addition of DECam u, VR filters

[katiefasbender]

Hello, Would it be possible to add the DECam u-band and VR-filters to gaiaxpy. They are available at https://noirlab.edu/science/programs/ctio/filters/Dark-Energy-Camera

Thank you! -Katie FAsbender

[fdeangeli]

Hi Katie,

I don't know if you are somehow connected with the user that made a similar request some time ago. To that request I replied the following: https://github.com/gaia-dpci/GaiaXPy/issues/20#issuecomment-1284199487

I never got any feedback from that user, so this has not progressed further. Let me know what you think.

Kind regards, Francesca

[katiefasbender]

Hi Francesca, Thank you for the response! I am working with the user that made the request, and am starting a new issue in his stead.

[fdeangeli]

Maybe then you could provide some feedback on the concerns I had raised following the initial request (I quote from my previous reply to your colleague):

I had a look at the DECam filters page. The system we offer in GaiaXPy is the first one from that page (DES standard bandpasses). The u and VR are only available from the second set, which also includes different definitions for grizY. Unfortunately, the two systems are not clearly labelled and we are concerned that if we now add u and VR, it will be unclear for users which of the grizY filters we have used. You should also be aware that the Gaia BP spectra do not cover the full range of the u band.

[katiefasbender]

Could a set of DECam u,VR filters be created with different labeling? Although the DECam u band is not fully covered by the XP spectra wavelength range, would it be possible to achieve a standardization with the same method used for the SDSS u band? We’re hoping to calibrate our all-sky catalog in the same format with Gaia synthetic photometry across all the DECam filters. Thanks!

[fdeangeli]

Sorry for the delay in replying to your last comment. Please follow the instructions detailed at

https://gaiaxpy.readthedocs.io/en/latest/usage.html#request-photometric-systems

to support your request, i.e. one file per band containing wavelength and total response, indication of type of response (photonic or energy curve) and preferred system (AB or VEGAMAG). We will then generate the corresponding GaiaXPy filters.

[katiefasbender]

decam_g_transmission.txt decam_z_transmission.txt decam_Y_transmission.txt decam_u_transmission.txt decam_VR_transmission.txt decam_i_transmission.txt decam_r_transmission.txt

Thank you, I've attached seven filter transmission percentage curves for ugrizY and VR, in the AB system, from https://noirlab.edu/science/programs/ctio/filters/Dark-Energy-Camera.

[fdeangeli]

I am not sure I understand what are the curves you are providing. If I plot them in lin and log scale this is what I get:

which is very different from the plot on the DECam webpage:

I also still need to know if these are photonic or energy curves. I assume you will want synthetic photometry in the AB system.

[katiefasbender]

Hi Francesca, I apologize for the confusion; I sent you the filter transmissions without the DECam instrument QE and atmospheric throughput included. Included are the full photonic curves (filter + instrument + atm) for DECam ugrizY and VR filters, and we'd like the synthetic photometry in the AB system.

decam_g_throughput.txt decam_i_throughput.txt decam_r_throughput.txt decam_u_throughput.txt decam_VR_throughput.txt decam_Y_throughput.txt decam_z_throughput.txt

[katiefasbender]

Hello, just checking in on this issue since I took such a long time in responding last.

[fdeangeli]

Hi Katie, Please find attached the configuration file for your filters. To ensure the new file is loaded in GaiaXPy you will need to use the load_additional_systems function and point it to the folder where the new file is located. By calling get_available_systems afterwards you can confirm that the new system has been loaded:

PhotometricSystem = load_additional_systems('PATH_TO_FOLDER_WITH_NEW_FILTER_FILE')
print(PhotometricSystem.get_available_systems())

Do not hesitate contacting us if you encounter issues.

In one of your previous comments you were asking about the possibility of applying the standardisation procedure for the u filter. I am afraid that at this time we are not able to help you with this.

Kind regards Decam.gaiaXPy_dr3_v1.xml.gz