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DECam Legacy Survey

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Greetings. Please post any questions or comments you have about the DECaLS (Dark Energy Camera Legacy Survey) data products.

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Zack Hutchens, … David Schlegel6

Feb 7

Partial/missing bricks in DR9 phot/pz sweeps

Zack, I just read in + plotted the coordinates for all the sources in those files, which doesn't

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Partial/missing bricks in DR9 phot/pz sweeps

Zack, I just read in + plotted the coordinates for all the sources in those files, which doesn't

Feb 7

Andrew Engel, … John Moustakas7

5/23/25

NERSC cutout service?

Thanks John + Dustin-- So to circle back on this thread for anybody who might find it useful in the

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NERSC cutout service?

Thanks John + Dustin-- So to circle back on this thread for anybody who might find it useful in the

5/23/25

Chris Snell, Dustin Lang3

5/13/25

Login failure on discuss.legacysurvey.org

Thanks! Now to happily replying! I've updated Chrome to the latest version and it seemed to have

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Login failure on discuss.legacysurvey.org

Thanks! Now to happily replying! I've updated Chrome to the latest version and it seemed to have

5/13/25

Juan, Dustin Lang6

3/28/25

Image Cutout Script No Longer Working

Yeah, could be, NERSC network operations does that sometimes when they see what looks like DOS

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Image Cutout Script No Longer Working

Yeah, could be, NERSC network operations does that sometimes when they see what looks like DOS

3/28/25

Yongmin Yoon, … Dustin Lang4

2/13/25

Internal server error (500) when requesting cutout FITS file images

Thanks for your message - this should be working again now. cheers, dustin On Thu, Feb 13, 2025 at 4:

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Internal server error (500) when requesting cutout FITS file images

Thanks for your message - this should be working again now. cheers, dustin On Thu, Feb 13, 2025 at 4:

2/13/25

Renhao Ye, Dustin Lang2

1/18/25

Legacy Survey Server Down?

Yes, we have had some outages lately. I think it's back to normal now. On Sat, Jan 18, 2025 at 10

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Legacy Survey Server Down?

Yes, we have had some outages lately. I think it's back to normal now. On Sat, Jan 18, 2025 at 10

1/18/25

Sagar Sethi, Dustin Lang2

1/6/25

Recreate the DESCaL RGB image in python/astropy

Hi, Here's the code that the viewer uses to make its RGB images: dr2_rgb() takes a list of images

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Recreate the DESCaL RGB image in python/astropy

Hi, Here's the code that the viewer uses to make its RGB images: dr2_rgb() takes a list of images

1/6/25

Alina, … Dustin Lang6

12/21/24

photo-z in particular area

Hi Jesse, Thanks for the example code! That's fantastic. cheers, dustin On Sat, Dec 21, 2024 at 7

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photo-z in particular area

Hi Jesse, Thanks for the example code! That's fantastic. cheers, dustin On Sat, Dec 21, 2024 at 7

12/21/24

Adam Watts, … Adam Watts3

12/12/24

Accessing DR10 inverse variance maps

Legend, thanks! On Thursday, 12 December 2024 at 21:07:46 UTC+8 Dustin Lang wrote: Hi, We call these

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Accessing DR10 inverse variance maps

Legend, thanks! On Thursday, 12 December 2024 at 21:07:46 UTC+8 Dustin Lang wrote: Hi, We call these

12/12/24

asd das, Dustin Lang2

12/3/24

How can I obtain a catalog of mixed stars more efficiently?

Hi, Can you please give at least one example of this working correctly (where it finds what are you

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How can I obtain a catalog of mixed stars more efficiently?

Hi, Can you please give at least one example of this working correctly (where it finds what are you

12/3/24

Emory Murff, Dustin Lang2

11/8/24

Photoz Catalogue

Hi, The "sweep" files for the photo-zs are here, https://portal.nersc.gov/cfs/cosmo/data/

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Photoz Catalogue

Hi, The "sweep" files for the photo-zs are here, https://portal.nersc.gov/cfs/cosmo/data/

11/8/24

asd das, Dustin Lang2

10/18/24

Hi, Images from the cutout service are resampled from the DR coadded images. If you request the

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Hi, Images from the cutout service are resampled from the DR coadded images. If you request the

10/18/24

Alina, Dustin Lang4

9/18/24

help to download a catalogue with mags for a particular area

Hi Alina, Glad it worked for you... the Datalab's added-value columns are certainly helpful :) (

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help to download a catalogue with mags for a particular area

Hi Alina, Glad it worked for you... the Datalab's added-value columns are certainly helpful :) (

9/18/24

Sagar Sethi, … Chris Cai6

9/3/24

Download a 1 degree cutout

Thank you very much, I download the fits successfully! 在2024年9月3日星期二 UTC+8 21:55:36<dstn...@gmail.

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Download a 1 degree cutout

Thank you very much, I download the fits successfully! 在2024年9月3日星期二 UTC+8 21:55:36<dstn...@gmail.

9/3/24

Rajnil Mukherjee, Dustin Lang3

7/15/24

Specifics and general query on using DR10 data products for science purposes

Thanks a lot for the quick reply! I will get back to you if I face any further issues! :D Regards,

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Specifics and general query on using DR10 data products for science purposes

Thanks a lot for the quick reply! I will get back to you if I face any further issues! :D Regards,

7/15/24

Dong-Woo Kim, Dustin Lang4

5/17/24

WISE data in ls_dr10.tractor table

Hi Dong-Woo, Thanks for your comments, I agree there are a lot of WISE photometry products around! We

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WISE data in ls_dr10.tractor table

Hi Dong-Woo, Thanks for your comments, I agree there are a lot of WISE photometry products around! We

5/17/24

Daviti Kobaidze, Dustin Lang2

5/16/24

About an image of Legacy Surveys

Hi, This page describes the filters on the Dark Energy Camera, https://noirlab.edu/science/programs/

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About an image of Legacy Surveys

Hi, This page describes the filters on the Dark Energy Camera, https://noirlab.edu/science/programs/

5/16/24

Vasco Cossa, Dustin Lang6

4/26/24

DECaLS DR10 source catalog

Thank you for the answer. That's the same value I got... -- Vasco On Fri, 26 Apr 2024 at 16:43,

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DECaLS DR10 source catalog

Thank you for the answer. That's the same value I got... -- Vasco On Fri, 26 Apr 2024 at 16:43,

4/26/24

Juan Pablo Calderón

4/1/24

Custom photometry on a set of bricks

Hello everyone. We were performing custom sextractor photometry on a set of bricks. If i understood

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Custom photometry on a set of bricks

Hello everyone. We were performing custom sextractor photometry on a set of bricks. If i understood

4/1/24

Jiaxuan Li, Dustin Lang3

3/18/24

DR10 PSF model in i-band

Awesome, thank you so much! On Mon, Mar 18, 2024 at 12:02 PM Dustin Lang <dstn...@gmail.com>

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DR10 PSF model in i-band

Awesome, thank you so much! On Mon, Mar 18, 2024 at 12:02 PM Dustin Lang <dstn...@gmail.com>

3/18/24

Este Padilla Gonzalez, … Dustin Lang4

3/4/24

Hi, Unless you're starting from *very* low-level simulations, you really probably don't need

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Hi, Unless you're starting from *very* low-level simulations, you really probably don't need

3/4/24

Aina, Dustin Lang2

2/4/24

the zero point magnitude or zero point flux

Hello, The catalog flux_g, flux_r, flux_z values are in units of "nanomaggies" -- a flux of

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the zero point magnitude or zero point flux

Hello, The catalog flux_g, flux_r, flux_z values are in units of "nanomaggies" -- a flux of

2/4/24

eeba...@gmail.com, Dustin Lang2

1/31/24

Documentation for DR10.1 and extras

Hi, The "lightcurves", "extras", and "photo-z" files are described here

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Documentation for DR10.1 and extras

Hi, The "lightcurves", "extras", and "photo-z" files are described here

1/31/24

HANJING SHI, Dustin Lang2

1/24/24

How to convert nanomaggie to counts?

Hi, If you are using cutout images from the Legacy Survey sky viewer, then (if you request cutouts at

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How to convert nanomaggie to counts?

Hi, If you are using cutout images from the Legacy Survey sky viewer, then (if you request cutouts at

1/24/24

Jiachuan Xu, Dustin Lang2

12/28/23

LS Shape Measurement

Hello, The SHAPE_E1,E2 values are the "above-the-atmosphere" intrinsic galaxy ellipticities

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LS Shape Measurement

Hello, The SHAPE_E1,E2 values are the "above-the-atmosphere" intrinsic galaxy ellipticities

12/28/23

11/1/23

Transformations from SDSS to Legacy Surveys Photometry

Hi, I'm working with the i-band images of DR10, and I want to know the conversions between the i-

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Transformations from SDSS to Legacy Surveys Photometry

Hi, I'm working with the i-band images of DR10, and I want to know the conversions between the i-

11/1/23

Imad Pasha, Dustin Lang4

10/16/23

Weights for image combination to roughly match legacy viewer?

Hi Imad, The `dr2_rgb` function wants a list of images, so I think you could do: out = dr2_rgb([im[:,

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Weights for image combination to roughly match legacy viewer?

Hi Imad, The `dr2_rgb` function wants a list of images, so I think you could do: out = dr2_rgb([im[:,

10/16/23

Jiachuan Xu, John Moustakas3

9/29/23

Tractor Catalog Photometry

Some other questions I have about BGS target selection paper https://arxiv.org/abs/2208.08512 - For

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Tractor Catalog Photometry

Some other questions I have about BGS target selection paper https://arxiv.org/abs/2208.08512 - For

9/29/23

ran zhang, Rongpu Zhou2

9/8/23

Photometric redshifts

Hi Ran, The ~0.02 photo-z error that you quoted is for the DESI LRGs. The z_training=False objects

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Photometric redshifts

Hi Ran, The ~0.02 photo-z error that you quoted is for the DESI LRGs. The z_training=False objects

9/8/23

John Winterflood

9/7/23

Legacy DR10 Unique Source Counts

The Legacy DR10 description page (https://www.legacysurvey.org/dr10/description/) lists the total

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Legacy DR10 Unique Source Counts

The Legacy DR10 description page (https://www.legacysurvey.org/dr10/description/) lists the total

9/7/23

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