Interesting and colorful

https://www.legacysurvey.org//viewer/?ra=204.4034&dec=11.3976&layer=ls-dr9&zoom=16

Unreported #supernova at one o’ clock. Visible in Legacy survey 6 & 7, 8, 9 and DECaLS DR7. Not visible in DECaLS DR5, SDSS or PanSTARRS. Not in Simbad Search, NED, the TNS or the RBS ( Rochester, Bright, Supernova) pages. No #asteroids.

Visible in four ‘single image cutouts’ from 2017 in g and r-band. First visible 2017-03-06 in g-band. It has given magnitudes in the DECaLS DR7 catalog and Legacy Survey 8 and 9 catalog. In g-band between 20.26 and 20.86 but maybe it is better if I calculate on.

Ine :stars::dizzy:

DECaLS DR7

cutout

SDSS

cutout (1)

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The Legacy Surveys magnitudes will be an average over all the exposures (including the ones before it has appeared and after it has faded), so will be a poor underestimate of the peak brightness. (I’m actually surprised we didn’t mask it as an outlier!)

So it is better to calculate one. TNS allows you to have an error marge of 1. Though it still will be an estimate.

Ine :stars::dizzy:

I looked at our forced-photometry measurements (single-exposure fluxes), and I get:
g band (mjd 57818.295) = 20.53
g band (mjd 57839.257) = 21.06
r band (mjd 57839.257) = 20.15
r band (mjd 57840.274) = 20.16
But I had to do this by subtracting off the flux we measure there before/after the SN (it’s not a difference image), so these are only approximate…

cheers,
–dustin

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Hi Dustin, :slightly_smiling_face:

Thank you very much for looking into this. I will calculate an Apparent mag. and compare it with your value from g band (mjd 57818.295) Because to report you need the Apparent magniturde from the image where the transient is visible for the first time. In this case it is the image of 2017-03-06 or g band (mjd 57818.295)

Ine :stars::dizzy:

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