RAPAS observation list starting 2024-12-27

RAPAS
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New Astrophysical Transient Alert: GRB 241228B

We invite all amateur astronomers to participate in the follow-up observations of this exciting new transient event. For more details, including visibility and coordinates, please visit the Astro-COLIBRI platform: GRB 241228B

Alerte Nouvel Événement Transitoire Astrophysique : GRB 241228B

Nous invitons tous les astronomes amateurs à participer aux observations de suivi de ce nouvel événement transitoire passionnant. Pour plus de détails, y compris la visibilité et les coordonnées, veuillez visiter la plateforme Astro-COLIBRI : GRB 241228B

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GRB 241228B is a GRB detected by Fermi-GBM. Its localisation uncertainty is therefore rather large (1.7deg radius).

Interestingly a possible optical counterpart has been detected by the GOTO survey. Is is called GOTO24jmz and is located just outside the 90% confidence region defined by the Fermi-GBM observation. Additional observations would allow to measure (or constrain) the continued fading of this source.

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New Astrophysical Transient Alert: AT 2024afyi

We invite all amateur astronomers to participate in the follow-up observations of this exciting new transient event. For more details, including visibility and coordinates, please visit the Astro-COLIBRI platform: AT 2024afyi

Alerte Nouvel Événement Transitoire Astrophysique : AT 2024afyi

Nous invitons tous les astronomes amateurs à participer aux observations de suivi de ce nouvel événement transitoire passionnant. Pour plus de détails, y compris la visibilité et les coordonnées, veuillez visiter la plateforme Astro-COLIBRI : AT 2024afyi

Cet évènement se situe dans M33. Je l’ai mesuré à G=17+/-0.03mag Gbp=17.26+/-0.04mag et Grp=16.53+/-0.05mag

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Going on it right now

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Photometry using RGB camera and no filter (… I know) : 17.47 +/- 0.16

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[animate output image]

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r’Vg’ image of AT2024afyi (30/12/24)

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Grp+G+Gbp image (30/12/24)

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Grp+G+Gbp image of AT2024afyi (1/1/24)

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Wich magnitude do you measure ? It seems to be decreasing

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Date G (mag) Gbp (mag) Grp (mag)
30/12/24 17 17.2 16.5
01/01/24 18.8 19.4 18
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So, yes it’s decreasing.

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Date JJ Mag GBp
01/01/2025 60677,545 19,3
02/01/2025 60678,541 19,7
03/01/2025 60679,537 19,6

I have made measurements the last 3 nights with GBp, g’, r’, i’ filters. I confirm Marc Serrau’s observation that the target has dropped a lot. It is possible that we having exceeded the maximum. Magnitude 20 is a limit for our instrument in relation to the observation conditions. Bad weather is now also a handicap in San-Pedro-Atacama-Chile for the next few days. We will close the observations.
PS : for the measurements with g’-r’-i’ filters, unfortunatly we did not found official magnitudes of the comparaison stars.
Roger Hellot, AITP

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The latest lightcurve using data from ATLAS and ZTF for AT 2024afyi given here:

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I could now measure my observations with g’-r’-i’ filters. I put them together with some other known mesures from ATLAS, Marc Serrau, Andreo Mantero and K. Yashimoto. Here is the lightcurve:

LightCurve of AT2024afyi-M33
LightCurve of AT2024afyi-M333428×2128 366 KB

It’s now gone for our small telescopes!
Roger

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