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Home > SVOM follow up > GRB 250818B

SVOM_FIELD00031

SVOM

31

/SVOM

GRB 250818B: Swift observation summary

This is a confirmed GRB (GRB 250818B), the afterglow is source 1 -- please see the GRB results at https://www.swift.ac.uk/xrt_products/03000030 for updated analysis

Data analysed so far:

• ObsID: 03000030001 with 0.6 ks exposure.

About tiled field analysis.

So far 1 fields have been scheduled for observations. Data are available and processed for 1 of these.

• 3000030 — 604 s of cleaned data taken between 2025-08-18 03:54:55 and 2025-08-18 04:07:15

Details of afterglow candidates

1 sources were found which matches the afterglow criteria.

#	RA (J2000)	Dec (J2000)	Err901	Detection Flag2	Rank3	Dist from SVOM/ECLAIRs pos	Exposure	Notes	Vizier
1 [details]	03h 04m 13.24s46.05517°	-03° 07′ 30.2″-3.12507°	3.6′′	Good	1 (T)	3.3′	604 s	The source is 4.0-σ above the RASS limit.
Mean XRT rate: 0.71 (±0.05) ct s-1 Peak XRT rate: 1.14 (±0.25) ct s-1 RASS PSPC 3-σ upper limit: 0.14 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.85 (±0.06) ct s-1 Peak XRT rate converted to PSPC: 1.36 (±0.30) ct s-1 Mean XRT flux: 2.87 (±0.21) ×10-11 erg cm-1s-1 Peak XRT flux: 4.6 (±1.0) ×10-11 erg cm-1s-1 Products: Light curve | Spectrum

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the LSXPS documentation.
³ T=Transient Source, O=Outbursting known source, U=Uncatalogued X-ray source, K=Known X-ray source.
^* The position was enhanced using astrometry derived from the Swift UVOT.
^† The position was astrometrically corrected using the XRT sources and the 2MASS catalogue.

Find an upper limit.

Sources found so far

So far 1 sources have been found in the XRT data. 0 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err901	Detection Flag2	Rank3	Dist from SVOM/ECLAIRs pos	Exposure	Notes	Vizier
1 [details]	03h 04m 13.24s46.05517°	-03° 07′ 30.2″-3.12507°	3.6′′	Good	1 (T)	3.3′	604 s	The source is 4.0-σ above the RASS limit.
Mean XRT rate: 0.71 (±0.05) ct s-1 Peak XRT rate: 1.14 (±0.25) ct s-1 RASS PSPC 3-σ upper limit: 0.14 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.85 (±0.06) ct s-1 Peak XRT rate converted to PSPC: 1.36 (±0.30) ct s-1 Mean XRT flux: 2.87 (±0.21) ×10-11 erg cm-1s-1 Peak XRT flux: 4.6 (±1.0) ×10-11 erg cm-1s-1 Products: Light curve | Spectrum

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the LSXPS documentation.
³ T=Transient Source, O=Outbursting known source, U=Uncatalogued X-ray source, K=Known X-ray source.
^* The position was enhanced using astrometry derived from the Swift UVOT.
^† The position was astrometrically corrected using the XRT sources and the 2MASS catalogue.

Image

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FITS image.

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Exposure map

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FITS exposure map.