeat for different Alts, and then repeat this whole process, holding one Az at a time fixed.

cheers,

--dustin

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[Adam Smith]

Hi Dustin,

Ah, that's certainly a way I hadn't thought of, and an interesting one too...

If I could create a single image of the plot as a png that I can use as a layer in photoshop, gimp, etc to put on top of images, that might be great. Or if astropy can easily take that same series of images and plot the same grid over top, cool, that's one less step I need to worry about.